Question: How to dispose of the methane produced by anaerobic digestion? How to take advantage?Answer: There are many ways to use it, such as fuel, power generation, etc. However, if it is used, the safety requirements are very high and the investment cost is also high. Therefore, post-combustion emissions are generally produced at home and abroad, such as those produced by anaerobic treatment devices such as AF and IC. The methane is automatically ignited and burned using a torch. It can also be used in biogas blowers, which is a good way to use it. This type of blower can be powered by electricity and biogas respectively.2. Question: This process uses submerged biofilm. Considering that adding an external carbon source requires more labor and is not economical, it also reduces dissolved oxygen and the ammonia nitrogen removal effect is not bad. The effluent nitrate is 11mg/L, but the nitrite is very high. Question: Can the denitrification effect be improved when C/N is low?Answer: Short-cut denitrification can be used, because short-cut denitrification directly denitrifies nitrite nitrogen into nitrogen gas, which can greatly save energy consumption. However, because nitrite nitrogen is unstable and difficult to accumulate, since the effluent nitrite nitrogen is so high Why not give it a try? If it can be achieved, it would be cost-effective to add an external carbon source.3．Question: Pig wastewater, incoming water: COD1500, ammonia nitrogen 500, TP60, alkalinity 3000, nitrate nitrogen and nitrite nitrogen cannot be detected by instruments, and the values ​​must be very low. Effluent: ammonia nitrogen 120, COD 700, but nitrate nitrogen is as high as 1200, nitrite nitrogen 250. SRT: Is this normal for 1 day? Where does such high nitrate come from? How to explain?Answer: If the data measurement is correct, there is only one explanation, that is, when the total nitrogen is much higher than ammonia nitrogen, nitrogen-containing organic matter continues to be ammonified, and ammonia nitrogen continues to be nitrified. At this time, the treatment system is under aerobic conditions, and nitrate nitrogen cannot react. A large amount of nitrification accumulates. In this case, if the treatment time is increased, the effluent ammonia nitrogen may decrease, and the effluent nitrate nitrogen will increase.4. Question: I debug a food wastewater. Before UASB produces granular sludge, the raw water COD was 2000-3000, and the effluent was always around 750. This period is about 50 days. Run a small amount of mud during this time. Afterwards, the concentration of wastewater reached 4000-5000, which reduced the amount of treated water and kept the effluent less than 1000. Then the processing volume started to increase. The mud leakage has become more serious, the amount of mud produced is large, and the three-phase separator is not good. When the designed treatment capacity reached half, the company asked me to quickly increase the water volume because the aerobic capacity was high. In the process of accelerating the water volume, the gas production volume continues to decrease, and the water output is 1100-1500. Fifteen days later, the flow rate was close to the design, but the cooperation with Party A was not good and sampling was not possible for acceptance. After that, Party A's output decreased, but the water quality concentration changed greatly by 3000-5500. After adjusting the flow rate, the gas production began to increase slightly, but the granular sludge flowed out in large quantities with the water, mainly non-bubbles. Even if no water entered, there would be A large amount of sludge floats up but never sinks. This phenomenon has been happening for more than ten days. What is going on?Answer: It may be that the load is too large, which prolongs the acidic fermentation process and causes the alkaline fermentation process to be incomplete. For treatment devices with unstable incoming water load, it is best to pre-acidify the sewage before entering the UASB device, so as to increase the pH and better ensure the treatment effect.5. Question: I am doing an UASB anaerobic biochemical treatment experiment for molasses alcohol waste liquid. The current inlet water concentration is 30000~50000mg/L, the removal rate is 55~60%, and the load is 20KG. I encountered many difficulties, mainly the influence of sulfate radicals and inoculation. Sludge (non-granular sludge) is severely lost and has poor biodegradability. I think the reason is mainly caused by poor acidification stage. I wonder if this is the case?Answer: Two comments for reference: (1) The acidification time should not be long to avoid low pH affecting subsequent biochemical treatment; (2) When cultivating granular sludge, an appropriate amount of activated carbon or PAM can be added to the inoculated sludge, which is beneficial to Granular sludge formation. Because I don’t know the specific situation, it is only for reference.6．Q: What matters should be paid attention to in the operation and management of the simultaneous phosphorus and denitrification process of denitrifying phosphate-accumulating bacteria (DPB)?Answer: There are many requirements for operation and management. For example, the anaerobic pool cannot have oxygen, but how to control it? Insufficient oxygen in the aerobic zone will affect nitrification and phosphorus accumulation. Too high oxygen will create a microaerobic environment in the anaerobic zone, affecting phosphorus release. Sometimes the dissolved oxygen in the aerobic zone is not high, and there may be microoxygen in the anaerobic zone. This is related to the good news. In addition to the level of dissolved oxygen in the oxygen zone, it is also related to factors such as the residence time of the sewage sedimentation tank and the degree of hypoxia. In addition, the sludge must be discharged in time according to process requirements. The final way to remove phosphorus is through the discharge of remaining sludge. If it is not discharged in time, the cycle of phosphorus accumulation and phosphorus release will be repeated in the system.7. Question: There is a company here that plans to reuse the treated sewage. The treatment process is: regulating tank - anaerobic tank - aerobic tank - a sedimentation tank - an air flotation tank - a sewage outlet, in which sulfuric acid is added to the first sedimentation tank. Ferrous iron and lime, aluminum chloride and polyacrylamide are added to the flotation tank. The iron ions in the effluent water are very high. I wonder if there is any good way to reduce their content. Of course, the cost should not be too high?Answer: Do not use air flotation. You can add lime to the aerobically treated water to adjust the pH to about 8, add PAM, and control the