CN114772875B

CN114772875B - Treatment method of high-salt-content wastewater

Info

Publication number: CN114772875B
Application number: CN202210714377.8A
Authority: CN
Inventors: 耿春茂; 赵曙光; 曹意茹; 宋乐山; 陈长松; 何超群; 李得元; 李橙; 单升益; 郑可卿; 王程程; 张颖; 曾子玥; 赵国华
Original assignee: Shenzhen Yonker Water Co ltd
Current assignee: Shenzhen Yonker Water Co ltd
Priority date: 2022-06-23
Filing date: 2022-06-23
Publication date: 2022-09-16
Anticipated expiration: 2042-06-23
Also published as: CN114772875A

Abstract

The invention relates to a method for treating high-salt-content wastewater, which comprises the following steps: (1) inputting the high-salinity wastewater and the sludge generated in the steps (3) and (6) into a hydrolysis acidification pool, and performing hydrolysis acidification by utilizing salt-tolerant facultative sludge digestion bacteria in an anaerobic environment; (2) the wastewater obtained in the step (1) is sequentially and alternately input into a plurality of aerobic units and anoxic units, organic matters are degraded in the aerobic units, and short-cut nitrification and full-cut nitrification are carried out; anaerobic ammonia oxidation and denitrification treatment are carried out in the anoxic unit; (3) carrying out sludge-water separation on the wastewater obtained in the step (2) through an MBR (membrane bioreactor) membrane device to obtain primary sludge and wastewater to be deeply oxidized, and inputting the primary sludge into a hydrolysis acidification tank; (4) inputting the wastewater to be deeply oxidized into an electrochemical reactor for deep oxidation; (5) inputting the wastewater obtained in the step (4) into a coagulation tank for coagulation; (6) and (5) inputting the wastewater obtained in the step (5) into a horizontal pipe sedimentation tank to obtain secondary sludge and produced water, and inputting the secondary sludge into a hydrolysis acidification tank.

Description

Treatment method of high-salt-content wastewater

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to a treatment method of high-salt-content wastewater.

Background

Water resource shortage is one of the major problems faced by China, and seawater substitution is a sustainable and long-term solution to water resource shortage, and can be used for cooling, dust removal, ash flushing, miscellaneous life use and the like. However, the salt content of seawater is high, the wastewater containing seawater is high-salt wastewater, and halophilic (tolerant) microorganisms are needed for treating the high-salt wastewater. In addition to seawater, many other petrochemical, chemical or biomedical industries generate salt-containing wastewater, and the types of inorganic salts in the salt-containing wastewater are many and complicated. At present, salt-philic (tolerant) microorganisms are added from an external source and a traditional A2/O biochemical treatment process is combined to treat the high-salt-content wastewater, phosphorus is released and organic matters are aminated in an anaerobic section, denitrification is carried out in an anoxic section, nitrification, phosphorus absorption and organic matter removal are carried out in an aerobic section, the retention time needs to be prolonged and a carbon source needs to be added in the operation process to realize good nitrification and denitrification effects, and for deep removal of phosphorus, the deep removal is usually carried out by adding a medicament and generating precipitates, so that the aim of reaching the effluent standard is finally achieved.

The above treatment process has the following problems: (1) the dephosphorization effect is difficult to improve, the sludge growth has a certain limit, and especially the P/BOD value is difficult to improve when being high; (2) the denitrification effect is difficult to be further improved, the internal circulation amount is generally limited to 2Q, and the internal circulation amount is not too high; (3) the treated water entering the sedimentation tank needs to keep dissolved oxygen with certain concentration, so that the retention time is reduced, the anaerobic state is prevented, and the phenomenon that the sludge releases phosphorus is avoided, but the concentration of the dissolved oxygen is not too high so as to prevent the circulating mixed liquid from interfering the anoxic reactor.

However, the salt-tolerant microorganisms, especially the salt-tolerant nitrifying bacteria, have the defects of long generation cycle and slow growth compared with the common nitrifying bacteria. Therefore, the retention time of the aerobic section needs to be prolonged, the energy consumption is also improved, the treatment cost is increased, the sludge yield is increased, the sludge contains higher salt, the sludge with high salt content is difficult to effectively treat and utilize in a traditional resource treatment mode, the salt-containing wastewater has relatively high density, the sludge agglomeration and sedimentation performance are poor, a large sedimentation tank needs to be designed, but the sedimentation effect is poor, the effluent exceeds the standard easily, and the biochemical effluent COD cannot reach the standard when the wastewater contains organic matters which are difficult to biochemically. In the process of deep phosphorus removal at the tail end, the flocculation and precipitation mode of a common inclined plate precipitation tank is adopted, so that the precipitation effect is poor due to the effect of sewage buoyancy, and the SS and total phosphorus of effluent exceed standards.

Disclosure of Invention

Aiming at the problems, the invention provides a method for treating high-salt-content wastewater, which can shorten the retention time of an aerobic section, further reduce the operation cost and reduce the sludge yield, cancels a traditional sedimentation tank, adopts a special advanced treatment process, ensures the stability of effluent COD, ammonia nitrogen, total nitrogen, SS and total phosphorus, and finally achieves the purposes of reducing the occupied area and the investment cost, reducing the operation cost and reducing the waste disposal cost.

The treatment method of the high-salt-content wastewater comprises the following steps:

s100: inputting the high-salinity wastewater, the primary sludge generated in the step S300 and the secondary sludge generated in the step S600 into a hydrolysis acidification pool, and performing hydrolysis acidification by utilizing salt-tolerant facultative sludge digestion bacteria in an anaerobic environment to realize sludge reduction and improve the biochemical ratio of the high-salinity wastewater;

s200: the wastewater obtained in the step S100 is sequentially and alternately input into a plurality of aerobic units and anoxic units, organic matters are degraded in the aerobic units, and short-cut nitrification and full-process nitrification are simultaneously carried out; anaerobic ammonia oxidation and denitrification treatment are carried out in the anoxic unit;

s300: performing sludge-water separation on the wastewater obtained in the step S200 by using an MBR (membrane bioreactor) membrane device to obtain primary sludge and wastewater to be deeply oxidized, and inputting the primary sludge into the hydrolysis acidification tank for anaerobic treatment;

inputting the wastewater to be deeply oxidized into a circulating barrel, and mixing the wastewater with a solution which flows back to the circulating barrel from an electrochemical reactor to obtain mixed wastewater;

s400: inputting the mixed wastewater into an electrochemical reactor for deep oxidation to remove refractory organic matters and remove phosphorus, and refluxing a water body part of the electrochemical reactor to a circulating barrel;

s500: inputting the wastewater obtained in the step S400 into a coagulation tank, and coagulating under the action of a flocculating agent;

s600: and (5) inputting the wastewater obtained in the step (S500) into a horizontal pipe sedimentation tank for mud-water separation to obtain secondary sludge and produced water, and inputting the secondary sludge into the hydrolysis acidification tank for anaerobic treatment.

