WO2013010388A1

WO2013010388A1 - Apparatus for treating landfill leachate and treatment method therefor

Info

Publication number: WO2013010388A1
Application number: PCT/CN2012/072076
Authority: WO
Inventors: 张世文
Original assignee: 波鹰(厦门)科技有限公司
Priority date: 2011-07-21
Filing date: 2012-03-08
Publication date: 2013-01-24
Also published as: CN102603119B; CN102276117A; CN102603119A

Abstract

An apparatus for treating a landfill leachate and a treatment method therefor, comprising a regulation pool (1), a coagulation pool (2), a primary sedimentation pool (3), an electrolysis apparatus (4), a hydrolysis acidification pool (5), an anaerobic pool (6), an aerobic pool (7), a secondary sedimentation pool (8), a sludge pool (9), and a sludge dehydration apparatus (10). Mutual collaborations between each of the processing units allow improved treatment effects for the landfill leachate. While at the same time, the treatment method comprises the following steps: regulation, coagulation, sedimentation, electrolysis, hydrolysis acidification, anaerobic treatment, aerobic treatment, and secondary sedimentation. The treatment method allows not only for the landfill leachate treated to meet national discharge standards but also for greatly reduced costs.

Description

Landfill leachate treatment device and treatment method thereof

Technical field

The invention belongs to the field of environmental engineering, and relates to a sewage treatment device, in particular to a treatment device for a landfill leachate with lower cost and better effect; the invention also relates to a treatment method for the landfill leachate, The wastewater treated by the method can meet the discharge standard of the Domestic Waste Landfill Pollution Control Standard (GB16889-2008).

Background technique

Landfill leachate is a kind of high-concentration organic wastewater that is difficult to treat. It mainly comes from the following three aspects: 1. Natural rainfall and runoff in the landfill; 2. Water contained in the garbage itself; 3. After landfill Water produced by anaerobic decomposition of microorganisms; precipitation in the landfill is the main part. Typical values of municipal landfill leachate pollutants are shown in Table 1. Shown.

Table 1 Main components of general landfill leachate (except pH, and sensory index, the unit is mg/L)

project	variation range	project	variation range
Sensory index	Black / stench	chloride	189~3262
pH value	3.7 to 8.5	Fe	50-600
total hardness	3000~10000	Cu	0.1 to 1.43
COD _Cr	1200~100000	Ca	200~300
BOD ₅	200～60000	Pb	0.1～2.0
NH3-N	20~7400	Cr	0.01 to 2.61
Total phosphorus	1 to 70	Hg	0~0.032

It can be seen from Table 1 that the water quality of landfill leachate has the following basic characteristics:

(1) High concentration of pollutants, COD_Cr, BOD ₅Most of the ammonia nitrogen and ammonia nitrogen are tens to hundreds of times higher than the national emission standards for industrial pollutants.

(2) There are both organic and inorganic pollutants, as well as some traces of heavy metal pollution, and the comprehensive pollution characteristics are obvious.

(3) There are many types of organic pollutants and the composition is complex. There are many organic pollutants in landfill leachate, up to 77 kinds, including non-chlorinated aromatic compounds such as naphthalene and phenanthrene, chlorinated aromatic compounds, phosphate esters, phthalates, phenolic compounds and Aniline compounds and the like.

(4) The landfill leachate contains more than 10 kinds of metal ions, and the heavy metal ions can seriously inhibit the biological treatment process.

(5) The proportion of microbial nutrients in leachate is seriously deregulated. Among them, the concentration of ammonia nitrogen is very high, and the ratio of C/N is imbalanced. The nutrient ratio is far less than the nutrient ratio required for microbial growth during biological treatment, which brings certain difficulties to biological treatment.

Ammonia nitrogen content and COD of landfill leachate_CrThe high concentration makes the surface water body lack of oxygen and the water quality deteriorates; nutrients such as nitrogen and phosphorus are the cause of eutrophication of water bodies, and may also seriously affect drinking water sources; in general, COD_Cr, BOD ₅ , BOD ₅ /COD_CrIt will decrease with the “age” of the landfill, and the alkalinity will increase. In addition, with the increase of the stacking period, the fresh garbage gradually turns into old garbage, and the organic matter content in the leachate decreases, but the ammonia nitrogen content increases and the biodegradability decreases, so the treatment is very difficult.