flocculation conditions such as stirring. This can improve the removal rate of iron ions. You can try it.8. Question: In the relationship between BOD and COD, is COD greater than BOD? COD-BOD is approximately equal to non-biochemical organic matter.Answer: This is not accurate, because COD=COD(B)+COD(NB), the former is the biodegradable part and the latter is the non-biodegradable part. It takes about 20 days for microorganisms to complete the carbonization process at 20 degrees (that is, BOD20 is close to CODB).9. Question: In a county with a population of about 200,000, a city sewage treatment plant is pre-built with a scale of 20,000 tons/day. Due to limited government funds, the construction cost wants to be controlled at around 15 million. Which process is more suitable?Answer: It is recommended to use the nano-diatom soil method. This method is particularly suitable for urban sewage treatment. The sludge produced can be used as insulation material. The investment is small and the operating cost is only half of the traditional method. The difference between nanodiatomaceous earth and ordinary diatomaceous earth is that it has a strong electrical neutralization effect through special treatment, and the specific surface area is also greatly increased.10．Question: This sewage treatment plant treats pulp and paper wastewater and uses the complete mixing method. Recently, the SV of the sludge has dropped to 5-6. There are only clockworms and rotifers in the sludge, and the treatment effect is average. Recently, F/M has been around 0.3 and the temperature has been relatively high. The temperature of the aeration tank has been between 37 and 39 degrees. Is it due to sludge poisoning? Or other reasons?Answer: The F/M is not too low, and it does not look like poisoning from a biological perspective, because clockworms are very sensitive to toxic substances. It may be due to the high water temperature. Generally speaking, water temperatures exceeding 38 degrees will have some impact on the activity of aerobic microorganisms.11. Question: I am currently debugging an SBR to treat slaughterhouse wastewater. After a few days of sedimentation, there are always fine mud particles suspended in the supernatant, which cannot be sedimented. As a result, the COD and SS of the effluent cannot meet the standards, and the water temperature is around 35-37 degrees. Is it caused by too high a temperature? What should I do?Answer: The sludge has signs of aging. Such temperature has some impact on microbial activity, but it is not the main reason. The main reason is that the aeration time is too long. To reduce the aeration time (such as intermittent aeration), the sludge needs to be discharged. Reducing the aeration time means reducing the time of the reaction stage. Since the time of an operation cycle is fixed, the idle stage time can be increased accordingly. If unlimited aeration is used in the water inlet stage, it will be changed to limited aeration.12. Question: When wastewater containing acrylonitrile is added with PAC and PAM, and then undergoes biochemical treatment, the ammonia nitrogen content will reach a maximum of 217 mg/L. The analysis may be that acrylonitrile is converted into acrylic acid and then into ammonia nitrogen, or the amide may also increase ammonia nitrogen. There is no theoretical and experimental data basis. Can it be explained?Answer: This situation is normal and is caused by ammoniation. This type of wastewater requires a long treatment time. Such high effluent ammonia nitrogen indicates that the ammoniation process of acrylonitrile has not been completed. To make the ammonia nitrogen reach the standard, the biochemical reaction time needs to be increased. .13．Question: How does the sludge from the three oxidation ditches and two secondary sedimentation tanks flow back? Two secondary sedimentation tanks have a sludge pump room. How can the return sludge be evenly distributed to the three oxidation ditches?Answer: There is a sludge collection tank in front of the sludge pump. The return sludge is lifted by the pump and transported to the front of the oxidation ditch through a return sludge main pipe, and then divided into three branch pipes to enter each oxidation ditch.14. Question: There is existing high-concentration wastewater (BOD value about 6,000). When treated with the activated sludge method (SBR method), is it appropriate to set a very large value (such as 20,000) for the MLSS value (such as 20,000) to meet the sludge load requirements? What kind of problems might arise? Is there any better way to avoid problems?Answer: Such a high concentration should not be treated directly with aerobic treatment. Anaerobic treatment should be used before aerobic treatment. Regardless of the SBR method or other activated sludge methods, MLSS should be controlled based on the F/M value and is limited by factors such as settling time and oxygen supply capacity.15. Question: I am working on aquatic product processing wastewater plan, using UASB. The water quality is as follows: Q=200t/d, COD=3000, BOD=1000, SS=300, total nitrogen=200, ammonia nitrogen=20. Sewage discharge standards: effluent requirements COD <300, bod <150, ss <200, total nitrogen <40, ammonia nitrogen <25. < span="">I would like to ask you about the following water quality conditions: (1) If BOD is less than 150 and BOD is not reduced to save project investment, can total nitrogen be removed? (2) Are the reaction end points for nitrogen elements in UASB are nh4+ and nh3? < span="">Answer: The conversion of nitrogen by UASB is mainly the ammonification of organic nitrogen. Therefore, ammoniation, nitrification and denitrification must continue after UASB. It is recommended to use the A2/0 contact oxidation method after UASB.16. Question: Pig wastewater COD: 10000, ammonia nitrogen 400, anaerobic + SBR effluent COD: 150, ammonia nitrogen 150, 300 m3/day, stabilizing pond 15 acres, can store water 1-1.5 meters deep, how to design the stabilizing pond? What kind of plants should I plant in early June? Will the water yield reach the first level?Answer: Second-level stabilizing ponds, first-level aeration ponds, and second-level static ponds can be used. A small number of floating aerators (the same as those used in fish ponds) can be installed in aeration ponds, which are generally not frequently aerated. Water hyacinths and other aquatic plants can be propagated in static ponds.17. Question: I am currently experimenting with the treatment of chemical wastewater. The main treatment difficulties are: poor biodegradability; easy to change color (more serious than dye wastewater); and the wastewater is highly corrosive, with a pH value of about 2 left and right; the COD after biochemistry is sometimes