CN103466893B

CN103466893B - Sewage recycling comprehensive treatment system

Info

Publication number: CN103466893B
Application number: CN201310432078.6A
Authority: CN
Inventors: 金晨光; 李林; 施明清; 王刚; 张敬
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-09-22
Filing date: 2013-09-22
Publication date: 2014-10-08
Anticipated expiration: 2033-09-22
Also published as: CN103466893A

Abstract

The invention discloses a sewage recycling comprehensive treatment system which at least comprises a pre-precipitation filter, a biological renewable ammonium ion exchange device, a medium-low pressure reverse osmosis treatment device with an operation pressure of 1-4MPa, an anaerobic biochemical reaction device, a mixed biochemical reaction device and a post-precipitation filter which are connected in sequence. According to the sewage recycling comprehensive treatment system disclosed by the invention, multiple biochemical technologies are combined by use of an improved membrane system with a high recovery rate, and high-quality softened water is produced while removing pollutants. The problems in treating thick water and ammonia nitrogen are solved, and the pollutants such as organic matters, nitrogen, phosphorus, sulfur, magnesium and the like are recycled.

Description

Sewage recycling comprehensive treatment system

Technical Field

The invention relates to a sewage treatment device, in particular to a sewage recycling comprehensive treatment system.

Background

The sewage contains pollutants represented by organic matters, nitrogen, phosphorus, heavy metals and bacteria, and the pollutants are usually removed through three modes of physics, chemistry and biology, so that the influence of the pollutants discharged into a water environment is reduced.

The currently common conventional reverse osmosis treatment method can only be suitable for the treatment of more than three levels of reclaimed water with low organic matter content, can obtain relatively high recovery rate, the designed membrane flux is usually less than half of the standard flux, and when the high recovery rate is obtained, the monthly cleaning frequency is needed, and the membrane consumption and energy loss are needed to be increased. The treatment of a large amount of concentrated water with poor biodegradability is a problem that the reverse osmosis process is relatively troublesome, and the concentrated water of the conventional reverse osmosis device contains a non-oxidizing bactericide, has low organic matter content and high salt concentration, is difficult to biochemically and is a treatment problem in the industry all the time.

In 1992, Fan Sheng. Tao et al proposed a new method for improving reverse osmosis recovery rate and salt rejection rate in the research of oil field reinjection water treatment, and acquired US5,250,185 patent in 1993, but the deep well injection method adopted for concentrated water treatment by the method still fails to fundamentally solve the problems of concentrated water treatment and secondary pollution.

US6,537,456 is an improvement over US5,250,185 in that it reduces the amount of pH raising agent used and the risk of fouling of the apparatus by removing alkalinity.

Although the methods provided by the two patents have mature engineering applications, no consideration is given to and no treatment method is provided for the problem of high ammonia nitrogen content in purified effluent caused by pH rise. And for the concentrated water of the system, although the discharged water amount is reduced by improving the recovery rate, the treatment method is limited, secondary liquid pollution is generated by deep well injection, and evaporative crystallization only transfers the pollutants from the liquid to solid waste and cannot fundamentally solve the problem.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a sewage recycling comprehensive treatment system to reduce or avoid the aforementioned problems.

Specifically, in order to solve the technical problems, the sewage recycling comprehensive treatment system at least comprises a pre-precipitation filter, a biological regeneration type ammonium ion exchange device, a medium and low pressure reverse osmosis treatment device with the operating pressure of 1-4 MPa, an anaerobic biochemical reaction device, a mixed biochemical reaction device and a post-precipitation filter, wherein a municipal or industrial sewage pipe network is connected with an inlet of the pre-precipitation filter through a pipeline, an outlet of the pre-precipitation filter is connected with an inlet of the biological regeneration type ammonium ion exchange device through a pipeline, an outlet of the biological regeneration type ammonium ion exchange device is connected with an inlet of the medium and low pressure reverse osmosis treatment device through a pipeline, a purified water outlet of the medium and low pressure reverse osmosis treatment device is connected with an industrial water supply pipe network through a pipeline, a concentrated wastewater outlet of the medium and low pressure reverse osmosis treatment device is connected with an inlet of the anaerobic biochemical reaction device through a pipeline, the outlet of the anaerobic biochemical reaction device is connected with the inlet of the mixed biochemical reaction device through a pipeline, the outlet of the mixed biochemical reaction device is connected with the inlet of the post-precipitation filter through a pipeline, and the outlet of the post-precipitation filter is connected with a municipal drainage pipeline.

Preferably, the sewage recycling integrated treatment system further comprises a brine concentrator and an evaporative crystallizer, wherein an outlet of the post-precipitation filter is connected with an inlet of the brine concentrator through a pipeline, a concentrated water outlet of the brine concentrator is connected with an inlet of the evaporative crystallizer, and a desalted water outlet of the brine concentrator and a desalted water outlet of the evaporative crystallizer are respectively connected with an industrial water supply network.

Preferably, the sewage recycling comprehensive treatment system further comprises a biological regeneration device, the biological regeneration type ammonium ion exchange device further comprises a regeneration liquid inlet and a regeneration waste liquid outlet, the regeneration liquid outlet of the biological regeneration device is connected with the regeneration liquid inlet of the biological regeneration type ammonium ion exchange device through a pipeline, and the regeneration waste liquid inlet of the biological regeneration device is connected with the regeneration waste liquid outlet of the biological regeneration type ammonium ion exchange device through a pipeline.

Preferably, the sewage recycling comprehensive treatment system further comprises an organic sludge concentrator, an organic sludge digester and an inorganic sludge dehydrator, the sludge discharge ports of the pre-precipitation filter, the anaerobic biochemical reaction device, the mixed biochemical reaction device and the biological regeneration device are respectively connected with the inlet of the organic sludge concentrator through pipelines, a concentrated sludge outlet of the organic sludge concentrator is connected with a sludge inlet of the organic sludge digester, a sludge discharge port of the organic sludge digester is connected with an inlet of the inorganic sludge dehydrator through a pipeline, the waste water outlet of the organic sludge concentrator is connected with the inlet of the pre-precipitation filter through a pipeline, the sludge discharge port of the post-precipitation filter is connected with the inlet of the inorganic sludge dehydrator through a pipeline, and a wastewater outlet of the inorganic sludge dehydrator is connected with an inlet of the post-precipitation filter through a pipeline.

Preferably, the sewage recycling comprehensive treatment system further comprises a gas washing and desulfurizing device, a regenerated liquid outlet of the biological regeneration device is connected with an absorption liquid inlet of the gas washing and desulfurizing device through a pipeline, a sulfur-containing waste liquid outlet of the gas washing and desulfurizing device is connected with a sulfur-containing waste liquid inlet of the biological regeneration device, and a methane outlet of the organic sludge digester and a methane outlet of the anaerobic biochemical reaction device are respectively connected with a gas inlet of the gas washing and desulfurizing device.

Preferably, the sewage recycling comprehensive treatment system further comprises a pre-softening processor, an anode bed softening device, a chemical regeneration type ammonium ion exchange device, a chemical regeneration device and a crystallization phosphorus remover, wherein a water inlet of the pre-softening processor is connected with an outlet of the biological regeneration type ammonium ion exchange device, a water outlet of the pre-softening processor is connected with a water inlet of the anode bed softening device, a sludge discharge port of the pre-softening processor is connected with an inlet of the inorganic sludge dehydrator, a water outlet of the anode bed softening device is connected with an inlet of the medium-low pressure reverse osmosis treatment device, a regeneration waste liquid outlet of the anode bed softening device is respectively connected with an inlet of the anaerobic biochemical reaction device and a medicine feeding port of the crystallization phosphorus remover, an inlet of the crystallization phosphorus remover is connected with a concentrated water outlet of the brine concentrator, and a water outlet of the crystallization phosphorus remover is connected with a water inlet of the evaporation crystallizer, struvite is discharged from a sludge discharge port of the crystallization phosphorus remover and is used as a slow release fertilizer for agriculture, a purified water outlet of the medium-low pressure reverse osmosis device is connected with an inlet of the chemical regeneration type ammonium ion exchange device through a pipeline, and a purified water outlet of the chemical regeneration type ammonium ion exchange device is connected with a municipal industrial reuse water pipe network through a pipeline. The chemical regeneration type ammonium ion exchange device is characterized in that a regenerated liquid inlet and an outlet of the chemical regeneration type ammonium ion exchange device are respectively connected with a regenerated liquid outlet and an inlet of the chemical regeneration device through pipelines, and an ammonia water outlet of the chemical regeneration device is connected with an inlet of the anaerobic biochemical reaction device through a pipeline.

According to the sewage recycling comprehensive treatment system provided by the invention, a plurality of biochemical processes are combined by utilizing the improved high-recovery membrane device, so that high-quality softened water is produced while pollutants are removed. Not only solves the problem of treating concentrated water and ammonia nitrogen, but also recycles pollutants such as organic matters, nitrogen, phosphorus, sulfur, magnesium and the like, can recycle more than 90 percent of sewage with high quality, further reduces the emission equivalent of the pollutants by more than 90 percent, and saves the occupied area of a system by more than 90 percent compared with the conventional process.

Drawings

The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein,

FIG. 1 is a schematic view of a sewage recycling integrated treatment system according to an embodiment of the present invention;

FIG. 2 shows a modified embodiment based on FIG. 1;

FIG. 3 shows a modified embodiment based on FIG. 2;

FIG. 4 shows a modified embodiment based on FIG. 3;

FIG. 5 shows a modified embodiment based on FIG. 4;

FIG. 6 shows a modified embodiment based on FIG. 5;

FIG. 7 is a graph showing the relationship between the solubility of organic substances and pH;

FIG. 8 is a graphical representation of silicon ion solubility versus pH;

FIG. 9 is a schematic structural view of the anaerobic biochemical reaction apparatus in FIG. 1.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings. In which like parts are designated by like reference numerals and the arrows in the figures are used to indicate the direction of transport of the gas, liquid or solid-liquid mixture in the pipe.

FIG. 1 is a schematic structural diagram of a sewage recycling integrated treatment system according to an embodiment of the present invention; referring to fig. 1, the sewage recycling comprehensive treatment system 1 of the present invention at least comprises a pre-precipitation filter 11, a biological regeneration type ammonium ion exchange device 12, a medium and low pressure reverse osmosis treatment device 13 with an operating pressure of 1-4 mpa, an anaerobic biochemical reaction device 14, a mixed biochemical reaction device 15 and a post-precipitation filter 16, wherein a municipal or industrial sewage pipe network 2 is connected with an inlet 111 of the pre-precipitation filter 11 through a pipeline, an outlet 112 of the pre-precipitation filter 11 is connected with an inlet 121 of the biological regeneration type ammonium ion exchange device 12 through a pipeline, an outlet 122 of the biological regeneration type ammonium ion exchange device 12 is connected with an inlet 131 of the medium and low pressure reverse osmosis treatment device 13 through a pipeline, a purified water outlet 132 of the medium and low pressure reverse osmosis treatment device 13 is connected with an industrial water supply network 3 through a pipeline, and a concentrated wastewater outlet 133 of the medium and low pressure reverse osmosis treatment device 13 is connected with the anaerobic biochemical reaction through a pipeline The inlet 141 of the device 14 is connected, the outlet 142 of the anaerobic biochemical reaction device 14 is connected with the inlet 151 of the mixed biochemical reaction device 15 through a pipeline, the outlet 152 of the mixed biochemical reaction device 15 is connected with the inlet 161 of the post-precipitation filter 16 through a pipeline, the outlet 162 of the post-precipitation filter 16 is connected with the municipal drainage pipeline 4,

the pre-settling filter 11 may comprise a coarse and fine grid, a settling tank, etc. and is mainly used for pre-treating sewage discharged from a municipal or industrial sewer network 2, for example, suspended substances in the sewage may be removed by the pre-settling filter 11. After sewage in the municipal or industrial sewage pipe network 2 enters the pre-precipitation filter 11 through the inlet 111, the sewage can be discharged through a coarse grid and a fine grid and discharged through a vortex sand basin, so that garbage, sand, scum and oil pollutants which may influence subsequent biochemical treatment in the sewage can be removed, and a few of attached small-particle suspended matters of the organic pollutants can be further removed by adding polyaluminium sulfate (PAC) and a polymeric flocculant (PAM) into a sedimentation basin for coagulation, flocculation and sedimentation, and a water outlet index of less than 20 mg/L of suspended matters can be obtained, so that the subsequent treatment of the sewage can be further facilitated.