The treatment of landfill leachate is focused on the treatment of COD and ammonia nitrogen, especially the treatment of ammonia nitrogen. A variety of processes and equipment for treating landfill leachate have appeared in the prior art. For example, in the patent document CN1485280A, a treatment process for landfill leachate by immersion combustion evaporation process is disclosed, which mainly processes the permeate by oxidizing organic matter into carbon dioxide and water and by evaporation and concentration. In the patent document CN1440941, a technique for treating landfill leachate by using an anaerobic molecular decomposition method is disclosed, which comprises a pre-decomposition step, an anaerobic step, a decomposition oxidation step, an adsorption step, a flocculation precipitation step, and a filtration step. It combines both physical and chemical treatments and biological treatments. Similarly, the landfill leachate disclosed in the patent document CN1478737 is also a combination of physicochemical treatment and biological treatment, in which the leachate subjected to electrolytic oxidation treatment is subjected to reverse osmosis treatment using a ceramic membrane.

Among the above treatment methods, in particular, the method used for treating ammonia nitrogen is an alkali stripping method or a chlorine folding method. As far as the current state of the art is concerned, the alkali stripping method cannot be popularized because of high suspended matter in the wastewater and high processing cost (20 yuan/m ³ ); the chlorine folding method has high ammonia nitrogen content and requires a large amount of chlorine gas and hydroxide. Sodium makes the cost very high (30 yuan / m ³ ), and it cannot be promoted.

In addition, the well-known electrolysis technology can effectively remove harmful substances in the landfill leachate, but the conventional electrolysis has low current density, high working potential, low electrical efficiency, large energy consumption, short life, and high cost. The effect of applying it to wastewater treatment is not satisfactory.

technical problem

The invention provides a treatment device for landfill leachate, and the landfill leachate treated by the treatment device can meet the discharge standard; the invention also provides a method for treating landfill leachate with simple process, low cost and good treatment effect, The purpose is to overcome the drawbacks of the prior art that the process is complicated and costly.

Technical solution

The technical solution of the present invention is as follows:

a treatment device for landfill leachate, comprising a regulating tank, a coagulation tank, a primary sedimentation tank, an electrolysis machine, a hydrolysis acidification tank, an anoxic tank, an aerobic tank, a secondary settling tank, a sludge tank and a sludge dewatering device; The inlet of the regulating tank is connected with the outlet of the landfill leachate, the water outlet of the regulating tank is connected with the water inlet of the concrete pool, the water outlet of the concrete pool is connected with the water inlet of the primary sedimentation tank, and the water outlet of the primary sedimentation tank is connected with the water inlet of the electrolytic machine. The water outlet of the electrolysis machine is connected with the water inlet of the hydrolysis acidification tank, the water outlet of the hydrolysis acidification tank is connected with the water inlet of the anoxic tank, the water outlet of the anoxic tank is connected with the inlet of the aerobic tank, and the water outlet of the aerobic tank is connected with the inlet of the second settling tank. The outlet of the secondary sedimentation tank is connected with the sewage discharge pipeline, the sludge outlet of the primary sedimentation tank and the secondary sedimentation tank is connected with the sludge tank, and a sludge pump is arranged between the sludge tank and the sludge dewatering device.

The adjustment tank and the coagulation tank respectively have a pH adjusting agent dosing device and a flocculating agent dosing device.

The processing apparatus further includes a mixed liquid reflux pump for returning a portion of the mixed liquid of the aerobic tank to the anoxic tank, the reflux ratio of the mixed liquid being 3:1 or 2:1.

The landfill leachate treatment method according to the present invention is realized by adopting the landfill leachate treatment device as described above and through the following steps:

a, flocculation and sedimentation

The landfill leachate enters the regulating tank through the pipeline, so that the flow and parameters of the different types of landfill leachate from all parts of the landfill can be fully adjusted to facilitate the subsequent unit treatment. Add pH adjuster to the adjustment tank to adjust the pH value to 7-10, then flow into the coagulation tank, add flocculant through the dosing device, enter the primary sedimentation tank after the reaction is complete, and the sediment (ie sludge) is sent to the sewage through the pump and pipeline. In the mud pool, finally, the filter is separated in the sludge dewatering device, and the wastewater enters the electrolysis machine;

b, electrolysis

The wastewater after flocculation and sedimentation treatment is pumped into the electrolysis machine for electrolysis. The working voltage of electrolysis is 2 to 1000V, the voltage between adjacent electrodes is 2 to 12V, the current density is 1 to 320 mA/cm ² , and the residence time of wastewater in the electrolysis machine is 2 to 50 s;