Optionally, in step S100, the sludge in the hydrolysis acidification tank is derived from the primary sludge generated by the MBR membrane device in step S300 and the secondary sludge generated by the horizontal pipe sedimentation tank in step S600, and after a period of anaerobic process is performed on the respective portions of the two types of sludge that exert the sedimentation effect, the aerobic microbial population in the sludge is greatly reduced, and the content of dissolved oxygen carried in the sludge is substantially reduced to zero, so that the original anaerobic microbial environment of the hydrolysis acidification tank is not damaged when the sludge flows back to the hydrolysis acidification tank.

The high-salt-content wastewater is input into a hydrolysis acidification tank, salt-tolerant facultative sludge digestion bacteria are added into the hydrolysis acidification tank, so that the tank has two functions of improving biochemical ratio (B/C) of the high-salt-content wastewater and reducing sludge, organic matters in the activated sludge are hydrolyzed and acidified by the microorganisms in an anaerobic environment of the hydrolysis acidification tank and are converted into micromolecule organic matters such as amino acid, volatile fatty acid, saccharides, alcohols, acetic acid, hydrogen, carbonic acid and the like, further sludge reduction is realized, the micromolecule organic matters enter a subsequent biochemical segment along with the wastewater and are degraded in an aerobic unit, a carbon source is provided for an anoxic unit, and the sludge yield is reduced on the whole.

Optionally, step S200 specifically includes the following steps:

(1) the wastewater obtained in the step S100 is input into a first-level aerobic unit to remove COD in the wastewater, and ammonia nitrogen in the wastewater is converted into nitrite nitrogen and nitrate nitrogen through short-cut nitrification and whole-process nitrification processes;

(2) inputting the wastewater obtained in the step (1) into a first-stage anoxic unit, removing nitrite nitrogen and residual ammonia nitrogen in the wastewater through an anaerobic ammonia oxidation process, taking COD (chemical oxygen demand) which is not degraded by a first-stage aerobic unit as a carbon source, and removing nitrate nitrogen by using a denitrification process;

(3) inputting the wastewater obtained in the step (2) into a secondary aerobic unit, removing residual organic matters, and continuing to perform short-cut nitrification and full-process nitrification processes to convert residual ammonia nitrogen into nitrite nitrogen and nitrate nitrogen;

(4) and (4) inputting the wastewater obtained in the step (3) into a secondary anoxic unit for denitrification and anaerobic ammonia oxidation.

Optionally, in the step (1), in the first-stage aerobic unit, part of organic matters in the wastewater are removed by oxidative decomposition, so that the COD content is reduced, and part of ammonia nitrogen is converted into nitrite nitrogen and nitrate nitrogen respectively through short-range nitrification and whole-process nitrification.

Further optionally, the hydraulic retention time in the primary aerobic unit is 10-12h, the dissolved oxygen concentration is controlled to be 1.7-2mg/L, the sludge concentration is 4-4.5g/L, and the sludge load is 0.4-0.5 kg/(kg. d).

Optionally, the bottoms of the primary aerobic unit and the secondary aerobic unit are respectively provided with a first aeration device for supplying and supplying air; aerobic microorganisms including but not limited to high-load-resistant carbonized bacteria and nitrifying bacteria are put into the primary aerobic unit; aerobic microorganisms, including but not limited to medium-low load carbonization bacteria and nitrobacteria, are put into the secondary aerobic unit;

the temperature in the first-stage aerobic unit and the second-stage aerobic unit is kept at 25-28 ℃, the pH value is 7.4-7.8, the hydraulic retention time ratio is 2:1, and the hydraulic retention time of the first-stage aerobic unit is 10-12 h.

Optionally, in the step (2), because the first-stage aerobic unit simultaneously performs partial short-cut nitrification and partial full-process nitrification, nitrite nitrogen and residual ammonia nitrogen in the wastewater are removed through an anaerobic ammonia oxidation process, and the undegraded COD of the first-stage aerobic unit is used as a carbon source, and the nitrate nitrogen is removed through a denitrification process, so that carbon and nitrogen can be removed in the same step under the condition of low energy consumption.

Optionally, the primary anoxic unit and the secondary anoxic unit are both provided with stirring devices, and a certain dissolved oxygen amount is kept according to the actual sewage condition; the primary anoxic unit puts in anoxic microorganisms including but not limited to high-load resistant denitrifying bacteria, and the secondary aerobic unit puts in anoxic microorganisms including but not limited to medium-low load resistant denitrifying bacteria;

the temperature in the first-stage anoxic unit and the second-stage anoxic unit is kept at 30-35 ℃, the pH value is 7.0-7.5, the hydraulic retention time ratio is 2:1, and the hydraulic retention time of the first-stage anoxic unit is 2-2.5 h.

Optionally, if the COD in the wastewater obtained in step S100 is high and the content of ammonia nitrogen is high, a plurality of aerobic units and a plurality of anoxic units may be alternately arranged, and the wastewater enters the aerobic and anoxic environments repeatedly as in steps (1) to (4), so that nitrogen is removed with low energy consumption, and under appropriate conditions, the last anoxic unit may add a carbon source appropriately to ensure the completeness of the denitrification process.

Compared with the traditional nitrification and denitrification process, the treatment method of the high-salt-content wastewater disclosed by the invention has the advantages that most of COD is removed through the preposed aerobic unit, so that the short-cut nitrification and anaerobic ammonia oxidation processes are easier to occur, the denitrification process of the biochemical part is mainly anaerobic ammonia oxidation, the energy consumption of the whole nitrification process is reduced, and the addition of a carbon source in the denitrification process is saved. Autotrophic bacteria in the aerobic unit take energy through bottom inorganic matters (COD) to degrade ammonia nitrogen, COD removal is realized first, then nitrification is carried out, and the residence time and energy consumption in the traditional nitrification process are greatly reduced.