high and sometimes low, and the main pollutants are also substances with benzene rings. What kind of process should be used?Answer: Regeneration treatment is required after pretreatment. Pretreatment can use electrolysis, fast ion removal method or acidification method.18. Question: Our factory is a large urban sewage treatment plant with a daily treatment capacity of 300,000 tons. It adopts an improved oxidation ditch process. Recently, the secondary sedimentation tank is particularly prone to mud leakage, and the oxidation ditch MLSS has been stable at 4000-5000mg/L. Why is this happening? ?Answer: It may be caused by the oxidation of the sludge itself, which causes part of the sludge to deflocculate. If so, the amount of sludge discharge should be increased and the amount of aeration should be reduced.19. Question: There is a sewage plant that uses an ordinary aeration tank and perforated pipe aeration. The sewage volume has exceeded the designed water volume and the treatment capacity needs to be improved. I would like to ask what measures can be taken to improve the processing capacity of the aeration tank without changing the volume of the aeration tank?Answer: The following measures are for reference: (1) Install fiber fillers in the pool and adopt biological contact oxidation method; (2) Change the perforated pipe to a microporous aeration hose, and the oxygen utilization rate can be increased several times. In this way, the volumetric load of the aeration tank can be more than doubled.20. Question: There is less and less sludge in the aeration tank. The COD of the incoming water is about 100~200 mg/L. It is difficult for sludge to grow. There is a lot of dead sludge in the pool that is not in use. What should I do?Answer: The intermittent aeration method can be used to discharge some sludge in an appropriate amount. Although the amount of sludge is very small, it will be even less if the sludge is not discharged.twenty one. Question: The contact oxidation method for treating wastewater requires that the BOD of the incoming water should not be too high. Can contact oxidation after hydrolysis and acidification ensure the BOD requirements of the incoming water of the contact oxidation tank? If not, what should I do?Answer: The removal of COD by hydrolysis and acidification is very limited, mainly to improve the biodegradability of wastewater. If the BOD of the incoming water in the contact oxidation tank is too high, anaerobic processes or other methods can be used for pretreatment.twenty two. Q: How to determine the amount of microorganisms exposed to the oxidation aeration tank? The traditional activated sludge method can be expressed by the sludge concentration (MLSS), which can be intuitively expressed by the sludge settling ratio (SV30). How should the amount of microorganisms in the contact oxidation aeration tank be visually expressed? Some people say that observing the thickness of the biofilm, what is the standard for thickness?Answer: It is impossible and unnecessary to measure the amount of biofilm in contact with the oxidation pond. If the film on the filler is too thick, the specific surface area will be small, and the amount of active biofilm per unit volume will be less. Too little film is not good either. Controlling the thickness of organisms in actual operation is one of the keys to operation management. If the film is too thick, air volume or flushing will be required. Since the biofilm is installed under the water surface in the pool, it is best to install the removable observation filler on the edge of the pool. The thickness of the biofilm is best when it just covers the filler.twenty three. Question: In some A/O processes, section A is an anaerobic section. Why is air tube aeration needed?Answer: Air tube aeration is used, which can operate anaerobically, anoxically or aerobically. At the same time, when the mixing effect is not good, the aeration tube can be used to assist stirring to prevent sludge settlement. Although Section A should be lacking Oxygen, but moderate aeration (DO<0.5mg l) is no problem. <="" p="">twenty four. Question: During the anaerobic + aerobic treatment process, if there is still a large amount of sulfur after the anaerobic treatment, how can it be removed?Answer: If there is still a large amount of hydrogen sulfide after anaerobic treatment, it means that the anaerobic reaction is incomplete and the reaction conditions must be controlled.25. Question: The secondary sedimentation tank we designed is the sedimentation tank after the Ober oxidation ditch. The return sludge concentration of the oxidation ditch requires 8g/L. We are afraid that the concentration of the return sludge that flows in and out weekly will not reach that level. Therefore, experts recommend using weekly inflow and weekly outflow. The manufacturer introduced that using a single-tube sludge suction machine for this process, the return sludge concentration can reach 8-12g/L, right?Answer: It should be used with caution. Devices with poor sludge settling performance are not suitable for use with weekly inlet and weekly out sedimentation tanks, and single-tube sludge suction machines are even less suitable.26. Question: In the 100-ton pilot project I am working on, the ammonia nitrogen removal effect is not good recently. According to the current observation: the oxygen supply should be OK, the alkalinity is sufficient, the biological activity is acceptable and there is no obvious toxicity, and the sewage exposure is still not OK. Is it OK? Can you assume that load is not a problem? Are ammoniation and nitrification of organic nitrogen carried out at the same time, with ammonification slightly ahead of nitrification? Are there other factors that affect nitrification?Answer: The ammonification process of nitrogen-containing organic matter precedes the nitrification process and is slower than the carbonization process of organic matter, but faster than the nitrification process of ammonia nitrogen. Nitrification can only occur at low organic loads. Although it cannot be said that the nitrification process can start after the ammonification process is completed, it can be considered that the ammoniation process will still occur in the early stage of the nitrification process, and the two processes will coexist for a certain period of time. The ammonia nitrogen in the incoming water of some devices is very low and the total nitrogen is very high. After biochemical treatment, the ammonia nitrogen in the effluent is higher than the incoming water, indicating that the device not only does not have enough time for the nitrification reaction, but also the ammoniation process may not be completed. From what you said, the load should be no problem. You