The bio-regenerative ammonium ion exchange device 12 is used for removing ammonium ions from water by using selective ammonium ion exchange packing, and may include zeolite packing ion exchange columns or pools with selective exchange properties for ammonium ions, wherein the zeolite packing may be of natural and modified types, and the working exchange capacity of the zeolite is generally in the range of 1-7 mg of ammonium nitrogen per gram of zeolite under different water amounts, water quality and hydraulic retention time.

The concentration of the ammonium nitrogen in the effluent at the outlet 122 can be controlled to meet the ammonia nitrogen requirements of the subsequent anaerobic biochemical reaction device 14 and the mixed biochemical reaction device 15.

The zeolite ion exchanger in the biological regeneration type ammonium ion exchange device 12 can adopt a one-use-one-standby mode, and the configuration can ensure that the device continuously works: when the ammonia nitrogen concentration of the ion exchange columns exceeds the standard, the operation mode is switched to the regeneration mode, the standby ion exchange columns are switched to the operation mode, one ion exchange column is in the regeneration mode and the other ion exchange column is in the operation mode at any time.

The biological regeneration type ammonium ion exchange device 12 adopts a biological regeneration mode, compared with chemical regeneration, can obviously reduce salt consumption of zeolite regeneration, and simultaneously avoids the problem of carbonate scaling caused by high pH during chemical regeneration.

The biological regeneration generally utilizes the characteristics of Ammonia Oxidizing Bacteria (AOBs), Nitrobacteria (NOBs) and oxygen to oxidize ammonia into anion nitrite nitrogen and nitrate nitrogen, and an aeration device is arranged inside or outside the zeolite ion exchanger to form a biological environment, so that the ammonia nitrogen in the regenerated waste liquid can be reused after being oxidized, the utilization efficiency of the regenerated liquid is improved, and the salt consumption is saved. It has been found that by introducing compressed air or oxygen into the biologically regenerative ammonium ion exchange device 12 and by using the biofilm of AOBs and NOBs cultured on zeolite, the regeneration needs can be satisfied by only maintaining the sodium ion concentration of 1,150 mg/l, the nitrification rate is the rate-limiting step of regeneration, and the added sodium ions can completely satisfy the ammonium ion exchange needs while adding the alkalinity of sodium carbonate or sodium bicarbonate that satisfies the nitrification.

During biological regeneration, a biological membrane is cultured on zeolite particles or activated sludge is utilized by referring to a CANON process, regeneration is completed in the same exchange column/tank, the biological membrane or activated sludge containing AOBs bacteria and part of ammonia nitrogen exchanged from the zeolite are subjected to biological reaction and oxidized into nitrate nitrogen, and then denitrification is realized by further utilizing anaerobic ammonia oxidizing bacteria (ANAMMOXs) biological membrane or activated sludge, so that the accumulation problem of conventional biological regeneration nitrous acid/nitrate can be solved, and the waste liquid amount is further reduced. The waste liquid containing nitrate nitrogen is discharged and sent to the mixed biochemical reactor 15 through a pipe (not shown) for denitrification.

On the other hand, the salt-containing wastewater discharged from the outlet 162 of the post-sedimentation filter 16 can be used as a regeneration solution, a biofilm or activated sludge enriched with AOBs bacteria is cultured, and the biofilm or activated sludge is used to perform a biological reaction with the exchanged ammonia nitrogen to generate nitrite nitrogen, and a waste solution containing nitrite nitrogen is discharged and sent to the mixed biochemical reactor 15 through a pipeline (not shown in the figure) to perform an amammox denitrification reaction with the ammonia nitrogen in the wastewater discharged from the outlet 142 of the anaerobic biochemical reactor 14.

The high-efficiency reaction temperature of each strain is comprehensively considered, the whole reaction can be controlled at 25-35 ℃, and high-efficiency treatment can be realized. According to most researches, the Dissolved Oxygen (DO) is controlled within the range of 0.5-1.5 mg/L, the advantageous growth of AOB can be realized, the growth and reaction are not facilitated when the Dissolved Oxygen (DO) is too low, the ANAMMOX bacteria need to react in an anaerobic environment, and the inhibition is generated when the Dissolved Oxygen (DO) is too high.

Details of the ammonium ion exchange of zeolites are described in Hedstrom, Environmental Engineering journal, journal of Environmental Engineering, volume 127, volume 8, published by Hedstrom, 8.2001, "review of ammonium zeolite ion exchange"

The research contents of the control factors of the nitrosation reactor are detailed in the article of ' research on the start-up and control factors of the nitrosation reactor ' published in 6 th volume of the book 42 of the university of Harbin ' in Chapter, Zhangi et al, 6.2010. The research on nitrosobacteria (ammonia oxidizing bacteria) is described in detail in "separation and characterization of nitrosobacteria" published in "biotechnology" volume 15, volume 1 of "Zeng national Driving in 2005, 2 months.

The CANON process is detailed in ' new development of CANON process research ' published in water treatment technology ' in 2008 & 2 months in Pengxihong.

Details of the anammox technology are described in zhun, which is equivalent to "anammox industry research progress" published in water treatment technology, volume 32, 8, 2006 and "anammox research progress in wastewater treatment" published in microbiology bulletin, 11, 2010 by Liao soldiers.

The operating pressure of the medium and low pressure reverse osmosis treatment device 13 can be 1-4 MPa, and the substances and water are separated by utilizing the principle that other substances cannot permeate a semipermeable membrane under the action of the osmotic pressure higher than the solution osmotic pressure. The membrane aperture of the reverse osmosis membrane of the medium and low pressure reverse osmosis treatment device 13 can be very small, the aperture is generally 0.1-4 nanometers, molecular substances with molecular weight more than 100 and ions with hydrated ion radius more than the aperture can be generally intercepted, and the removal rate of most of molecular and ionic impurities in water can reach more than 99%. Therefore, dissolved salts, colloids, microorganisms, organic substances, and the like in water can be effectively removed. After the treatment by the middle and low pressure reverse osmosis treatment device 13, most of the wastewater can be treated into reclaimed water which can be directly used for industrial purposes such as cooling and the like, and is discharged into the industrial water supply network 3 through the purified water outlet 132.

Reverse osmosis membranes can fail due to organic contamination, biological contamination, and inorganic salt scaling. The higher organic matter concentration can be separated out and precipitate leads to organic pollution in the reverse osmosis membrane subassembly, hardly washs, should avoid as far as possible, and in addition, high organic dirty concentration still can cause the microorganism to breed rapidly, blocks up reverse osmosis membrane fast, leads to becoming invalid.

FIG. 7 is a graph showing the relationship between the solubility of organic substances and pH; as shown in FIG. 7, the solubility of organic substances has a positive correlation with pH, and increases with increasing pH, and at a pH of 6-8, the solubility measured as Total Organic Carbon (TOC) rapidly increases from 60 mg/L to 300 mg/L, while the pH slowly increases from 8-11 to 350 mg/L. Assuming that all the chemical oxygen demand is oxidized into organic matter, the corresponding ratio of TOC to COD is 2.67, but the consumption of organic carbon to oxygen in the actual sewage generally accounts for 40% -80% of COD, and because reducing inorganic matters such as sulfide consume oxygen, the actual ratio of TOC to COD is larger than the theoretical value, generally ranges from 3 to 6, the problem of organic matter precipitation cannot occur in the range of pH 8-11, COD is 900 mg/L-2, and 100 mg/L.

Currently commercialized reverse osmosis membrane modules include roll type, hollow fiber, plate type, butterfly tube type, and the like. The lowest unit cost is roll-type components which are commonly used, in recent years, roll-type membrane manufacturers improve the anti-pollution performance of the membrane through material improvement and component optimization, but due to inherent shortage in construction, special pretreatment is generally required for treating sewage containing higher-concentration organic matters. The disc tube type reverse osmosis component (DTRO) can be operated under the conditions of the pollution blockage coefficient (SDI) up to 6.5, the Chemical Oxygen Demand (COD) being more than 62,000 mg/L, the Biological Oxygen Demand (BOD) being more than 40,000 mg/L, the suspended matter (SS) being more than 4,000 mg/L and the ammonia nitrogen (NH 3-N) being more than 4,000 mg/L due to the special design. At present, the disc-tube reverse osmosis is successfully applied to the treatment of high-pollution and non-concentration landfill leachate, and the large-scale application is limited due to the higher manufacturing cost at present.

The hardness formed by divalent metal cations such as calcium, magnesium, strontium, barium and the like in inorganic salt can form crystals with anions such as sulfate radical, carbonate radical and the like in water to be precipitated on the surface of the membrane and can be recovered through acid cleaning, and silicon dioxide ions can be combined with water to form substances such as metasilicic acid and the like to precipitate small crystals and can be adsorbed in membrane pores to cause irreversible pollution. Inorganic pollution caused by hardness can be avoided by lowering pH and improving solubility or adding a scale inhibitor, and metal precipitates can be removed in advance by adopting softening pretreatment modes such as chemical precipitation and ion exchange. The solubility of silicon dioxide ions increases with increasing pH, so that crystallization can be reduced by increasing pH, and a special silicon scale inhibitor can be added.

The unit cost of the scale inhibitor is greatly higher than that of a common chemical agent for adjusting the pH value, the use of the scale inhibitor is generally reduced as much as possible, the pH value is increased to reduce the scaling of silicon ions, the scaling tendency caused by the hardness of divalent cations is increased, the silicon scaling is extremely difficult to clean, the irreversible pollution of the reverse osmosis membrane is caused, and the concentration of the silicon ions and the solubility of the corresponding pH value are generally used as the primary limiting conditions for controlling the recovery rate of the reverse osmosis membrane.

FIG. 8 is a graph showing the relationship between the solubility of silicon ions and pH, and as shown in FIG. 8, the concentration of silicon ions is in the range of 6-8, and the solubility is maintained at about 100 mg/L; the pH is in the range of 8-10, and the solubility is gradually increased from 100 mg/L to 300 mg/L; the solubility reached 1,500 mg/l when the pH started to rise rapidly above 10 and reached 11.

In the embodiment, the pH fluctuation is controlled within the range of 6-8, and the high reverse osmosis recovery rate is realized by adding drugs and selecting a corresponding membrane module, so that the high-rate sewage concentration is realized.