Optionally, in step S300, the wastewater obtained in step S200 is input into a sludge-water separation unit, the sludge-water separation unit includes, from top to bottom, an MBR membrane device, a second aeration device, a water discharge port, a conical bottom and a first sludge discharge port, and the wastewater subjected to aerobic and anoxic alternate biochemical treatment is subjected to sludge-water separation in the MBR membrane device;

the MBR membrane device is a tubular integrated MBR membrane device, the MBR membrane is a PVDF membrane, the sludge concentration is 10g/L, and the membrane flux is 10-15L/m ² H, membrane filament area 900m ² Operating negative pressure of-0.06-0.02 Mpa, aeration rate of 10.8m ³ /min。

The bottom of the mud-water separation unit is conical, so that primary sludge can be discharged conveniently; the first sludge discharge port is connected with the hydrolysis acidification tank through a reflux pump and a pipeline and is used for periodically inputting primary sludge into the hydrolysis acidification tank.

Further optionally, in the step S300, the retention time of the primary sludge at the bottom of the mud-water separation unit is 2-2.5 h.

Optionally, the circulating barrel is arranged between the mud-water separation unit and the electrochemical reactor, a water outlet of the mud-water separation unit is connected with a water inlet of the circulating barrel, a backflow outlet of the electrochemical reactor is connected with a backflow inlet of the circulating barrel, and the circulating barrel is connected with the water inlet of the electrochemical reactor through a first pump and a pipeline;

and (3) inputting the wastewater to be deeply oxidized and the backflow wastewater of the electrochemical reactor into a circulating barrel, uniformly mixing to obtain mixed wastewater, and inputting the mixed wastewater into the electrochemical reactor through a first pump.

Optionally, the electrochemical reactor includes an anode plate, a cathode plate, a third aeration device and a dc power supply, the anode plate is electrically connected to the positive interface of the dc power supply, and the cathode plate is electrically connected to the negative interface of the dc power supply; the third aeration device is arranged at the bottom of the electrochemical reactor, and the direct-current power supply is arranged outside the electrochemical reactor;

the anode plate is selected from a BDD anode plate, a Fe film electrode anode plate and an Al film electrode anode plate, and the cathode plate is a stainless steel film electrode cathode plate;

the backflow outlet is arranged at the lower part of the electrochemical reactor and is used for refluxing the water body part in the electrochemical reactor to the circulating barrel, and the backflow ratio is 25-30%.

As a specific embodiment, the electrode plates within the electrochemical reactor are arranged such that: the stainless steel thin film electrode cathode plate, the BDD anode plate, the stainless steel thin film electrode cathode plate, the Fe thin film electrode anode plate, the stainless steel thin film electrode cathode plate, the Al thin film electrode anode plate and the stainless steel thin film electrode cathode plate are arranged in this way.

In the electrochemical reactor, a BDD anode plate loses electrons, directly oxidizes and generates hydroxyl radicals and the like, opens a ring and breaks a chain of organic matters which are difficult to biochemically in the mixed wastewater, removes the biochemical residual hard-to-degrade COD, destroys carbon-phosphorus bonds of organic phosphorus, oxidizes hypophosphite into orthophosphate, converts the organic phosphorus into inorganic phosphorus, further oxidizes ammonia nitrogen, and improves the removal rate of the ammonia nitrogen; the Fe film electrode anode plate and the Al film electrode anode plate lose electrons and release ferric salt and aluminum salt, and the ferric salt and the aluminum salt have flocculation effect on phosphorus, so that the using amount of the flocculating agent in the step S500 is reduced; electrons are obtained from the stainless steel membrane electrode cathode plate, and partial nitrate nitrogen is reduced at the electrons; the wastewater in the electrochemical reactor is thoroughly mixed by the third aeration device and part of the SS is prevented from being deposited in this area.

The technical personnel in the field can regulate and control the flow of the first pump according to the actual COD water quality condition of the water outlet of the electrochemical reactor, further control the liquid flow of the water inlet of the electrochemical reactor, and realize the lowest ton water power consumption of water treatment reaching the standard. Optionally, the ratio of the amount of water flowing from the return outlet to the circulation tank to the total amount of water in the electrochemical reactor is (0.25-0.28): 1.

Optionally, in step S500, a flocculant storage tank is arranged outside the coagulation tank, the flocculant storage tank is connected to the coagulation tank through a second pump and a pipeline, the coagulation tank is provided with a fourth aeration device from the bottom for sufficiently mixing a flocculant with wastewater, the flocculant includes a PAM and a PAC flocculant, the flocculant generates alum flocs in the coagulation tank, the alum flocs is sufficiently decomposed with the wastewater, and pollutants in the wastewater are adsorbed and captured by a net.

Optionally, in step S600, the upper part of the horizontal pipe sedimentation tank is provided with a plurality of sludge discharge slideways parallel to each other, and the sludge discharge slideways are obliquely arranged and used for separating and discharging sludge in the wastewater obtained in step S500 to the lower part of the horizontal pipe sedimentation tank; the bottom of the horizontal pipe sedimentation tank is conical, so that secondary sludge is conveniently discharged; and a second sludge discharge port is formed in the bottom of the horizontal pipe sedimentation tank and connected with the reflux pump through a pipeline and used for inputting secondary sludge into the hydrolysis acidification tank.

Preferably, one side of the sludge discharge slideway is provided with a plurality of inclined plates which are parallel to each other from top to bottom, one end of each inclined plate is connected with the side wall of the sludge discharge slideway, the other end of each inclined plate is provided with a partition plate, the partition plates are parallel to the side wall of the sludge discharge slideway, and the inclined plates and the side wall of the sludge discharge slideway form a certain angle; the wastewater obtained in the step S500 is precipitated in a short distance through the sludge discharge slideway, so that the interference of the water flow state on suspended matter precipitation is reduced, the space utilization rate of the horizontal pipe sedimentation tank is increased, sludge enters the conical bottom below the sludge discharge slideway, and the supernatant is the produced water. The inclined plates are arranged on one side of the mud discharge slideway from top to bottom, the partition plate separates a plurality of water flow channels with rhombic cross sections between the adjacent upper inclined plate and the adjacent lower inclined plate, the lower inclined plate is not in contact with the bottom end of the partition plate above, and a mud discharge opening is formed at the position. When the horizontal pipe sedimentation tank is fed with water, suspended matters in water are continuously precipitated under the action of self gravity, slide down along the partition plate or the inclined plate, continuously enter the sludge discharge slideway through the sludge discharge opening, and are separated from the water flow main body and then discharged into the sludge hopper through the sludge discharge slideway. The sludge discharge slideway is a still water area, and sediments cannot be washed and stirred at the still water area, so that the sediments and clear water are separated timely and thoroughly, and the sedimentation efficiency is ensured.