should also confirm whether the nutritional ratio is satisfied, such as whether there is a phosphorus deficiency, etc.27. Question: We are doing a juice wastewater treatment, using UASB+ contact oxidation process. The COD is around 8000, the BOD is around 4000, the pH fluctuates greatly, around 9-13, and sometimes the pH is around 5. The incoming water volume is 1200, and the water volume is unstable. What conditions should be paid attention to when debugging?Answer: It is very important to adjust the water quality and quantity of this type of water. The capacity of the regulating pool must be large enough to ensure stable operation of the treatment device.28. Question: The waste alkali from alkali washing in a refinery (liquefied gas, straight-run diesel, catalytic cracked gasoline) has a water volume of about 4KL/HR and a COD of about 40,000. What method is used to pretreat it?Answer: Pretreatment suggestions: Because the lye inevitably contains some oil, a waste lye regulating storage tank with an oil decanting function should be set up to neutralize the waste lye. Generally, waste lye also contains high concentrations of sulfide, which can be treated with air or other oxidation methods (before the neutralization process).29. Ask a few questions: How to operate the waste alkali regulating storage tank with oil decanting function? Separation by gravity? What should I do if the emulsification is severe? Recently, due to blockage of the tower tube in the sewage cooling tower, the water temperature can reach as high as 44.7 after opening the bypass. Although it can speed up the reaction rate, it is also close to the limit of mesophilic microorganisms (THH is set at 45C). As a last resort, the highest temperature tributary in the water inlet pipe has to be cut off. out of the system; does the activated sludge method have any restrictions on the methanol content in the incoming water? Because there is a problem with the methanol storage tank and needs to be cleaned, and we are worried about impacting the biochemical treatment site. I have checked some information, and some say that it is extremely biodegradable, while others say that if it is too high, it will be toxic. Is that correct?Answer: The answers to the three questions are as follows: (1) Strictly speaking, if there is oil in the waste lye, it should be washed with gasoline first. The lye storage tank must also have an oil decanting function. The simple way is to set it up at different heights between the upper and middle parts of the tank. Drain the oil pipe and install the valve so that oil can be decanted at different levels. (2) Such a temperature will seriously affect the biochemical treatment effect (unless it is anaerobic method), cooling measures must be taken. (3) Although methanol has good biodegradability, it will not work if the concentration is too high, unless it is an anaerobic method.30. Question: Our factory uses an improved SBR. The so-called improvement means continuous water inflow. It just divides the reaction tank into two steps with a retaining wall, a so-called pre-reaction zone and the main reaction tank. There are 2 at the bottom of the retaining wall. The square meters of holes are connected, and there is no sludge backflow. The pre-reaction zone is exactly the same as the main reaction tank. The pre-reaction zone is 3.5 meters long, the main reaction tank is 36 meters long, the tank depth is 4.7 meters, the tank width is 12.5 meters, and the decanting height is 1.3 meters, the incoming water is mainly domestic sewage COD400BOD180 total nitrogen 80 total phosphorus 8, the water inflow is 10,000 cubic meters per day, and now two reaction tanks are running! Please tell me what is the appropriate sludge concentration control? The aeration hose is used for aeration. It may be that the aeration pipe is not very good. The reaction tank is only aerated at both ends but not in the middle! It has been in operation for half a year, but the effluent is still not up to standard. The COD is always around 80, and the sludge concentration is around 6,000. A cycle of four hours, two hours of aeration, one hour of quieting, and one hour of decanting! Please give expert guidance! The dissolved oxygen during aeration is 2!Answer: According to what you said, it should be the ICEAS process. It is recommended that you check whether there is an air bag installed in the air pipe in front of the aeration hose, and whether the air pipe system is equipped with an exhaust pipe (also called a sewage pipe), because these are all related to what you said about the aeration pipe having air at both ends and no air in the middle. situation related. As for the high MLSS, this is only one reason, and there are also factors such as aeration time.31. Question: I am debugging a slaughtering wastewater. The process is: septic tank (HRT>2d) - regulating tank - hydrolysis tank (HRT=5) - contact oxidation tank (HRT=6) - secondary sedimentation tank. Due to the pre-chemical The COD of the effluent from the septic tank is 700, and the contact oxidation time is relatively short, so the water contact tank is changed to an aeration tank. However, the effect of a submersible aerator added is limited. The DO is generally below 0.5. The original aeration tank DO normal. The SV of both pools can reach 20-30. Now the inlet water volume is 70% of the designed water volume. The outlet water quality is still very poor, with more SS. The original aeration tank has a certain amount of foam and is relatively thick. Is it because of the aging of the sludge? Caused by?Answer: It is normal for aerobic water to have COD 700. The foam has nothing to do with ammonia nitrogen. Do you need to determine whether it is biological foam or chemical foam? If it is a chemical foam, it will gradually decrease if it is maintained at such a sludge concentration. If it is not possible, it can be defoamed by spraying with water. It feels like your sludge activity is very poor. The reason may be that nutrients, such as nitrogen and phosphorus, are not well controlled.32. Question: One of our projects has been running for a year. Recently, due to the deterioration of the incoming water quality, the S content of the incoming water to the biochemical device has reached around 100. Now the incoming water S is around 10. It has taken five days to recover. The incoming water COD is 600 and the effluent COD is 300. Left and right, under a 10x16 microscope, I saw some dendritic things and some extremely small (needle-tip-sized) things. I don’t know what they are. The sludge concentration is almost non-existent. How should I adjust it now? Is the sludge oxidized? The gas volume should be reduced. point?Answer: It means that the sludge has been seriously damaged and disintegrated, and needs to be cultured again.33．