CN104310585B - The apparatus and method of half nitrification-denitrification Anammox process low ratio of carbon to ammonium municipal effluent - Google Patents

Abstract

The invention relates to a device and a method for treating urban sewage with a low carbon-nitrogen ratio by semi-nitrification-denitrification anaerobic ammonium oxidation, belonging to the technical field of sewage biological treatment. The device includes: a raw water tank, a semi-nitrification reactor, an intermediate water tank, a denitrification anaerobic ammonium oxidation reactor, and an external carbon source device. The method comprises the following steps: urban sewage first enters a semi-nitrification reactor to convert part of the ammonia nitrogen into nitrate, the effluent of the semi-nitrification reactor enters a denitrification anaerobic ammonium oxidation reactor, and denitrification bacteria use organic matter to reduce the nitrate to nitrate Nitrate, simultaneously with the ammonia nitrogen in the raw water, is removed by anaerobic ammonium oxidation. Accumulation of nitrite is achieved through denitrification, which solves the problem that the accumulation of short-range nitrified nitrite in urban domestic sewage with low carbon-to-nitrogen ratio is difficult to stabilize, improves the denitrification efficiency of the anaerobic ammonium oxidation process, saves operating costs, simplifies control operations, and is low-cost. The carbon-nitrogen ratio provides an effective and feasible way to denitrify urban domestic sewage.

Description

Semi-nitrification-denitrification anaerobic ammonia oxidation device and method for treating low carbon-nitrogen ratio urban sewage

technical field

The invention relates to a low-energy-consumption device and method for treating urban sewage with a low carbon-to-nitrogen ratio, which belongs to the technical field of sewage biological treatment, and specifically enters urban domestic sewage into a semi-nitrification reactor, and converts part of ammonia nitrogen in raw water through aerobic aeration nitrate, the effluent enters the denitrification anammox reactor, and the denitrification bacteria use an external organic carbon source to reduce nitrate to nitrite, provide electron acceptors for the anammox bacteria, and the accumulated nitrite is regenerated The ammonia nitrogen that has not been oxidized in the raw water is generated through anaerobic ammonium oxidation to remove nitrogen, and the denitrification of urban domestic sewage with high efficiency and low energy consumption is stably realized.

Background technique

With the development of cities and the improvement of people's living standards, the discharge of urban sewage is increasing day by day, and the composition of sewage is becoming more and more complex. The eutrophication caused by water nitrogen and phosphorus pollution seriously affects the water environment and endangers animals, plants and human health. . Therefore, stricter sewage discharge standards are the general development trend of all countries. The removal of nitrogen and phosphorus for the purpose of controlling eutrophication has become an important goal of sewage treatment. There is an urgent need for sewage that meets the goals of economic development and environmental protection in various places. Treatment technology, research and development of efficient and economical phosphorus and nitrogen removal process has become a hot spot in the current urban sewage treatment technology research.

Ammonia nitrogen removal in traditional wastewater treatment is generally achieved through nitrification and denitrification processes, but this process requires a large amount of aeration, additional addition of organic carbon sources and alkalinity, and high investment and operating costs. Anaerobic ammonium oxidation process is a new type of high-efficiency biological nitrogen removal technology proposed by the Delft University of Technology in the Netherlands in the 1990s. This process refers to the process in which anammox bacteria use nitrite as an electron acceptor to directly oxidize ammonia nitrogen into nitrogen gas under anaerobic or anoxic conditions. Compared with the traditional process, the anammox process does not need to supply oxygen, does not need to add organic carbon sources, and does not need to add acid-base neutralization reagents. At the same time, due to the long generation time of anammox bacteria, the sludge production can be reduced, which is an economical process. Efficient biological denitrification pathway. In practical engineering, short-range nitrification process is often required as a pretreatment process to provide reaction substrate nitrite for anammox. The short-range nitrification process is to control the oxidation of ammonia nitrogen in the nitrosation stage, without the conversion of nitrite to nitrate. In practice, the accumulation of short-range nitrification and nitrite is often achieved by controlling high temperature, dissolved oxygen, and high ammonia nitrogen. But so far, the successful application of biological denitrification through the nitrite pathway in actual engineering is rare. The main reason is that the control factors affecting the accumulation of nitrite are relatively complex, and nitrifying bacteria (NOB) can quickly convert nitrite into nitrate, which will cause the short-cut nitrification denitrification process that has been realized to return to the full-scale nitrification process. Lead to excessive nitrate in the effluent, affecting the denitrification effect.