Further optionally, the mud discharging slideway comprises a plurality of sections of inclined sub-slideways connected end to end, two adjacent sub-slideways incline to different directions respectively, for example, the first sub-slideway inclines to the left, the second sub-slideway inclines to the right, the third sub-slideway inclines to the left, the fourth sub-slideway inclines to the right, the first sub-slideway and the fourth sub-slideway are sequentially connected end to end from top to bottom, preferably, the first sub-slideway is parallel to the third sub-slideway, and the second sub-slideway is parallel to the fourth sub-slideway, so that the mud discharging slideway is in a zigzag manner;

the top of the partition plate of the odd numbered slide way is connected with the corresponding inclined plate, so that the partition plates of the odd numbered slide way point to the inclined lower part; the bottom of the partition board of the double-fraction slide way is connected with the corresponding inclined board, so that the partition board of the double-fraction slide way points to the inclined upper side. Thus, the water body input into the horizontal pipe sedimentation tank sequentially and alternately passes through the downward-facing inclined plate and the downward-facing partition plate and then passes through the upward-facing inclined plate and the upward-facing partition plate.

Optionally, the inclined plates at the head-to-tail connection positions of the two adjacent sub-slideways are not connected with the partition plate but connected with each other, and form a quadrangle with the respective sub-slideways, so that the two sub-slideways are more stable.

Optionally, one end of the sloping plate of the double-fraction slide way is rotated to connect the side wall of the mud discharge slide way, so that the sloping plate drives the partition plate to rotate up and down, and the partition plate is used for adjusting the water flow speed and the turbulent flow condition in the horizontal tube sedimentation tank.

The invention designs the zigzag sludge discharge slideway, prolongs the length of the sludge discharge slideway in a limited sedimentation tank and improves the separation efficiency of the wastewater and the sludge. The odd number and the even number of the branch slideways are provided with inclined plates and partition plates with different directions, and the rhombic water channels formed by the odd number of the branch slideways promote the sludge precipitation. When the water flow is fast, the inclined plate of the double-fractional slideway is fixed, so that the effect of intercepting part of the water flow is achieved, and the flow speed is stable; when the water flow is slow, the inclined plate of the double-fractional slideway swings up and down to increase the disturbance of the water flow, the inclined plate can freely swing under the action of the water flow and also can be controlled to swing mechanically, and the mechanical control can be realized by adopting a technical means commonly used in the field.

Optionally, a cooling coil is embedded inside the inclined plate of the odd number of the sub-slideways and is used for cooling the wastewater passing through the sub-slideways, so that partial salt is separated from the cooled wastewater, the salt content of the wastewater is properly reduced, and the separation of mud and water below the horizontal pipe sedimentation tank is facilitated;

the cooling water inlet pipe and the cooling water outlet pipe respectively penetrate through the top wall of the horizontal pipe sedimentation tank and are connected with a plurality of water inlet branch pipes and a plurality of water outlet branch pipes in parallel, the water inlet branch pipes and the water outlet branch pipes extend and are embedded in the side wall of each mud discharge slideway, which is provided with the inclined plate, and extend downwards to the side wall of each branch slideway, and are connected with the cooling coil pipes of the inclined plates of the odd branch slideways to supply cooling water for the cooling coil pipes; and the sloping plate of the double-fraction slideway is not provided with a cooling coil, so that the cooling capacity can be saved.

Optionally, the top of the baffle of double-fraction slide is connected one side of crystallization net, and the opposite side of crystallization net is fixed on another lateral wall of double-fraction slide, and the crystallization net level when the swash plate of double-fraction slide is static, and the crystallization net comprises for violently indulging criss-cross net twine, and the criss-cross node of net twine becomes crystallization nucleation site, provides the crystal nucleus for the salt crystallization in the waste water.

Optionally, because the row's mud slide is the slope, and the horizontal pipe sedimentation tank outer wall is vertical, has the space between horizontal pipe sedimentation tank inner wall and the nearest row's mud slide, and this space is cooling jacket, can let in the cooling water and be used for assisting waste water to separate out the salinity.

When the wastewater passes through the sludge discharge slideway, the wastewater is cooled and begins to separate out a small amount of salt through the odd-numbered slideway, the salt continues to separate out through the even-numbered slideway, passes through the crystallization net, and wraps the crystal nucleus crystals by taking the net wire cross nodes on the net as crystal nuclei to promote wastewater desalination; meanwhile, the sludge in the wastewater is flocculated to be crystal nucleus, so that the crystallization can be promoted. The mesh of crystal net is great, can not intercept the mud wadding in the waste water, even a small amount of mud wadding is intercepted, shakes off under the swing effect that also can subsequent waste water stream effect or swash plate, even there is very little mud wadding to be intercepted, also can become the crystal nucleus site that increases crystal net mutually. The density of the waste water with salt separated out is reduced, which is beneficial to the precipitation at the middle lower part of the horizontal tube sedimentation tank. And most of the separated salt is remained on the crystallization net, the content of the separated salt in the secondary sludge discharged from the horizontal tube sedimentation tank is low, and the separation of the separated salt and the sludge is realized.

Optionally, a water inlet is formed in the top of the horizontal pipe sedimentation tank and used for inputting wastewater, and the wastewater enters each sludge discharge slideway from the top of the horizontal pipe sedimentation tank; the middle part of the horizontal pipe sedimentation tank is provided with a water outlet for discharging produced water.

Optionally, the first aeration device, the second aeration device, the third aeration device and the fourth aeration device are all aeration pipes or aeration discs.