Question: The sewage treatment system has just been built and is ready to start operation. The process is: regulating tank---hydrolysis tank---anaerobic tank---aerobic tank---sedimentation tank---sludge treatment system. It will start soon. It has been put into trial operation and it is planned to use vaccination for domestication. What are the specific precautions during driving and domestication?Answer: Static culture should be used in the initial stage of bacterial culture. After the sludge is initially formed, care should be taken to prevent excessive self-oxidation of the sludge. This situation has occurred in many factories. The sludge does not increase for a long time, or even decreases. The reason is that nutrition and aeration time are not controlled well, and the sludge is growing while constantly oxidizing itself, a vicious cycle process. In the later stage of activated sludge culture, although the sludge concentration is low, some sludge should be discharged appropriately, which will be conducive to further growth and reproduction of microorganisms.34. Question: Our unit’s anaerobic treatment device will begin debugging. Please tell us about the anaerobic sludge cultivation method and precautions during the debugging process.Answer: There are many methods for cultivating anaerobic sludge. It is recommended to adopt the stepwise cultivation method. The general process is as follows: the remaining sludge (already anaerobic) from the aerobic system is put into the anaerobic reaction tank through the concentration tank. The dosage is approximately 20~30% of the reactor capacity, then heat (if heating is required), gradually increase the temperature so that the temperature rises to 1°C per hour, and maintain the temperature when the temperature rises to the temperature required for digestion (according to the design temperature). The amount of nutrients should be gradually increased as the amount of microorganisms increases, and should not be done too hastily. When the organic matter is hydrolyzed and liquefied (it takes one or two months), and the sludge matures and biogas is produced, the biogas composition is analyzed, and an ignition test is performed under normal circumstances. Then the biogas is used and put into daily operation. Generally, the organic load should be kept low during startup. When the CODcr removal rate reaches 80%, the organic load can be gradually increased. The acetic acid concentration after completion of startup should be controlled below 1000 mg/L. The above are only general requirements. It is best to ask experienced people for guidance.35. Question: Our factory is a refinery. The current sewage treatment process is as follows: after the high-concentration sewage is treated in the aerated biological filter, part of it enters the low-concentration sewage treatment system to contact the oxidation tank, and part of it is used as SBR (SBR to treat alkali after wet oxidation). Slag) dilution water, after SBR treatment, enters the low-concentration sewage treatment system contact oxidation tank. The low-concentration sewage treatment system includes oil separation, air flotation, contact oxidation tank, secondary sedimentation tank, sand filter, and reuse. There is a problem. The ammonia nitrogen of high-concentration sewage before entering the aerated biological filter is always higher than that of the water leaving the aerated filter. Is this what is the reason?Answer: It is normal, because part of the ammonia nitrogen is removed in the biological filter, not through dissimilation, but through assimilation, that is, through synthesis of bacterial cells.36. Question: I would like to ask about the removal rate. If the inlet BOD/COD of a sewage treatment plant that mainly produces domestic sewage is 0.4~0.5, is it possible for the effluent BOD/COD to reach 0.8~0.9? In other words, the effluent COD is 40~50, but the BOD is still not up to standard. Why does this happen? How to adjust the process (the treatment process is SBR or oxidation ditch)?Answer: This is abnormal. You need to confirm whether there is any problem with the BOD5 measurement, such as whether a blank control is used during the measurement; the fine flocs in the effluent cannot be taken in during sampling, etc.37. Question: Our sewage tank is 9 meters deep, 50 meters long and 15 meters wide. There is a lot of silt at the bottom of the tank. How to remove it? The pond has water all year round.Answer: Please tell me clearly what kind of process it is? What kind of pool is it? It is probably a regulating tank. The regulating tank should be equipped with a stirring device to homogenize the sewage. If not, it must be emptied and cleaned.Question 38: If the secondary effluent of urban sewage is only filtered and used directly, what kind of filtration method should be used? How to filter out impurities such as particulate matter, hair, and algae? Please give me some adviceAnswer: It depends on the water requirements. For general miscellaneous water, it must go through at least three processes of coagulation, filtration and sterilization. There are many filtration methods. The more economical and effective one is to use quartz sand filtration. As for hair and the like in the water, Substances should be removed in the front sewage treatment device.39. Question: The anaerobic process I use is UASB. There is no heating device. There is no sludge return system in the entire process. The wastewater overflows to the aerobic pool through UASB. The aerobic pool uses the biofilm method. Now I need to carry out sewage treatment. Mud cultivation, what should we pay attention to during the cultivation process?Answer: UASB sludge culture can be transplanted and cultured with the concentrated anaerobic sludge from other sewage plants. The amount of sludge added should be more, about 1/3 of the height of the anaerobic reaction device, and the sludge layer should be at least 1m. If there is no anaerobic sludge, the aerobic sludge that has been left for a period of time can also be used for transplantation and culture. Because it is not necessary to pursue strict anaerobic conditions in the early stage of culture, even if the oxygen in the transplanted sludge will be quickly consumed, forming anaerobic sludge. Oxygen conditions, but the culture time will be longer. During the cultivation process, the pH must be measured frequently and controlled at around 7. Nutrition must also be controlled. For specific training requirements, please refer to relevant information.40. Question: We deal with semiconductor wastewater (containing fluoride, ammonia nitrogen, and phosphate). Due to poor consideration in the original design, there is now only one aerobic