CN111762960A - System and method for treating percolate of old-age domestic garbage landfill - Google Patents

System and method for treating percolate of old-age domestic garbage landfill Download PDF

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CN111762960A
CN111762960A CN202010513100.XA CN202010513100A CN111762960A CN 111762960 A CN111762960 A CN 111762960A CN 202010513100 A CN202010513100 A CN 202010513100A CN 111762960 A CN111762960 A CN 111762960A
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黄开明
高本修
冷超群
李红
吕露
李明
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Wuhan Tianyuan Environmental Protection Co ltd
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2101/10—Inorganic compounds
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2101/30—Organic compounds
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/06—Contaminated groundwater or leachate
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/30—Aerobic and anaerobic processes

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Abstract

The invention provides a system and a method for treating percolate of an old life garbage landfill, wherein the system comprises a flocculation precipitation unit, a non-biochemical treatment mechanism and a biochemical treatment mechanism, a liquid outlet of the flocculation precipitation unit is respectively communicated with liquid inlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism through two branch pipelines, water production outlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism are respectively connected with a liquid inlet of the reverse osmosis treatment unit, concentrated water outlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism are respectively connected with a liquid inlet of the material film treatment unit, and a liquid outlet of the material film treatment unit is connected with a liquid inlet of the evaporation treatment unit. The invention integrates non-biochemical treatment, membrane treatment, evaporation and other processes, can realize independent operation of a plurality of processes, has flexible and changeable process combination and strong adaptability, effectively solves the problems of poor biodegradability of the existing old refuse landfill, reduced capacity of a treatment system and gradual increase of stock percolate, and realizes harmless treatment of percolate of the old refuse landfill.

Description

System and method for treating percolate of old-age domestic garbage landfill
Technical Field
The invention belongs to the technical field of wastewater treatment, and particularly relates to a system and a method for treating percolate of an old domestic garbage landfill.
Background
With the continuous high-speed growth of Chinese economy and the improvement of urbanization rate, the production amount of municipal solid waste is also rapidly increased. Compared with disposal methods such as incineration, composting and the like, the landfill disposal of the municipal solid waste is the cheapest in terms of development and construction costs, and is still applied on a large scale at present. In China, the garbage treated by adopting a landfill mode accounts for about 70% of all the treated garbage, and huge garbage percolate generated by landfill has increasingly attracted wide attention to the harm of ecological environment and human health. Along with the stricter pollution control and discharge standard of the landfill leachate, higher requirements are also put forward on the improvement and development of the landfill leachate treatment technology.
The landfill leachate contains a large amount of organic matters (including phenolic compounds, nitrogen-containing compounds, esters and ketones, olefins, alkanes, alcohols, polycyclic aromatic hydrocarbons, amines and phthalic acids) with difficult biodegradability, ammonia nitrogen, inorganic salts, heavy metals and the like, and the components of the organic matters are related to various factors, such as rainfall, climatic conditions, garbage types and compositions, and the like, particularly the landfill age. Generally speaking, as the landfill age increases, the pH value of landfill leachate is changed from acidity to alkalinity, the ammonia nitrogen concentration is gradually increased, and the biodegradability is gradually reduced. The landfill age of the aged landfill leachate generally reaches more than 10 years, and organic matters of the aged landfill leachate mainly comprise refractory substances such as humic acid, fulvic acid and the like, and have the characteristics of poor biodegradability, high ammonia nitrogen concentration and the like. At present, the domestic landfill leachate treatment technologies are roughly as follows:
(one) combination treatment method
The combined treatment method is a method for uniformly treating the landfill leachate by sending the landfill leachate to an urban domestic sewage plant or an industrial wastewater treatment plant. The Canadian scientific research institution treats the landfill leachate by a combined treatment method, and the operation is good when the mixing ratio is about 2 percent and the COD concentration is 24000 mg/L; the in-site pretreatment (stripping, coagulating sedimentation and coke adsorption) and merging treatment in an urban sewage treatment plant are adopted for treating the leachate in the Suzhou Qizi mountain landfill by the process of in-site pretreatment (stripping, coagulating sedimentation and coke adsorption) and merging treatment in the urban sewage treatment plant, so that the process is feasible, the merging treatment process is low in investment and low in operation cost, and a better effect can be achieved under the condition that the proportion of the two is well controlled, but the defects of the process are that the conveying cost is high, the urban sewage treatment plant is easy to impact, the sludge recycling is influenced by high-concentration heavy metal ions and the like, and the pollution control standard (GB 16889-2008) for the domestic garbage landfill specifies that the domestic garbage landfill is required to automatically treat the domestic leachate to the emission concentration limit value from 7/1 2011.
(II) land treatment method
The land treatment method is a method for purifying landfill leachate by utilizing an ecological system consisting of soil, microorganisms and plants under artificial regulation and control, and mainly comprises a landfill leachate recharging method, a slow infiltration method, a fast infiltration method, a surface overflow method, a wetland system, a soil plant treatment system (S-P system) and the like. The land treatment method and the combined treatment method have the advantages of low investment and low operation cost, but have the hidden dangers of large occupied area, improper operation, easy soil secondary pollution and the like, so the actual application is not wide.