c, anaerobic treatment

The electrolyzed wastewater enters the hydrolysis acidification tank and the anoxic tank in turn, so that the macromolecular organic matter in the wastewater is hydrolyzed and acidified into small molecule organic matter by the acid-producing bacteria, and then passes through the anaerobic and facultative bacteria in the anoxic tank. Decompose into methane and carbon dioxide by adsorption, fermentation, and methanogenesis of various microorganisms, increase B/C value, improve biodegradability, and remove denitrification from denitrifying bacteria in anoxic tank. Ammonia nitrogen

d, aerobic treatment

The anaerobic treated wastewater enters an aerobic tank containing aerobic bacteria and nitric acid bacteria, and further decomposes the organic matter in the wastewater by aerobic microorganisms, deeply removes COD _Cr and BOD ₅ from the wastewater, and utilizes the nitrification of nitrifying bacteria and Nitrosation of nitrosated bacteria converts ammonia nitrogen into nitrate nitrogen or nitrite nitrogen;

e, precipitation

The aerobic treated wastewater flows into the secondary settling tank to further remove COD _Cr , BOD ₅ , SS, etc. from the wastewater. The effluent from the secondary settling tank can reach the standard discharge, and a part of the sludge at the bottom of the secondary settling tank is pumped back to the anoxic tank. The other part flows into the sludge tank through the pipeline, and then is separated into the filtrate and the mud cake by the sludge dewatering device. The filtrate is returned to the adjustment tank through the pipeline, and the mud cake is transported.

In the step a, the flocculating agent is aluminum salt (aluminum sulfate, aluminum chloride), iron salt (iron sulfate, ferrous sulfate, ferric chloride), poly aluminum (polyaluminum chloride, polyaluminum sulfate, polymerization) One or more combinations of aluminum silicate), polyferric iron (polyferric chloride, polyferric sulfate, and polymeric ferric silicate); the pH adjuster is sulfuric acid, sodium hydroxide, sodium carbonate, sodium hydrogencarbonate, One of the limes.

In the step a, the optimal flocculating agent is polyferric sulfate (PFS), and the dosage is 200-2000 g per ton of wastewater.

In the step a, the optimal flocculant is ferrous sulfate (FeSO ₄ ), and the dosage is 230-1800 g per ton of wastewater.

In step b, the anode of the electrolyzer is a metal or graphite electrode, and the cathode of the electrolyzer is an iron cathode, an aluminum cathode, a stainless steel cathode, a nickel cathode, a titanium or a zinc cathode.

Further, in step b, the structure of the nano catalytic electrolyzer is described in Chinese patent CN102010038A, the anode is a substrate made of titanium, and the surface of the substrate is covered with an inert electrode of a nanometer precious metal oxygen coating with a crystal grain size of 15 to 32 nm. . The cathode of the nano catalytic electrolysis machine is an iron cathode, an aluminum cathode, a stainless steel cathode, a nickel cathode, a titanium or a zinc cathode, and the like. The working voltage of the nano catalytic electrolysis machine is 2 to 500 V, the voltage between the two electrodes is 2 to 8 V, the electrolytic density is 10 to 300 mA/cm ² , and the residence time of the wastewater in the nano catalytic electrolysis machine is 2 to 30 s.

When the nano-catalyzed landfill leachate is produced, the free radical chlorine [Cl], free radical oxygen [O] and hydroxyl [OH] are produced to kill microorganisms in the wastewater, oxidize and decompose organic matter and ammonium ions in the wastewater, and make the organic in the wastewater. The material is opened in a large ring and the long chain is broken. It not only eliminates the chromaticity of the wastewater, but also removes the odor. It also improves the biodegradability of the wastewater and destabilizes the wastewater under the action of an electric field. Suspended matter and colloid in the wastewater. , charged particles, forming larger particles. In addition, the cations and anions in the wastewater move to the cathode and the anode, respectively, and an electric double layer and a multi-electrode layer act on the cathode and the anode to form a precipitation-induced flocculation and accelerate the sedimentation of the impurities; the small bubbles of hydrogen generated by the electrolysis also have an air flotation. effect.

The use of nanocatalysis has the following outstanding effects:

First, the macrocyclic compound in the wastewater is opened by electrolysis, and the long chain is broken, and the generated radical oxidizes and decomposes the organic matter, rapidly lowers the COD _Cr , and improves the biodegradability of the wastewater, thereby creating a more anaerobic unit for the subsequent anaerobic unit. Good biochemical conditions.

