WO2019119756A1

WO2019119756A1 - Half shortcut nitration starting method for kitchen anaerobic wastewater

Info

Publication number: WO2019119756A1
Application number: PCT/CN2018/092179
Authority: WO
Inventors: 张周; 阮文权; 赵明星; 缪恒锋
Original assignee: 江南大学
Priority date: 2017-12-19
Filing date: 2018-06-21
Publication date: 2019-06-27
Also published as: CN107986434A; CN107986434B

Abstract

A half shortcut nitration starting method for kitchen anaerobic wastewater. On the basis of the characteristics of wastewater, such as high ammonia nitrogen and low C/N ratio, by using a shortcut nitration reactor and utilizing the difference between AOB and NOB oxygen saturation constants, AOB is enriched by limiting the concentration of DO in the reactor, and at the same time, other conditions such as temperature and alkalinity are controlled to accumulate nitrite, so as to start the half shortcut nitration process quickly; and the effluent can meet the inflow requirements of a subsequence anaerobic ammoxidation process. Also disclosed is a half shortcut nitration reactor.

Description

Semi-short-range nitrification starting method for kitchen anaerobic wastewater

Technical field

The invention relates to a semi-short-length nitrification starting method for a kitchen anaerobic wastewater, belonging to the field of kitchen wastewater treatment.

Background technique

With the rapid economic growth and the acceleration of urban processes, the amount of urban kitchen waste generated continues to grow, and the pollution caused by the environment is becoming more and more serious. The reduction, harmlessness and resource disposal of kitchen waste have become The hot spot of today's research. Kitchen waste is a major component of urban domestic waste, accounting for about 37-62% of urban domestic waste. According to statistics from the Institute of Solid Waste Pollution Control and Resource Reconstruction of Tsinghua University, China's cities produce more than 60 million tons of kitchen waste per year. Kitchen waste is mainly composed of organic substances such as starch, food cellulose and animal fat. Therefore, kitchen waste is a misplaced resource. The utilization of kitchen waste resources can solve the problem of “garbage pigs” caused by improper disposal of kitchen waste and the return of the “ditch oil” to the table to endanger human health.

Kitchen waste will inevitably be produced in the process of kitchen waste. Usually, anaerobic digestion is used to remove a large amount of organic matter from the kitchen waste water. The kitchen waste water after anaerobic digestion has high COD and high NH ₄ ⁺ -N. Low C/N and other characteristics, if the traditional denitrification process will inevitably lead to long processing flow, high operating costs, and because of its C / N imbalance, denitrification process carbon source is insufficient, resulting in low TN removal rate, difficult to meet standard emissions. In recent years, with the rise of some new denitrification processes, such as anaerobic ammonium oxidation process, short-cut nitrification and denitrification process, there are some better high-COD, high NH ₄ ⁺ -N, low C / N wastewater. Disposal method. Compared with the traditional nitrogen removal process, the new biological nitrogen removal process has obvious advantages over traditional nitrogen removal processes in terms of energy, carbon source and floor space.

The short-cut nitrification process can control the nitrification process in the NO ₂ ^- -N stage and accumulate a large amount of nitrite. Semi-short-length nitrification can be combined with denitrification or anaerobic ammonium oxidation to form a better combination of biological denitrification, especially for the treatment of high NH ₄ ⁺ -N and low C / N wastewater. Regardless of the short-cut nitrification and denitrification or anaerobic ammonium oxidation process, how to control the nitrification process in the NO ₂ ^- -N stage, accumulating a large amount of nitrite is the research focus. The current research on short-cut nitrification technology is mainly to control DO concentration, FA concentration, temperature and pH. However, for a wastewater such as kitchen waste water with a COD concentration higher than 1500 mg/L, a NH ₄ ⁺ -N concentration higher than 1000 mg/L and a lower C/N, the semi-short-length nitrification process needs to be properly diluted to gradually increase the substrate concentration. Or a chemical inhibitor such as potassium chlorate (KClO ₃ ) is needed to inhibit the activity of nitrite oxidizing bacteria (NOB) to achieve the start-up and operation of the semi-short-length nitrification reaction.