The method for treating the high-salt-content wastewater has the following beneficial effects:

the process with the preposed aerobic section is adopted, so that the shortcut nitrification is easier to control on the premise of high-efficiency COD removal, the anaerobic ammonia oxidation with higher proportion is finally realized, and the energy consumption is saved; the retention time of the aerobic nitrification is shortened, and the investment and the operation cost are greatly reduced; the sludge yield is low, the sludge digestion function is realized, the zero-sludge operation can be realized, and the problem of sludge disposal cost is solved; the invention cancels the traditional sedimentation tank, adopts MBR membrane separation mode to separate mud and water, and avoids the SS standard exceeding of produced water; the biochemical rear end adopts an electrolysis and horizontal pipe sedimentation tank, so that the quality of the produced water reaches a higher standard, and the sedimentation efficiency is improved; the sludge of the invention is longer in age, and the anaerobic ammonia oxidation bacteria are easier to enrich without using filler in the anoxic unit, thereby being easy to realize anaerobic ammonia oxidation with higher proportion.

Step S200 is mainly aimed at removing COD and ammonia nitrogen, phosphorus is not removed, the retention time of an aerobic unit is short, denitrification and anaerobic ammonia oxidation are mainly used, and the sludge yield of the system is low; the step S400 mainly comprises deep phosphorus removal and removal of COD which is difficult to biochemically degrade, the whole system can realize zero biochemical sludge operation, and the problem that biochemical sludge is difficult to dispose is solved.

Drawings

FIG. 1 is a flow chart of the equipment of the method for treating the wastewater with high salinity;

fig. 2 is a schematic structural view of a sludge discharge chute according to embodiment 2;

fig. 3 is a schematic structural view of a mud discharge chute according to embodiment 3;

fig. 4 is a schematic structural view of the swash plate of embodiment 4.

In the attached figure, 1-a hydrolysis acidification tank, 2-a first-stage aerobic unit, 3-a second-stage aerobic unit, 4-a first-stage anoxic unit, 5-a second-stage anoxic unit, 6-a mud-water separation unit, 7-an MBR membrane device, 8-a reflux pump, 9-an electrochemical reactor, 10-a circulating barrel, 11-a reflux outlet, 12-a reflux inlet, 13-a first pump, 14-a direct current power supply, 15-a coagulation tank, 16-a flocculating agent storage tank, 17-a second pump, 18-a horizontal pipe sedimentation tank, 19-a mud discharge slideway, 20-an inclined plate, 21-a partition plate and 22-a cooling coil.

Detailed Description

The scale of treating raw water of high-salinity wastewater treated in the following examples and comparative examples was 10m ³ The potassium nitrate concentration in the raw water is 47g/mL, and the raw water is sequentially treated by a grating and an adjusting tank to obtain the high-salt-content wastewater with the following water quality:

example 1

The method for treating wastewater with high salt content, as shown in fig. 1, includes the following steps:

s100: inputting the high-salinity wastewater, the primary sludge generated in the step S300 and the secondary sludge generated in the step S600 into a hydrolysis acidification pool 1, and performing hydrolysis acidification by utilizing salt-tolerant facultative sludge digestion bacteria in an anaerobic environment to realize sludge reduction and improve the biochemical ratio of the high-salinity wastewater;

the sludge in the hydrolysis acidification tank 1 comes from the primary sludge generated by the MBR membrane device 7 in the step S300 and the secondary sludge generated by the horizontal pipe sedimentation tank 18 in the step S600;

s200: the wastewater obtained in the step S100 is sequentially and alternately input into an aerobic unit and an anoxic unit, organic matters are degraded in the aerobic unit, and short-cut nitrification and full-process nitrification are simultaneously carried out; anaerobic ammonia oxidation and denitrification treatment are carried out in an anoxic unit;

s300: performing sludge-water separation on the wastewater obtained in the step S200 through an MBR (membrane bioreactor) membrane device 7 to obtain primary sludge and wastewater to be deeply oxidized, and inputting the primary sludge into the hydrolysis acidification tank 1 for anaerobic treatment;

inputting the wastewater to be deeply oxidized into a circulating barrel 10, and mixing the wastewater with a solution which flows back to the circulating barrel 10 from an electrochemical reactor 9 to obtain mixed wastewater;

s400: the mixed wastewater is input into an electrochemical reactor 9 for deep oxidation to remove refractory organic matters and remove phosphorus, and a water body part of the electrochemical reactor flows back to a circulating barrel;

s500: the wastewater obtained in the step S400 is input into a coagulation tank 15 and coagulated under the action of a flocculating agent;

s600: and (5) inputting the wastewater obtained in the step (S500) into a horizontal pipe sedimentation tank 18 for mud-water separation to obtain secondary sludge and produced water, and inputting the secondary sludge into the hydrolysis acidification tank 1 for anaerobic treatment.

The salt-tolerant facultative sludge digestion bacteria are Geobacillus stearothermophilus domesticated in high salinity, and the specific domestication method comprises the following steps: adding 20wt% of activated sludge into the hydrolysis acidification tank 1, and adding 1 wt% of Geobacillus stearothermophilus (purchased from Fonsbi Voofeng company), wherein the COD of the inlet water is 500mg/L, the ammonia nitrogen is 50mg/L, the nitrate nitrogen is 50mg/L, and the salinity (sodium chloride and ammonium sulfate) of the inlet water is 2%; the temperature of the hydrolysis acidification tank 1 is controlled at 35 ℃, and the pH value is controlled at 7.2-7.6. And (3) determining the effluent ss of the hydrolysis acidification tank every day until the sludge concentration is reduced by more than 40%, completing the domestication of 2% of high-salinity Geobacillus stearothermophilus, gradually increasing the environmental salinity (to 3-5%), and completing the domestication of the salt-tolerant Geobacillus stearothermophilus in a higher salinity environment.

The step S200 specifically includes the following steps:

(1) the wastewater obtained in the step S100 is input into the first-stage aerobic unit 2 to remove COD in the wastewater, and ammonia nitrogen in the wastewater is converted into nitrite nitrogen and nitrate nitrogen through short-range nitrification and whole-process nitrification processes;

the hydraulic retention time in the primary aerobic unit 2 is 12h, the dissolved oxygen concentration is controlled to be 2mg/L, the sludge concentration is 4g/L, and the sludge load is 0.4 kg/(kg. d);

putting high-load-resistant carbonized bacteria into the primary aerobic unit 2, keeping the temperature at 25 ℃, the pH value at 7.4-7.8, and setting the hydraulic retention time to be 12 h;