Secondly, a variety of free radicals (strong oxidizing substances) produced by electrolysis kill microorganisms in the wastewater, so that subsequent anaerobic treatment can produce a larger dominant flora, exert better biochemical effects, and make anaerobic The treated effluent water quality is better.

Third, the inorganic ammonium in the wastewater is oxidatively decomposed, and the ammonium ion is converted into nitrogen, nitrate, nitrite and water. The removal rate of ammonia nitrogen can reach 80-90%, and the ammonia nitrogen entering the pre-biochemical wastewater is less than 100 mg/L. At the same time, eliminate the smell of water.

Fourth, the chromaticity of the wastewater is greatly reduced. The strong oxidizing radicals such as chlorine [Cl], hydroxyl [OH] and oxygen [O] generated by electrolysis can oxidatively decompose the chromophores and the color-assisting groups remaining in the wastewater. , to reduce the color of the wastewater, to achieve the purpose of decolorization.

Fifth, deodorization, various radicals (strong oxidizing substances) generated by electrolysis oxidize and decompose the odorous groups in the wastewater to remove malodors in the wastewater.

Sixth, during the electrolysis, the cations and anions in the wastewater move to the cathode and anode of the electrolysis cell, respectively, and an electric double layer acts to form a precipitate near the cathode and the anode, thereby reducing the heavy metal ion content in the wastewater, thereby reducing heavy metal ions. The inhibition and toxic effects of anaerobic and aerobic microorganisms in subsequent units.

In the step d, the mixed liquid in the aerobic tank is partially returned to the anoxic tank, and the reflux ratio is 3:1 or 2:1, which is beneficial to the denitrification of the denitrifying bacteria in the anoxic tank to remove the ammonia nitrogen of the wastewater. .

Beneficial effect

From the above description of the invention, it is apparent that the advantages of the present invention over the prior art are:

(1) Through the electrolysis step, not only can COD _Cr be quickly reduced, but also the biodegradability of wastewater can be improved, and the removal rate of ammonia nitrogen can reach 80-90%. At the same time, heavy metal ions in wastewater can be effectively removed by electrolytic flocculation and sedimentation. Subsequent processing creates better biochemical conditions.

(2) The nano-catalytic electrolysis machine adopts an inert electrode whose surface is covered with a nano-catalytic coating with a good catalytic effect of 15 to 32 nm as an anode. The anode is not consumed, the cost is low, and the electric efficiency is high, which is the electrolysis efficiency of the common electrode. More than double, the electrical energy consumed by tons of wastewater treatment is greatly reduced.

(3) The biological treatment methods of anaerobic treatment and aerobic treatment can further effectively reduce ammonia nitrogen, COD _Cr and BOD _{5 in} landfill leachate.

(4) Through the orderly cooperation of the above steps, it can ensure that the discharge standard of the Domestic Waste Landfill Pollution Control Standard (GB16889-2008) is met after the landfill leachate treatment.

DRAWINGS

Figure 1 is a process flow diagram of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIG.

Referring to Fig. 1, a treatment device for landfill leachate comprises: a regulating tank 1, a coagulation tank 2, a primary sedimentation tank 3, an electrolysis machine 4, a hydrolysis acidification tank 5, an anoxic tank 6, an aerobic tank 7, and a secondary sedimentation tank. 8. Sludge tank 9 and sludge dewatering device 10; the inlet of the regulating tank 1 is connected with the outlet of the landfill leachate, the water outlet of the regulating tank 1 is connected with the water inlet of the coagulation tank 2, and the water outlet of the concrete pool 2 and the primary sedimentation tank 3 Inlet connection, the outlet of the primary sedimentation tank 3 is connected to the inlet of the electrolysis machine 4 via the water pump 34, the outlet of the electrolysis machine 4 is connected with the inlet of the hydrolysis acidification tank 5, and the outlet of the hydrolysis acidification tank 5 is connected with the inlet of the anoxic tank 6 The water outlet of the anoxic tank 6 is connected with the inlet of the aerobic tank 7, the outlet of the aerobic tank 7 is connected with the inlet of the second settling tank 8, and the outlet of the secondary settling tank 8 is connected with the sewage discharge pipe. The sludge outlets of the primary sedimentation tank 3 and the secondary sedimentation tank 8 are connected to the sludge tank 9, and a sludge pump 11 is provided between the sludge tank 9 and the sludge dewatering device 10, and the sludge pump 11 can be used for the sludge tank. The sludge in 9 is pumped into the sludge dewatering device 10 for treatment. The adjusting tank 1 and the coagulation tank 2 respectively have a pH adjusting agent dosing device (not shown) and a flocculating agent dosing device (not shown), and the dosing device can respectively adjust the adjusting tank 1 and A pH adjuster and a flocculant are added to the coagulation tank 2.