pool and no anaerobic pool. The inlet water ammonia nitrogen of the aerobic tank is about 30 mg/L (the average flow rate is 30t/h), and sodium carbonate is added to adjust the pH value and alkalinity. The pH value is generally around 7.5, and aeration is carried out for 24 hours; a 5t/ The h sludge pump also has a 24-hour backflow. Because it is not easy to control, the backflow is sometimes sludge and sometimes sewage. The ammonia nitrogen in the effluent is almost 0. It has been running stably for 2 months. Can it still run stably like this?Answer: It is unreasonable in two aspects: first, it has no phosphorus removal function, and anaerobic should not be cancelled; second, the amount of return sludge should be relatively stable, and it cannot be discharged with a pump at the bottom of the pool. Judging from the reaction time of the aerobic pool and the concentration of ammonia nitrogen in the incoming water, ammonia nitrogen removal should be no problem.41. Question: Our unit uses the front-mounted Obel oxidation ditch process, and has recently experienced operational problems. The designed water inflow is 50,000 tons/day, COD350, BOD150, SS220, and the actual water inflow is 5,000m3/d per day, COD300, BOD120, SS180; the operation mode is that the four propellers in the inner and outer ditch are fully opened, and the dissolved oxygen in the inner and outer ditch is controlled at 3mg/L (Recently, the dissolved oxygen detected by the laboratory is different from the online instrument data. The instrument is 3mg/L higher than the laboratory data, and the laboratory test started after two months of operation.) Intermittent aeration, aeration for 5 hours and silencing for 1 hour (all propellers are turned off) ), water inflow for 1.5 hours, water inflow for one minute, turn on the propeller, start aeration, the sludge concentration in the oxidation ditch is about 100, a return pump returns the sludge for a long time, the flow rate is 700m3/h, the return sludge concentration is 100 The sludge concentration in the oxidation ditch remains unchanged at around 200, the effluent COD140 is preferably around 100, BOD50, SS50, and the effluent from the secondary sedimentation tank is turbid. (1) The sludge in the secondary sedimentation tank does not settle, and the entire pool surface is very turbid. (2) The sludge in the oxidation ditch has no flocs, and is all very fine particles. (3) Microscopic examination revealed only one kind of microorganism, which looked like carob seeds with bubbles in the middle and more heads. (4) There is always white sticky foam in the oxidation ditch. (5) All the sewage we treat is domestic sewage. The sludge concentration has not increased after 3 months of operation, and the water output has been poor. Please help analyze the reasons for this situation.Answer: It means that the sludge has been seriously aged and disintegrated. This is caused by the sludge load being too low and the aeration time being too long. During the cultivation process, the sludge is growing and oxidizing itself, so the sludge concentration will certainly not increase. The sludge needs to be re-cultivated, but the problem is if the water inflow and sewage concentration do not increase, how can the cultured sludge be maintained? Your current operation method is not feasible. High dissolved oxygen is not the main reason. The key is the control of aeration time. The underwater propeller does not need to be stopped when using intermittent aeration, and the inner ditch does not need to be aerated. It can be used as a passage for the mixed liquid to flow to the sedimentation tank, but the propeller cannot be stopped.42. Question: For the secondary sedimentation tank with peripheral water inlet and peripheral water outlet, has it overcome the shortcomings of the secondary sedimentation tank with central water inlet and peripheral water outlet? Moreover, I found that the auxiliary flow secondary sedimentation tank here will have a small sludge floc phenomenon. What is the reason?Answer: I think that the peripheral inlet-type sedimentation tank only reduces the impact of inlet water energy on sedimentation and the problem of short flow of the central mixed liquid, but does not comprehensively change the problems existing in the amplitude-flow sedimentation tank. Theoretically, the peripheral sedimentation efficiency should be very high, but the requirements for water inlet and distribution are very high.43. Question: I often see statements like this on some forums: "If the aeration is too large, the DO is too high, the bacteria will oxidize themselves. If the load is too low, the microorganisms will oxidize themselves, leading to flocculation." In the ASM1#, ASM2#, ASM3# models and the wastewater biological treatment guru McCarty, the attenuation coefficient of microorganisms is used as a constant, represented by b, that is, attenuation (self-oxidation) occurs at any time according to a certain proportion b, and is carried out of. The growth coefficient of microorganisms is closely related to the substrate concentration and is a variable. When the organic load is low and the oxygen supply is sufficient, the microorganisms will quickly consume the BOD in the water, causing the growth to stop and only decay, resulting in The net increase is 0, or even negative, causing the biomass to decrease instead of increasing. Therefore, it is said that self-oxidation occurs at any time, not only under low load and high DO. Is it appropriate to say this?Answer: It is true in theory, but in actual operation, the understanding of sludge aging is not limited to this. Although sludge aging is mainly caused by the lack of nutrients for microorganisms for a long time, that is, the imbalance between nutrients and microbial mass, the microorganisms cannot grow normally. However, the actual operation of the treatment device is more complicated, and the activity of sludge is also related to operating control conditions, nutrient ratio and other factors. In some devices, the following situation will occur: when the inlet water concentration is normal but the carbon-to-nitrogen ratio or carbon-to-phosphorus ratio is low, the activity of the sludge will be very poor, which will limit the degradation of organic matter by microorganisms and reduce the energy generated; The incoming water concentration and nutrient ratio are normal, but the remaining sludge is not discharged as required, and the aeration time is too long, which will cause the sludge to become loose and have poor activity. Such sludge is also traditionally called aging.44. Question: There is a 25000T domestic sewage treatment plant using the Orbal oxidation ditch process. The designed inlet water COD is 370mg/L. The actual inlet water