(2) inputting the wastewater obtained in the step (1) into a first-stage anoxic unit 4, removing nitrite nitrogen and residual ammonia nitrogen in the wastewater through an anaerobic ammonia oxidation process, taking undegraded COD (chemical oxygen demand) of a first-stage aerobic unit 2 as a carbon source, and removing nitrate nitrogen by using a denitrification process;

high-load-resistant denitrifying bacteria are put into the first-stage anoxic unit 4, the temperature is kept at 30-35 ℃, the pH value is 7.0-7.5, and the hydraulic retention time is set to be 2 hours;

(3) inputting the wastewater obtained in the step (2) into a secondary aerobic unit 3, removing residual organic matters, and continuing to perform short-cut nitrification and full-process nitrification processes to convert residual ammonia nitrogen into nitrite nitrogen and nitrate nitrogen;

the secondary aerobic unit 3 puts in medium and low load resistant carbonized bacteria, the temperature is kept at 25 ℃, the pH value is 7.4-7.8, and the hydraulic retention time is set to be 6 h;

(4) inputting the wastewater obtained in the step (3) into a secondary anoxic unit 5 for denitrification and anaerobic ammonia oxidation;

the secondary aerobic unit 5 is added with medium and low load resistant denitrifying bacteria, the temperature is kept at 30-35 ℃, the pH value is 7.0-7.5, and the hydraulic retention time is set as 1 h;

the microorganisms of both the aerobic and anoxic units were purchased from Foshan Biwofeng.

The bottom of the first-stage aerobic unit 2 and the bottom of the second-stage aerobic unit 3 are both provided with first aeration devices which are aeration coil pipes for supplying air and oxygen. The first-stage oxygen-poor unit 4 and the second-stage oxygen-poor unit 5 are both provided with stirring devices for slowly stirring liquid in the corresponding oxygen-poor units. The total effective volume of the hydrolysis acidification tank 1, the aerobic unit and the anoxic unit is 200m ³ Wherein the effective volume ratio of the hydrolysis acidification tank 1, the primary aerobic unit 2, the primary anoxic unit 4, the secondary aerobic unit 3 and the secondary anoxic unit 5 is 4:2:1:3: 2.

In step S300, the wastewater obtained in step S200 is input into a sludge-water separation unit 6, the sludge-water separation unit 6 comprises an MBR membrane device 7, a second aeration device, a water outlet, a conical bottom and a first sludge outlet from top to bottom, and the wastewater subjected to aerobic and anoxic alternate biochemical treatment is subjected to MBR membrane treatmentThe device 7 is used for separating mud and water, the MBR membrane device is a tubular integrated MBR membrane device, the MBR membrane is a PVDF membrane, the sludge concentration is 10g/L, and the membrane flux is 10-15L/m ² H, membrane filament area 900m ² Operating negative pressure of-0.06-0.02 Mpa, aeration rate of 10.8m ³ /min；

The bottom of the mud-water separation unit 6 is conical, so that primary sludge can be discharged conveniently; the first sludge discharge port is connected with the hydrolysis acidification tank 1 through a reflux pump 8 and a pipeline and is used for periodically inputting primary sludge into the hydrolysis acidification tank 1. The second aeration device is an aeration coil pipe.

The circulating barrel 10 is arranged between the mud-water separation unit 6 and the electrochemical reactor 9, a water outlet of the mud-water separation unit 6 is connected with a water inlet of the circulating barrel 10, a backflow outlet 11 of the electrochemical reactor 9 is connected with a backflow inlet 12 of the circulating barrel 10, and the circulating barrel 10 is connected with the water inlet of the electrochemical reactor 9 through a first pump 13 and a pipeline;

and (3) inputting the wastewater to be deeply oxidized and the backflow wastewater of the electrochemical reactor 9 into a circulating barrel 10, uniformly mixing to obtain mixed wastewater, and inputting the mixed wastewater into the electrochemical reactor 9 through a first pump 13.

The electrochemical reactor 9 comprises an anode plate, a cathode plate, a third aeration device and a direct current power supply 14, wherein the anode plate is electrically connected with a positive electrode interface of the direct current power supply 14, and the cathode plate is electrically connected with a negative electrode interface of the direct current power supply 14; the third aeration device is arranged at the bottom of the electrochemical reactor 9, and the direct current power supply 14 is arranged outside the electrochemical reactor 9;

the anode plate is selected from a BDD anode plate, a Fe film electrode anode plate and an Al film electrode anode plate, and the cathode plate is a stainless steel film electrode cathode plate; the third aeration device is an aeration coil pipe.

The backflow outlet 11 is arranged at the lower part of the electrochemical reactor 9 and is used for returning the water body part in the electrochemical reactor 9 to the circulating barrel 10, and the backflow ratio is 25%.

The electrode plates within the electrochemical reactor 9 are arranged such that: the stainless steel thin film electrode cathode plate, the BDD anode plate, the stainless steel thin film electrode cathode plate, the Fe thin film electrode anode plate, the stainless steel thin film electrode cathode plate, the Al thin film electrode anode plate and the stainless steel thin film electrode cathode plate are arranged in this way.

The ratio of the amount of water refluxed from the reflux outlet 11 to the circulation tub 10 to the total amount of water in the electrochemical reactor 9 was 0.25: 1.

In the step S500, a flocculant storage tank 16 is arranged outside the coagulation tank 15, the flocculant storage tank 16 is connected with the coagulation tank 15 through a second pump 17 and a pipeline, a fourth aeration device is arranged at the bottom of the coagulation tank 15 and is used for fully mixing a flocculant with wastewater, the flocculant comprises PAM and PAC flocculant, the flocculant generates alum flocs in the coagulation tank 15, the alum flocs are sufficiently decomposed with the wastewater, and pollutants in the wastewater are adsorbed and captured by a net. The fourth aeration device is an aeration coil pipe.

In the step S600, three sludge discharge slideways 19 which are parallel to each other are uniformly arranged at the upper part of the horizontal pipe sedimentation tank 18, the sludge discharge slideways 19 are obliquely arranged, and the included angle between the sludge discharge slideways 19 and the horizontal line is 70 degrees, so that the sludge in the wastewater obtained in the step S500 is separated and discharged to the lower part of the horizontal pipe sedimentation tank 18; the bottom of the horizontal pipe sedimentation tank 18 is conical, so that secondary sludge is conveniently discharged; and a second sludge discharge port is formed in the bottom of the horizontal pipe sedimentation tank 18 and connected with the reflux pump 8 through a pipeline and used for inputting secondary sludge into the hydrolysis acidification tank 1.