(III) physicochemical method
The physical and chemical method is a garbage leachate treatment method combining a physical process and a chemical process or comprising a single physical process and a single chemical process, such as coagulation, adsorption, chemical oxidation, photocatalytic oxidation, ultrasound, electrolysis, electrodialysis, ion exchange, reverse osmosis and the like. The physicochemical method has stable operation, small occupied area and high adaptability to wastewater, and is gradually applied to the field of landfill leachate treatment in recent years, but the physicochemical method has high operation cost, large material consumption or energy consumption and is difficult to reach the national discharge standard by single treatment.
(IV) biological treatment
The biological treatment method of the landfill leachate is a method for separating and removing pollutants by adsorbing and degrading the pollutants by utilizing the characteristic that microorganisms can propagate in large quantities under certain conditions and the metabolism of the microorganisms. The biological treatment generally mainly includes three types of aerobic, anaerobic and anaerobic-aerobic biological combined treatment (facultative treatment) according to the respiration type of the microorganism.
Aerobic biological treatment is a method for degrading organic matters by aerobic microorganisms (aerobic bacteria play a main role and also comprise compatible microorganisms) in the presence of molecular oxygen in sewage, so that the organic matters are stabilized and harmlessly treated, the aerobic biological treatment has good operation efficiency, COD (chemical oxygen demand), BODS (boron Ds) and heavy metals can be effectively removed, and the main treatment methods comprise two major treatment methods, namely an activated sludge method and a biofilm method, and methods such as a biological filter, a Sequencing Batch Reactor (SBR), a biological rotating disk (RBC) and a stabilization pond. The activated sludge process is an aerobic biological process, and mainly comprises introducing a large amount of oxygen into sewage to accelerate the physiological activity of microorganisms and degrade pollutants by the microorganisms. It is widely used because of its low treatment cost and high efficiency.
Anaerobic biological treatment is a biological treatment method for degrading and stabilizing organic matters by utilizing facultative anaerobic bacteria under the anaerobic condition, has the advantages of low operation cost, no need of providing oxygen, easy operation and capability of improving the biodegradability of sewage, and the treatment process mainly comprises an Anaerobic Baffled Reactor (ABR), an EGSB reactor, an Upflow Anaerobic Sludge Blanket (UASB), an anaerobic biological filter, an Anaerobic Sequencing Batch Reactor (ASBR) and the like.
The development of the landfill leachate treatment technology goes through three stages of combined treatment, land treatment to physical and chemical treatment and biological treatment, and then to combined treatment of a plurality of technologies. According to the current development and application state of the landfill leachate treatment technology, biological treatment and physical and chemical treatment are mainstream treatment technologies, and a combined biological treatment and physical and chemical treatment process, a multi-stage biological combined treatment process and a multi-stage physical and chemical combined treatment process are combined treatment processes which are applied more generally. With the increasingly severe environmental situation and the implementation of more strict national and local pollutant emission standards, the development and optimization of various physicochemical technologies and high-efficiency biological treatment technologies are the main technical development directions in the next step; meanwhile, the existing treatment technology is integrated, a novel integrated combined treatment technology which is easy to operate and manage and meets the emission standard is developed, the construction cost of the landfill leachate treatment project and the daily operation cost of the landfill leachate treatment project are reduced, the treatment efficiency of the landfill leachate is integrally improved, and the integrated combined treatment technology is an application development direction of the landfill leachate treatment technology.
Disclosure of Invention
The invention aims to solve the problems of poor biodegradability of old refuse landfill, low capacity of a treatment system and gradual increase of stored percolate, and realize harmless treatment of percolate of old refuse landfill.
Therefore, the invention provides a percolate treatment system for an old-age domestic garbage landfill, which comprises a flocculation precipitation unit, a non-biochemical treatment mechanism and a biochemical treatment mechanism, wherein a liquid outlet of the flocculation precipitation unit is respectively communicated with liquid inlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism through two branch pipelines, water production outlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism are respectively connected with a liquid inlet of a reverse osmosis treatment unit, concentrated water outlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism are respectively connected with a liquid inlet of a material membrane treatment unit, and a liquid outlet of the material membrane treatment unit is connected with a liquid inlet of an evaporation treatment unit.
Furthermore, the flocculation and precipitation unit is provided with a dosing area, a reaction area, a precipitation area and a water production area, calcium oxide, sodium hydroxide, PAC (polyaluminium chloride) and PAM (polyacrylamide) reagents for flocculating and precipitating suspended matters and calcium and magnesium ions in the percolate are added into the reaction area, and the water production area is respectively communicated with liquid inlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism.