As can be seen in Figure 1, the processing apparatus also includes a mixed liquid return pump 67 that returns a portion of the aerobic tank 7 to the anoxic tank 6.

Embodiments of the invention

A specific embodiment of the landfill leachate treatment apparatus method is given below in conjunction with FIG.

Example 1

Leachate treatment project of 800 tons/day in a garbage sanitary landfill

The measured indexes of the raw water of the landfill leachate are shown in Table 2.

Table 2 Water quality of landfill leachate raw water.

Serial number	project	unit	measured value	Serial number	project	unit	measured value
1	COD _Cr	Mg/L	4000	5	Ammonia nitrogen	Mg/L	900
2	SS	Mg/L	600	6	Chroma	Times	1000
3	Turbidity	NTU	510	7	pH value	-	7.0
4	BOD ₅	Mg/L	2500	8	Conductivity	μS/cm	8500

It can be seen from Table 2 that the concentration of pollutants in landfill leachate is high, and COD _Cr , BOD ₅ and ammonia nitrogen are mostly tens to hundreds of times higher than the national emission standards for industrial pollutants. This embodiment can effectively utilize the above processing device to treat landfill leachate, and the specific processing method is as follows:

Step a, flocculation and sedimentation

The wastewater enters the adjustment tank 1 at a flow rate of 40 m ³ /h through water, and is fully mixed and then enters the coagulation tank 2. The reaction of adding 300 g of polyferric sulfate (PFS) per ton of wastewater is completed and then enters the primary settling tank 3, and the primary settling tank 3 The sludge is sent to the sludge tank 9 through a pump and a pipe, and finally filtered and separated in the sludge dewatering device 10, and the wastewater of the primary sedimentation tank 3 flows into the electrolysis machine 4 through the pump 34.

Step b, electrolysis

The wastewater is subjected to flocculation and sedimentation and then flows into the electrolysis machine 4 for electrolysis. The electrolysis machine 4 is a nano catalytic electrolysis machine having an operating voltage of 48 V, a current density of 200 mA/cm ² , a voltage between the two electrodes of 3.6 V, and waste water in the electrolysis machine 4 . The stay time is 10s. The highly oxidizing free radicals chlorine [Cl], oxygen [O] and hydroxyl [OH] produced by nanocatalytic microelectrolysis can rapidly oxidize and decompose organic substances in wastewater, and open and break large organic molecules that are difficult to biodegrade in wastewater. The chain and macromolecules are decomposed into small molecules, which reduce COD _Cr and improve the biodegradability of wastewater, and provide better conditions for biochemistry. At the same time, the chromophore and the chromophore of the dye molecules in the wastewater are oxidized or reduced to colorless. The group achieves the purpose of decolorization; in addition, the cations and anions in the wastewater move to the cathode and anode of the electrolysis cell 4, respectively, forming a precipitate near the cathode and the anode, thereby reducing the heavy metal ion content in the wastewater, thereby reducing heavy metals. The ions inhibit the anaerobic and aerobic microorganisms in the subsequent unit; in addition, the microorganisms in the wastewater can be killed, and the suspended solids, colloids and charged particles in the wastewater form larger particles under the action of the electric field.

Step c, anaerobic treatment

The electrolyzed wastewater enters the hydrolysis acidification tank 5 and the anoxic acid tank 6 in turn, so that the macromolecular organic matter in the wastewater is hydrolyzed and acidified into small molecular organic substances by the acid-producing bacteria, and then passes through the anaerobic bacteria in the anoxic tank 6, Decomposition into methane and carbon dioxide by adsorption, fermentation, and methanogenesis of various microorganisms such as facultative bacteria, increasing B/C value and improving biodegradability; and denitrifying by denitrifying bacteria in anoxic cell 6 In addition to ammonia nitrogen in wastewater.

Step d, aerobic treatment

The anaerobic treated wastewater enters the aerobic tank 7 in turn, and further decomposes the organic matter in the wastewater by aerobic microorganisms, and deeply removes COD _Cr and BOD ₅ from the wastewater, while utilizing the nitrification of nitrifying bacteria and the sub-nitrosation bacteria. Nitrification converts ammonia nitrogen into nitrate or nitrite. The mixed liquid in the aerobic tank 7 is returned to the anoxic tank 6 through the mixed liquid reflux pump 67 at a ratio of 2:1, and the ammonia nitrogen of the wastewater is removed by denitrification of the denitrifying bacteria in the anoxic tank 6.