Arrange mud slide 19's one side and evenly be equipped with four swash plates 20 that are parallel to each other, swash plate 20 and row mud slide 19 lateral wall looks perpendicular, and row mud slide 19's lateral wall is connected to swash plate 20's one end, and the other end is equipped with baffle 21, and baffle 21 parallels with row mud slide 19's lateral wall.

The top of the horizontal pipe sedimentation tank 18 is provided with a water inlet for inputting wastewater, and the wastewater enters each sludge discharge slideway 19 from the top in the horizontal pipe sedimentation tank 18; the middle part of the horizontal pipe sedimentation tank 18 is provided with a water outlet for discharging produced water.

Comparative example 1

The comparative example adopts the traditional A/O process to treat the high-salt-content wastewater, namely the high-salt-content wastewater directly enters the anoxic tank, the aerobic tank and the sedimentation tank from the regulating tank in sequence to finally obtain the produced water. The total effective volume of the reaction tank of the anoxic tank and the aerobic tank is 200m ³ Wherein the effective volume ratio of the anoxic tank to the aerobic tank is 3: 5. Anoxic tank structure, microorganism and process operation conditions andthe anoxic unit of example 1 is the same, and the structure, microorganisms and process operating conditions of the aerobic tank are the same as those of the aerobic unit of example 1. The sedimentation tank is a common inclined plate sedimentation tank, the nitrified liquid in the aerobic tank flows back to the anoxic tank, the reflux ratio is 100 percent, and part of sludge in the sedimentation tank flows back to the anoxic tank.

Comparative example 2

The method for treating wastewater with high salt content in the comparative example is the same as that in example 1, except that the aerobic units and the anoxic units in step S200 are switched in sequence, that is, the wastewater obtained in step S100 passes through the primary anoxic unit 4, the primary aerobic unit 2, the secondary anoxic unit 5 and the secondary aerobic unit 3 in sequence.

Comparative example 3

The method for treating high-salinity wastewater in the comparative example is the same as that in example 1, except that a MICROPLEX ™ CAB-AD anaerobic microbial agent is added into the hydrolysis acidification tank 1 in the step S100, and the microorganisms cannot digest sludge, so that a large amount of sludge residue is caused.

Comparative example 4

The method for treating wastewater containing high salt in this comparative example is the same as in example 1 except that the sludge-water separation unit 6 of step S300 is not provided with the MBR membrane device 7 and the second aeration device, and sludge-water separation is performed by natural sedimentation.

Table 1 comparison of water quality of produced water for example 1 and comparative example

From the above table, it can be known that the produced water in example 1 reaches the first grade a standard in pollutant discharge standard of municipal wastewater treatment plant (GB 18918-2002), and the quality of the produced water is good, and the method for treating high-salt-content wastewater according to the present invention has a good treatment effect on high-salt-content wastewater. As seen from comparative example 2, the aerobic, anoxic process sequence of step S200 has an important effect on the removal of total nitrogen. It is seen from comparative example 4 that the MBR membrane apparatus of step 300 can be matched with a horizontal pipe sedimentation tank to enhance the removal of sludge and also has an effect on the removal of ammonia nitrogen and COD.

Example 2

The method for treating wastewater containing high salt content in this embodiment is the same as that in embodiment 1, except that, as shown in fig. 2, the sludge discharge chute 19 of the horizontal pipe sedimentation tank 18 includes four sections of inclined branch chutes connected end to end, two adjacent branch chutes incline to different directions, respectively, the first branch chute inclines to the left, the second branch chute inclines to the right, the third branch chute inclines to the left, the fourth branch chute inclines to the right, the first branch chute and the fourth branch chute are sequentially connected end to end from top to bottom, the first branch chute is parallel to the third branch chute, and the second branch chute is parallel to the fourth branch chute, so that the sludge discharge chute 19 is in a zigzag manner; the partition plate of each branch slideway points to the oblique lower side.

The inclined plates 20 at the head-tail connection positions of the two adjacent sub-slideways are not connected with the partition plates 21 but are connected with each other and form a quadrangle with the respective sub-slideways, so that the two sub-slideways are more stable.

Example 3

The method for treating wastewater with high salt content in this embodiment is the same as that in embodiment 2, except that, as shown in fig. 3, the top of the partition plate 21 of the single-number partial slide way (i.e. the first partial slide way and the third partial slide way) is connected with the corresponding inclined plate 20, so that the partition plates 21 of the single-number partial slide way are all directed obliquely downward; the bottom of the partition board 21 of the double-fraction slide way (i.e. the second and fourth fraction slide ways) is connected with the corresponding inclined board 20, so that the partition boards 21 of the double-fraction slide way are all directed obliquely upwards. One end of the sloping plate 20 of the double-fraction slide way is rotatably connected with the side wall of the mud discharge slide way 19, so that the sloping plate 20 drives the partition plate 21 to rotate up and down for adjusting the water velocity and the turbulent flow condition in the horizontal tube sedimentation tank 18. When the water flow is fast, the inclined plate 20 of the double-fractional slideway is fixed, so that the function of intercepting part of the water flow is achieved, and the flow speed is stable; when the water flow is slow, the inclined plate 20 of the double-fractional slideway swings up and down to increase the disturbance of the water flow, and the inclined plate 20 swings freely under the action of the water flow. The flow rate of the water inlet pipe of the horizontal pipe sedimentation tank is 0.4m/s, and the flow rate of the water outlet pipe is 0.7-1.0 m/s.

Example 4

The method for treating wastewater with high salt content in the embodiment is the same as that in embodiment 3, except that as shown in fig. 4, a row of serpentine cooling coils 22 are embedded inside the inclined plates 20 of the single sub-slide for cooling the wastewater passing through the sub-slides;

the cooling water inlet pipe and the cooling water outlet pipe respectively penetrate through the top wall of the horizontal pipe sedimentation tank 18 and are connected with three water inlet branch pipes and three water outlet branch pipes in parallel, the water inlet branch pipes and the water outlet branch pipes extend and are embedded in the side wall, provided with the inclined plate 20, of each sludge discharge slideway 19, and extend downwards to the side wall of each branch slideway, and are connected with the cooling coil 22 of the inclined plate 20 of the odd branch slideway to supply cooling water for the cooling coil 22; and the sloping plate 20 of the double-fraction slideway is not provided with the cooling coil 22, so that the cold energy can be saved.