Furthermore, the biochemical treatment mechanism comprises a two-stage AO treatment unit, an ultrafiltration treatment unit and a nanofiltration treatment unit which are sequentially communicated, the liquid outlet of the flocculation precipitation unit is communicated with the liquid inlet of the two-stage AO treatment unit, the water outlet of the nanofiltration treatment unit is connected with the liquid inlet of the reverse osmosis treatment unit, and the concentrated water outlet of the nanofiltration treatment unit is connected with the liquid inlet of the material membrane treatment unit.
Furthermore, the non-biochemical treatment mechanism comprises an MBR pretreatment unit and a single-stage DT treatment unit, wherein a liquid inlet of the MBR pretreatment unit is communicated with a liquid outlet of the flocculation precipitation unit, a liquid outlet of the MBR pretreatment unit is communicated with a liquid inlet of the single-stage DT treatment unit, a water production outlet of the single-stage DT treatment unit is connected with a liquid inlet of the reverse osmosis treatment unit, and a concentrated water outlet of the single-stage DT treatment unit is connected with a liquid inlet of the material membrane treatment unit.
Furthermore, a concentrated water outlet of the reverse osmosis treatment unit is communicated with a liquid inlet of the single-stage DT treatment unit through a pipeline.
Furthermore, a concentrated water outlet of the reverse osmosis treatment unit is communicated with a liquid inlet of the material membrane treatment unit.
Furthermore, the reverse osmosis treatment unit is provided with an over-pass pipeline for directly discharging water produced by the non-biochemical treatment mechanism and the biochemical treatment mechanism.
In addition, the invention also provides a method for treating percolate of the aged domestic garbage landfill, which comprises the following steps:
1) introducing the aged domestic garbage landfill leachate into a flocculation precipitation unit, and passing suspended matters, colloidal particles and calcium-magnesium metal ions in the early leachate through the flocculation precipitation unit;
2) introducing a part of the effluent treated by the flocculation precipitation unit into a biochemical treatment mechanism for treatment, introducing a part of the effluent into a non-biochemical treatment mechanism for treatment, and forming water and concentrated water after the treatment of the biochemical treatment mechanism and the non-biochemical treatment mechanism;
3) the produced water obtained after the treatment of the biochemical treatment mechanism and the non-biochemical treatment mechanism is directly discharged outside or is treated by a reverse osmosis treatment unit to reach the standard and discharged according to the water quality condition;
4) introducing concentrated water obtained after treatment by the biochemical treatment mechanism and the non-biochemical treatment mechanism into the material membrane treatment unit, and intercepting macromolecular organic matters and divalent ions in the concentrated water;
5) and introducing the effluent treated by the material membrane treatment unit into an evaporation treatment unit for evaporation, discharging the evaporation produced water after reaching the standard, and returning the evaporation mother liquor to a refuse landfill for landfill.
Further, in the step 2), effluent treated by the flocculation precipitation unit sequentially passes through the two-stage AO treatment unit, the ultrafiltration treatment unit and the nanofiltration treatment unit in the biochemical treatment mechanism, water produced by the nanofiltration treatment unit enters the reverse osmosis treatment unit, and concentrated water produced by the nanofiltration treatment unit enters the material membrane treatment unit; effluent treated by the flocculation precipitation unit sequentially passes through the MBR pretreatment unit and the single-stage DT treatment unit in the non-biochemical treatment mechanism, produced water of the single-stage DT treatment unit enters the reverse osmosis treatment unit, and concentrated water of the single-stage DT treatment unit enters the material membrane treatment unit.
Further, in the step 3), part of the concentrated water generated by the reverse osmosis treatment unit enters the material membrane treatment unit for pretreatment, then enters the evaporation treatment unit for treatment, and the other part of the concentrated water returns to the single-stage DT treatment unit of the non-biochemical treatment mechanism for secondary treatment.
Compared with the prior art, the invention has the beneficial effects that:
(1) the percolate treatment system and method for the aged domestic refuse landfill provided by the invention integrate the processes of non-biochemical treatment, membrane treatment, evaporation and the like, can realize independent operation of a plurality of processes, can realize combined treatment of a plurality of process routes, can be adjusted in time according to the water quality condition, has flexible and changeable process combinations and strong adaptability, effectively solves the problems of poor biodegradability of the existing aged refuse landfill, reduced capacity of a treatment system and gradual increase of stored percolate, and realizes harmless treatment of percolate of the aged refuse landfill.
(2) The leachate treatment system for the old domestic garbage landfill provided by the invention adopts the material membrane to pretreat the evaporation treatment unit, effectively intercepts COD (chemical oxygen demand) and calcium and magnesium ions, and avoids the problems of bubbles and scaling generated by the evaporation treatment unit.
The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
FIG. 1 is a schematic view of a leachate treatment system of an aged domestic garbage landfill in an embodiment of the present invention.
