CN105129991A - Method for treating municipal wastewater with low C/N ratio by adopting nitrification/partial denitrification/anaerobic ammonium oxidation coupling technology - Google Patents

Abstract

The invention provides a method for treating municipal wastewater with a low C/N ratio by adopting a nitrification/partial denitrification/anaerobic ammonium oxidation coupling technology, and belongs to the field of wastewater treatment. The device comprises a raw water tank and a nitrification/partial denitrification/anaerobic ammonium oxidation reactor; the method comprises the following steps: municipal domestic wastewater enters the nitrification/partial denitrification/anaerobic ammonium oxidation reactor in multiple steps, each time after a certain amount of wastewater enters the reactor, the wastewater is stirred under an anaerobic condition for a certain period of time, so that incomplete denitrification and anaerobic ammonium oxidation reaction can be carried out, then aeration is carried out for aerobic nitrification reaction, a certain amount of municipal wastewater with a low C/N ratio is pumped again into the reactor, the wastewater is stirred under an anoxic condition and subjected to aerobic nitrification, and finally total nitrogen in the domestic wastewater can be efficiently removed.

Description

A method of nitrification/partial denitrification/ANAMMOX coupled process for treating low C/N urban sewage

technical field

The invention relates to a method for treating low C/N urban sewage by a nitrification/partial denitrification/anaerobic ammonium oxidation coupling process, which belongs to the technical field of sewage biological treatment. Oxygen ammonium oxidation reactor, every time after pumping sewage, first anoxic stirring for a period of time, incomplete denitrification and anaerobic ammonium oxidation reaction, followed by aeration for aerobic nitrification reaction, and finally achieve high efficiency of total nitrogen in domestic sewage remove. The invention makes full use of the carbon source in domestic sewage, has low sludge yield, simple and easy-to-control process, and is a low-energy, high-efficiency and stable new way to treat low-C/N urban sewage.

Background technique

In recent years, the degree of eutrophication in my country's water bodies has become increasingly serious, causing serious harm to people's health, water ecological environment, tourism and aquaculture. In order to prevent the further deterioration of the water body environment and take into account the regeneration and recycling of water resources, the sewage nitrogen (N) and phosphorus (P) discharge standards in many countries and regions are becoming increasingly stringent. Traditional denitrification methods are generally achieved through nitrification and denitrification processes. When dealing with low C/N domestic sewage, this process requires high aeration, additional carbon sources and alkalinity, and its sewage denitrification efficiency Can not meet strict emission standards. The research and development of highly efficient and economical phosphorus and nitrogen removal processes has become a hot spot in the current urban sewage treatment technology research.

Anammox (Anammox) is a new type of biological denitrification technology developed by the Delft University of Technology in the Netherlands in the mid-1990s. It means that under anaerobic or anoxic conditions, microorganisms directly use NO ₂ ^- -N as an electron acceptor. , using ammonia nitrogen (NH ₄ ⁺ -N) as the electron donor, the biological reaction process of simultaneously converting two kinds of nitrogen into nitrogen gas. Compared with the traditional nitrification and denitrification process, it does not require additional organic carbon sources, has less sludge output, does not require oxygen at all, saves a lot of operating costs, does not require acid-base neutralizers, and avoids secondary pollution. Economical and efficient biological denitrification technology has received widespread attention.

One of the substrates required for anaerobic ammonium oxidation is nitrite, and nitrite generally does not exist in natural water bodies, so pre-treatment measures are required. The current common method is to set up a short-range nitrification process before the anaerobic ammonium oxidation process, oxidize the ammonia nitrogen in the sewage to nitrite through aeration, adjust the ratio of ammonia nitrogen and nitrite in the influent to 1:1.32, and then pass the anaerobic ammonium oxidation process. Oxyammooxidation for autotrophic denitrification. The short-cut nitrification process is mainly realized by controlling dissolved oxygen, temperature, pH or the inhibition of free ammonia, but the biggest problem faced by short-cut nitrification is to obtain sufficient and stable nitrite accumulation. For urban domestic sewage with a low carbon-to-nitrogen ratio, short-cut nitrification at room temperature is difficult to maintain stability, resulting in low efficiency of subsequent anammox denitrification and complicated control process, which also limits the application of short-cut nitrification-anammox technology in cities The bottleneck of sewage.