Because the sludge discharge slide ways 19 are inclined, the outer walls of the horizontal tube sedimentation tanks 18 are vertical, and a space is arranged between the inner wall of the horizontal tube sedimentation tank 18 and the nearest sludge discharge slide way 19 and is a cooling jacket, and cooling water is introduced to assist the wastewater to separate out salt. The cooling coil and the cooling jacket are filled with cooling water at 10 ℃.

Example 5

The method for treating wastewater with high salt content in the embodiment is the same as that in embodiment 4, except that the top end of the partition plate 21 of the double-fractional slide is connected to one side of the crystallization net, the other side of the crystallization net is fixed on the other side wall of the double-fractional slide, the crystallization net is horizontal when the inclined plate 20 of the double-fractional slide is static, the crystallization net is composed of transverse and longitudinal crossed net lines, and the crossed nodes of the net lines become crystallization nucleation sites to provide crystal nuclei for salt crystallization in the wastewater.

TABLE 2 comparison of precipitation Effect of examples 1 to 3 and comparative example 5

Table 3 comparison of produced water salinity for examples 1, 4, 5

As can be seen from Table 2, the horizontal pipe sedimentation tank of the invention has good effect on sludge sedimentation in high-salinity wastewater, the design of the multistage slide way strengthens the separation effect, and the inclined plate and the partition plate are improved to further promote sludge sedimentation. As can be seen from table 3, the concentration of potassium salt in the produced water of example 1 is close to that of the inlet water, the salt content is high, the salt content in the produced water is obviously reduced after the sludge discharge slideway with the cooling effect is adopted, and the potassium salt precipitation effect is better when the crystal net is used.

Claims

1. The method for treating the high-salt-content wastewater is characterized by comprising the following steps of:

s100: inputting the high-salinity wastewater, the primary sludge generated in the step S300 and the secondary sludge generated in the step S600 into a hydrolysis acidification pool, and performing hydrolysis acidification by utilizing salt-tolerant facultative sludge digestion bacteria in an anaerobic environment to realize sludge reduction and improve the biodegradability of the high-salinity wastewater;

s600: inputting the wastewater obtained in the step S500 into a horizontal pipe sedimentation tank for mud-water separation to obtain secondary sludge and produced water, and inputting the secondary sludge into the hydrolysis acidification tank for anaerobic treatment;

in the step S600, a plurality of sludge discharge slideways which are parallel to each other are arranged at the upper part of the horizontal pipe sedimentation tank, and the sludge discharge slideways are obliquely arranged and are used for separating sludge in the wastewater obtained in the step S500 and discharging the sludge to the lower part of the horizontal pipe sedimentation tank;

one side of the sludge discharge slideway is provided with a plurality of inclined plates which are parallel to each other from top to bottom, one end of each inclined plate is connected with the side wall of the sludge discharge slideway, and the other end of each inclined plate is provided with a partition plate which is parallel to the side wall of the sludge discharge slideway;

the mud discharging slideway comprises a plurality of sections of inclined sub-slideways which are connected end to end, and two adjacent sub-slideways are respectively inclined towards different directions, so that the mud discharging slideway is in a zigzag type;

the top of the partition plate of the odd numbered slide way is connected with the corresponding inclined plate, so that the partition plates of the odd numbered slide way point to the inclined lower part; the bottom of the partition plate of the double-fraction slide way is connected with a corresponding inclined plate, so that the partition plates of the double-fraction slide way point to the obliquely upper side;

a cooling coil is embedded in the inclined plate of the odd number branch slide way and is used for cooling the wastewater passing through the branch slide way, so that the salinity of the cooled wastewater is separated out;

the one side of crystal net is connected on the top of the baffle of double fraction slide, and the opposite side of crystal net is fixed on another lateral wall of double fraction slide, and the crystal net is for violently indulging criss-cross net twine and constitute, and the criss-cross node of net twine becomes crystallization nucleation site, provides the crystal nucleus for the salinity crystallization in the waste water.

2. The method for treating wastewater containing high salt content according to claim 1, wherein step S200 comprises the following steps:

(2) inputting the wastewater obtained in the step (1) into a first-stage anoxic unit, removing nitrite nitrogen and residual ammonia nitrogen in the wastewater through an anaerobic ammonia oxidation process, taking COD (chemical oxygen demand) which is not degraded by the first-stage aerobic unit as a carbon source, and removing nitrate nitrogen by using a denitrification process;

3. The method for treating wastewater with high salt content according to claim 2, wherein in the step (1), the hydraulic retention time in the primary aerobic unit is 10-12h, the sludge concentration is 4-4.5g/L, and the sludge load is 0.4-0.5 kg/(kg-d).

4. The method for treating wastewater with high salt content according to claim 3, wherein the temperature in the primary aerobic unit and the secondary aerobic unit is kept at 25-28 ℃, the pH value is 7.4-7.8, the hydraulic retention time ratio is 2:1, and the hydraulic retention time of the primary aerobic unit is 10-12 h.

5. The method for treating high-salinity wastewater according to claim 2, wherein the temperature in the primary anoxic unit and the secondary anoxic unit is kept at 30-35 ℃, the pH value is 7.0-7.5, the hydraulic retention time ratio is 2:1, and the hydraulic retention time of the primary anoxic unit is 2-2.5 h.

6. The method for treating wastewater with high salt content according to claim 1, wherein in step S300, the wastewater obtained in step S200 is fed into a sludge-water separation unit, the sludge-water separation unit comprises an MBR membrane device, a second aeration device, a water discharge port, a conical bottom and a first sludge discharge port from top to bottom, and the wastewater subjected to aerobic and anoxic alternate biochemical treatment is subjected to sludge-water separation in the MBR membrane device;

7. The method for treating high salinity wastewater according to claim 6, wherein the circulating barrel is arranged between the mud-water separation unit and the electrochemical reactor, the water outlet of the mud-water separation unit is connected with the water inlet of the circulating barrel, the backflow outlet of the electrochemical reactor is connected with the backflow inlet of the circulating barrel, and the circulating barrel is connected with the water inlet of the electrochemical reactor through the first pump and a pipeline;

8. The method for treating high salinity wastewater according to claim 6, wherein the bottom of the horizontal pipe sedimentation tank is tapered to facilitate the discharge of secondary sludge; and a second sludge discharge port is formed in the bottom of the horizontal pipe sedimentation tank and connected with the reflux pump through a pipeline and used for inputting secondary sludge into the hydrolysis acidification tank.