When a roll-type membrane component is adopted, due to the characteristics that precipitates are easy to intercept and bacteria are bred, the main limiting condition is the concentration of organic matters entering water, the pH value of the entering water is regulated to the upper limit of 8 by adding acid and alkali, so that the solubility of the organic matters represented by COD on the concentrated water side is improved to 900-1,800 mg/L, and a scale inhibitor is added to assist in preventing inorganic matters from scaling, hypochlorous acid and ozone can be added in front of the biological regeneration type ammonium ion exchange device 12, or sterilization treatment is carried out by irradiating an ultraviolet lamp, in order to prevent the reverse osmosis membrane from being oxidized, a sodium bisulfite reducing agent is added into the entering water, the residual hypochlorous acid and other oxidizing substances can be reduced, and the influence on subsequent anaerobic biochemical reaction microorganisms is eliminated. Eliminates the water inflow of organic pollution, inorganic pollution and biological pollution, and ensures the stable work of the roll type reverse osmosis membrane. The reaction formula is as follows:

NaHSO₃+HClO==NaHSO₄+HCl

NaHSO₃+O₃==NaHSO₄+Cl^-+O₂

when a disc-tube reverse osmosis module is used, the COD of the module can be up to 62,000 mg/l, and the silicon ions and hardness become the main factors limiting the recovery rate, wherein the hardness can be adjusted to a lower pH value by adding acid so that the saturated carbonate index (also called langgerl saturation index, abbreviated as LSI) is less than zero to prevent scaling, and the silicon is added with a special silicon scale inhibitor to prevent the reverse osmosis membrane from being polluted.

The pollution blocking tendency of the reverse osmosis membrane can be greatly reduced by adding drugs and pretreatment, but the reverse osmosis membrane can be slowly polluted along with the increase of the operation time, which is shown in the pressure difference of the inlet water and the outlet water of the reverse osmosis membrane, the pollutant content of the permeated water and the water yield, when the three factors are obviously changed, the reverse osmosis membrane needs to be cleaned, hydrochloric acid or sulfuric acid is generally adopted for cleaning scales formed by inorganic salts, sodium hydroxide is adopted for cleaning deposited pollutants, microorganisms, bacteria and the like, and a special non-oxidizing bactericide is also required to be added for sterilization treatment if necessary, and the Caoshan can successfully remove organic pollutants which are difficult to be cleaned by a chemical method by a biological mode.

The medium and low pressure reverse osmosis treatment device 13 can concentrate salinity to more than 40,000 mg/l under the highest working pressure of 4.1 mpa, but because the tolerance of the anaerobic biochemical reaction device 14 to salinity is limited, the working efficiency of microorganisms is ensured by controlling the concentration salinity of the medium and low pressure reverse osmosis treatment device 13 to be less than 30,000 mg/l. When a common roll type reverse osmosis membrane is adopted, the pH value is controlled to be close to 8 as much as possible, the solubility of organic carbon is about 300 mg/L, if the concentration exceeds the concentration, precipitation is generated, the pollution of the common membrane is caused, and the COD concentration is limited to 900-1,800 mg/L according to the COD/TOC ratio of 3-6. If a disk and tube reverse osmosis membrane module is used, the COD concentration limit can be as high as 62,000 mg/L. A certain concentration of sulfate radicals can promote anaerobic reactions, but too high a concentration can result in the toxic effect of excess hydrogen sulfide on microorganisms, and the concentration of sulfate radicals is generally controlled to be less than 3,000 mg/L.

For example, if the total salt content of the domestic sewage is about 500 mg/l, the COD content is 300 mg/l, and the sulfate content is 100 mg/l, and the reverse osmosis treatment apparatus 13 of the present invention is controlled to operate at a recovery rate of 90%, the total salt content of the wastewater discharged from the concentrate side 142 is 5,000 mg/l, the COD content is 3,000 mg/l, and the sulfate content is 1,000 mg/l, which meet the water inlet requirements of the subsequent anaerobic biochemical reaction apparatus 14.

The reverse osmosis membrane used in the present invention may be any commercially available one, and its structure and principle are well known and will not be described in detail. The technical contents related to the reverse osmosis membrane can be referred to the description in US5,250,185A or US6,537,456B2. The cleaning of reverse osmosis membrane organic pollution is detailed in the research of reverse osmosis membrane organic pollution and microorganism cleaning, which is published in 2008 in 2 months in "water treatment technology" 24 nd volume 2 in Cao Ming.

In order to effectively remove the biochemical oxygen demand of the concentrated wastewater treated by the medium and low pressure reverse osmosis treatment device 13 and remove other pollutants such as ammonia nitrogen and phosphorus, the anaerobic biochemical reaction device 14 and the mixed biochemical reaction device 15 can further utilize microorganisms to degrade organic pollutants, so that the organic pollutants can be metabolized by saprophytic bacteria and converted into organic acids, and then the organic acids can be degraded into methane and carbon dioxide by methane bacteria to remove the biochemical oxygen demand of the concentrated wastewater treated by the medium and low pressure reverse osmosis treatment device 13 and also remove other pollutants such as ammonia nitrogen and phosphorus.

The anaerobic biochemical reaction device 14 can convert chemical oxygen demand into renewable energy methane gas, and the mixed biochemical reaction device 15 can further remove pollutants such as chemical oxygen demand and ammonia nitrogen.

The anaerobic biochemical reaction device 14 can use anaerobes cultured by salt tolerance, the highest reaction efficiency can be achieved when the temperature of anaerobic ammonia oxidation reaction is 30 ℃,1 kilogram of COD can be converted into methane gas of 0.35-0.4m3, and the wastewater treated by the anaerobic biochemical reaction device 14 is conveyed to the mixed biochemical reaction device 15 through a pipeline.

Compared with an aerobic reactor, the volume load of the anaerobic biochemical reaction device 14 is more than ten times, the volume of the corresponding required reactor is reduced by 90%, the average concentration of the biological sludge is ten times to tens of times, the sludge production is 1/6-1/10 of the biological sludge, the sludge treatment cost is greatly reduced, and the methane generated by the anaerobic reaction is also a good biomass energy source.

The concentrated water at the concentrated wastewater outlet 133 of the medium and low pressure reverse osmosis treatment device 13 is sent to the inlet 141 of the anaerobic biochemical reaction device 14 for high-efficiency anaerobic biochemical treatment. The sewage is concentrated by the medium-low pressure reverse osmosis treatment device 13, so that the concentration of organic matters is increased to the water inlet requirement of the anaerobic biochemical reaction device 14, organic pollutants are converted into methane by the cooperative work of anaerobic microorganisms, and the removal efficiency of the organic matters can reach more than 90%. In the anaerobic biochemical reaction, a small amount of nitrogen and phosphorus can participate in the synthesis of cells and be consumed along with the discharge of sludge, but nitrogen and phosphorus pollutants in organic matters are released at the same time, which is generally expressed that the concentration of nitrogen and phosphorus in effluent is increased or approaches to that of influent water by anaerobic treatment. Therefore, the effluent from the anaerobic biochemical reactor 14 is sent from the outlet 142 to the inlet 151 of the mixed biochemical reactor 15 for further treatment.

The concentrated water from the outlet 133 of the medium and low pressure reverse osmosis treatment device 13 can be formed by a single-phase reactor when the sulfate radical concentration is low, and under the condition of low sulfate radical content of the inlet water, the pH fluctuation is small because the competition effect of acid-producing bacteria is reduced, and the hydrolysis acidification and methanation reaction can be simultaneously carried out in a single phase. When the sulfate concentration is high, the generation cycle of the methanogenic bacteria can be as long as 4-6 days, and the generation cycle of the acid-producing bacteria is as short as 10-30 minutes, particularly when the sulfate concentration is high, the pH value is reduced to below 6.5 due to acidification of the reactor, and the methanogenic bacteria is very sensitive to the pH value and suitable for growing in the range of pH 6.8-7.2, so that the acid-producing bacteria and the methanogenic bacteria are separated by adopting two-phase anaerobic, competition of the acid-producing bacteria and the methanogenic bacteria can be avoided, and the methanogenic bacteria can be ensured to grow under stable pH value.

Fig. 9 is a schematic structural diagram of the anaerobic biochemical reaction device in fig. 1, and as shown in fig. 9, in the present invention, after the concentration is performed by the medium-low pressure reverse osmosis treatment device 13, the concentration of sulfate is generally high, so that the anaerobic biochemical reaction device 14 may include an intermediate desulfurization two-phase anaerobic digestion manner of a hydrolysis acidification reaction unit 14A, a hydrogen sulfide removal unit 14B and a methanation reactor 14C, sulfate reacts to generate sulfide under the action of Sulfate Reducing Bacteria (SRB), wherein the increase of the concentration of hydrogen sulfide inhibits SRB and methanogenic bacteria (MPB), and a part of SRB generates a dissimilatory reaction under the condition of insufficient organic matters to compete with MPB for substrate acetic acid. In the case of a relatively low mass of carbon sulfur (COD/SO 4), such as near 0.67, the carbon source will be completely oxidized to carbon dioxide to provide electrons for sulfate reduction. While in the case of a carbon-sulfur mass ratio of more than 1.5, assimilation (incomplete oxidation) of the carbon source occurs mainly, and at this time, SRB mainly degrades the organic matter into acetic acid utilized by MPB, which is expressed as an increase in gas yield. Research on Liu Yan shows that although the gas yield is improved, the methane proportion in the biogas is reduced as long as part of the reaction with SRB only produces acetic acid and does not produce hydrogen, so that methane bacteria lack hydrogen required for synthesizing methane, the carbon dioxide proportion is increased, and the methane proportion is reduced. Raney monarch and other researches show that when the concentration of sulfate radicals is below 3,000 mg/L, the sulfate radicals can promote anaerobic granular sludge to some extent along with the increase of the concentration, the Specific Methanogenic Activity (SMA) is slowly increased along with the increase of the concentration, and at the moment, the SRB microorganisms mainly carry out assimilation reaction, reduce the sulfate and simultaneously generate organic matrix acetic acid which can be utilized by Methanogen (MPB). When the amount exceeds 3,000 mg/L, inhibition is caused by excessive hydrogen sulfide, and the sulfate-reducing bacteria are dissimilated to the methane bacteria to compete for the available substrate. In order to ensure the operation efficiency of the anaerobic biochemical reaction device 14, the concentration of sulfate entering the anaerobic biochemical reaction device 14 should be controlled to be lower than 3,000 mg/L. The hydrogen sulfide gas in the sulfide generated in the anaerobic biochemical reaction device 14 can inhibit biological reaction, so the content of the hydrogen sulfide is reduced as much as possible, the hydrogen sulfide is treated by setting an independent hydrogen sulfide treatment unit 14B, and in 14B, iron sulfide precipitate is removed by a physical and chemical method, including increasing pH to increase ionization of the hydrogen sulfide, or reducing pH to increase free hydrogen sulfide, blowing off, or adding iron salt; the method can also adopt a biological method, and a sustainable biological treatment technology for oxidizing the sulfide into elemental sulfur and recovering the elemental sulfur by using photosynthetic sulfur bacteria, colorless sulfur bacteria, thiobacillus denitrificans and oxygen. Liling et al, by adding an air stripping reactor between two phase UASB reactors, under the condition of reflux ratio of 15:1, the concentration of sulfate radical in inlet water is 1000 mg/L, the volume load of sulfate radical can be treated to 10.5 kg/cubic meter.d, the reduction rate of sulfate is kept to be above 80%, under the condition of pH of inlet water of air stripping reactor being 6.5, the removal rate of hydrogen sulfide can be ensured to be above 90%, and when COD load is 15 kg/cubic meter.d, the removal rate can be above 85%.