On the other hand, controlling factors such as carbon-nitrogen ratio and reaction time in the denitrification process can realize the accumulation of nitrite, thereby providing a substrate for the anammox reaction. Combining the accumulation of nitrite in the denitrification process with the anammox process can solve the problem of unstable accumulation of nitrite, and can further reduce the nitrate produced in the process of anaerobic ammonium oxidation. Therefore, it can greatly improve the sewage biological The denitrification efficiency further improves the effluent water quality.

Contents of the invention

The purpose of the present invention is in order to solve above-mentioned technical problem, proposes a kind of device and the method for processing low carbon nitrogen ratio urban domestic sewage by semi-nitrification-denitrification anammox oxidation, specifically urban domestic sewage first enters semi-nitrification reactor, will Part of the ammonia nitrogen is oxidized to nitrate in the aerobic aeration stage, and the effluent from the semi-nitrification reactor enters the denitrification anammox reactor, and the denitrification bacteria with incomplete denitrification characteristics are inoculated by adding an organic carbon source Nitrate is reduced to nitrite, and the accumulated nitrite nitrogen and unoxidized ammonia nitrogen in the raw sewage are simultaneously removed through anaerobic ammonium oxidation, realizing efficient and low-energy denitrification of urban sewage with low carbon-to-nitrogen ratio.

The purpose of the present invention is achieved through the following technical solutions:

The semi-nitrification-denitrification anaerobic ammonium oxidation device for treating low-carbon-nitrogen ratio urban domestic sewage is characterized in that it includes a raw water tank 1, a semi-nitrification reactor 2, an intermediate water tank 3, a denitrification anammox reactor 4, and an external Carbon source storage box 5;

The raw water tank 1 is connected to the water inlet of the semi-nitrification reactor 2 through the first peristaltic pump 2.1; the outlet water of the semi-nitrification reactor is discharged into the intermediate water tank 3; the intermediate water tank is connected to the water inlet of the denitrification anaerobic ammonium oxidation reactor 4 through the second peristaltic pump 4.1 connected; the additional carbon source storage box 5 is connected to the carbon source addition port of the denitrification anammox reactor through the carbon source addition peristaltic pump 5.1;

Described semi-nitration reactor 2 is provided with first stirring device 2.2 and water outlet 2.3, and reactor bottom is provided with aeration head 2.4, and air pump 2.5 is connected with aeration head by gas flow meter 2.6;

The denitrification anaerobic ammonium oxidation reactor is a closed type, equipped with a second stirring device 4.2 and a temperature control device 4.3.

The method for semi-nitrification-denitrification anaerobic ammonium oxidation treatment of low carbon nitrogen ratio urban domestic sewage is characterized in that it includes the following process:

Inoculate the remaining sludge from the urban sewage plant in the semi-nitrification reactor, and control the sludge concentration in the reactor to 2000-4000 mg/L; mix the anaerobic ammonia oxidation sludge and denitrification sludge with incomplete denitrification characteristics according to the volume ratio Inoculate the 2:1-4:1 mixed sludge into the denitrification anammox reactor, and control the sludge concentration after inoculation to 1400-4000mg/L; among them, the inoculated denitrification with incomplete denitrification characteristics The nitrite accumulation rate of the sludge reaches 70% to 100%, and the total nitrogen removal rate of the inoculated anammox sludge is greater than 70%;

The urban domestic sewage with low carbon-to-nitrogen ratio is collected into the raw water tank, and the mass concentration ratio of COD and ammonia nitrogen in the urban domestic sewage is less than 4.0; the sewage in the raw water tank enters the semi-nitrification reactor through the first peristaltic pump, and is aerated after the water intake is completed 1 to 3 hours, the dissolved oxygen concentration is controlled at 2.0 to 4.0 mg/L during the aeration process; after the aeration, the sedimentation is 30 to 60 minutes, and then the nitrifying liquid is discharged to the intermediate water tank, and the drainage ratio is 40% to 60%;

The wastewater in the intermediate water tank enters the denitrification anammox reactor through the second peristaltic pump; at the end of the water inflow, the organic carbon source solution in the carbon source storage tank enters the denitrification anammox reaction through the carbon source dosing peristaltic pump Control the ratio of the mass concentration of initial COD to nitrate nitrogen in the reactor to be 2.0-3.5; after adding the organic carbon source, stir in anoxic state for 3-6 hours; after stirring, let it stand for 30-60 minutes, and discharge the supernatant. The drainage ratio is 30-70%.