Description of reference numerals: 1. a flocculation precipitation unit; 2. an MBR pretreatment unit; 3. a single stage DT processing unit; 4. a two-stage AO processing unit; 5. an ultrafiltration treatment unit; 6. a nanofiltration treatment unit; 7. a reverse osmosis treatment unit; 8. a material film processing unit; 9. and an evaporation treatment unit.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
as shown in fig. 1, the embodiment provides a leachate treatment system for an old-age domestic garbage landfill, comprising a flocculation precipitation unit 1, a non-biochemical treatment mechanism and a biochemical treatment mechanism, wherein a liquid outlet of the flocculation precipitation unit 1 is respectively communicated with liquid inlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism through two branch pipelines, water production outlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism are respectively connected with a liquid inlet of a reverse osmosis treatment unit 7, concentrated water outlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism are respectively connected with a liquid inlet of a material membrane treatment unit 8, and a liquid outlet of the material membrane treatment unit 8 is connected with a liquid inlet of an evaporation treatment unit 9. The method integrates non-biochemical treatment, membrane treatment, evaporation and other processes, can realize independent operation of a plurality of processes, can realize combined treatment of a plurality of process routes, can be adjusted in time according to water quality conditions, has flexible and changeable process combinations and strong adaptability, effectively solves the problems of poor biodegradability of the existing old refuse landfill, reduced capacity of a treatment system and gradually increased stock leachate, and realizes innocent treatment of leachate of the old refuse landfill.
The biochemical treatment mechanism comprises a two-stage AO treatment unit 4, an Ultrafiltration (UF) treatment unit 5 and a Nanofiltration (NF) treatment unit 6 which are sequentially communicated, a liquid outlet of the flocculation precipitation unit 1 is communicated with a liquid inlet of the two-stage AO treatment unit 4, a water production outlet of the nanofiltration treatment unit 6 is connected with a liquid inlet of a Reverse Osmosis (RO) treatment unit 7, and a concentrated water outlet of the nanofiltration treatment unit 6 is connected with a liquid inlet of a material membrane treatment unit 8. The non-biochemical treatment mechanism comprises an MBR pretreatment unit 2 and a single-stage DT treatment unit 3, wherein a liquid inlet of the MBR pretreatment unit 2 is communicated with a liquid outlet of the flocculation precipitation unit 1, a liquid outlet of the MBR pretreatment unit 2 is communicated with a liquid inlet of the single-stage DT treatment unit 3, a water production outlet of the single-stage DT treatment unit 3 is connected with a liquid inlet of the reverse osmosis treatment unit 7, and a concentrated water outlet of the single-stage DT treatment unit 3 is connected with a liquid inlet of the material membrane treatment unit 8.
Specifically, as the leachate of the old refuse landfill has high suspended matters and high salinity, the leachate directly enters a biochemical treatment unit or a non-biochemical treatment unit, scaling is easy, cleaning is frequent, and the system operation stability is poor, the flocculation precipitation unit 1 is firstly adopted to precipitate suspended matters and colloidal particles; the flocculation precipitation unit 1 is provided with a dosing area, a reaction area, a precipitation area and a water production area, sludge at the bottom of the precipitation area enters a sludge concentrated solution pool through a sludge discharge pump, part of water produced in the water production area enters a two-stage AO treatment unit 4 in a biochemical treatment mechanism, and part of the water produced in the water production area enters an MBR pretreatment unit 2 in a non-biochemical treatment mechanism. The aged refuse landfill leachate stays in the flocculation precipitation unit 1 for 2-5 hours, and calcium oxide, PAC and PAM are added into the flocculation precipitation unit 1 as medicaments to perform flocculation precipitation reaction with the aged refuse landfill leachate. The calcium oxide can adjust the pH value of the solution to enable metal ions such as magnesium ions and the like to form complex compound precipitation separation, and can reduce sulfate radicals, bicarbonate radicals and alkalinity, the adding amount of the calcium oxide is 0.01-0.5% of the quality of percolate of an old garbage landfill, the adding amount of the sodium hydroxide is 0.01-0.5% of the quality of percolate of the old garbage landfill, the PAC and the PAM are respectively an inorganic polymer flocculant and an organic polymer flocculant to enable large-particle matters such as suspended matters, colloids and the like in the solution to be coagulated and precipitated, the adding amount of the PAC is 0.05-0.5% of the quality of the percolate of the old garbage landfill, and the adding amount of the PAM is 0.001-0.005% of the quality of the percolate of the old garbage landfill.
Part of effluent of the flocculation precipitation unit 1 enters a two-stage AO treatment unit 4 through a lift pump, and the two-stage AO treatment unit 4 is provided with a stirring device, an aeration device and a reflux pump. Firstly, performing denitrification reaction on percolate in an anoxic section, wherein in order to avoid the phenomenon that the carbon source is insufficient in a primary denitrification section caused by water quality fluctuation, a denitrification tank is provided with a submersible stirrer, a carbon source storage tank and an adding device; nitrites and nitrates which flow back from the nitrification section and the ultrafiltration membrane device are subjected to denitrification reaction and reduced into nitrogen, and part of COD is removed; then enters the nitrification section, most of organic pollutants are degraded in the nitrification section, and most of NH in the sewage is treated by the action of nitrifying bacteria3-N is oxidized to nitrite or nitrate; the effluent of the first grade A/O denitrification unit enters a second grade A/O denitrification unit for enhanced denitrification, a large amount of nitrite and nitrate in the water are subjected to denitrification reaction and reduced into nitrogen, and COD and BOD in the water are further removed5Ammonia nitrogen, total nitrogen and other pollutants. The effluent of the flocculation precipitation unit 1 stays for 8-12 days in the two-stage AO treatment unit 4, the COD removal rate reaches 60-85%, and the ammonia nitrogen removal rate reaches 90-99%.