Another way to obtain nitrite is to reduce nitrate to nitrite by denitrification, ie partial denitrification. Complete heterotrophic denitrification is the reduction of nitrate to nitrite by organic carbon source, then to nitric oxide, nitrous oxide, and finally to nitrogen. Inoculation of appropriate seed sludge and control of appropriate carbon-nitrogen ratio and reaction time can achieve higher nitrite accumulation during denitrification, thereby providing electron acceptors for anammox. Provide a stable and effective method for the practical application of anaerobic ammonium oxidation.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned technical problems, and proposes a method for treating low C/N urban sewage by nitrification/partial denitrification/ANAMMOX coupling process, specifically, urban domestic sewage enters nitrification/partial denitrification multiple times. Nitrification/ANAMMOX reactor, each time a certain amount of urban sewage enters, first anaerobic stirring for a period of time, incomplete denitrification and anammox reaction, followed by aeration for aerobic nitrification, and then again Pump a certain amount of low C/N ratio urban sewage, anoxic stirring, aerobic nitrification. Finally, the efficient removal of total nitrogen in domestic sewage is realized.

A nitrification/partial denitrification/ANAMMOX coupling process method for treating low C/N urban sewage, characterized in that the following devices are used:

Including raw water tank (1), nitrification/partial denitrification/anammox reactor (3); raw water tank (1) and nitrification/partial denitrification/anammox reactor (3) through peristaltic pump (2) Connect; the reactor is provided with a stirrer (4), aeration head (5), drain valve (7), ORP online measuring instrument (8), pH online measuring instrument (9), DO online measuring instrument (10); The air pump (6) is connected with the aeration head (5); the peristaltic pump (2), air pump (6), agitator (4), ORP online measuring instrument (8), pH online measuring instrument (9), DO online The measuring instrument (10) and the computer (12) are connected with the automatic control device (11).

It is characterized in that the method steps are as follows:

1) Inoculate the remaining sludge, partial denitrification sludge and anammox sludge from urban sewage plant in the nitrification/partial denitrification/anammox reactor. :2～1:1:4, control the sludge mass concentration in the reactor after inoculation to 2000mg/L～4000mg/L.

2) Pump 1/5 to 1/3 of domestic sewage into the nitrification/partial denitrification/ANAMMOX reactor at the same time, turn on the agitator at the same time, and stir for 10 to 40 minutes in the absence of oxygen.

3) After anoxic stirring, turn on the air pump for aerobic nitrification, and turn off the air pump after aeration for 20-60 minutes;

4) Repeat steps 2) to 3) 3 to 5 times, turn off the agitator, settle for 30 to 60 minutes, open the drain valve, and the drainage ratio is 40% to 60%;

5) After being idle for 60-120 minutes, start the cycle from step 2) and enter the next cycle.

Part of the denitrification sludge in the step 1) can convert nitrate nitrogen into nitrite nitrogen during the denitrification process, and the conversion percentage is maintained at 80% to 90%;

The urban sewage in the step 2) is low C/N ratio sewage, NH ₄ ⁺ -N=50～80mg/L, COD=100～280mg/L;

In step 3) during the aerobic nitrification process, the dissolved oxygen concentration in the reactor is controlled at 1.5-3 mg/L;

In the method for treating low C/N urban sewage by nitrification/partial denitrification/ANAMMOX coupled process, the sludge age SRT in the system is 30-60 days during stable operation.

Technical principle

A nitrification/partial denitrification/ANAMMOX coupled process for treating low C/N urban sewage The raw water treated in each cycle enters the main reactor multiple times, and after each pumping of the raw water, it is anoxic and stirred for a certain period of time , use the inoculated part of the denitrification sludge and the organic matter in the raw water to reduce the nitrate in the reactor to nitrite, and at the same time use the inoculated anammox sludge to simultaneously remove part of the ammonia nitrogen in the raw water, and then carry out Aerobic aeration oxidizes unremoved ammonia nitrogen to nitrate, then pumps a certain amount of raw water, repeats the above steps, and finally achieves efficient denitrification of low C/N urban sewage. The purpose of adopting the method of multiple water inflow is to make full use of the limited carbon source in urban domestic sewage for partial denitrification to produce nitrite, so that no additional carbon source is needed and the operating cost is reduced.

A nitrification/partial denitrification/ANAMMOX coupled process method for treating low C/N urban sewage related to the present invention has the following advantages:

1) Adopt the method of water inflow for multiple times, make full use of the limited carbon source in urban domestic sewage to reduce nitrate to nitrite, so as to eliminate or reduce external carbon source and reduce operating costs;

2) The product of aerobic nitrification is nitrate. Compared with short-range nitrification, it does not need complex external condition control and real-time monitoring, and the operation is simple and stable;

3) The accumulation rate of partial denitrification nitrite is high, the reaction conditions are easy to control, and it can run stably for a long time;

4) Some denitrifying bacteria can reduce the nitrate nitrogen produced by anammox in situ, improve the denitrification efficiency of the reactor, and the effluent water quality is high.

