CN111573822A - Bioelectrochemical treatment process for high-ammonia-nitrogen high-sulfate wastewater - Google Patents

Abstract

The invention provides a bioelectrochemical treatment process of high ammonia nitrogen high sulfate wastewater, belonging to the technical field of sewage treatment. The treatment process is to form NH₄ ⁺/SO₄ ^2‑And the COD wastewater is sequentially sent into a pretreatment area, an electrode treatment area and a denitrification area for treatment, wherein the pretreatment area comprises an anaerobic area and a micro-aerobic aeration area, and the electrode treatment area comprises an anode area and a cathode area which are connected with each other. The process combines sulfate reduction, partial nitrification, anaerobic ammonia oxidation and electrochemical processes, treats pollutants step by step, ensures that a single substrate is removed, namely the stable operation of the anaerobic ammonia oxidation process is ensured, and also meets the requirement that the pollutants are finally removed efficiently through multi-stage treatment.

Description

Bioelectrochemical treatment process for high-ammonia-nitrogen high-sulfate wastewater

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to an efficient denitrification and desulfurization process based on an anaerobic ammonia oxidation-bioelectrode.

Background

High ammonia nitrogen and high sulfate content wastewater caused by SO₄ ^2-And NH₄ ⁺The high content results in waste water which is difficult to treat by common biological method, and the treatment of waste water by sulfate type anaerobic ammonium oxidation requires strict control of substrate concentration and H₂S is generated, so that the reaction condition is difficult to adjust in time; generation of H₂S also has influence on the anaerobic ammoxidation reaction, and is difficult to be directly aligned and removed in the nitrite type anaerobic ammoxidation or sulfur anaerobic ammoxidation mode.

The method has certain difficulty in treating the high-ammonia-nitrogen high-sulfate wastewater by using an anaerobic ammonia oxidation mode alone, and the internal substrate is firstly converted and then efficiently denitrified by anaerobic ammonia oxidation. The sewage is rich in NH₄ ⁺/SO₄ ^2-COD, bound H₂S can be oxidized at the anode, NO₃ ^-Can be reduced at the cathode, the two can be spontaneously carried out by connecting an external circuit, and the sewage is treated and then enters an anaerobic ammonia oxidation process to realize denitrification and desulfurization.

Aerating the high ammonia nitrogen high sulfate wastewater to generate NO in the system₃ ^-/NO₂ ^-Treatment of SO by anaerobic ammoxidation₄ ^2-、NO₃ ^-、NO₂ ^-、NH₄ ⁺And there is a certain contradiction between COD. If the aeration time is prolonged, the COD concentration can be reduced, but NH₄ ⁺Will generate excessive NO₃ ^-Not only cause NH₄ ⁺With NO₂ ^-In inconsistent proportions, also produces NO₃ ^-Accumulating; if the aeration time is reduced, NO can be realized₃ ^-Little or NO generation of NO₂ ^-Can produce accumulation, the nitrogen composition meets the requirement of the anaerobic ammonia oxidation reaction, but COD residue still remains in the sewage, which is not beneficial to the anaerobic ammonia oxidation denitrification. The aeration and biological reaction need to be regulated and controlled according to the composition of the substrate, and certain difficulty exists. If only pass throughAnaerobic removal of COD and SO₄ ^2-NO NO in the system₂ ^-And anaerobic ammonia oxidation treatment cannot be adopted. Therefore, the invention realizes high-efficiency denitrification and desulfurization by dividing the inlet water into two processes.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides an efficient denitrification and desulfurization process based on an anaerobic ammonia oxidation-bioelectrode, which is used for performing sectional pretreatment on high-ammonia nitrogen and high-sulfate wastewater so as to realize efficient denitrification of anaerobic ammonia oxidation and efficient removal of sulfate.

In order to achieve the above object, the present application adopts the following technical means:

a bioelectrochemical treatment process for high-ammonia nitrogen high-sulfate wastewater is to form NH₄ ⁺/SO₄ ^2-And COD wastewater is sequentially sent into a pretreatment area, an electrode treatment area and a denitrification area for treatment, wherein the pretreatment area comprises an anaerobic area and a micro-aerobic aeration area, and the electrode treatment area comprises an anode area and a cathode area which are connected with each other;

the treatment process comprises the following steps:

step 1, composition is NH₄ ⁺、SO₄ ^2-And COD waste water respectively enters an anaerobic zone and a micro-aerobic aeration zone,