After the enhanced denitrification of the secondary denitrification section, the leachate enters an external Ultrafiltration (UF) treatment unit 5, an ultrafiltration membrane in the ultrafiltration treatment unit 5 effectively intercepts biochemical sludge, the sludge loss is avoided, and the intercepted biochemical sludge flows back to the primary denitrification. The ultrafiltration membrane adopts a tubular ultrafiltration membrane, the water yield of an ultrafiltration system is ensured by a high-speed cross flow operation mode, a reflux pump and a circulating pump are arranged, the reflux ratio is 8-12 times, and the circulating flow is 100-265 square/hour.
The produced water of the ultrafiltration treatment unit 5 also has a part of COD and ammonia nitrogen, and needs to be further treated by a nanofiltration treatment unit 6, and the nanofiltration treatment unit 6 can treat the COD and the BOD5The interception rate of divalent ions is more than 90%, but ammonia nitrogen and total nitrogen are difficult to reach the discharge standard, so that the produced water of the nanofiltration treatment unit 6 enters the reverse osmosis treatment unit 7 to further treat the ammonia nitrogen and the total nitrogen, the water production rate of the nanofiltration treatment unit 6 is 70-85%, and the concentrated water of the nanofiltration treatment unit 6 enters a material membraneThe processing unit 8 processes the waste water and then enters the evaporation processing unit 9 for processing.
The Reverse Osmosis (RO) processing unit 7 carries out treatment on COD and BOD in the percolate5The ammonia nitrogen, the total nitrogen, the heavy metal and the like have the rejection rate of more than 90 percent, so that the effluent quality is better, and the effluent of the reverse osmosis treatment unit 7 can reach the standard discharge or reuse. Furthermore, a surpassing pipeline which can be used for directly discharging water produced by the non-biochemical treatment mechanism and the biochemical treatment mechanism is arranged on the reverse osmosis treatment unit 7, and when the effluent of the nanofiltration treatment unit 6 or the single-stage DT treatment unit 3 can reach the standard, the effluent of the nanofiltration treatment unit 6 or the single-stage DT treatment unit 3 is directly discharged through the surpassing pipeline. The water yield of the reverse osmosis treatment unit 7 is 70-80%, part of the concentrated water of the reverse osmosis treatment unit 7 enters the material membrane treatment unit 8 for pretreatment and then enters the evaporation treatment unit 9 for treatment, and part of the concentrated water returns to the single-stage DT treatment unit 3 for secondary treatment.
For the aged refuse landfill leachate with poor biodegradability, a biochemical-free treatment process route is set for ensuring the stability of the treatment process, part of produced water of the flocculation precipitation unit 1 enters an MBR pretreatment unit 2 of a non-biochemical treatment mechanism, SS and sulfur simple substances are further reduced, and the stable operation of a single-stage DT treatment unit 3 is ensured due to the produced water. An aeration device, a reflux pump and a cleaning pump are arranged in the MBR pretreatment unit 2.
As COD, ammonia nitrogen and total nitrogen in the produced water of the MBR pretreatment unit 2 are high, the COD, ammonia nitrogen and total nitrogen are reduced to the discharge standard by adopting a DT high-pressure reverse osmosis technology, the water production rate of the single-stage DT treatment unit 3 is 70-80%, the operation pressure is 30-90 Bar, the produced water of the single-stage DT treatment unit 3 can be directly discharged outwards or enters a reverse osmosis treatment unit 7 for further treatment according to the water quality condition of the produced water, and the concentrated water of the single-stage DT treatment unit 3 enters a material membrane treatment unit 8 for pretreatment and then enters an evaporation treatment unit 9 for treatment.
Because the concentrated water of the nanofiltration treatment unit 6, the concentrated water of the reverse osmosis treatment unit 7 and the concentrated water of the single-stage DT treatment unit 3 contain a large amount of water, the separation and extraction can be further carried out, and the water yield of the percolate is further improved. At present, the process suitable for the membrane concentrated solution treatment process is an evaporation process, but the membrane concentrated solution has high organic matter and high salt content, the evaporation treatment is directly adopted, the system stability is poor, and the cleaning is frequent. Macromolecular organic matter in the membrane concentrate can effectively be drawed through material membrane processing unit 8 in this embodiment, and then solve evaporation system's bubble problem, and in addition, material membrane processing unit 8 can effectively hold back divalent ion, reduces the hardness in the membrane concentrate for evaporimeter scale deposit problem can delay. The yield of the material membrane treatment unit 8 can reach 90-98%, divalent ions can be intercepted by 50-70%, and concentrated water of the material membrane treatment unit 8 returns to a refuse landfill for landfill.