Summary of the invention

The object of the present invention is to provide a method for starting a semi-short-length nitrification process for anaerobic wastewater of a kitchen, to provide an appropriate influent water for the anaerobic ammonium oxidation process, and to solve the problem of low TN removal rate of the anaerobic wastewater of the kitchen.

A first object of the present invention is to provide a semi-short-length nitrification reactor comprising a reactor body, an aeration device, a temperature on-line monitor, a DO online monitor, a pH on-line analyzer, and a PLC control system; The monitor, the DO online monitor, and the pH on-line analyzer respectively extend into the reactor through the probe, and the other end is connected to the PLC control system; the bottom of the reactor body is provided with an aeration device, the aeration device is disposed on the reactor body The external air pump is connected; the air pump is also connected to the PLC control system; the heating device is connected to the side wall of the reactor, and the heating device is connected to the PLC control system; the stirring device is arranged inside the reactor, and the stirring device is connected with the PLC control system.

In one embodiment of the invention, the agitation device is a precision agitator.

In an embodiment of the invention, the PLC control system is also connected to the remote monitoring system and exchanges data information and control information with the remote monitoring system via a wired network.

In an embodiment of the present invention, a drain valve and a mud discharge valve are further disposed on a sidewall of the reactor body; the sludge discharge valve is disposed at a bottom of the reactor; the drain valve is disposed at an upper portion of the reactor body .

In an embodiment of the invention, the bottom of the reactor is provided with an air inlet, the air inlet is connected to the air pump through a pipeline, and a gas flow meter is arranged between the air inlet and the air pump.

In one embodiment of the invention, the reactor is made of stainless steel.

In one embodiment of the invention, the heating device is a silicone heating belt.

In an embodiment of the invention, an asbestos layer is further disposed on the outer side of the silica gel heating belt.

A second object of the present invention is to provide a method for starting a semi-short-length nitrification process for a kitchen anaerobic wastewater, which is to inoculate sludge with aerobic sludge in the process of kitchen waste water treatment, and to treat kitchen waste. The oxygen wastewater is used as the influent water, and the reactor is used to control the reactor DO to start the semi-short-length nitrification process at 0.5-0.6 mg/L.

In one embodiment of the invention, the operating cycle of the reactor includes a water infusion phase, a continuous agitation and aeration phase, a stationary precipitation phase, and a transient drainage phase.

In an embodiment of the present invention, the starting process specifically includes the following steps:

1) Inoculation of aerobic sludge from the kitchen wastewater treatment process, sludge concentration of 4 ~ 6g / L and strong aeration, DO concentration is controlled at 6 ~ 8mg / L;

2) Dilution rate of anaerobic wastewater in the kitchen: diluted 5 to 0 times, gradually increasing the influent ammonia nitrogen concentration in stages; after 5 times dilution, the COD is 356-487 mg/L, and the NH ₄ ⁺ -N is 156-262 mg/L. After dilution 2 times, COD 645 ~ 842mg / L, NH ₄ ⁺ -N 553 ~ 731mg / L; undiluted kitchen anaerobic raw water COD is 1510 ~ 2130mg / L, NH ₄ ⁺ - N is 983 ~ 1510mg / L , the pH of the reactor water is controlled to be maintained at 7-8 by sodium bicarbonate;

3) The SBR operation mode is adopted. The operation cycle includes: 8 to 10 minutes of influent water, continuous aeration and aeration for 6 to 8 hours, static precipitation for 2 to 3 hours, drainage for 8 to 15 minutes, and hydraulic retention time (HRT) of 8 to 10 hours.

In an embodiment of the present invention, the step is specifically:

1) Inoculation of aerobic pool sludge in the kitchen wastewater treatment process, the sludge concentration is 6g/L, the aerobic sludge to be taken out needs to be strongly aerated for 1d, the DO concentration is controlled at 6-8mg/L, and the sludge is completely Nitrification capacity;

2) The three different dilution rates of the kitchen anaerobic wastewater are: diluted 5 times, 2 times, 0 times to gradually increase the influent ammonia nitrogen concentration; after 5 times dilution, the COD is 356 ~ 487 mg / L, NH ₄ ⁺ -N is 156 ~ 262mg / L; diluted 2 times, COD 645 ~ 842mg / L, NH ₄ ⁺ -N 553 ~ 731mg / L; undiluted kitchen anaerobic raw water COD is 1510 ~ 2130mg / L, NH ₄ ⁺ -N is 983 ~ 1510mg / L, the pH of the reactor water is controlled to be maintained at 7 ~ 8 by sodium bicarbonate;

3) The test adopts SBR operation mode. The operation cycle includes: water inflow for 10 min, continuous stirring and aeration for 8 h, static sedimentation for 2 h, drainage for 10 min, hydraulic retention time (HRT) for 10 h, two cycles per day, each cycle The water intake and displacement are both 5L.