Technical principle:

Semi-nitrification-denitrification anaerobic ammonium oxidation process to treat urban domestic sewage with low carbon-to-nitrogen ratio means that the raw water is first entered into the semi-nitrification reactor, and the aeration time and dissolved oxygen concentration are controlled through aerobic aeration. ~60% of ammonia nitrogen is oxidized to nitrate, and the effluent contains both ammonia nitrogen and nitrate; the inoculated sludge of the denitrification anammox reactor is sludge with incomplete denitrification characteristics and anammox sludge, of which Denitrification sludge contains a type of incomplete denitrification bacteria, which can only reduce nitrate to nitrite, and do not perform the process of reducing nitrite to nitrogen. The accumulation of nitrite in the incomplete denitrification process can Reach 80% to 100%, so as to achieve stable nitrite accumulation and provide electron acceptors for anammox bacteria. The effluent from the semi-nitrification reactor enters the denitrification anammox reactor, and a certain amount of additional carbon source is added to control the appropriate mass concentration ratio of COD to nitrate nitrogen and the anoxic concentration required for the incomplete denitrification process. Reaction time, incomplete denitrifiers can use organic matter to reduce nitrate to nitrite. This part of nitrite and ammonia nitrogen that has not been oxidized in the aerobic stage in the raw sewage can generate nitrogen through the action of anammox bacteria, thereby realizing the denitrification of urban domestic sewage. The denitrification process can also reduce a small amount of nitrate produced by the anammox process, improving the nitrogen removal efficiency of the system.

The process and method for the semi-nitrification-denitrification anammox treatment of low-carbon-nitrogen ratio urban sewage related to the present invention has the following advantages:

1) In the aerobic nitrification stage, only part of the ammonia nitrogen is oxidized to nitrate, which saves aeration volume and aeration time, and reduces operating costs;

2) Using the incomplete denitrification process to realize the reduction of nitrate to nitrite, the accumulation rate of nitrite is high and can be maintained stably, providing an appropriate proportion of influent water for the anaerobic ammonium oxidation process. Compared with the short-range nitrification process, denitrification The control of nitrite accumulation in the process is relatively simple, the operation is easy to realize, and the nitrite accumulation rate is stable;

3) The combination of denitrification and anammox process can reduce the nitrate in the influent and the nitrate generated in the anammox process to nitrogen, improve the denitrification efficiency of the system, and improve the quality of the effluent.

Description of drawings

Fig. 1 is a flow chart of a method for treating urban sewage with a low carbon-to-nitrogen ratio by semi-nitrification-denitrification anaerobic ammonium oxidation.

detailed description

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

As shown in Figure 1, the process of semi-nitrification-denitrification anaerobic ammonium oxidation treatment of low carbon nitrogen ratio urban domestic sewage is characterized in that it includes raw water tank 1, semi-nitrification reactor 2, intermediate water tank 3, denitrification anaerobic Ammoxidation reactor 4, additional carbon source storage tank 5.

The raw water tank 1 is connected to the semi-nitration reactor 2 through the first peristaltic pump 2.1; the semi-nitration reactor is provided with a first stirring device 2.2 and a water outlet 2.3, and the bottom of the reactor is provided with an aeration head 2.4, and an air pump 2.5 passes through a gas flow meter 2.6 is connected to the aeration head; the semi-nitrification reactor is connected to the intermediate water tank 3; the intermediate water tank is connected to the denitrification anammox reactor 4 through the second peristaltic pump 4.1; the denitrification anammox reactor is provided with a second stirring The device 4.2 and the temperature control device 4.3; the additional carbon source storage tank 5 is connected to the denitrification anammox reactor through the third peristaltic pump 5.1.

Specifically include the following processes:

Inoculate the remaining sludge of urban sewage plant in the semi-nitrification reactor, and the sludge concentration in the reactor after inoculation is 3000mg/L; the volume ratio of inoculated anaerobic ammonium oxidation sludge and denitrification sludge with incomplete denitrification characteristics is 2.5 : 1 mixed sludge in the denitrification anaerobic ammonium oxidation reactor, the sludge concentration in the reactor after inoculation is 2500mg/L; wherein, the denitrification sludge inoculated comes from the denitrification reactor that has been in operation for more than 1 year. Sludge has the characteristics of incomplete denitrification. When the concentration of organic carbon source is low, it can only reduce nitrate to nitrite, and its nitrite accumulation rate reaches 80%. The inoculated anammox sludge comes from the operation The total nitrogen removal rate of the anaerobic ammonium oxidation reactor for more than 6 months can reach 75%.

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 is a typical urban sewage with low C/N ratio; the raw water is collected into the raw water tank;

The semi-nitration reactor adopts SBR reactor, the reactor has an effective volume of 12L, and the total amount of sewage treated per cycle is 6L. The urban domestic sewage with low carbon-to-nitrogen ratio in the raw water tank enters the semi-nitrification SBR reactor through the first peristaltic pump, and the inflow volume is 6L. After the water inflow, it is aerated and stirred for 2 hours, and the dissolved oxygen concentration is controlled at 2.5mg/L during the aeration process; Precipitate for 40 minutes after the gas is over, then discharge the supernatant to the intermediate water tank, the drainage ratio is 50%, the average concentration of ammonia nitrogen in the effluent is 30mg/L, and the average concentration of nitrate nitrogen is 40mg/L.