The membrane concentrated solution enters an evaporation treatment unit 9 after being pretreated by a material membrane treatment unit 8, the evaporation treatment unit 9 is a low-temperature forced circulation evaporator, the pH of inlet water of the low-temperature forced circulation evaporator is controlled between 4 and 6 by adding acid, the evaporator is prevented from scaling, and meanwhile, a defoaming agent and a scale inhibitor are configured in the evaporator. And in the evaporation process, the temperature is controlled to be 30-70 ℃, the vacuum degree is 0.01-0.006 Mpa, the water production rate is 80-95%, the produced water is discharged after reaching standards, and the mother liquor returns to a refuse landfill for landfill.
Example 2:
a certain landfill leachate COD of Anhui province is 1800mg/L, ammonia nitrogen is 1400 mg/L, conductivity is 27000uS/cm, and a 400t/d treatment system is designed. By adopting the percolate treatment system for the aged domestic garbage landfill, firstly, the percolate firstly enters a flocculation precipitation unit, 0.05 percent of calcium oxide, 0.1 percent of sodium hydroxide, 0.2 percent of PAC and 0.001 percent of PAM are added, and after 3 hours of precipitation, the percolate respectively enters a two-stage AO treatment unit and an MBR pretreatment unit in two paths, wherein the COD removal rate at the stage reaches 20 percent, the ammonia nitrogen removal rate at the stage reaches 10 percent, the total nitrogen removal rate at the stage reaches 15 percent, and the conductivity removal rate at the stage reaches 5 percent. The design scale of the two-stage AO treatment unit is 200t/d, the retention time is 12 days, the reflux ratio of nitrate is 4:1, the COD removal rate reaches 60%, and the ammonia nitrogen removal rate reaches 95%. The water produced by the two-stage AO treatment unit enters an ultrafiltration treatment unit, the reflux ratio of the ultrafiltration treatment unit is 11 times, a circulating pump is 265 square/hour, the water produced by the ultrafiltration treatment unit enters a nanofiltration treatment unit, the water production rate of the nanofiltration treatment unit is 80 percent, the COD removal rate is 85 percent, and the ammonia nitrogen removal rate is 50 percent. 50% of produced water of the nanofiltration treatment unit and produced water of the reverse osmosis treatment unit are mixed and directly discharged, the other 50% of produced water of the nanofiltration treatment unit enters the reverse osmosis treatment unit for further treatment, and concentrated solution of the reverse osmosis treatment unit enters the material membrane treatment unit for treatment. 50% of the water produced by the flocculation precipitation unit enters an MBR pretreatment unit, the design scale of the MBR pretreatment unit is 200t/d, the retention time is 30 minutes, 3 times of backflow is set, the SS removal rate reaches 90%, and the sulfide removal rate reaches 95%. The water produced by the MBR pretreatment unit enters a single-stage DT treatment unit, the water production rate of the single-stage DT treatment unit is 67%, the operating pressure is 90bar, the COD removal rate reaches 95%, the ammonia nitrogen removal rate reaches 85%, the total nitrogen removal rate reaches 80%, 50% of the water produced by the single-stage DT treatment unit and the water produced by the reverse osmosis treatment unit are mixed and discharged, and the other 50% of the water produced by the single-stage DT treatment unit enters the reverse osmosis treatment unit for treatment and then reaches the standard and is discharged. The water produced by the nanofiltration unit and the water produced by the single-stage DT treatment unit enter a reverse osmosis treatment unit, the water production rate of the reverse osmosis treatment unit is 78 percent, the COD removal rate reaches 91 percent, the ammonia nitrogen removal rate reaches 85 percent, the total nitrogen removal rate reaches 80 percent, the water produced by the reverse osmosis treatment unit, 50 percent of nanofiltration water produced and 50 percent of DT water produced are mixed and discharged. 90% of the concentrated water of the reverse osmosis treatment unit enters the material membrane treatment unit for treatment, and 10% of the concentrated water enters the single-stage DT treatment unit for secondary treatment. The nanofiltration treatment unit concentrated water, the reverse osmosis treatment unit concentrated water and the single-stage DT treatment unit concentrated water enter the material membrane treatment unit for treatment, the water yield of the material membrane treatment unit is 90%, the COD removal rate is 85%, and the calcium and magnesium removal rate is 60%. And the produced water of the material membrane treatment unit enters an evaporation treatment unit for reduction treatment. And returning the concentrated solution and the evaporation mother solution of the material membrane treatment unit to a refuse landfill for landfill. 90% of water produced by the evaporation treatment unit, the pH value of inlet water is controlled to be 5.1, the operation temperature is 80 ℃, the vacuum degree is 0.01Mpa, the produced water reaches the standard and is discharged, and evaporation mother liquor returns to a landfill site for landfill.