In one embodiment of the invention, the temperature of the startup process is controlled at 30 ± 1 ° C, and the temperature is stabilized by the on-line temperature control system and the heating device.

In one embodiment of the invention, the continuous agitation and aeration stage control DO is between 0.5 and 0.6 mg/L.

Advantageous Effects: (1) By limiting the DO concentration of the system, the NOB in the system is inhibited, and the AOB is enriched, and the activation of the semi-nitrosation system can be quickly realized. After the stabilization, the NH ₄ ⁺ -N conversion rate is 60. About 9%, the nitrosation rate is above 90%, the effluent COD removal rate is maintained between 60% and 70%, and the effluent nitrite nitrogen to ammonia nitrogen molar ratio is 1.0 to 1.3:1, which meets the requirements of anaerobic ammonium oxidation. Provide basic conditions for deep denitrification treatment of anaerobic wastewater from kitchen appliances.

(2) The method of the invention utilizes a semi-short-length nitrification reactor independently designed and developed, and the DO concentration of the system is linked with the air pump to limit the DO concentration in the system, and simultaneously control the reaction temperature and pH to obtain a better nitrite nitrogen. Accumulated, the ratio of ammonia nitrogen and nitrite nitrogen in the effluent is suitable for anaerobic ammonium oxidation process. By controlling the concentration of DO, enriching a large amount of AOB, eliminating NOB, using this technology to control ammonia nitrogen in the nitrite stage, controlling effluent nitrite nitrogen and The ammonia-nitrogen molar ratio provides favorable conditions for the subsequent treatment process, which saves a large amount of carbon source and energy compared to conventional nitrification and denitrification. Since the influent COD of the final stage of the reactor is 1510-2130 mg/L and the NH ₄ ⁺ -N is 983-1510 mg/L, the semi-short-length nitrification process initiated by the method of the invention has high ammonia nitrogen and COD load, and can be better. Treatment of high concentration ammonia nitrogen wastewater. The semi-short-length nitrification process initiated by the method of the present invention is stable in operation and can maintain a high nitrosation rate for a long time. The nitrite nitrogen to ammonia nitrogen molar ratio is suitable for the hydration demand of the anaerobic ammonium oxidation process.

DRAWINGS

Figure 1 is a schematic view showing the structure of a semi-short-length nitrification reactor of the present invention; wherein; 1, an air pump; 2, a gas flow meter; 3, an aeration device; 4, a temperature online monitor; 5, a precision agitator; Monitor; 7, pH on-line analyzer; .8, heating device; 9, PLC control system; 10, remote monitoring system; 11, drain valve; 12, mud valve;

Figure 2 shows the trend of trinitrogen evolution during startup;

Figure 3 shows the trend of COD change during startup;

Figure 4 shows the effect of DO concentration on the operating efficiency of a semi-short-length nitrification system.

Detailed ways

In the formula:

The difference in concentration of nitrite nitrogen and nitrate nitrogen in the influent and water, respectively, is mg/L.