The sludge type of the anaerobic biochemical reaction device 14 adopts granular sludge, the acclimated granular sludge is adaptive to salinity of 20 g/L compared with flocculent sludge, the sludge ratio methanogenic activity (SMA) can be improved along with the rise of salinity within 10 g/L, slight inhibition can be generated only when the salinity is more than 20 g/L, an Expanded Granular Sludge Bed (EGSB) is used as a third-generation anaerobic biochemical process, the Expanded Granular Sludge Bed (EGSB) can operate at low temperature and low concentration due to high volume load and becomes a research hotspot in the anaerobic biochemical field from the end of the last century, an Expanded Granular Sludge (EGSB) process is adopted, the Expanded Granular Sludge Bed (EGSB) can operate at low temperature of dozens of degrees centigrade and under the low-concentration environment of COD of hundreds of milligrams per liter, the biological reaction units (A, C) of the anaerobic biochemical reaction device 14 preferably adopt the Expanded Granular Sludge Bed (EGSB) process for treating low suspended matters discharged by the low-pressure medium-low-pressure reverse osmosis treatment device 13, research shows that the EGSB process can reach over 14 deg.c and water inlet volume load over 10 kg COD/cubic meter day, and has COD eliminating rate over 85%. Under extreme environment water temperature (< 10 ℃), the inlet water can be heated, the treatment efficiency is ensured, and the water temperature can be further improved under the condition that the peripheral waste heat is sufficient, so that the reaction efficiency can be improved, and higher removal rate can be obtained. The granular sludge of EGSB needs a certain amount of trace elements, wherein magnesium ions are important elements, which can promote the formation of the granular sludge and the growth of methane bacteria, but if the concentration is too high, the metabolism of cells can be hindered, and researches show that when the waste water contains 5 mg/L magnesium ions, 12 mg/L calcium ions can accelerate the granulation of the sludge, thereby improving the operation effect. The hardness of the original sewage can meet the requirement after high-power concentration.

The anaerobic reaction methane bacteria have a proper pH value of 6.5-7.5 (preferably 6.8-7.2), and when Volatile Fatty Acid (VFA) generated in an acidification stage cannot be effectively synthesized into methane by the methane bacteria, the acidification of the reactor can be caused, and the activity of the methane bacteria can be influenced. Alkalinity is an important parameter in the anaerobic biochemical reaction device 14, and can effectively neutralize hydrogen ions caused by increase of VFA, buffer pH and prevent acidification of the reactor.

Lime, caustic soda, soda ash, baking soda and the like can be used as alkalinity increasing agents, and baking soda (sodium bicarbonate) is the first agent because no side effect is generated. Studies of dunaliella and the like have shown that the cost incurred when sodium bicarbonate was added as alkalinity at 67 mg/l offset the gain from converting 1,000 mg/l COD to methane. Measures should therefore be taken to minimise the need for added alkalinity. Because methanation is a reaction for generating alkalinity, the alkalinity requirement can be reduced by increasing an internal reflux mode, meanwhile, the culture of acid-resistant methanobacteria is also proved to be feasible, the EGSB reactor is operated under the parameters of inflow COD of 2,000 mg/L, alkalinity of 250 mg/L, pH of 6.2, volume load of 7 kg/cubic meter/day and the like, the removal rate of 96% of COD is obtained, and the alkalinity of the outflow water is stabilized at 500-600 mg/L. Studies have also found that higher removal rates and methane yields can be obtained under low alkalinity conditions than under high alkalinity conditions. Therefore, by using the EGSB process, proper reflux and acid-fast bacteria culture, the alkalinity requirement of the anaerobic biochemical reactor 14 can be reduced to below 300 mg/L. As long as the alkalinity of the inlet water of the medium-low pressure reverse osmosis treatment device 13 is higher than 30 mg/L, the alkalinity of the inlet water is higher than 300 mg/L on the concentrated water side.

The techniques related to the anaerobic biochemical reaction device 14 can be found in the following literature:

the details of the related technology of the two-phase anaerobic digestion process are disclosed in 'research progress of the two-phase anaerobic digestion process and application thereof' published in the first stage of 'energy environmental protection' volume 20 by 2006, Guangsheng et al; the technical contents of the EGSB granular sludge expanded bed and the operation thereof at low temperature and high salt are described in the biological characteristics and research progress of the EGSB reactor published in Industrial safety and environmental protection 2006 by Du Runpong, the research on the high-concentration organic wastewater treated by the EGSB at the environmental temperature published in the No. 22 volume 19 of China Water supply and drainage Vol.2006 by Zhonghai Tao and the description of the influence of the salt contents of NaCL and KCL on the acclimation of anaerobic sludge and the comparative methanogenic activity published in China Marsh 27 (3) in 2009 by Xiaoling and the like by Du Runpong; the specific technical content about the control of the sulfate concentration is detailed in Ruan Jun et al, China biogas 2008, 26 (1) published as SO₄ ^2-The influence on the activity of anaerobic granular sludge and the influence of sulfate radicals on the anaerobic biological treatment of organic wastewater, which are published by Liuyan in 1992 in environmental science 13, volume 5; the details of the treatment technology of hydrogen sulfide are described in "control of hydrogen sulfide in anaerobic digestion" published in "pollution prevention and control technology" volume 16, volume 4, of dauber, et al, 12 months 2003, and "two-phase UASB reactor treating high-concentration sulfate wastewater" published in "environmental science and technology" volume 24, volume 2, of lieling, et al, 2 months 2011. For partial contents of biological desulfurization of biogas, see the research on biological desulfurization technology of biogas published in the 5 th phase of applied energy technology by wang steel equal to 2008; regarding the alkalinity requirement, please refer to the Dong Chun Juan in 2003-4 monthsThe patent of "effective way to reduce alkalinity required for anaerobic treatment of wastewater" published in volume 4 of the technical and equipment, and the patent of "operation of methanogenic EGSB reactor under acidic condition of pH 6.0" published in volume 25 of the environmental sciences "in 1 st of 2004 at the snow peak, which is equal to 2004.

The effluent from the outlet 142 of the anaerobic biochemical reaction device 14 belongs to sewage with low carbon-nitrogen ratio, and enters the mixed biochemical reaction device 15 through the inlet 151 for nitrogen and phosphorus removal treatment.

The residual ammonia nitrogen, organic matters and phosphorus can be removed in the mixed biochemical reaction device 15 by creating an aerobic and anaerobic alternate environment, and the ammonia nitrogen is oxidized into nitrite state and nitrate nitrogen in an aerobic state; under the anaerobic state, nitrite nitrogen and residual organic matters can be decomposed under the action of denitrifying bacteria to generate nitrogen and carbon dioxide to be removed, and the nitrite nitrogen and ammonia nitrogen are subjected to autotrophic denitrification (anaerobic ammonia oxidation) reaction and are simultaneously removed; under the action of the denitrifying bacteria, nitrate nitrogen and sulfide also undergo synchronous denitrifying and desulfurizing reaction. Through the sludge backflow, phosphorus removal bacteria in the sludge are in an alternate aerobic and anaerobic environment to generate aerobic phosphorus absorption and anaerobic phosphorus release metabolism, and biological phosphorus removal can be realized through sludge discharge in an aerobic section.

The low-carbon-nitrogen-ratio wastewater treatment mainly controls the nitrification-denitrification reaction to be carried out in a short distance, and the influence of factors such as temperature, sludge age, operating conditions, dissolved oxygen, pH, substrate concentration, inhibitors and the like on the reaction is researched by the nobody and the like, and the effective method for successfully realizing the short-distance nitrification-denitrification is found by controlling the Dissolved Oxygen (DO) to be lower than 1.5 mg/L.

The mixed biochemical reaction device 15 can adopt a biofilm method, an activated sludge method or a method combining the biofilm method and the activated sludge method, the current biofilm method is typically a Biofilter (BAF) process, the combination of the biofilm method and the activated sludge is typically a moving bed membrane bioreactor (MBBR) process, the activated sludge process for realizing the short-cut nitrification and denitrification is typically a Bio-Dopp process developed by Engelbart in Germany in 1988, the concentration gradient is reduced through a high reflux ratio, and a specially designed aeration device successfully realizes the short-cut nitrification and denitrification, the biological phosphorus removal and the precipitation, and the engineering operation is realized for many years.

The related art of the mixed biochemical reaction device 15 can be found in the following literature:

for the contents of the short-cut nitrification and denitrification process, reference is made to a paper of short-cut nitrification and denitrification biological denitrification technology published by Guiller et al in the journal of Harbin university of Industrial science, volume 10, volume 40 in 2008. The Bio-dopp process is described in Zhongchang et al, 2008, 10.20, volume 10, in environmental sciences and management, for municipal wastewater treatment by the Bio-doubling (Bio-dopp) process. Specific contents related to synchronous denitrification and desulfurization are shown in Heli, which is equal to 'research progress of synchronous denitrification and desulfurization technology' published in No. 1 of renewable energy resources '29 at 24 months of 2011,' research progress of novel biological denitrification and desulfurization process 'published in No. 6 of scientific notice' 27 of 11 months of Zaijing and Zheng, and 'research on separation identification and denitrification characteristics of thiobacillus denitrificans' published in No. 29 of environmental science 10 of 2008 of Xuan et al.

The sewage treated by the mixed biochemical reaction device 15 flows into the post-precipitation filter 16 from the outlet 152 through the inlet 161, chemical precipitation is carried out in the post-precipitation filter, lime is added to increase the pH value to be more than 10, synchronous hardness and phosphorus removal can be realized, and the effluent can be filtered to reduce suspended matters in the water. The effluent water after being subjected to precipitation, filtration, hardness removal, phosphorus removal and suspended matters can be connected with the municipal drainage pipeline 4 through an outlet 162 and discharged after reaching the standard.

The engineering for realizing synchronous hardness and phosphorus removal is typically France Wiriaya water engineering and ACTISOFT device developed in 2008, and calcium carbonate crystal sand generated by precipitation is used for refluxing and accelerating precipitation, so that the consumption of flocculant is greatly reduced.

The chemical reactions of hardness and phosphorus removal are as follows:

5Ca²⁺+4OH^-+3HPO₄ ^2-==Ca₅（OH）(PO₄)₃↓+3H₂O

Ca²⁺+HCO₃ ^-+OH-==CaCO₃↓+H₂O

as for the chemical phosphorus removal, reference can be made to the article "the current situation and progress of chemical phosphorus removal in boiling water" published in "industrial water treatment" volume 5 of Xufeng fruit equal to 5 months 2003.

Fig. 2 shows a modified embodiment based on fig. 1, and as shown in fig. 2, in the integrated sewage recycling system 1 shown in fig. 2 based on the embodiment shown in fig. 1, the integrated sewage recycling system 1 further comprises a brine concentrator 17 and an evaporative crystallizer 18, the outlet 162 of the post-precipitation filter 16 is connected with the inlet 171 of the brine concentrator 17 through a pipeline, the concentrated water outlet 172 of the brine concentrator 17 is connected with the inlet 181 of the evaporative crystallizer 18, and the desalted water outlet 173 of the brine concentrator 17 and the desalted water outlet 182 of the evaporative crystallizer 18 are respectively connected with the industrial water supply network 3.

When the resource utilization rate of the sewage needs to be further improved, the sewage discharged by the post-precipitation filter 16 can be conveyed to the brine concentrator 17 for concentration treatment instead of being discharged to the municipal drainage pipeline 4, and the brine concentrator 17 can be a high-pressure reverse osmosis membrane or an evaporator, so that the brine can be concentrated to more than 80,000 mg/L for subsequent evaporation and crystallization treatment. The treated desalted water can be delivered to an industrial water supply network 3, the concentrated water is further delivered to the evaporative crystallizer 18, the concentrated water can be forcibly circulated in the evaporative crystallizer 18 at a flow rate of 1-3 m/s, the concentrated water is evaporated and crystallized in the circulation process, so that inorganic salt sludge solid which can be comprehensively utilized as chemical raw materials is obtained, and the desalted water collected after evaporation can be delivered to the industrial water supply network 3.