Example 3:
the COD of the percolate of a certain refuse landfill in Hubei is 4500mg/L, the ammonia nitrogen is 2800 mg/L, the conductivity is 35000uS/cm, and a 300t/d treatment system is designed. By adopting the percolate treatment system for the aged domestic garbage landfill, firstly, the percolate firstly enters a flocculation precipitation unit, 0.05 percent of calcium oxide, 0.1 percent of sodium hydroxide, 0.2 percent of PAC and 0.001 percent of PAM are added, and after 3 hours of precipitation, the percolate respectively enters a two-stage AO treatment unit and an MBR pretreatment unit in two paths, wherein the COD removal rate at the stage reaches 30 percent, the ammonia nitrogen removal rate at the stage reaches 20 percent, the total nitrogen removal rate at the stage reaches 15 percent, and the conductivity removal rate at the stage reaches 15 percent. The design scale of the two-stage AO treatment unit is 200t/d, the retention time is 10 days, the reflux ratio of nitrate is 8:1, the COD removal rate reaches 80%, and the ammonia nitrogen removal rate reaches 98%. The water produced by the two-stage AO treatment unit enters an ultrafiltration treatment unit, the reflux ratio of the ultrafiltration treatment unit is 11 times, the circulating pump is 265 square/hour, the water produced by the ultrafiltration treatment unit enters a nanofiltration treatment unit, the water production rate of the nanofiltration treatment unit is 85 percent, the COD removal rate is 80 percent, and the ammonia nitrogen removal rate is 40 percent. 50% of produced water of the nanofiltration treatment unit and produced water of the reverse osmosis treatment unit are mixed and directly discharged, the other 50% of produced water of the nanofiltration treatment unit enters the reverse osmosis treatment unit for further treatment, and concentrated water of the nanofiltration treatment unit enters the material membrane treatment unit for treatment. 50% of the water produced by the flocculation precipitation unit enters an MBR pretreatment unit, the design scale of the MBR pretreatment unit is 100t/d, the retention time is 30 minutes, 3 times of backflow is set, the SS removal rate reaches 90%, and the sulfide removal rate reaches 95%. The water produced by the MBR pretreatment unit enters a single-stage DT treatment unit, the water production rate of the single-stage DT treatment unit is 65%, the operating pressure is 90bar, the COD removal rate reaches 90%, the ammonia nitrogen removal rate reaches 89%, and the total nitrogen removal rate reaches 90%. 50% of produced water of the single-stage DT treatment unit and the reverse osmosis treatment unit are discharged in a mixed manner, and the other 50% of produced water of the single-stage DT treatment unit is discharged after reaching the standard after entering the reverse osmosis treatment unit for treatment. The water produced by the nanofiltration treatment unit and the water produced by the single-stage DT treatment unit enter the reverse osmosis treatment unit, the water production rate of the reverse osmosis treatment unit is 78 percent, the COD removal rate reaches 95 percent, the ammonia nitrogen removal rate reaches 90 percent, and the total nitrogen removal rate reaches 85 percent. The water produced by the reverse osmosis treatment unit, 50 percent of nanofiltration water and 50 percent of DT water are mixed and discharged, 90 percent of concentrated water of the reverse osmosis treatment unit enters the material membrane treatment unit for treatment, and 10 percent of concentrated water enters the single-stage DT treatment unit for secondary treatment. The nanofiltration treatment unit concentrated water, the reverse osmosis treatment unit concentrated water and the single-stage DT treatment unit concentrated water enter the material membrane treatment unit for treatment, the water yield of the material membrane treatment unit is 90%, the COD removal rate is 90%, and the calcium and magnesium removal rate is 70%. And the produced water of the material membrane treatment unit enters an evaporation treatment unit for reduction treatment. And returning the concentrated solution and the evaporation mother solution of the material membrane treatment unit to a refuse landfill for landfill. 90% of water produced by the evaporation treatment unit, 5.4% of inlet water pH of the evaporation treatment unit, 75 ℃ of operation temperature, 0.01Mpa of vacuum degree and standard discharge of the produced water.
The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention.

Claims (10)

1. The utility model provides an old age domestic waste landfill leachate treatment system which characterized in that: including flocculation and precipitation unit, non-biochemical treatment mechanism and biochemical treatment mechanism, the liquid outlet of flocculation and precipitation unit communicates with the inlet of non-biochemical treatment mechanism and biochemical treatment mechanism respectively through two branch pipelines, the product water outlet of non-biochemical treatment mechanism and biochemical treatment mechanism all is connected with the inlet of reverse osmosis treatment unit, the dense water outlet of non-biochemical treatment mechanism and biochemical treatment mechanism all is connected with the inlet of material membrane processing unit, the liquid outlet of material membrane processing unit is connected with the inlet of evaporation treatment unit.