Example 1

The semi-short-length nitrification reactor is a stainless steel tubular structure. The design parameters are: bottom diameter (φ) × height (H) = 30cm × 30cm, effective volume is 15L, and the inlet side of the reactor is provided with an air inlet and an air inlet. Connected to the air pump 1 through a pipe, the other end of the air pump 1 is connected to the PLC control system 9; a gas flow meter 2 is arranged between the air inlet and the air pump 1; an aeration device 3 is arranged at the bottom of the reactor, and the air is passed by the air pump 1 The gas flow meter 2 reaches the aeration device 3 provided at the bottom of the reactor, and is aerated by the air pump 1 during the aeration period to provide dissolved oxygen inside the system. The aeration device 3 is composed of 16 microporous aeration heads, and is uniformly distributed by the ventilation duct from the center position of the bottom of the reactor to the periphery, and each aeration head has a diameter (φ)=2 cm. The side wall of the reactor is provided with a drain valve 11 and a mud discharge valve 12, and the mud discharge valve 12 is disposed in the near bottom region; after the end of each cycle, the drain valve is used for drainage, and at the same time, the reactor is regularly drained. The top of the reactor is equipped with a precision stirrer. The power of the stirrer is constant at 100W and the speed is 0-300rpm. The reactor is also equipped with a temperature online monitor 4, a DO online monitor 6, and a pH online analyzer 7, which are respectively arranged in the reactor. The internal probe connection monitors the internal parameters of the reactor; the temperature online monitor 4, the DO online monitor 6, and the pH online analyzer 7 are also respectively connected with the PLC control system 9 to transmit signals to the PLC control system 9; DO The probe transmits the DO concentration in the reactor to the PLC control system 9, and the PLC control system feeds back to the air pump 1 to form a linkage to more accurately control the DO concentration in the system; the reactor is provided with a heating and insulating belt 8 along the sidewall; the heating The heat insulating tape 8 is a silica gel heating belt, and the heating and heat insulating tape 8 is connected with the PLC control system 9 and is linked with the temperature online monitor 4, and the temperature of the reactor is monitored by the temperature online monitor 4, and the temperature information is transmitted to the PLC control system. Then, the heating state of the heating and heat insulating belt 8 is adjusted by the PLC control system, that is, when the temperature exceeds the set temperature, the heating and insulating belt 8 stops heating; when the temperature is lower than the set temperature, 8 starts heating with thermal insulation. The silica gel heating belt is fixed to the stainless steel plate of the pool body by glass glue, and the distribution pattern is arranged around the bottom of the pool body at 5, 15, and 25 cm, and the total power of the heating belt is 3×100 W=300 W. An asbestos layer is placed on the periphery of the heating belt for heat preservation, and the heat preservation area is 0.25 m ² .

The PLC control system 9 is also connected to the remote monitoring system 10, transmits real-time data of the reactor to the remote monitoring system 10 through wired data transmission, or transmits the control operation of the remote monitoring system 10 to the PLC control system to implement feedback control.

Example 2

The sludge was inoculated into the semi-short-length nitrification reactor, and the sludge was inoculated from the aerobic tank sludge in the A ³ /O ³ process of the kitchen waste water treatment plant. The sludge concentration was 6 g/L, and the sludge after inoculation was strong in the reactor. Aeration 1d, DO control at 6 ~ 8mg / L, temperature control 30 ± 1 ° C, so that the sludge has complete nitrification capacity.

The SBR operation mode is adopted, and the operation cycle includes water inflow for 10 min, continuous stirring and aeration for 8 h, static precipitation for 2 h, and drainage for 10 min. It runs two cycles a day, each with a water intake and displacement of 5L. At the beginning of the cycle, 5L of water enters the reactor through the peristaltic pump, and at the same time, the precision stirring device is started, so that the muddy water is fully mixed. When the water inlet phase is completed, the air pump is turned on to aerate the reactor to control the DO concentration and the reactor temperature. And stirring speed. After 8 hours, the stirring and aeration devices were turned off at the same time, and the static sedimentation stage was entered. After standing for 2 hours, the drainage valve 12 was used to drain 5 L. The sludge discharge frequency was 1 time/week during the test period.