Fig. 3 shows a modified embodiment based on fig. 2, as shown in fig. 3, based on the embodiment shown in fig. 2, the sewage recycling integrated treatment system 1 shown in fig. 3 further comprises a biological regeneration device 19, the biological regeneration type ammonium ion exchange device 12 further comprises a regeneration liquid inlet 123 and a regeneration waste liquid outlet 124, the regeneration liquid outlet 191 of the biological regeneration device 19 is connected with the regeneration liquid inlet 123 of the biological regeneration type ammonium ion exchange device 12 through a pipeline, and the regeneration waste liquid inlet 192 of the biological regeneration device 19 is connected with the regeneration waste liquid outlet 124 of the biological regeneration type ammonium ion exchange device 12 through a pipeline.

By providing the biological regeneration apparatus 19, biological denitrification is separated from ammonium ion exchange, and effluent water by biological denitrification is recycled back to the biological regeneration type ammonium ion exchange apparatus 12 for regeneration.

The biological regeneration device 19 can realize synchronous denitrification and desulfurization by utilizing the characteristics of nitrosobacteria, anaerobic ammonium oxidation bacteria and thiobacillus denitrificans, and reduce the discharge of waste liquid to the maximum extent.

The biological regeneration device 19 can comprise a nitrosation reactor, an anaerobic ammonia oxidation reactor and a sulfur and nitrogen removal reactor, during the biological regeneration process, sodium ions in the regeneration liquid exchange with ammonium ions on zeolite, the eluted regeneration liquid containing ammonium ions enters the biological regeneration device 19 to be completely converted into nitrogen for removal, and the regeneration liquid can be recycled at the same time.

The regeneration waste liquid containing high-concentration ammonia nitrogen firstly enters a nitrosation reactor from a regeneration waste liquid inlet 192 to carry out nitrosation reaction, Ammonia Oxidizing Bacteria (AOB) are mainly cultured in the nitrosation reactor to convert the ammonia nitrogen into nitrite nitrogen, and the conversion rate of the ammonia nitrogen is controlled to be 50% -60%, so that the condition of entering a subsequent reactor is met. In the invention, the concentration of dissolved oxygen in the nitrosation reactor can be kept between 0.2 and 1.5 mg/L, and the pH value is kept at about 8, so that the nitrosation reaction can be ensured. The nitrosation reaction formula that mainly occurs in the nitrosation reactor is as follows:

2NH₄ ⁺+3O₂→2NO₂ ^-+2H₂O+4H⁺

the ammonia nitrogen and nitrite nitrogen mixed solution after the nitrosation reaction is controlled in the proportion of 1: 1-1.5, entering an anaerobic ammonia oxidation reactor to perform autotrophic denitrification reaction under the action of anaerobic ammonia oxidation bacteria (ANAMMOX), and directly adding sodium bicarbonate to maintain the pH value of the anaerobic ammonia oxidation reactor. The formula of the anaerobic ammonia oxidation reaction containing microbial metabolism is as follows:

1NH₄ ⁺+1.32NO₂ ^-+0.066HCO₃ ^-+0.13H⁺→1.02N₂+0.26NO₃ ^-+0.066CH₂O_0.5N_0.15+2.03H₂O

the sulfur and nitrogen removal reactor unit carries out synchronous nitrogen and sulfur removal treatment on the effluent of the anaerobic ammonia oxidation device, thereby realizing cyclic utilization of the scrubbing desulfurization absorption liquid and simultaneously eliminating accumulation of nitrate radicals. The denitrification and desulfurization reaction formula considering the microbial metabolism is as follows:

14.5HS^-+5NO₃ ^-+0.2NH₄ ⁺+HCO3^-+20.3H⁺=CH_1.8O_0.5N_0.2+2.5N₂+14.5S⁰+27.4H₂O

by integrating the three formulas of nitrosation, denitrification, desulfurization and anaerobic ammonia oxidation, the biochemical reaction comprehensive formula of the biomass regeneration device 19 can be obtained:

1.004NH₃+0.32HS^-+0.05HCO₃ ^-+0.375H⁺→0.55N₂+0.32S⁰+0.028CH₂O_0.5N_0.15+0.022CH_1.8O_0.5N_0.2+1.48H₂O

according to the biochemical reaction comprehensive formula of the biological regeneration device 19, each mole of ammonia nitrogen needs 0.32 mole of hydrogen sulfide to participate in the reaction, the mass ratio of sulfate radicals to ammonia nitrogen is 2.2, the ammonia nitrogen content of the general domestic sewage is about 30 mg/L, the sulfate radicals are about 100 mg/L, and the calculation can be satisfied as long as the conversion rate of the sulfate radicals to generate hydrogen sulfide reaches 60%.

The biological regeneration device 19 comprises three microbial community reactions, namely denitrogenation thiobacillus communities (TDs), ammonia oxidation communities (AOBs) and anaerobic ammonia oxidation communities (ANAMMOXs), the suitable reaction temperature is respectively 28-30, 29-35 and 32-37 ℃, and the lowest stable reaction temperature is respectively 10, 15 and 20 ℃. Comprehensively considering, controlling the reaction temperature of the whole biological regeneration device to be 25-30 ℃.

For the nitrosation reaction, the research of Jinrencun and the like finds that the biological regeneration device 19 can adapt to the salinity of 25 g/L by gradually increasing the salinity, while the research of the national drive and the like finds that the ammonia oxidizing bacteria have higher salt resistance and can reach the ammonia nitrogen removal rate of 90 percent under the salinity of 50 g/L; for anammox reaction, liu cheng utilizes UASB reactor research to find that anammox reactor can be adapted to salinity as high as 30 g/l by gradually increasing salinity. For simultaneous denitrogenation and desulfurization reactions, the thiobacillus denitrogenation is adapted to a sulfate upper limit of 250 millimoles, amounting to a salinity of about 30 g/l. The invention therefore controls the salinity of biorenewable device 19 to be less than 30 grams per liter.

The volume of the required biological regeneration reactor can be greatly reduced by improving the volume load, the ammonia nitrogen volume load of the reactor is expected to be improved to 3-6 kg/cubic meter per day by carrying out nitrosation reaction and culturing Aerobic Granular Sludge (AGS), the total nitrogen volume load of the anaerobic ammonia oxidation granular sludge can be as high as 50-70 kg/cubic meter per day at most, in the conventional biological treatment process, the upper limit of an activated sludge method is generally 0.1 kg ammonia nitrogen/cubic meter per day, the maximum ammonia nitrogen/cubic meter per day of a biological membrane method is 1 kg ammonia nitrogen/cubic meter per day, and the granular sludge treatment is several times to dozens of times of that of the conventional activated sludge and biological membrane methods. The research of Liuhuan good and the like finds that under the condition that the salinity of a UASB reactor is lower than 30,000 mg/L, the biological activity of anaerobic ammonia oxidation is increased along with the increase of the salinity, the salinity of nitrosation and anaerobic ammonia oxidation reaction which normally proceeds is controlled to be below 30,000 mg/L, and in the process of biological regeneration, the concentration of ammonia nitrogen is gradually reduced along with the exchange time, so that natural lean and rich concentration alternation is created, and the culture of the granular sludge is very facilitated.

The related art of the biological regeneration device 19 can be found in the following documents:

The study on the influence of bicarbonate ions on the anammox reaction is detailed in Li Xiang et al, published in 2 months 2012 in environmental science journal, volume 32, second period of "HCO₃ ^-Effect of concentration on denitrification efficacy of anammox reactor ". The impact of pH on the anammox reactor is disclosed in "the influence of low pH on the performance of the high-load anammox reactor" published in 2010, 4-month 4, volume 24, 2, by chenjianwei et al. The substrate inhibition problem related to anammox is disclosed in the article of 'substrate inhibition of anammox process and recovery strategy thereof' published in the 18 th volume of the journal of application and engineering science, which is filed in 8 months in 2010 by Tang Chong and frugal.

Specific contents related to synchronous denitrification and desulfurization are shown in Heli, which is equal to 'research progress of synchronous denitrification and desulfurization technology' published in No. 1 of renewable energy resources '29 at 24 months of 2011,' research progress of novel biological denitrification and desulfurization process 'published in No. 6 of scientific notice' 27 of 11 months of Zaijing and Zheng, and 'research on separation identification and denitrification characteristics of thiobacillus denitrificans' published in No. 29 of environmental science 10 of 2008 of Xuan et al.

The information on the overall temperature control of various microbial reactions is detailed in the research progress of 'synchronous denitrification and desulfurization technology' published in No. 1 of renewable energy source 29, 24 th of 2011, Leli; wangxiao equals to 'high-concentration ammonia nitrogen wastewater short-cut nitrification research' published in the 2 nd phase of Shanghai environmental science in 2006; "research on start-up and control factors of nitrosation reactor", published by Zhangi et al, 6.2010, Haerbin university of Industrial science, Vol.42, No. 6 "; li is an article on the influence of temperature on the denitrification efficiency stability of an anaerobic ammoxidation reactor published in environmental science, volume 33, No. 4 of 4.2012.

The influence of salinity on nitrosation is detailed in the article of 'influence of sodium acetate and inorganic salt on the running performance of a partial nitrosation reactor' published in environmental science bulletin 3.2010 in Jinren village and 'separation and characteristic research of nitrosation bacteria' published in Biotechnology 15 volume 1 in 2005 in 2.2005 in Zhongguoshan et al. The influence of salinity on the anammox reaction is detailed in an article of 'research on the influence of salinity on the denitrification efficiency of anammox organisms' published in environmental science bulletin 2011, 9 months. The influence of the salinity of denitrogenation and desulfurization is disclosed in the article "ecological characteristics of denitrogenation thiobacillus and its application" published in the second phase of chemical and biological engineering 2005.

For the detailed content of the EGSB granular sludge, reference is made to the article of 'operation of a high-load anaerobic ammonia oxidation EGSB reactor and ECP characteristics of the granular sludge' published by Tang Chong, frugal and the like at 3 rd volume 61 of the chemical academy in 2010, 3 months.

Fig. 4 shows a modified embodiment based on fig. 3, and as shown in fig. 4, based on the embodiment shown in fig. 3, the integrated sewage recycling treatment system 1 shown in fig. 4 further includes an organic sludge concentrator 20, an organic sludge digester 21 and an inorganic sludge dewatering machine 22, the sludge discharge ports 113, 143, 153, 194 of the pre-precipitation filter 11, the anaerobic biochemical reaction device 14, the hybrid biochemical reaction device 15 and the biological regeneration device 19 are respectively connected with the inlet 201 of the organic sludge concentrator 20 through pipes, the concentrated sludge outlet 202 of the organic sludge concentrator 20 is connected with the sludge inlet 211 of the organic sludge digester 21, the sludge discharge port 212 of the organic sludge digester 21 is connected with the inlet 221 of the inorganic sludge dewatering machine 22 through a pipe, the wastewater outlet 203 of the organic sludge concentrator 20 is connected with the inlet 111 of the pre-precipitation filter 11 through a pipe, the sludge discharge port 163 of the post-precipitation filter 16 is connected to the inlet 221 of the inorganic sludge dewatering machine 22 through a pipe, and the wastewater outlet 222 of the inorganic sludge dewatering machine 22 is connected to the inlet 161 of the post-precipitation filter 16 through a pipe.