Step e, precipitation

The aerobic treated wastewater flows into the secondary settling tank 8 for sedimentation and separation, further removing COD _Cr , BOD ₅ , SS, etc. from the wastewater. The effluent of the secondary settling tank 8 can reach the standard discharge, and the water quality of the effluent is shown in Table 3; A part of the sludge at the bottom of the sinking tank 8 is returned to the anoxic tank 6 via the pump 68, and the other part flows into the sludge tank 9 through the pipeline, and is separated into a filtrate and a mud cake by the sludge dewatering device 10, and the filtrate is returned to the pipeline through the pipeline. Adjust the pool 1 while the mud cake is shipped out.

Table 3 Water quality of landfill leachate after treatment

Serial number	project	unit	measured value	Serial number	project	unit	measured value
1	COD _Cr	Mg/L	80	5	Ammonia nitrogen	Mg/L	10
2	SS	Mg/L	30	6	Chroma	Times		10
3	Turbidity	NTU	twenty two	7	pH value	-	7.5
4	BOD ₅	Mg/L	30	8	Conductivity	μS/cm	6100

It can be seen from Table 3 that the content of COD _Cr and ammonia nitrogen is significantly reduced, and all the indicators can meet the discharge standard of “Standard for Pollution Control of Domestic Waste Landfill” (GB16889-2008).

Example 2

Leachate treatment project of 500 tons/day in a garbage sanitary landfill

The measured indexes of the raw water of the landfill leachate are shown in Table 4.

Table 4 Water quality of landfill leachate raw water.

Serial number	project	unit	measured value	Serial number	project	unit	measured value
1	COD _Cr	Mg/L	3610	5	Ammonia nitrogen	Mg/L	250
2	SS	Mg/L	248	6	Chroma	Times	600
3	Turbidity	NTU	300	7	pH value	-	7.0
4	BOD ₅	Mg/L	1920	8	Conductivity	μS/cm	7480

This embodiment can effectively utilize the above processing device to treat landfill leachate, and the specific processing method is as follows:

Step a, flocculation and sedimentation

The wastewater enters the adjustment tank 1 at a flow rate of 25 m ³ /h through water, and is fully mixed and then enters the coagulation tank 2, 500 g of ferrous sulfate is added per ton of wastewater, and after completion of the reaction, it enters the primary settling tank 3, and the sludge of the primary settling tank 3 is precipitated. It is sent to the sludge tank 9 via a pump and a pipe, and finally filtered and separated in the sludge dewatering device 10, and the wastewater of the primary settling tank 3 flows into the electrolysis machine 4 through the pump 34.

Step b, electrolysis

The wastewater is subjected to flocculation and sedimentation and then flows into the electrolysis machine 4 for electrolysis. The electrolysis machine 4 has an operating voltage of 4 V, a current density of 15 mA/cm ² , a voltage between the two electrodes of 2 V, and a residence time of the wastewater in the electrolysis machine 4 of 10 s.

Step c, anaerobic treatment

Step d, aerobic treatment

The anaerobic treated wastewater enters the aerobic tank 7 in turn, and further decomposes the organic matter in the wastewater by aerobic microorganisms, and deeply removes COD _Cr and BOD ₅ from the wastewater, while utilizing the nitrification of nitrifying bacteria and the sub-nitrosation bacteria. Nitrification converts ammonia nitrogen into nitrate or nitrite. The mixture in the aerobic tank 7 is returned to the anoxic tank 6 through the mixed liquid reflux pump 67 at a ratio of 3:1, and the ammonia nitrogen of the wastewater is removed by denitrification of the denitrifying bacteria in the anoxic tank 6.

Step e, precipitation

The aerobic treated wastewater flows into the secondary settling tank 8 for sedimentation and separation, further removing COD _Cr , BOD ₅ , SS, etc. from the wastewater. The effluent of the secondary settling tank 8 can reach the standard discharge, and the water quality of the effluent is shown in Table 5; A part of the sludge at the bottom of the sinking tank 8 is returned to the anoxic tank 6 via the pump 68, and the other part flows into the sludge tank 9 through the pipeline, and is separated into a filtrate and a mud cake by the sludge dewatering device 10, and the filtrate is returned to the pipeline through the pipeline. Adjust the pool 1 while the mud cake is shipped out.