The semi-short-length nitrification start-up process of anaerobic wastewater in kitchen is divided into three stages. The first stage dilutes the influent water by 5 times. After the effluent sub-digestibility and ammonia-nitrogen conversion rate are stable for 3 to 5 cycles, the second stage is entered. In the stage, the influent water is diluted twice, and the effluent sub-digestibility and ammonia-nitrogen conversion rate are stabilized for 3 to 5 cycles, and then enter the third stage. The temperature of the reactor is controlled to 30±1°C throughout the process, and the DO concentration in the aeration phase is controlled to 0.5-0.6mg/L. In order to make the sludge have better adaptability at the beginning of the startup, the kitchen wastewater was diluted 5 times as the reactor water. The diluted COD was 356-487 mg/L, with an average of 404 mg/L and NH ₄ ⁺ -N 156. ~ 262 mg / L, an average of 199 mg / L. The conversion of NH ₄ ⁺ -N in the first 6 cycles showed a downward trend (Fig. 1), indicating that low dissolved oxygen hindered the ammoxidation, and the accumulation of NO ₂ ^- -N in the effluent did not completely convert to NO as in the whole process. ₃ ^- -N, and the concentration of NO ₃ ^- -N in the effluent of the first 6 cycles increased slightly, but as the reaction progressed, the conversion rate of ammonia nitrogen was basically maintained at about 60%, and the NO ₃ ^- -N in the effluent decreased. The nitrosation rate is increasing, indicating that the oxygen saturation constant of nitrifying bacteria is higher than the oxygen saturation constant of nitrosated bacteria. In the lower DO environment, the activity of nitrifying bacteria is greatly inhibited, and the growth rate is slow, NO ₂ ^- -N The process of conversion to NO ₃ ^- -N is inhibited. Since the sludge inoculated at the initial stage of the reactor operation is better than the strongly aerated sludge heterotrophic bacteria, the COD removal rate is kept at a high level, and the activity of the heterotrophic bacteria is inhibited as the reactor is oxygen-limited. In the 10th to 24th cycles, the effluent COD value showed an upward trend, while the COD removal rate remained at about 60% (Fig. 2).

After 24 cycles of initial start-up, it entered the activity improvement period and began to reduce the dilution rate of the kitchen waste water. After diluting twice, the water quality of the kitchen waste water was COD 645-842 mg/L, NH ₄ ⁺ -N 553-731 mg/L. . During the activity increase period, the NH ₄ ⁺ -N conversion rate is maintained at about 60%. The lower DO environment caused the nitrate bacteria to be unable to adapt, and its activity was gradually inhibited, and the entire nitrosation system was gradually eliminated. After entering the second stage, the NO ₃ ^- -N in the effluent showed a downward trend, while NO ₂ ^- - N has a steady upward trend, and the nitrosation rate of the whole process has increased significantly, gradually increasing to over 80%. During the first few cycles of the activity improvement period, the COD removal rate decreased significantly, which may be due to the sudden increase of COD load, the failure of heterotrophic bacteria to adapt, and the low COD removal rate. However, with the operation of the reactor, the removal rate of COD has a tendency to rise slowly, and finally it is maintained at about 63%.

In the third stage, the undiluted kitchen waste water was directly added to the reaction system, the COD was 1510-2130 mg/L, and the NH ₄ ⁺ -N was 983-1510 mg/L. In this process, the NH ₄ ⁺ -N conversion rate is basically maintained above 60%, the effluent NO ₃ ^- -N continues to decline, while the NO ₂ ^- -N concentration continues to rise, and the nitrosation rate also rises, basically maintaining at 90%. Above, the effluent COD removal rate is maintained between 60% and 70%, and the effluent nitrite nitrogen to ammonia nitrogen molar ratio is 1.0 to 1.3:1, which satisfies the influent requirements for subsequent treatment. At this point the semi-short-length nitrification system has been successfully started.

Example 3

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As with Embodiment 2, the difference is that the DO concentration is controlled, and the influence of the DO concentration on the reaction system is studied. After the SBR process successfully achieves stable NO ₂ ^- -N accumulation, the DO concentration in the system is changed, and the DO concentration is examined. The impact of the operating efficiency of the lower nitrosation system. At this stage, the influent COD concentration averaged 1874 mg/L, NH ₄ ⁺ -N, NO ₂ ^- -N, and NO ₃ ^- -N averaged 1231 mg/L, 2 mg/L and 29 mg/L, and 6 different DOs were set. Concentration stage.

The DO concentration is lower than 0.5mg/L, the system COD removal rate is lower, the sub-digestibility is low, and the molar ratio of effluent nitrite nitrogen to ammonia nitrogen is 1:2～1:4; the aeration time increases, and the same amount of NH _{4 is} oxidized. ^{The +} -N rate is slower and the startup time required is longer. However, the too low DO concentration inhibits the growth of AOB while suppressing NOB, so the nitrosation rate also decreases.