in the anaerobic zone, COD and SO contained in the wastewater₄ ^2-Generating H under the action of sulfate reducing bacteria in anaerobic environment₂S/HS^-/S^2-And generating an alkalinity of HCO₃ ^-The removal of COD is realized, and SO is removed₄ ^2-Conversion to S^2-，NH₄ ⁺No reaction, NH contained in the wastewater in the micro-aerobic aeration zone₄ ⁺And COD is nitrified into NO in short distance under the aeration condition₂ ^-And NO₃ ^-And effecting removal of COD, SO₄ ^2-No reaction occurs;

step 2, H produced by anaerobic sulfate reduction treatment₂S/HS^-/S^2-And the rest COD enters the anode area,oxidized into S under the action of anode sulfur oxidizing bacteria and electrogenesis biological bacteria⁰/H⁺And CO₂/H⁺The electrons generated are transferred to the cathode via an external power connection, H⁺Mass transfer through the proton membrane to the cathode region;

step 3, NO produced by short-cut nitration₃ ^-Entering the cathode region, receiving anode electrons and H under the action of cathode autotrophic denitrifying bacteria⁺Reduced to NO₂ ^-；

Step 4, unreacted NH in the anaerobic zone₄ ⁺With NO produced at the cathode₂ ^-Entering a denitrification area together to generate N through anaerobic ammonia oxidation₂And NO₃ ^-The effluent returns to the initial inlet water, and is divided to treat SO₄ ^2-。

Has the advantages that:

1. the high-ammonia nitrogen high-sulfate wastewater is subjected to the steps to realize high-efficiency treatment;

2. anaerobic reduction of SO₄ ^2-With aeration oxidation of NH₄ ⁺The reaction conditions of the two steps are in certain contradiction with the growth conditions of the bacteria. By separating the two reactions, the anaerobic reduction of SO can be satisfied₄ ^2-And aeration oxidation of NH₄ ⁺The two steps can also avoid the mutual inhibition of different strains;

3. anaerobic reduction of SO₄ ^2-Step (c) can generate an alkalinity HCO₃ ^-，HCO₃ ^-Can be used as an anaerobic ammonium oxidation inorganic carbon source;

4. h produced at the anode⁺Electrons and the water can be provided to the cathode, so that the consumption of cathode reaction is met, the pH value balance of a cathode region is maintained, and the guarantee of reaction conditions is provided for the anaerobic ammonia oxidation reaction;

5. after anammox denitrification, unreacted SO remains in section 1b₄ ^2-Reflowing to water inlet, and then treating through an anaerobic section.

Drawings

FIG. 1 is a mechanism flow chart of the bioelectrochemical treatment process of the high ammonia nitrogen high sulfate wastewater.

FIG. 2 is a flow chart of the bioelectrochemical treatment process of the high ammonia nitrogen high sulfate wastewater.

Detailed Description

The technical solution of the present invention is further explained with reference to the accompanying drawings and specific embodiments.

The invention provides a bioelectrochemical treatment process of high ammonia nitrogen high sulfate wastewater, as shown in figure 1, the treatment is carried out on two parts of inlet water, 1a) an anaerobic zone: removing sulfate and COD to produce H₂S/HS^-/S^2-Then oxidized by 2 anode regions to generate S⁰Desulfurization, step NH₄ ⁺The change is not changed; 1b) a micro-oxygen aeration zone: short-range nitration of ammonia nitrogen to NO₂ ^-Into the 3 cathode region for additional generation of NO₃ ^-Conversion to NO₂ ^-Part of SO₄ ^2-The change is not changed; 4, denitrification area: finally, the effluent of the anode region and the effluent of the cathode region enter anaerobic ammonia oxidation to realize denitrification; the anaerobic ammonia oxidation effluent comprises SO of a second path₄ ^2-And a small amount of NO produced₃ ^-And refluxing until the inflow water is removed again.

The process combines sulfate reduction, partial nitrification, anaerobic ammonia oxidation and electrochemical processes, treats pollutants step by step, ensures that a single substrate is removed, namely the stable operation of the anaerobic ammonia oxidation process is ensured, and also meets the requirement that the pollutants are finally removed efficiently through multi-stage treatment.

Example 1

Waste water from NH₄ ⁺、SO₄ ^2-And COD composition.