Table 5 effluent quality of landfill leachate after treatment

Serial number	project	unit	measured value	Serial number	project	unit	measured value
1	COD _Cr	Mg/L	69	5	Ammonia nitrogen	Mg/L	9.2
2	SS	Mg/L	25	6	Chroma	Times	5
3	Turbidity	NTU	20	7	pH value	-	7.5
4	BOD ₅	Mg/L	30	8	Conductivity	μS/cm	5350

Example 3

Leachate treatment project of 1000 tons/day in a garbage sanitary landfill

The measured indexes of the raw water of the landfill leachate are shown in Table 6.

Table 6 Water quality of landfill leachate raw water.

Serial number	project	unit	measured value	Serial number	project	unit	measured value
1	COD _Cr	Mg/L	5000	5	Ammonia nitrogen	Mg/L	400
2	SS	Mg/L	420	6	Chroma	Times	680
3	Turbidity	NTU	400	7	pH value	-	6.5
4	BOD ₅	Mg/L	3100	8	Conductivity	μS/cm	8040

Step a, flocculation and sedimentation

The wastewater enters the adjustment tank 1 at a flow rate of 50 m ³ /h through water, and is fully mixed and then enters the coagulation tank 2. The reaction of adding 1500 g of polyferric sulfate (PFS) per ton of wastewater is completed and then enters the primary settling tank 3, and the primary settling tank 3 The sludge is sent to the sludge tank 9 through a pump and a pipe, and finally filtered and separated in the sludge dewatering device 10, and the wastewater of the primary sedimentation tank 3 flows into the electrolysis machine 4 through the pump 34.

Step b, electrolysis

The wastewater is subjected to flocculation and sedimentation and flows into the electrolysis machine 4 for electrolysis. The electrolysis machine 4 has an operating voltage of 960 V, a current density of 320 mA/cm ² , a voltage between the two electrodes of 12 V, and a residence time of the wastewater in the electrolysis machine 4 of 50 s.

Step c, anaerobic treatment

Step d, aerobic treatment

Step e, precipitation

The aerobic treated wastewater flows into the secondary settling tank 8 for sedimentation and separation, further removing COD _Cr , BOD ₅ , SS, etc. from the wastewater. The effluent of the secondary settling tank 8 can reach the standard discharge, and the water quality of the effluent is shown in Table 7; A part of the sludge at the bottom of the sinking tank 8 is returned to the anoxic tank 6 via the pump 68, and the other part flows into the sludge tank 9 through the pipeline, and is separated into a filtrate and a mud cake by the sludge dewatering device 10, and the filtrate is returned to the pipeline through the pipeline. Adjust the pool 1 while the mud cake is shipped out.

Table 7 Water quality of landfill leachate after treatment

Serial number	project	unit	measured value	Serial number	project	unit	measured value
1	COD _Cr	Mg/L	75	5	Ammonia nitrogen	Mg/L	12
2	SS	Mg/L	30	6	Chroma	Times	5
3	Turbidity	NTU	28	7	pH value	-	7.0
4	BOD ₅	Mg/L	twenty four	8	Conductivity	μS/cm	5400

Industrial applicability

The invention not only can rapidly reduce COD _Cr by electrolysis, but also improves the biodegradability of the wastewater, and the removal rate of ammonia nitrogen can reach 80-90%, and at the same time, the heavy metal ions in the wastewater are effectively removed by electrolytic flocculation and sedimentation for subsequent treatment. The process creates better biochemical conditions, and the biological treatment methods of anaerobic treatment and aerobic treatment can further effectively reduce ammonia nitrogen, COD _Cr and BOD ₅ in the landfill leachate, so the invention has good industrial applicability.