5) Autotrophic nitrifying bacteria, anammox bacteria and partial denitrification process have low sludge yield and long sludge age in the system, which can effectively retain anammox bacteria and reduce sludge production, thereby reducing sludge disposal costs, further reducing the operating costs of the actual water plant.

Description of drawings

Figure 1 is a schematic diagram of the structure of a nitrification/partial denitrification/anammox coupled process for treating low C/N urban sewage.

Fig. 2 is a schematic diagram of the operation steps of the nitrification/partial denitrification/ANAMMOX coupled process for treating low C/N urban sewage.

Detailed ways

Below in conjunction with accompanying drawing and specific examples the present invention will be further described:

As shown in Fig. 1, a kind of nitrification/partial denitrification/ANAMMOX coupled process method for treating low C/N urban sewage is characterized in that the following devices are used: comprising raw water tank (1), nitrification/partial denitrification/ Anammox reactor (3); raw water tank (1) is connected with nitrification/partial denitrification/anammox reactor (3) through peristaltic pump (2); the reactor is provided with agitator (4), Aeration head (5), drain valve (7), ORP online measuring instrument (8), pH online measuring instrument (9), DO online measuring instrument (10); air pump (6) is connected with aeration head (5) ; Peristaltic pump (2), air pump (6), agitator (4), ORP online measuring instrument (8), pH online measuring instrument (9), DO online measuring instrument (10), computer (12) and automatic control device (11) CONNECTION.

The method steps are as follows:

1) Inoculate the remaining sludge, partial denitrification sludge and anammox sludge from urban sewage plant in the nitrification/partial denitrification/anammox reactor. :2～1:1:4, control the sludge mass concentration in the reactor after inoculation to 2000mg/L～4000mg/L.

2) Pump 1/5 to 1/3 of the domestic sewage of the water inflow per cycle into the nitrification/partial denitrification/ANAMMOX reactor. After the water inflow is complete, turn on the agitator and stir for 10 to 40 minutes in the absence of oxygen.

3) After anoxic stirring, turn on the air pump for aerobic nitrification, and turn off the air pump after aeration for 20-60 minutes;

4) Repeat steps 2) to 3) 3 to 5 times, turn off the agitator, settle for 30 to 60 minutes, open the drain valve, and the drainage ratio is 40% to 60%;

5) After being idle for 60-120 minutes, start the cycle from step 2) and enter the next cycle.

Part of the denitrification sludge in the step 1) can convert nitrate nitrogen into nitrite nitrogen during the denitrification process, and the conversion percentage is maintained at 80% to 90%;

The urban sewage in the step 2) is low C/N ratio sewage, NH ₄ ⁺ -N=50～80mg/L, COD=100～280mg/L;

Described step 3) in the aerobic nitrification process, control the dissolved oxygen concentration in the reactor at 2mg/L;

In the method for treating low C/N urban sewage by nitrification/partial denitrification/ANAMMOX coupled process, the sludge age SRT in the system is 30-60 days during stable operation.

Specifically include the following processes:

The raw water used in the experiment is domestic sewage from the Family Hospital of Beijing University of Technology. The main parameters are: COD = 200-300mg/L, NH ₄ ⁺ -N = 60-85mg/L, TN = 60-90mg/L; the quality of its COD and ammonia nitrogen The concentration ratio is between 2.2 and 3.5, which belongs to typical urban sewage with low C/N ratio; the raw water is collected into the raw water tank.

Inoculate residual sludge, partial denitrification sludge and anammox sludge from urban sewage plant in nitrification/partial denitrification/anammox reactor, and the ratio of three kinds of inoculated sludge mass concentration MLVSS is 1:1:3 , the sludge concentration in the reactor after inoculation was 3150 mg/L; among them, part of the inoculated denitrification sludge came from a denitrification reactor that had been in operation for more than 1 year, and the sludge had incomplete denitrification characteristics. Under low conditions, only nitrate can be reduced to nitrite, and the nitrite accumulation rate reaches 80%.

Nitrification/partial denitrification/ANAMMOX reactor adopts SBR reactor, the reactor has an effective volume of 12L, and the total water volume per cycle is 6L. Urban domestic sewage with a low carbon-to-nitrogen ratio in the raw water tank enters the nitrification/partial denitrification/ANAMMOX reactor through a peristaltic pump. The influent volume is 1.5 L. After the inflow, it is stirred for 30 minutes in the absence of oxygen. At this time, the average concentration of ammonia nitrogen in the reactor is 13.14mg/L, the average concentration of nitrite nitrogen is 0.11mg/L, and the average concentration of nitrate nitrogen is 0.23mg/L. Then aerate for 30min, the aeration process controls the dissolved oxygen at 2mg/L, and the ammonia nitrogen in the reactor is oxidized.