The organic sludge concentrator 20 may include a gravity concentration tank, a centrifuge or a filter press. The sludge treatment device is mainly used for concentrating sludge, and the sludge is concentrated to more than 3% and then sent to the organic sludge digester 21.

The organic sludge digester 21 is used for anaerobic digestion treatment of sludge, anaerobic digestion (fermentation) of sludge mainly utilizes acidogenic bacteria and methanogenic bacteria to decompose organic matters, so that sludge reduction and harmlessness are achieved, and because methanogenic engineering bacteria are sensitive to temperature, two operation modes of medium temperature and high temperature are generally adopted, according to the best activity research of methanogenic bacteria, the medium temperature digestion temperature range is controlled to be about 35 ℃, and the high temperature digestion requires that the temperature is controlled to be about 55 ℃, so most of sludge needs to be heated before entering a digestion system, and the digestion device is insulated. International research for many years shows that methane flora can grow in the temperature range of 0-100 ℃, so that corresponding flora can be cultured according to the environmental temperature and the reaction requirement, and the energy consumption and the investment are reduced. In the operation mode, the anaerobic fermentation can be performed by sections, and pretreatment is performed by high-temperature pyrohydrolysis, acid-base, ultrasonic waves and the like, so that the sludge gas production rate is improved.

The content of anaerobic digestion of sludge can be referred to the article "research progress of anaerobic fermentation treatment of urban sewage and excess sludge in China" published by "Xiaomei equals to" Chinese biogas "26 (1) in 2008. For the relevant information on methanobacteria, reference may be made to the article "progress in the study of methanobacteria" published in "brewing science" 5 of 2009, which is the leimei group.

The sludge discharged from the organic sludge digester 21 and the sludge discharged from the post-precipitation filter 16 are respectively sent to the inorganic sludge dehydrator 22 for dehydration treatment, and the dehydrated sludge is discharged after dehydration treatment, generally has a solid content of more than 20%, can be used as a synthetic fertilizer, and can also be used for comprehensive utilization such as soil improvement and brick making.

Fig. 5 shows a modified embodiment based on fig. 4, and as shown in fig. 5, based on the embodiment shown in fig. 4, the sewage recycling integrated processing system 1 shown in fig. 5 further includes a scrubbing desulfurization device 23, the regeneration liquid outlet 191 of the biological regeneration device 19 is connected to the absorption liquid inlet 231 of the scrubbing desulfurization device 23 through a pipeline, the sulfur-containing waste liquid outlet 232 of the scrubbing desulfurization device 23 is connected to the sulfur-containing waste liquid inlet 193 of the biological regeneration device, and the biogas outlet of the organic sludge digester 21 and the biogas outlet of the anaerobic biochemical reaction device 14 are respectively connected to the gas inlet 233 of the scrubbing desulfurization device 23.

In the invention, preferably, gas stripping is used as a sulfur removal process of the hydrogen sulfide removal functional unit 14B in the anaerobic biochemical reaction device 14, the exhaust gas in 14B is mixed with the gas generated by the acidification unit 14A and the methanation unit 14C and is sent to a gas washing desulfurization unit 23, the alkaline water at the regeneration liquid outlet 191 of the biological regeneration device 19 is sent to an absorption liquid inlet 231 of the gas washing desulfurization unit 23 for absorbing hydrogen sulfide, the desulfurized gas mainly contains a methane and carbon dioxide mixed gas part which is returned to 14B for supplementing gas stripping gas inlet gas, the rest part can be sent to devices such as a gas power generation device, a gas boiler and the like for use as fuel gas, and the wastewater generated by the gas washing desulfurization device 23 can also be discharged and sent to the biological regeneration device 19 for recycling after being treated with desulfurized nitrogen.

Biogas from the anaerobic biochemical reaction device 14 and the organic sludge digester 21 is sent to the scrubbing desulfurization device 23 for scrubbing desulfurization treatment, the regenerated liquid outlet 191 of the biological regeneration device 19 is connected with the absorption liquid inlet 231 of the scrubbing desulfurization device 23 through a pipeline, and the sulfur-containing waste liquid outlet 232 of the scrubbing desulfurization device 23 is connected with the sulfur-containing waste liquid inlet 193 of the biological regeneration device, so that the hydrogen sulfide absorption liquid can be recycled. The absorption liquid for gas washing and desulfurization can improve the elution efficiency of the hydrogen sulfide by selecting a mode of improving pH and increasing circulation flow. The biogas desulfurized by the scrubbing and desulfurizing device 23 can be sent to a municipal natural gas pipe network, and can also be sent to devices for heat supply, power supply and the like for comprehensive utilization.

The gas washing and desulfurizing device 23 comprises a gas washing tower, hydrogen sulfide is generally introduced from the bottom of the gas washing tower, absorption liquid is sprayed from the top, packing can be filled in the tower to increase gas-liquid contact, biogas containing 1000 mg/L of hydrogen sulfide can be removed by more than 90%, two sections of gas washing towers which are connected in series can be adopted in engineering to treat biogas containing 2000 mg/L of hydrogen sulfide and 40 cubic meters/hour, and the removal rate can reach 99%.

Since a small portion (about 3.5%) of elemental sulfur in the denitrogenation and desulfurization unit reacts further to form sulfuric acid consuming alkalinity, it is usually necessary to add alkali to maintain the pH of the system, while periodically draining certain solutions to prevent salinity build-up due to sulfate.

In a special sewage system, the proportion of sulfate radicals to ammonia nitrogen is greatly unbalanced, when the mass of the sulfate radicals is higher, on one hand, excessive hydrogen sulfide is generated, the alkalinity consumption is increased, and the hydrogen sulfur radicals of the biological regeneration device 19 are accumulated, so that the situation is avoided, part of the effluent of the scrubbing desulfurization device 23 can flow back to the inlet of the nitrosation reactor of the biological regeneration device 19, desulfurization bacteria are cultured in the nitrosation reactor, and the aeration quantity in the nitritation reactor of the biological regeneration device 19 is increased, so that the excessive nitrite nitrogen and oxygen react with the excessive hydrogen sulfur radicals to generate elemental sulfur for recovery. The formula is as follows:

2HS^-+O₂=2S⁰+2OH^-

2HS^-+NO₂ ^-=2S⁰+0.5N₂+2OH^-

it is seen from the above formula that the excess hydrogen sulfide radicals also produce the same amount of alkalinity as elemental sulfur, just balancing the alkalinity consumption for neutralizing hydrogen sulfide.

Under the conditions of low raw water sulfate radical concentration and low molar sulfur and nitrogen, elemental sulfur can be further oxidized into sulfate radical by thiobacillus denitrificans as an electron donor to complete denitrification, and the alkalinity can be consumed at the moment. The formula is as follows:

5S⁰+6NO₃ ^-+8H₂0=5SO₄ ^2-+4H⁺+3N₂+6H₂O

according to the above formula, the excess nitrate nitrogen can also be removed by the simultaneous denitrification and desulfurization reaction by adding sulfur and alkalinity.

According to the comprehensive formula of biochemical reaction of the biological regeneration device 19, it is found that each mole of inlet ammonia nitrogen (ammonium ion) entering the biological regeneration device 19 consumes 0.375 mole of hydrogen ions and generates 0.375 mole of alkalinity, wherein 0.32 mole of hydrogen sulfide ions participating in the reaction is obtained by absorbing and ionizing hydrogen sulfide by alkali liquor, and the formula is as follows:

H₂S+OH^-→HS^-+H₂O

H₂S+HCO₃ ^-→HS^-+H₂O+CO₂

thus, the consumed 0.32 mol of alkalinity can be supplemented by 0.375 mol of total alkalinity generated by the device, and the rest of alkalinity can also be subjected to neutralization reaction with the ammonium ions exchanged in the biological regeneration type ammonium ion exchange device 12:

NH4⁺+OH^-=NH₃+H₂O

NH4⁺+HCO₃ ^-=NH₃+H₂O+CO₂

therefore, the invention can complete denitrification and desulfurization without adding extra alkalinity by combining three biochemical processes of nitrosation, anaerobic ammonia oxidation and synchronous denitrification and desulfurization.

Every 1 mol of ammonia nitrogen exchanged from the biological regeneration type ammonium ion exchange device 12 can be consumed by 1 mol of sodium ions, the sodium ions of the sodium hydroxide are mainly used for supplementing consumption by supplementing caustic soda and a small amount of soda and lime at the inlet of the biological regeneration type ammonium ion exchange device 12 and the inlet of the scrubbing desulfurization device 23, the pH value can be properly increased by increasing the hydroxide ions, the absorption of hydrogen sulfide gas and the removal of ammonia nitrogen are facilitated, and only water can be generated by combining with the hydrogen ions, the problem of ion accumulation causing the salinity to be increased is avoided, so that the waste liquid discharge amount of the device is greatly reduced.

Fig. 6 shows a modified embodiment based on fig. 5, and as shown in fig. 6, based on the embodiment shown in fig. 5, the sewage recycling integrated processing system 1 shown in fig. 6 further includes a pre-softening processor 24, an anode bed softening device 25, a chemical regeneration type ammonium ion exchange device 26, a chemical regeneration device 27, and a crystal phosphorus remover 28, an inlet 241 of the pre-softening processor 24 is connected to an outlet 122 of the biological regeneration type ammonium ion exchange device 12, an outlet 242 of the pre-softening processor 24 is connected to an inlet 251 of the anode bed softening device 25, a sludge discharge 243 of the pre-softening processor 24 is connected to an inlet 221 of the inorganic sludge dewatering machine 22, an outlet 252 of the anode bed softening device 25 is connected to an inlet 131 of the medium and low pressure reverse osmosis treatment device 13, a regeneration waste liquid outlet 253 of the anode bed softening device 25 is connected to an inlet 141 of the biochemical reaction device 14 and a medicine feeding port 281 of the crystal phosphorus remover 28, the inlet 282 of the crystal phosphorus remover 28 is connected with the concentrated water outlet 172 of the brine concentrator 17, the water outlet 283 of the crystal phosphorus remover 28 is connected with the water inlet 181 of the evaporative crystallizer 18, struvite is discharged from a sludge discharge port (not shown) of the crystal phosphorus remover 28 to serve as slow release fertilizer for agriculture, the purified water outlet 132 of the medium-low pressure reverse osmosis treatment device 13 is connected with the inlet 261 of the chemical regeneration type ammonium ion exchange device 26 through a pipeline, and the purified water outlet 262 of the chemical regeneration type ammonium ion exchange device 26 is connected with the industrial water supply network 3 through a pipeline. The inlet 263 and the outlet 264 of the regeneration liquid and the waste liquid of the chemical regeneration type ammonium ion exchange device 26 are respectively connected with the outlet 272 and the inlet 273 of the regeneration liquid and the waste liquid of the chemical regeneration device 27 through pipelines. The ammonia water outlet 271 of the chemical regeneration device 27 is connected with the inlet 141 of the anaerobic biochemical reaction device 14 through a pipeline.

The pre-softening processor 24 may include a coagulation sedimentation tank, a filter and other functional units, and may add alkali to the coagulation sedimentation tank to adjust the pH value to 10-11, so as to remove most of the calcium hardness, magnesium hardness and carbonate alkalinity by sedimentation. The effluent is sent from the outlet 242 to the cation bed softening device 25 for further hardness removal, and the sludge is discharged from the sludge discharge port 243 to the inorganic sludge dewatering machine 22 for further treatment.