1 anaerobic sulfate reduction stage

1a) The composition of the wastewater is NH₄ ⁺/SO₄ ^2-And COD: COD and SO in anaerobic zone₄ ^2-Production of H under the action of sulfate-reducing bacteria₂S/HS^-/S^2-And generating an alkalinity of HCO₃ ^-At this stage, COD can be removed and SO can be removed₄ ^2-Conversion to S^2-Form storageAt this point. NH entering this stage₄ ⁺Remain unchanged.

1b) Short-cut nitrification stage

1b) The composition of the wastewater is NH₄ ⁺/SO₄ ^2-And COD: micro-aerobic aeration by aeration, NH₄ ⁺And COD is short-range nitrated to NO₂ ^-Small amount of being nitrated to NO₃ ^-Form NO₂ ^-And NO₃ ^-Can accumulate and reduce NO directionally reduced at cathode₃ ^-Pressure of (SO)₄ ^2-Remain unchanged. The removal of COD and NH can be realized at the stage₄ ⁺The morphological transformation of (1).

2 anodic desulfurization and 3 cathodic NO₃ ^-Transformation of

H₂S/HS^-/S^2-And the residual COD in the anaerobic zone can be oxidized into S under the action of anode sulfur oxidizing bacteria and electrogenesis biological bacteria⁰/H⁺And CO₂/H⁺And generates electrons. Electrons are transferred to the cathode via an external power connection, H⁺Mass transfer to the cathode region can occur through the proton membrane.

NO₃ ^-H for receiving anode electrons and mass transfer⁺Is directionally reduced to NO under the action of cathode autotrophic denitrifying bacteria₂ ^-. Generated NO₂ ^-Produce and accumulate, SO₄ ^2-Remain unchanged.

4 anammox denitrogenation

The anammox here is treated with 1a) NH which remains unchanged₄ ⁺NO accumulated as an electron donor at the 3 cathode₂ ^-Converting both into N as an electron acceptor₂And a small amount of NO₃ ^-Residual SO₄ ^2-Remain unchanged. The anaerobic ammonia oxidation effluent returns to the initial water inlet and is divided to treat SO₄ ^2-。

5 theoretical contaminant removal calculation: anaerobic reduction of SO₄ ^2-In step (2), NH₄ ⁺No reaction; NH (NH)₄ ⁺In the short-cut nitration stage, SO₄ ^2-Does not react, and is not separately introduced into anaerobic ammonia oxidation for reaction. Let's speak of NH₄ ⁺In 1a) anaerobic reduction of SO₄ ^2-In step (2), NH₄ ⁺No reaction occurs, the sewage flows to the anode, NH occurs at the anode₄ ⁺The wastewater does not react and flows to the anaerobic ammonia oxidation area to be denitrified; SO (SO)₄ ^2-1b) short-cut nitrification and the cathode zone are the same in flow, and finally the obtained product reaches anaerobic ammonia oxidation to realize denitrification and is shunted to SO of the cathode zone₄ ^2-And SO to the anammox zone₄ ^2-Is consistent, the SO of this fraction₄ ^2-Returning to the water inlet in a reflux mode, and carrying out sulfur removal reaction by shunting.

Theoretically: with SO₄ ^2-From the point of view, if the initial influent is 100, assuming the influent is distributed at 1:1, 50 is removed by anaerobic reduction and anodic oxidation, 50 is unchanged; after the first reflux, 25 is removed by anaerobic reduction and anodic oxidation, and 25 is unchanged; after the second reflux, 12.5 was removed, 12.5 was unchanged, and so on (100, 50, 25, and 12.5 are dimensionless values as described herein). SO of influent water₄ ^2-It is necessary to finally realize desulfurization through the cyclic removal. The calculation can be done in a way that the limit is found by the following formula: x mg/L represents SO₄ ^2-Assuming that the water inflow distribution ratio of the anaerobic reduction stage and the short-cut nitrification stage is 1:1, the SO passing through the anaerobic reduction stage in an ideal state₄ ^2-Can be completely reduced, can realize complete sulfur removal at the anode, and can realize SO removal at other stages₄ ^2-The content is not changed, the effluent flows back for n times, and the SO can be removed₄ ^2-The total amount of Rq (remevalability) can be calculated by the following formula:

when SO is generated₄ ^2-SO with concentration of x mg/L, removed after n times of refluxing₄ ^2-The total amount is as follows:

by NH₄ ⁺In view of (1), it is assumed that the feed water ratio of the two-stage pretreatment is 1:1, i.e. 1 (dimensionless) NH₄ ⁺Entering an anaerobic reduction section, 1 (dimensionless) NH₄ ⁺Entering a short-cut nitrification section. In one aspect, NH is in the anaerobic reduction stage and the anodic oxidation stage₄ ⁺NH which is not reacted and has constant content and enters a denitrification area for anaerobic ammoxidation and final denitrification₄ ⁺The ratio of (a) to (b) is 1 (dimensionless). On the other hand, NH₄ ⁺Oxidized to NO by short-cut nitration₂ ^-If only NO is used in the short-cut nitrification stage₂ ^-For the end product, here 1 (dimensionless) NH₄ ⁺Complete conversion to 1 (dimensionless) NO₂ ^-NO without passing through cathode pair₃ ^-Carrying out quantitative reduction; if NO is produced in the partial nitrification stage₂ ^-And a part of NO₃ ^-No. at this stage₃ ^-The amount of produced is determined by NH₄ ⁺Excess oxidation is converted to form, in the cathode region, part of the NO₃ ^-Is directionally reduced to NO₂ ^-NO entering final denitrification by anammox₂ ^-Are all 1 (dimensionless) NH₄ ⁺Transformed (1-step transformation or 2-step transformation). Thus, NH in the final denitrification stage of anammox₄ ⁺:NO₂ ^-Is 1:1 (dimensionless). In order to realize efficient anammox denitrification, the ratio of feed water is 1:1.32 (dimensionless) in the anammox reaction formula, and 0.26 (dimensionless) NO is generated₃ ^-Then reflowing to the cathode region to reduce NO₂ ^-And then denitrification is carried out again.

Thus, from SO₄ ^2-When the proportion of the anaerobic reduction to the shortcut nitrification water inlet is 1:1, the system can completely remove sulfur; from NH₄ ⁺In the angle of (2), when the ratio of the anaerobic reduction to the shortcut nitrification feed water is 1:1.32, the system can completely denitrify. In combination with the actual sewage and wastewater discharge standard, a certain amount of NH is allowed to exist in the effluent₄ ⁺、NO₃ ^-And SO₄ ^2-The NH can be realized by adjusting the ratio of anaerobic reduction to shortcut nitrification water inflow to be between 1:1 and 1:1.32 according to the fluctuation of wastewater pollutants in combination with the conditions of reactor operation, target bacteria activity, actual water quality and the like₄ ⁺And SO₄ ^2-Efficient removal of the active species.

Claims (1)

1. A bioelectrochemical treatment process of high ammonia nitrogen high sulfate wastewater is characterized in that: will have the composition NH₄ ⁺/SO₄ ^2-And COD wastewater is sequentially sent into a pretreatment area, an electrode treatment area and a denitrification area for treatment, wherein the pretreatment area comprises an anaerobic area and a micro-aerobic aeration area, and the electrode is positionedThe physical region comprises an anode region and a cathode region which are connected with each other;

the treatment process comprises the following steps:

step 1, composition is NH₄ ⁺、SO₄ ^2-And COD waste water respectively enters an anaerobic zone and a micro-aerobic aeration zone,

in the anaerobic zone, COD and SO contained in the wastewater₄ ^2-Generating H under the action of sulfate reducing bacteria in anaerobic environment₂S/HS^-/S^2-And generating an alkalinity of HCO₃ ^-The removal of COD is realized, and SO is removed₄ ^2-Conversion to S^2-，NH₄ ⁺The reaction does not occur and the reaction is not carried out,

in the micro-oxygen aeration zone, NH contained in the wastewater₄ ⁺And COD is nitrified into NO in short distance under the aeration condition₂ ^-And NO₃ ^-And effecting removal of COD, SO₄ ^2-No reaction occurs;

step 2, H produced by anaerobic sulfate reduction treatment₂S/HS^-/S^2-And the rest COD enters an anode region and is oxidized into S under the action of anode sulfur oxidizing bacteria and electrogenesis biological bacteria⁰/H⁺And CO₂/H⁺The electrons generated are transferred to the cathode via an external power connection, H⁺Mass transfer through the proton membrane to the cathode region;

step 3, NO produced by short-cut nitration₃ ^-Entering the cathode region, receiving anode electrons and H under the action of cathode autotrophic denitrifying bacteria⁺Reduced to NO₂ ^-；

Step 4, unreacted NH in the anaerobic zone₄ ⁺With NO produced at the cathode₂ ^-Entering a denitrification area together to generate N through anaerobic ammonia oxidation₂And NO₃ ^-The effluent returns to the initial inlet water, and is divided to treat SO₄ ^2-。

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