Sequence table free content

Claims

The treatment device for landfill leachate is characterized in that it comprises: regulating tank, coagulation tank, primary sedimentation tank, electrolysis machine, hydrolysis acidification tank, anoxic tank, aerobic tank, secondary sedimentation tank, sludge tank and sludge dewatering The inlet of the regulating tank is connected with the outlet of the landfill leachate, the water outlet of the regulating tank is connected with the water inlet of the concrete pool, the water outlet of the concrete pool is connected with the water inlet of the primary sedimentation tank, the water outlet of the primary sedimentation tank and the electrolysis machine The water inlet is connected, the water outlet of the electrolysis machine is connected with the water inlet of the hydrolysis acidification tank, the water outlet of the hydrolysis acidification tank is connected with the water inlet of the anoxic tank, the water outlet of the anoxic tank is connected with the inlet of the aerobic pool, the outlet of the aerobic tank and the second sink The water inlet of the pool is connected, the water outlet of the secondary sedimentation tank is connected with the sewage discharge pipeline, the sludge outlet of the primary sedimentation tank and the secondary sedimentation tank is connected with the sludge tank, and a sludge pump is arranged between the sludge tank and the sludge dewatering device.
The treatment device for landfill leachate according to claim 1, wherein the regulating tank and the coagulation tank respectively have a pH adjusting agent dosing device and a flocculating agent dosing device.
The treatment device for landfill leachate according to claim 1, wherein the treatment device further comprises a mixed liquid reflux pump for returning a part of the mixed liquid of the aerobic tank to the anoxic tank, and the reflux of the mixed liquid The ratio is 3:1 or 2:1.
A hair product waste water recycling device according to claim 1, wherein the anode of the electrolysis machine is a metal or graphite electrode, and the cathode of the electrolysis machine is an iron cathode, an aluminum cathode, a stainless steel cathode, and a nickel cathode. , titanium or zinc cathode.
A method for treating landfill leachate, characterized in that it uses the treatment device for landfill leachate according to claim 1, the treatment method adopting the following steps:

a, flocculation and sedimentation

The landfill leachate enters the regulating tank through the pipeline, and the pH adjusting agent is added to the regulating tank to adjust the pH value to 7-10, and then flows into the coagulation tank, and an appropriate amount of flocculating agent is added into the coagulation tank, and the reaction is completed and then enters the primary settling tank. The sedimentation of the primary sedimentation tank is sent to the sludge tank through the pump and pipeline, and finally filtered and separated in the sludge dewatering device; the wastewater from the primary sedimentation tank is pumped into the electrolysis machine;

b, electrolysis

The working voltage of the electrolysis machine is 2 to 1000V, the voltage between adjacent electrodes is 2 to 12V, the current density is 1 to 320 mA/cm 2 , and the residence time of the wastewater in the electrolysis machine is 2 to 50 s;

c, anaerobic treatment

The electrolyzed wastewater enters the hydrolysis acidification tank and the anoxic tank in turn, and the macromolecular organic matter in the wastewater in the hydrolysis acidification tank is hydrolyzed and acidified into small molecular organic substances by the acid-producing bacteria, and then passes through the anaerobic bacteria in the anoxic tank. The adsorption, fermentation and methanogenesis of facultative bacteria are decomposed into methane and carbon dioxide to increase the B/C value and improve biodegradability. At the same time, the ammonia nitrogen in the wastewater is removed by denitrification of denitrifying bacteria in the anoxic tank;

d, aerobic treatment

The anaerobic treated wastewater enters an aerobic tank containing aerobic bacteria and nitric acid bacteria, and further decomposes the organic matter in the wastewater by aerobic microorganisms, deeply removes COD Cr and BOD 5 from the wastewater, and utilizes the nitrification of nitrifying bacteria and Nitrosation of nitrosated bacteria converts ammonia nitrogen into nitrate nitrogen or nitrite nitrogen;

e, precipitation

The aerobic treated wastewater flows into the secondary settling tank to further remove COD Cr , BOD 5 , SS, etc. from the wastewater. The effluent from the secondary settling tank can reach the standard discharge, and a part of the sludge at the bottom of the secondary settling tank is pumped back to the anoxic tank. The other part flows into the sludge tank through the pipeline, and then is separated into the filtrate and the mud cake by the sludge dewatering device. The filtrate is returned to the adjustment tank through the pipeline, and the mud cake is transported.
The method for treating landfill leachate according to claim 5, wherein the flocculating agent in step a is one or a combination of aluminum salt, iron salt, poly aluminum, and poly iron; The pH adjusting agent is one of sulfuric acid, hydrochloric acid, sodium hydroxide, sodium carbonate, sodium hydrogencarbonate, and lime.
The method for treating landfill leachate according to claim 5, wherein the optimal electrolysis described in step b is nano catalytic electrolysis, and the working voltage of electrolysis is 2 to 500 V, and the voltage between adjacent electrodes It is 2 to 8 V, the current density is 10 to 300 mA/cm 2 , and the residence time of the wastewater in the electrolysis machine is 2 to 30 s.
The method for treating landfill leachate according to claim 5, wherein the optimal flocculating agent in the step a is polyferric sulfate, and the dosage is 200-2000 g per ton of wastewater.
The method for treating landfill leachate according to claim 5, wherein the optimal flocculating agent in the step a is ferrous sulfate, and the dosage is 230-1800 g per ton of wastewater.