2. The leachate treatment system of the aged domestic garbage landfill site of claim 1, wherein: the flocculation and precipitation unit is provided with a dosing area, a reaction area, a precipitation area and a water production area, calcium oxide, sodium hydroxide, PAC (polyaluminium chloride) and PAM (polyacrylamide) reagents for flocculating and precipitating suspended matters and calcium and magnesium ions in the leachate are added into the reaction area, and the water production area is respectively communicated with liquid inlets of the non-biochemical treatment mechanism and the biochemical treatment mechanism.
3. The leachate treatment system of the aged domestic garbage landfill site of claim 1, wherein: the biochemical treatment mechanism comprises a two-stage AO treatment unit, an ultrafiltration treatment unit and a nanofiltration treatment unit which are sequentially communicated, the liquid outlet of the flocculation precipitation unit is communicated with the liquid inlet of the two-stage AO treatment unit, the water production outlet of the nanofiltration treatment unit is connected with the liquid inlet of the reverse osmosis treatment unit, and the concentrated water outlet of the nanofiltration treatment unit is connected with the liquid inlet of the material membrane treatment unit.
4. The leachate treatment system of the aged domestic garbage landfill site of claim 1, wherein: the non-biochemical treatment mechanism comprises an MBR pretreatment unit and a single-stage DT treatment unit, wherein a liquid inlet of the MBR pretreatment unit is communicated with a liquid outlet of the flocculation precipitation unit, a liquid outlet of the MBR pretreatment unit is communicated with a liquid inlet of the single-stage DT treatment unit, a water production outlet of the single-stage DT treatment unit is connected with a liquid inlet of the reverse osmosis treatment unit, and a concentrated water outlet of the single-stage DT treatment unit is connected with a liquid inlet of the material membrane treatment unit.
5. The leachate treatment system of the aged domestic garbage landfill site of claim 4, wherein: and a concentrated water outlet of the reverse osmosis treatment unit is communicated with a liquid inlet of the single-stage DT treatment unit through a pipeline.
6. The leachate treatment system of the aged domestic garbage landfill site as claimed in claim 1 or 5, wherein: and a concentrated water outlet of the reverse osmosis treatment unit is communicated with a liquid inlet of the material membrane treatment unit.
7. The leachate treatment system of the aged domestic garbage landfill site of claim 1, wherein: the reverse osmosis treatment unit is provided with an overrunning pipeline for directly discharging water produced by the non-biochemical treatment mechanism and the biochemical treatment mechanism.
8. A method for treating percolate of an old domestic garbage landfill is characterized by comprising the following steps:
1) introducing the aged domestic garbage landfill leachate into a flocculation precipitation unit, and passing suspended matters, colloidal particles and calcium-magnesium metal ions in the early leachate through the flocculation precipitation unit;
2) introducing a part of the effluent treated by the flocculation precipitation unit into a biochemical treatment mechanism for treatment, introducing a part of the effluent into a non-biochemical treatment mechanism for treatment, and forming water and concentrated water after the treatment of the biochemical treatment mechanism and the non-biochemical treatment mechanism;
3) the produced water obtained after the treatment of the biochemical treatment mechanism and the non-biochemical treatment mechanism is directly discharged outside or is treated by a reverse osmosis treatment unit to reach the standard and discharged according to the water quality condition;
4) introducing concentrated water obtained after treatment by the biochemical treatment mechanism and the non-biochemical treatment mechanism into the material membrane treatment unit, and intercepting macromolecular organic matters and divalent ions in the concentrated water;
5) and introducing the effluent treated by the material membrane treatment unit into an evaporation treatment unit for evaporation, discharging the evaporation produced water after reaching the standard, and returning the evaporation mother liquor to a refuse landfill for landfill.
9. The method for treating leachate from old domestic refuse landfill as claimed in claim 8, wherein in step 2), effluent treated by the flocculation precipitation unit passes through the two-stage AO treatment unit, the ultrafiltration treatment unit and the nanofiltration treatment unit in the biochemical treatment mechanism in sequence, the produced water of the nanofiltration treatment unit enters the reverse osmosis treatment unit, and the concentrated water of the nanofiltration treatment unit enters the material membrane treatment unit; effluent treated by the flocculation precipitation unit sequentially passes through the MBR pretreatment unit and the single-stage DT treatment unit in the non-biochemical treatment mechanism, produced water of the single-stage DT treatment unit enters the reverse osmosis treatment unit, and concentrated water of the single-stage DT treatment unit enters the material membrane treatment unit.
10. The method for treating leachate from old domestic refuse landfill as claimed in claim 9, wherein in step 3), part of the concentrated water generated by the reverse osmosis treatment unit enters the material membrane treatment unit for pretreatment, then enters the evaporation treatment unit for treatment, and part of the concentrated water returns to the single-stage DT treatment unit of the non-biochemical treatment mechanism for secondary treatment.
CN202010513100.XA 2020-06-08 2020-06-08 System and method for treating percolate of old-age domestic garbage landfill Pending CN111762960A (en)

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