COD is about 150mg/L, TP is about 2mg/L, and ammonia nitrogen is about 20mg/L. , total nitrogen is about 6mg/L higher than ammonia nitrogen, MLSS is between 2000~2500mg/L, SV is less than 15%, SVI is about 50ml/g, MLVSS/MLSS=0.5. The effluent COD is less than 40mg/L, TP has almost no removal effect, ammonia nitrogen is about 8mg/L, and the total nitrogen removal rate is less than 50%. The problem now is that there is mud running out of the outlet weir of the secondary sedimentation tank. It has been running without interruption since July last year. In addition, each of the three ditches has four rotating brush aerators. Due to the low load, 1, 2, and 2 aerators are opened in the outer, middle, and inner rings respectively. The dissolved oxygen in the inner ring is 2.0 mg/L. Left and right, the outer ring online monitoring OBP is as low as -400. I would like to ask: What is the reason for the secondary sedimentation and sludge? Is this appropriate way to control aeration?Answer: The sludge has aged to a certain extent and its activity is very poor. The effluent brings out aged deflocculated sludge. The main reason is that the sludge load is too low. Countermeasures: (1) Reduce the aeration time, stop the outer ditch, and the sewage directly enters the middle ditch; (2) You can also not stop the outer ditch, increase the amount of mud discharge, and significantly reduce MLSS. These two measures are both to increase the sludge load. The former is to increase the sludge load by reducing the reaction time, and the latter is to increase the load by reducing the sludge concentration. Of course, in order to maintain the balance of the three phases of water, gas and mud, exposure Don't be too big either.45. Question: The requirements for water distribution are very strict during the week-in and week-out. In fact, there are baffles at the water distribution inlets that go in and out of the week that go deep into the bottom of the secondary sedimentation tank, but I can't find the information on how deep it should go. Because it is said that the technology is directly imported from abroad, and its calculations are not available. I wonder what your opinion is on this issue?Answer: You are right. There are baffles around the water inlets. It is estimated that there are many water inlets under the water inlet. After the water energy dissipates, it flows downward and then spreads from under the water inlet baffle into the pool. I will tell you the specific location. Not sure, it should be about 2 meters above the water. I think the key technology should be uniform water distribution and water dissipation.46. Question: How to distinguish between sludge poisoning and sludge aging?Answer: Generally speaking, severe aging of sludge will have a development process, and sludge poisoning will quickly cause cell disintegration. The effluent ESS will increase significantly when the sludge is aged and poisoned, and experienced people can distinguish it from the appearance. When sludge ages, the suspended solid particles in the effluent are relatively larger, mostly in the form of fragments. The suspended solid particles in the effluent during sludge poisoning are relatively small.Sludge poisoning and sludge aging can also be distinguished from the changes in DO value. The process of sludge poisoning is relatively fast, which will cause DO to rise in a short period of time, while sludge aging has a gradual process, and the rising process of DO It is also gradual.47．Question: When the amount of mud fed into the sludge dewatering machine does not change, the moisture content of the mud cake increases significantly after dehydration. What is the reason?Answer: In addition to the operating conditions of the dehydrator itself, there may be problems with the sludge dosing and conditioning process, or it may be caused by the failure of the mixer in the previous sludge homogenization tank or the failure of the scraper in the sludge concentration tank. of.48. Question: Recently, the filter cloth of our unit's sludge dewatering machine (belt filter press) often goes astray. What is the reason?Answer: It is necessary to confirm whether the surface of the roller is bonded or worn, whether the parallelism of the roller shaft is good, etc. If the filter belt is damaged, it must be replaced in time.49. Question: There is a lot of oil in wastewater recently, especially in areas with gridded wells. There is black scaled oil. How do you usually deal with it?Answer: First use manual cleaning, and then use oil-absorbing felt or oil-absorbing media to absorb the oil.50. Question: The contact oxidation method has many advantages in treating low-concentration domestic sewage (small communities), but it is difficult for N and P to meet the discharge standards (secondary). How to improve the process so that it can remove N and P?Answer: I think it is not that the contact oxidation method is not effective in removing nitrogen and phosphorus, but it may be caused by problems in the control link. For example, the DO control of the aerobic tank must be higher than that of the activated sludge method, and the anoxic zone must have a sufficient mixing function. , as well as factors such as alkalinity control.51．Question: Now the concentration tank is full of floating mud (the color is gray). We have extended the age of the mud and reduced the amount of mud entering the concentration tank. But why does this happen?Answer: Such measures are not targeted. The amount of sludge produced in the concentration tank should be increased to reduce the residence time of sludge in the concentration tank to prevent anaerobic fermentation.52. Question: Can the UNITANK process be used in large-scale sewage plants? Engineers who have used this new process say that it is not suitable for application in large-scale sewage plants because the automatic control is very complicated and the phosphorus removal effect is poor. Is this true? Guangdong Liede Sewage Plant is 220,000 tons/day, and Shanghai Shidongkou Sewage Plant is 400,000 tons/day (in the near future). It is said that the overall operation condition is good, and Shidongkou Sewage Plant is competing for the Zhan Tianyou Award. This process is used in large-scale sewage treatment. How is the factory? Please answer.Answer: I think the UNITANK process is also suitable for large-scale sewage treatment plants, but it is not suitable for sewage with high phosphorus removal requirements.53. Question: Our aerobic pool is a biological contact oxidation pool. The purpose is to reduce the ammonia nitrogen from 30 to below 10. In fact, after adding the chromogenic agent, it is almost the same as the blank. Sodium carbonate is added to adjust the alkalinity, and the sludge flows back from the