Lime, soda ash and flocculating agent coagulant aid can be added in sequence in a coagulating sedimentation tank to ensure that suspended matters, hardness and carbonate alkalinity in sewage form calcium carbonate and floc, and the calcium carbonate and the floc are precipitated and removed in a sedimentation tank provided with an inclined tube or an inclined plate. Under the condition that the inlet water hardness is less than 1,000 mg/L, the outlet water hardness of the sedimentation tank can be controlled below 50 mg/L, suspended matters are controlled to be less than 3 mg/L, and the hardness can be controlled to be less than 10 mg/L and suspended matters are controlled to be less than 1 mg/L by further combining ultrafiltration membrane filtration.

The contents of lime softening and lime soda softening can be found in the handbook of water supply and drainage 4, volume of industrial water supply.

The cation bed softening device 25 can comprise a strong acid or weak acid cation exchange resin tank and a resin regeneration functional unit, and can exchange and remove cations such as calcium and magnesium in the water through the selective exchange property of the ion exchange resin, so that the concentration of calcium and magnesium ions in the effluent can be reduced to less than 1 mg/L.

The strong acid cation exchange resin generally needs 3% -8% of strong brine for regeneration, while the weak acid cation exchange resin needs to be regenerated by hydrochloric acid or sulfuric acid, so the cation bed softening device 25 is provided with a regeneration liquid inlet (not shown in the figure) for adding regeneration liquid, the regeneration and acid cleaning functions are also realized, precipitates attached to the resin can be cleaned, then the hydrogen type weak acid cation exchange resin is converted into the sodium type cation exchange resin by caustic soda, so that the pH value of the effluent can be kept stable, and the weak acid resin can be used under the condition of high salt concentration in the water. In addition, it should be noted that when the pH is greater than 8.5, most of the bicarbonate begins to convert to carbonate until the pH increases to 10.5, about 50% of the bicarbonate is converted to carbonate, and therefore when the calcium ion concentration on the resin is higher, some of the carbonate reacts with water to precipitate, and for strong acid cation exchange resins, periodic acid washing is considered. Therefore, in the case of acid and base which are easily available, it is recommended to use a weak acid cation exchange resin as the main working medium of the cation bed softening device 25.

The used regeneration liquid is rich in calcium and magnesium ions, and is respectively conveyed to the inlet 141 of the anaerobic biochemical reaction device 14 and the dosing port 281 of the crystal phosphorus remover 28 through the regeneration waste liquid outlet 253 of the cation bed softening device 25 for further utilization.

The sulphur and nitrogen removal reactor and the anaerobic ammonia oxidation reactor in the biological regeneration device 19 operate in an anaerobic granular sludge state, the nitrosation reactor is operated in an aerobic granular sludge state, and the anaerobic/aerobic granular sludge is maintained to be in a normal operation state and needs sufficient nutrients such as carbon, nitrogen, phosphorus and the like, wherein the nitrogen nutrient substance is mainly from the regeneration waste liquid of the biological regeneration type ammonium ion exchange device 12, and nutrients such as carbon, phosphorus and the like are added by utilizing the concentrated wastewater which is rich in carbon, phosphorus and trace elements and is discharged from the middle and low pressure reverse osmosis treatment device 13, and in addition, research on the EGSB granular sludge shows that small amount of calcium (12 mg/L) and magnesium (5 mg/L) ions are beneficial to the formation and sedimentation of the granular sludge, thus, a portion of the regeneration effluent from the cation bed softener 25 is added to the biological regeneration unit 19 as a source of calcium and magnesium ions. The arrangement ensures that the invention can realize the nutrient balance of the whole system by utilizing the existing resources in the system without an additional nutrient source.

In the invention, a scale inhibitor or a dispersing agent can be added into a pipeline between the water outlet 252 of the cation bed softening device 25 and the inlet 131 of the medium-low pressure reverse osmosis treatment device 13 to reduce the scaling tendency of wastewater, and the scale inhibitor can be added at the concentration of 3-6 mg/L.

In the invention, after most of ammonia nitrogen is removed by the biological regeneration type ammonium ion exchange device 12, alkali is added into the pre-softening processor 24 to adjust the pH value to 10-11 to remove hardness, divalent cations are further removed by the cation bed softening device 25 in sequence, and a scale inhibitor is added before entering the medium-low pressure reverse osmosis treatment device 13 to avoid scaling. Thereby effectively ensuring the stable operation of the subsequent anaerobic biochemical device 14.

The anaerobic biochemical reaction device 14 generally requires that the mass ratio of the influent COD to ammonia nitrogen and phosphorus is 200-300: 5:1 to meet the biochemical reaction requirements, and the influent COD is 3,000 mg/L, 50 mg/L ammonia nitrogen and 10 mg/L phosphorus are correspondingly required. Entering the system according to the ammonia nitrogen concentration of 30 mg/L and total phosphorus of 5 mg/L of general domestic raw sewage, wherein after the treatment of the pre-softening treatment device 24, 50% of the total phosphorus can be removed, the residual phosphorus is about 2.5 mg/L, and the concentration is 10 times and then reaches 25 mg/L; the pH value of the softened sewage is 10.5, at the moment, 90% of ammonia nitrogen is in a molecular state, only a small amount of ammonia nitrogen is adsorbed after being treated by the cation bed softening device 25, and most of the ammonia nitrogen enters the medium and low pressure reverse osmosis treatment device 13, wherein about 3 mg/L of 10% of ionic ammonia nitrogen can be concentrated by 10 times, so that the ammonia nitrogen concentration of the concentrated wastewater outlet 132 of the medium and low pressure reverse osmosis treatment device 13 is increased by 30 mg/L, and the total ammonia nitrogen concentration is increased to 60 mg/L. At this time, the ammonia nitrogen and phosphorus concentrations can both meet the nutritional requirements of the anaerobic biochemical reaction device 14.

Under high pH conditions, the ionization of anions and weakly ionized species in the water is enhanced, thereby making the reverse osmosis membrane more effective in removing these species than in conventional operation. The desalination rate of nitrate such as organic matters is improved to more than 99% from 90-95%, and particularly the desalination rate of weak ionization low molecular weight substance boron is improved to more than 98% from 60-70%. Under the condition that the pH value of inlet water of the reverse osmosis membrane is more than 10, organic acid ionization is enhanced, so that the solubility of organic matters difficult to clean is greatly improved, and the membrane is always in an alkali washing state, so that the organic pollution of the membrane is greatly reduced, and the engineering practice shows that under the condition of high pH, the concentrated water of the reverse osmosis membrane can stably run under the condition that the Chemical Oxygen Demand (COD) for representing the content of the organic matters is up to 15,000 mg/L, so that the reverse osmosis membrane can run under the condition of high organic matter inlet water; the solubility of silicon inorganic substances which form unrecoverable pollution to the membrane is greatly improved, and when the pH value is 11, the content of dissolved silicon (existing in the form of metasilicic acid) in concentrated water can reach 1,500 mg/L, so that the unrecoverable inorganic pollution of the membrane is reduced, and the reverse osmosis membrane can operate under the condition of high silicon-containing inlet water; bacteria are difficult to survive at high pH, and biological pollution of the membrane is reduced; the laminar flow boundary of the reverse osmosis membrane water inlet channel becomes thin, so that particles are not easy to adhere to the surface, the particulate matter pollution of the membrane is reduced, the reverse osmosis membrane can operate under the condition that the pollution index (SDI) is less than 5, and the water inlet requirement of a common reverse osmosis device is that SDI is less than 1; due to the removal of hardness and the use of the scale inhibitor, the scaling tendency of the reverse osmosis membrane is greatly reduced, and the requirement of acid washing is reduced.

By utilizing the unique performance of the reverse osmosis device operated at high pH, the medium-low pressure reverse osmosis treatment device 13 can generally treat sewage with inflow water solubility COD of 50-2 and 500 mg/L, the water production rate is controlled to be 80-99 percent, the sewage is stably operated, the volume of the sewage is concentrated by 5-100 times while high-quality softened water is produced, so that the temperature rise cost of the sewage is reduced by 5-100 times, the anaerobic biochemical reaction device 14 is convenient to operate at a proper temperature, and organic pollutants are converted into recyclable methane and carbon dioxide.

High pH transportThe technical content of the reverse osmosis device can be described in Fan Sheng TAO in 1992 in U.S. Pat. No. US5250,185A or Debasish Mukhopadhyay in 1997 in U.S. Pat. No. US6,537,456B2. The concrete technical contents related to the control of the sulfate concentration are detailed in 'SO' published by Rankine et al in 'Chinese biogas' 2008, 26 (1)₄ ^2-The influence on the activity of anaerobic granular sludge and the influence of sulfate radicals on the anaerobic biological treatment of organic wastewater, which are published by Liuyan in 1992 in environmental science 13, volume 5, are described. The cleaning of reverse osmosis organic pollution is detailed in the research of reverse osmosis membrane organic pollution and microorganism cleaning, which is published in 2008 in 2 months in "water treatment technology" 24 nd volume 2 in Cao Ming.

The chemically regenerative ammonium ion exchange device 26 may comprise an ion exchange column or a tank of zeolite filler having selective exchange properties for ammonium ions, the zeolite filler may be classified into natural and modified types, and the working exchange capacity of the zeolite filler may be generally in the range of 1-7 mg of ammonia nitrogen per gram of zeolite under different water volumes, water quality and hydraulic retention time.

At high pH, ammonia is mostly present in molecular form in water, and given that the ionization equilibrium constant pkb1 of ammonia in water is 4.74 at 25 ℃, ammonia gas and ammonium ions each account for 50% concentration at this time, corresponding to pH 9.26, and ammonia molecules account for more than 90% when pH is increased to 10.25. Because the reverse osmosis membrane has no removing effect on gas molecules, more than 90% of ammonia nitrogen can be stored in the permeated water, so that the concentration of the ammonia nitrogen in the effluent is too high, and the quality of the recycled water is influenced.

In the invention, carbon dioxide can be added into the permeate water of the medium and low pressure reverse osmosis treatment device 13, and the pH is adjusted to be 6-8, so that the ionization degree of ammonium ions is improved, and 90% of ammonia nitrogen is ionized into an ammonium ion form so as to be effectively removed by ion exchange through zeolite.

After 90% of ammonia nitrogen is removed by the biological regeneration type ammonium ion exchange device 12 and the pH value is increased to 10-11, more than 90% of ammonia nitrogen exists in a gas form, so that the ratio of COD (chemical oxygen demand) to ammonia nitrogen entering the anaerobic biochemical reaction device 14 is 100 times of the original ratio. The effluent ammonia nitrogen can be recovered by the chemical regeneration type ammonium ion exchange device 26, and the ratio can be reduced to 10 times.

For example, assuming that the raw sewage COD is 300 mg/L and the ammonia nitrogen is 60 mg/L, when entering the anaerobic biochemical reaction device 14, the COD and the ammonia nitrogen become 500: 1, far lower than 200-300 in the anaerobic biochemical reaction device 14: 5, if the chemical regeneration ammonia nitrogen is recycled and supplemented, the ratio is changed into 250: 5, the proportion requirement of the anaerobic biochemical reaction device 14 is just met.

The chemical regeneration device 27 can comprise an air stripping or steam stripping deamination tower unit and an ammonia gas pickling or steam cooling absorption tower unit, and ammonia nitrogen can be extracted by air stripping or steam stripping and then by an acid absorption or steam condensation method. The ammonia separation efficiency can generally reach 90-99%, and the regenerated waste liquid after stripping can be recycled by the chemical regeneration type ammonium ion exchange device 26. The pH can be raised by addition of caustic soda while replenishing the sodium ions consumed for regeneration. The recovered ammonia water can be supplemented to the anaerobic biochemical reaction device 14.