When DO is higher than 0.6mg/L, the system COD removal rate increases, the nitrosation rate decreases, the effluent cannot reduce the ammonia nitrogen oxidation control in the nitrous acid phase, and a large part of the nitrite nitrogen is oxidized to nitrate nitrogen; The concentration may damage the stability of the system. When the DO concentration is higher than 1.0 mg/L, the DO concentration no longer becomes the influencing factor of NOB inhibition. As the NOB activity gradually recovers, NO ₃ ^- -N is further oxidized to NO ₃ by NOB. ^— N, the reaction system was destroyed.

Although the present invention has been disclosed in the above preferred embodiments, the present invention is not limited thereto, and various modifications and changes can be made thereto without departing from the spirit and scope of the invention. The scope of the invention should be determined by the scope of the claims.

Claims

A semi-short-range nitrification reactor, comprising: a reactor body, an aeration device, a temperature online monitor, a DO online monitor, a pH on-line analyzer and a PLC control system; the temperature online monitor, DO online monitoring One end of the instrument and the pH on-line measuring instrument are respectively inserted into the reactor body through the probe, and the other end is connected with the PLC control system; the bottom of the reactor body is provided with an aeration device, the aeration device and the air disposed outside the reactor body The pump is connected; the air pump is also connected to the PLC control system; the reactor side wall is provided with a heating device, the heating device is connected with the PLC control system; the reactor is internally provided with a stirring device, and the stirring device is connected with the PLC control system.
A semi-short-length nitrification reactor according to claim 1, wherein said heating means is a silica gel heating belt.
A semi-short-length nitrification reactor according to claim 2, wherein an asbestos layer is further disposed outside the silica gel heating belt.
A semi-short-length nitrification reactor according to claim 1, wherein the bottom of the reactor body is provided with an air inlet, the air inlet is connected to the air pump through a pipe, and a gas is disposed between the air inlet and the air pump. Flow meter.
A semi-short-length nitrification reactor according to claim 4, wherein a drain valve and a mud discharge valve are further disposed on the side wall of the reactor body; the sludge discharge valve is disposed at the bottom of the near reactor; The valve is placed on the upper portion of the reactor body.
A semi-short-length nitrification reactor according to any one of claims 1 to 5, wherein the PLC control system is further connected to the remote monitoring system and exchanges data information and control information with the remote monitoring system via a wired network.
The invention relates to a method for starting a semi-short-length nitrification process for anaerobic wastewater of a kitchen, characterized in that the aerobic sludge in the process of treating the kitchen waste water is used as the inoculation sludge, and the anaerobic wastewater of the kitchen waste is used as the influent, the application claim The reactor of any of 1 to 5 is activated by a semi-short-length nitrification process.
The method according to claim 7, wherein the reactor DO is controlled at 0.5 to 0.6 mg/L; and the temperature during the startup is controlled at 29 to 31 °C.
The method of claim 7 wherein the operating cycle of the reactor comprises an influent stage, a continuous agitation and aeration stage, a stationary settling stage, and a transient drainage stage.
The method according to any one of claims 7 to 9, wherein the starting process specifically comprises the following steps:

1) Inoculation of aerobic sludge from the kitchen wastewater treatment process, sludge concentration of 4 ~ 6g / L and strong aeration, DO concentration is controlled at 6 ~ 8mg / L;

2) Dilution rate of anaerobic wastewater in the kitchen: diluted 5 to 0 times, gradually increasing the influent ammonia nitrogen concentration in stages; after the first stage dilution, the COD is 356-487 mg/L, and the NH 4 + -N is 156-262 mg/ L; after the second stage dilution, COD 645 ~ 842mg / L, NH 4 + - N 553 ~ 731mg / L; undiluted kitchen anaerobic raw water COD is 1510 ~ 2130mg / L, NH 4 + - N is 983 ~ 1510mg / L, through the sodium bicarbonate control reactor water pH maintained at 7 ~ 8;

3) The SBR operation mode is adopted. The operation cycle includes: 8 to 10 minutes of influent water, continuous aeration and aeration for 6 to 8 hours, static precipitation for 2 to 3 hours, drainage for 8 to 15 minutes, and hydraulic retention time (HRT) of 8 to 10 hours.