The wastewater in the intermediate water tank enters the denitrification anammox reactor through the second peristaltic pump. The reactor adopts SBR, the effective volume is 12L, and the total sewage volume is 6L per cycle. The organic carbon source in the source storage tank enters the denitrification anaerobic ammonium oxidation reactor through the third peristaltic pump. In the experiment, sodium acetate was used as the external carbon source, and the ratio of the mass concentration of initial COD to nitrate nitrogen in the reactor was controlled to be 2.8 ; Stir for 5 hours without oxygen after entering the water, and control the temperature at 28° C.; after the stirring is completed, let it settle for 1 hour, and drain the supernatant, with a drainage ratio of 50%.

Continuous test results show that:

Taking actual domestic sewage as influent, the sludge concentration of the semi-nitrification SBR reactor is controlled at 3000mg/L, aeration and stirring for 2 hours, and the drainage ratio is 50%; at the same time, the sludge concentration of the denitrification and ammonia oxidation reactor is controlled at 2500mg/L, and the drainage The ratio is 50%; when the entire system treats 6L of sewage per cycle, the effluent NH ₄ ⁺ -N < 3mg/L, TN < 5mg/L, and the TN removal rate reaches 92% to 97%, which can achieve a low carbon-nitrogen ratio for urban domestic sewage Stable and efficient nitrogen removal.

Claims (2)

1. the device of half nitrification-denitrification Anammox process low ratio of carbon to ammonium city domestic sewage, it is characterized in that, comprise raw water box (1), half nitrator (2), intermediate water tank (3), denitrification anaerobic ammonia oxidation reactor (4), additional carbon reserve tank (5);

Raw water box (1) is connected with half nitrator (2) water-in by the first peristaltic pump (2.1); Half nitrator water outlet enters intermediate water tank (3); Intermediate water tank is connected with denitrification anaerobic ammonia oxidation reactor (4) water-in by the second peristaltic pump (4.1); Additional carbon reserve tank (5) adds peristaltic pump (5.1) by carbon source and adds mouth with denitrification anaerobic ammonia oxidation reactor carbon source and be connected;

Described half nitrator (2) is provided with the first whipping appts (2.2) and water outlet (2.3), half nitrator (2) bottom is provided with aeration head (2.4), and pneumatic pump (2.5) is connected with aeration head by gas meter (2.6);

Described denitrification anaerobic ammonia oxidation reactor is closed, is provided with the second whipping appts (4.2) and temperature-control device (4.3).

2. application rights requires that described in 1, device carries out the method for half nitrification-denitrification Anammox process low ratio of carbon to ammonium city domestic sewage, is characterized in that, comprises following process:

Inoculation municipal effluent plant excess sludge is in half nitrator, and controlling sludge concentration in half nitrator is 2000 ~ 4000mg/L; By anaerobic ammonium oxidation sludge and there is incomplete Denitrification Characteristics denitrification mud by volume for the mixed sludge seeding of 2:1 ~ 4:1 is to denitrification anaerobic ammonia oxidation reactor, controlling the rear sludge concentration of inoculation is 1400 ~ 4000mg/L; Wherein, the nitrite accumulation rate with the denitrification mud of incomplete Denitrification Characteristics of inoculation reaches 70% ~ 100%, and the anaerobic ammonium oxidation sludge nitrogen removal rate of inoculation is greater than 70%;

Low ratio of carbon to ammonium city domestic sewage is collected in raw water box, and in this city domestic sewage, COD is less than 4.0 with the ratio of the mass concentration of ammonia nitrogen; In raw water box, sewage enters half nitrator by the first peristaltic pump, aeration 1 ~ 3h after water inlet end, and in aeration process, Dissolved Oxygen concentration Control is at 2.0 ~ 4.0mg/L; Aeration terminates postprecipitation 30 ~ 60min, then nitrification liquid is expelled to intermediate water tank, and draining ratio is 40% ~ 60%;

Waste water in intermediate water tank enters denitrification anaerobic ammonia oxidation reactor by the second peristaltic pump; Organic carbon source solution during water inlet end in additional carbon reserve tank adds peristaltic pump by carbon source and enters denitrification anaerobic ammonia oxidation reactor, and controlling initial COD in reactor is 2.0 ~ 3.5 with the ratio of the mass concentration of nitrate nitrogen; Add anoxia stirring 3 ~ 6h after organic carbon source; Staticly settle 30 ~ 60min after stirring terminates, discharge supernatant liquor, draining ratio is 30 ~ 70%.