The chemical REGENERATION research is detailed in "ammonia ZEOLITE Ion EXCHANGE Review" (Ion EXCHANGE OF Ammonium in Zeolites: A performance Review) published BY Hedstrom in the Journal OF Environmental Engineering, volume 8, volume 127, volume 8, and "oblique petrochemical REGENERATION experimental research" published BY Von Ganoderma in Water purification, volume 28, volume 2, and "NATURAL oblique ZEOLITE gas extraction REGENERATION research" (amino conversion adsorption filtration chemistry research) published BY Rahmani, equivalent to Environmental Health Science and Engineering, volume 6, volume 3, in 2009, chemical REGENERATION liquid recycling is detailed in Ranian Journal OF Environmental Health Science and Engineering, Iranian Journal OF Environmental Health Science and Engineering, volume 6, volume 3.

In the crystal phosphorus removal device 28, by adjusting the pH value to be within the range of 8.5-9.5, phosphorus can be extracted and converted into high-quality slow-release fertilizer, namely struvite, by using a magnesium ammonium phosphate crystallization Method (MAP), and then agricultural recycling is carried out. The phosphorus removal rate of 90 percent can be generally ensured by adopting the crystal phosphorus removal.

Under certain conditions, nitrogen, phosphorus and magnesium can be crystallized to generate magnesium ammonium phosphate hexahydrate (MgNH 4PO4 & 6H 2O), namely struvite (MAP), which is a high-quality slow-release fertilizer with high quality, and the reaction formula is as follows:

Mg²⁺+NH₄ ⁺+PO₄ ^3-+6H₂O-->MgNH₄PO₄·6H2O

according to the formula, theoretically, the magnesium, the nitrogen and the phosphorus are mixed according to the proportion of 1: 1: 1 mol ratio reaction can crystallize struvite, but practical research finds that the phosphorus concentration and the pH are necessary parameters for generating the struvite under the theoretical ratio, and the phosphorus concentration is higher than 110 mg/L when the pH is 8.5-9.5; at the concentration of 10-70 mg/L, the nitrogen-phosphorus ratio is required to be 2-4: 1; below 10 mg/l, nitrogen to phosphorus ratio as high as 32:1 is required to meet the production conditions. At pH9.5, the ratio of magnesium to phosphorus should be controlled to be less than 2, and excessive magnesium to phosphorus ratio can cause the formation of magnesium phosphate as a by-product and affect the purity of struvite. Increasing the concentration of phosphorus effectively reduces the proportion of nitrogen and phosphorus required to generate MAP. Therefore, the brine concentrator 17 can be used for concentrating the concentrated effluent containing higher phosphorus concentration as water for crystallizing and removing phosphorus, thereby reducing the required amount of magnesium and ammonia nitrogen and lightening the burden of a subsequent treatment device.

Carbon dioxide is readily soluble in water and reacts as follows:

CO₂+H₂O→H₂CO₃

H₂CO₃→H⁺+HCO₃ ^-

HCO₃ ^-→H⁺+CO₃ ^2-

H⁺+OH^-→H₂O

therefore, carbon dioxide is added to generate carbonic acid, the first-order ionization generates the same amount of hydrogen ions and bicarbonate ions, and the hydrogen ions react with the carbonate ions and the hydroxide ions in the water, so that the pH is reduced and the alkalinity of the bicarbonate is increased. Bicarbonate is an important buffering substance for anaerobic reactions. Generally, the carbon dioxide contained in the biogas is 1/3, which can be approximately understood as about 1/3 conversion of organic matter, and assuming that the total amount of degraded COD is 300 mg/l, 100 mg/l of COD is converted into carbon dioxide, which is converted into 137 mg/l of CO2 by mass. The carbonic acid is dibasic acid, and under the standard state of 25 ℃, Pka1=6.36, Pka2=10.25, and the pH is in the range of 10-12, and the carbonic acid is completely ionized into bicarbonate ions and carbonate ions. If the pH is lowered from 11 to 8.5, all carbonate ions will be converted to bicarbonate ions and the hydroxyl ions will be completely neutralized, and approximately 1 mmol/L of hydrogen ions is added, which is converted to about 44 mg/L of carbon dioxide, i.e., the amount of carbon dioxide generated by degrading 100 mg/L of COD will satisfy the neutralization requirement to maintain the feed water of the anaerobic biochemical reaction device 14 and the bio-regenerative ammonium ion exchange device 12 at the desired pH range, and the increased bicarbonate alkalinity will provide a good buffer for the acidification reaction in the anaerobic biochemical reaction device 14. The biogas generated by the invention is used as fuel to be supplied to the gas boiler and gas to generate power, carbon dioxide in tail gas generated after combustion can be recovered, one part of the biogas is used for pH adjustment before entering the anaerobic biochemical reaction device 14, and the other part of the biogas can be purified and utilized, thereby finally realizing zero emission of carbon dioxide.

Due to the shortage of water resources and the increase of the cost of tap water, sewage secondary discharge water (low-quality medium water) is adopted in many areas to replace tap water to be used as circulating cooling water, and because the water contains a large amount of organic matters, microorganisms and calcium-magnesium hardness, a large amount of slow-release scale inhibitors, acids and bactericides are required to be added to ensure the water quality, the concentration multiple is usually below 2 times, on one hand, a large amount of medium water is required, and on the other hand, half of the sewage containing a large amount of medicaments is discharged to cause secondary pollution. The water produced by the invention through desalination, hardness removal, organic matter, ammonia nitrogen removal, bacteria and microorganism removal and carbonate alkalinity increase is an ideal water source of industrial water. Desalting to remove chlorine radical and hardness, and containing carbonate alkalinity reuse water can greatly reduce metal electrochemical corrosion, and is very favorable for pipeline transportation and used as cooling circulation device for water supplement. The water replenishing of the cooling circulation system can improve the concentration multiple to more than 10 times, so that the water consumption of fresh water and the water discharge of the cooling tower are greatly reduced, the addition of corresponding slow-release scale inhibitor, bactericide, acid-base and other medicaments is greatly reduced, the secondary pollution to the environment is reduced, and the dual functions of water conservation and emission reduction are achieved.

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations can be made by those skilled in the art without departing from the spirit and principles of the invention.

Claims

1. A sewage recycling comprehensive treatment system is characterized by at least comprising a pre-precipitation filter, a biological regeneration type ammonium ion exchange device, a medium and low pressure reverse osmosis treatment device with the operating pressure of 1-4 MPa, an anaerobic biochemical reaction device, a mixed biochemical reaction device and a post-precipitation filter, wherein a municipal or industrial sewage pipe network is connected with an inlet of the pre-precipitation filter through a pipeline, an outlet of the pre-precipitation filter is connected with an inlet of the biological regeneration type ammonium ion exchange device through a pipeline, an outlet of the biological regeneration type ammonium ion exchange device is connected with an inlet of the medium and low pressure reverse osmosis treatment device through a pipeline, a purified water outlet of the medium and low pressure reverse osmosis treatment device is connected with an industrial water supply pipe network through a pipeline, a concentrated wastewater outlet of the medium and low pressure reverse osmosis treatment device is connected with an inlet of the anaerobic biochemical reaction device through a pipeline, the outlet of the anaerobic biochemical reaction device is connected with the inlet of the mixed biochemical reaction device through a pipeline, the outlet of the mixed biochemical reaction device is connected with the inlet of the post-precipitation filter through a pipeline, and the outlet of the post-precipitation filter is connected with a municipal drainage pipeline;

the sewage recycling comprehensive treatment system further comprises a brine concentrator and an evaporation crystallizer, wherein an outlet of the post-precipitation filter is connected with an inlet of the brine concentrator through a pipeline, a concentrated water outlet of the brine concentrator is connected with an inlet of the evaporation crystallizer, and a desalted water outlet of the brine concentrator and a desalted water outlet of the evaporation crystallizer are respectively connected with an industrial water supply network;

the sewage recycling comprehensive treatment system further comprises a biological regeneration device, the biological regeneration type ammonium ion exchange device further comprises a regeneration liquid inlet and a regeneration waste liquid outlet, the regeneration liquid outlet of the biological regeneration device is connected with the regeneration liquid inlet of the biological regeneration type ammonium ion exchange device through a pipeline, and the regeneration waste liquid inlet of the biological regeneration device is connected with the regeneration waste liquid outlet of the biological regeneration type ammonium ion exchange device through a pipeline;

the sewage recycling comprehensive treatment system further comprises an organic sludge concentrator, an organic sludge digester and an inorganic sludge dehydrator, the sludge discharge ports of the pre-precipitation filter, the anaerobic biochemical reaction device, the mixed biochemical reaction device and the biological regeneration device are respectively connected with the inlet of the organic sludge concentrator through pipelines, a concentrated sludge outlet of the organic sludge concentrator is connected with a sludge inlet of the organic sludge digester, a sludge discharge port of the organic sludge digester is connected with an inlet of the inorganic sludge dehydrator through a pipeline, the waste water outlet of the organic sludge concentrator is connected with the inlet of the pre-precipitation filter through a pipeline, the sludge discharge port of the post-precipitation filter is connected with the inlet of the inorganic sludge dehydrator through a pipeline, a waste water outlet of the inorganic sludge dehydrator is connected with an inlet of the post-precipitation filter through a pipeline;

the sewage recycling comprehensive treatment system further comprises a gas washing and desulfurizing device, a regenerated liquid outlet of the biological regeneration device is connected with an absorption liquid inlet of the gas washing and desulfurizing device through a pipeline, a sulfur-containing waste liquid outlet of the gas washing and desulfurizing device is connected with a sulfur-containing waste liquid inlet of the biological regeneration device, and a methane outlet of the organic mud digester and a methane outlet of the anaerobic biochemical reaction device are respectively connected with an air inlet of the gas washing and desulfurizing device.

2. The integrated sewage recycling system according to claim 1, further comprising a pre-softening device, a cation bed softening device, a chemical regeneration type ammonium ion exchange device, a chemical regeneration device, and a crystal phosphorus removal device, wherein the water inlet of the pre-softening device is connected to the outlet of the biological regeneration type ammonium ion exchange device, the water outlet of the pre-softening device is connected to the water inlet of the cation bed softening device, the sludge outlet of the pre-softening device is connected to the inlet of the inorganic sludge dewatering machine, the water outlet of the cation bed softening device is connected to the inlet of the medium-low pressure reverse osmosis treatment device, the regenerated waste liquid outlet of the cation bed softening device is connected to the inlet of the anaerobic biochemical reaction device and the chemical feeding port of the crystal phosphorus removal device, respectively, and the inlet of the crystal phosphorus removal device is connected to the concentrated water outlet of the brine concentrator, the water outlet of the crystal phosphorus remover is connected with the water inlet of the evaporative crystallizer, struvite is discharged from a sludge discharge port of the crystal phosphorus remover and used as a slow-release fertilizer for agriculture, a purified water outlet of the medium-low pressure reverse osmosis device is connected with an inlet of the chemical regeneration type ammonium ion exchange device through a pipeline, a purified water outlet of the chemical regeneration type ammonium ion exchange device is connected with a municipal industrial recycled water pipe network through a pipeline, a regenerated liquid inlet and a waste liquid outlet of the chemical regeneration type ammonium ion exchange device are respectively connected with a regenerated liquid of the chemical regeneration device and a waste liquid outlet and an inlet of the chemical regeneration device through pipelines, and an ammonia water outlet of the chemical regeneration device is connected with an inlet of the anaerobic biochemical reaction device through a pipeline.