Water was fed into the reactor again through a peristaltic pump, and the volume of water was 3L. After the water was fed, the anoxic mixture was stirred for 3 hours. At this time, the average concentration of ammonia nitrogen in the reactor was 13.98 mg/L, and the average concentration of nitrite nitrogen was 0.13 mg/L. The average concentration of nitrate nitrogen is 0.15mg/L. Then aerate for 40min, the aeration process controls the dissolved oxygen at 2mg/L, and the ammonia nitrogen in the reactor is oxidized.

Finally, 1.5L of water was fed into the reactor through a peristaltic pump, and after the water was fed, it was stirred for 3 hours without oxygen. At this time, the average concentration of ammonia nitrogen in the reactor was 1.05mg/L, the average concentration of nitrite nitrogen was 0.12mg/L, and the average concentration of nitrate nitrogen The average concentration is 0.31mg/L. Then aerated for 10 minutes, the ammonia nitrogen in the reactor was oxidized. Stop stirring, let the supernatant drain out after 30 minutes of static settling, and the drainage ratio is 50%.

The results of continuous experiments show that:

The sludge concentration of the nitrification/partial denitrification/ANAMMOX reactor is controlled at 3150mg/L, and the water is divided into three times, the first water intake is 1.5L, the anoxic stirring is 30min, and the aeration is 30min; the second water intake is 3L, Anoxic stirring for 3 hours, aeration for 40 minutes; third water intake of 1.5L, anoxic stirring for 3 hours, aeration for 10 minutes; static settling for 30 minutes, drainage ratio 50%; effluent ammonia nitrogen <1mg/L, total nitrogen <5mg/L, total The nitrogen removal rate reaches 90% to 95%, which can realize stable and efficient denitrification of urban domestic sewage with low carbon-to-nitrogen ratio.

Claims (2)

1. a device for nitrated/low C/N municipal effluent of part denitrification/Anammox coupling technique process, is characterized in that:

Comprise raw water box (1), nitrated/part denitrification/anaerobic ammonia oxidation reactor (3); Raw water box (1) is connected with nitrated/part denitrification/anaerobic ammonia oxidation reactor (3) by peristaltic pump (2); This reactor is provided with agitator (4), aeration head (5), water discharge valve (7), ORP on-line determination instrument (8), pH on-line determination instrument (9), DO on-line determination instrument (10); Pneumatic pump (6) is connected with aeration head (5); Peristaltic pump (2), pneumatic pump (6), agitator (4), ORP on-line determination instrument (8), pH on-line determination instrument (9), DO on-line determination instrument (10) are connected with self-con-tained unit (11) with computer (12).

2. application rights requires the method for the low C/N municipal effluent of device process described in 1, and it is characterized in that, described method steps is as follows:

1) municipal effluent plant excess sludge, part denitrification mud and anaerobic ammonium oxidation sludge is inoculated in nitrated/part denitrification/anaerobic ammonia oxidation reactor, three kinds of seed sludge mass concentration MLVSS ratios are 1:1:2 ~ 1:1:4, and controlling sludge quality concentration in inoculation post-reactor is 2000mg/L ~ 4000mg/L;

2) 1/5 ~ 1/3 sanitary sewage of each cycle flooding quantity is pumped in nitrated/part denitrification/anaerobic ammonia oxidation reactor, simultaneously turn on agitator, anoxia stirring 10 ~ 40min;

3) after anoxia stirring terminates, open pneumatic pump and carry out aerobic nitrification, after aeration 20min ~ 60min, close pneumatic pump;

4) repeating step 2) ~ 3) 3 ~ 5 times, close agitator, quiet heavy 30 ~ 60min, open water discharge valve, draining ratio is 40% ~ 60%;

5) after idle 60 ~ 120min, from step 2) circulation, enter next cycle and run;

Described step 1) in part denitrification mud in denitrification process, nitrate nitrogen can be converted into nitrite nitrogen, conversion percentages stable maintenance is 80% ~ 90%;

Described step 2) in municipal effluent be low C/N than sewage, wherein NH ₄ ⁺-N=50 ~ 80mg/L, COD=100 ~ 280mg/L;

Described step 3) in aerobic nitrification process, in control reactor, dissolved oxygen concentration is at 1.5 ~ 3mg/L;

In operational process, sludge age SRT is 30 ~ 60 days.