sedimentation tank at the back. Since the backflow is difficult to control, sometimes it is mud and sometimes it is water. Previously, it was found that the pH value of the entire aerobic tank dropped sharply along the direction of the water flow when there was no sludge backflow, but this did not happen when there was sludge backflow, and the pH value of the effluent could be guaranteed to be between 6.5-7. However, in recent days, it has been found that the pH value of the entire aerobic tank is low, with the front end only being 6.9 and the effluent being around 5.8 (all indicators of the inlet water and the amount of sodium carbonate have not changed, and the ammonia nitrogen concentration is still undetectable). Even if the sludge return status is improved compared to before, This is also the case. What is the reason for this? In addition, the sedimentation tank behind our aerobic tank is a vertical flow sedimentation tank (148m3, water volume 30m3/h). There are four small mud buckets below. What measures should be taken to improve the return sludge status of the aerobic tank under the current situation?Answer: The sludge (shedded biofilm) in the contact oxidation sedimentation tank generally does not flow back, so you need to first confirm whether the biofilm on the filler is normal? If the organisms are too thick, increase the air flow, otherwise the treatment effect will be seriously affected.Such a large drop in pH is a bit abnormal and cannot be explained theoretically, because the ammonia nitrogen in the incoming water is not high, and the hydrogen ions generated during the nitrification process will not drop by more than one pH unit. The only possibility is that there is too much mud in the sedimentation tank, and there is a shortage of it. Under oxygen conditions, acidifying bacteria in the sludge multiply in large numbers, and acidification occurs after returning to the aerobic tank. This is of course only speculation. Therefore, it is recommended to confirm the growth of biofilm on the filler, and do not return the settled sludge for the time being, but observe it for a period of time.54．Question: (Question after replying to the previous post) Our system used to have no backflow. Of course, ammonia nitrogen did not need to be considered during the design. I had never taken this aerobic pool seriously before. During monitoring, I found that the pH value of the entire aerobic pool range The downward trend (according to the direction of water flow is 6.3-5.5-5.3-5.1); at the same time, due to the increased concentration of ammonia nitrogen in the incoming water, it cannot be treated. When someone came to see it, there were two suggestions: one is to increase the alkalinity, and the other is to return the sludge. At that time, only the first suggestion was adopted. After adding sodium carbonate, the ammonia nitrogen was indeed effectively removed, but the pH value still dropped significantly, and it was difficult to control. Later, the sludge was recirculated and it was found that it had a better effect on stabilizing the pH value. The effect is now flowing back. I always feel uneasy about the aerobic pool system. Firstly, the aerobic process only converts nitrogen from ammonia nitrogen into nitrate nitrogen, but does not remove it from the water, and the harm to the environment is not reduced; secondly, I There are often doubts about the stability and durability of this system. Please help analyze and propose solutions.Answer: Talking on paper may not be accurate and can only be used as a reference. If the pH of the biochemical tank can be stabilized after backflow, there is only one explanation, that is, denitrification occurs in the sludge in the sedimentation tank, and the reflux liquid contains OH-, which can neutralize part of the H+ after entering the aerobic tank. Of course this is just speculation, but in any case, it shows that the effect of the system on removing ammonia nitrogen is good. If you want denitrification and you don’t know if the reaction time is enough, you can try to set up an anoxic zone in the middle of the aerobic tank (residence time is about half an hour to one hour, a small amount of aeration, DO below 0.5), so that you can Remove part of the nitrate and stabilize the pH. Also note: the DO in the second half of the aerobic pool is higher, at least above 3mg/L.Supplementary explanation: In my previous analysis, I said that the pH drop in the aerobic tank may be caused by excessive mud accumulation in the sedimentation tank. Under anaerobic conditions, acidifying bacteria in the sludge multiply in large numbers and acidification occurs after returning to the aerobic tank. ; In the latter post, it is said that denitrification occurs in the sedimentation tank, and the reflux liquid contains OH-. After entering the aerobic tank, it can neutralize part of the H+ and stabilize the pH of the aerobic tank. These two posts seem to be contradictory, but this is an analysis of two possibilities. The former is if the sludge has been anaerobically fermented into acidification reaction, and the latter is possible denitrification due to lack of oxygen. Now it seems the latter is more likely.55．Question: Please tell me what range the dissolved oxygen in the hydrolysis acidification tank should be controlled within. Is it necessary to install aeration and stirring devices?Answer: Is the hydrolysis acidification tank using the mud method or the membrane method? If it is the mud method, a stirrer is enough. If it is the contact oxidation method, in addition to installing a stirrer, it is best to install aeration such as perforated pipes or aeration hoses. The device mainly plays the role of auxiliary stirring. There is no need to worry that aeration will affect the acidification effect, because the load of the acidification tank is high, and the impact of adding some oxygen will be negligible.56．Question: Our factory is located in Beijing, with a scale of 30,000 tons. It adopts hydrolysis + biological contact oxidation treatment process. In the past two years of operation, if we open two pumps and the secondary sedimentation tank (load is about 0.9), there will always be floating mud, and sometimes there will be floating mud. Needle-like floc. Affects the water outlet SS. But when I opened the Yitai pump, the effect was very good. Please give me a diagnosis!Answer: The main reason is that the surface load of the secondary sedimentation tank is too small. Because the settling performance of biofilm is worse than that of the activated sludge method, the surface load must be at least twice that of the activated sludge sedimentation tank during design.57．Question: We deal with papermaking wastewater and chemical mixed wastewater, using Carrousel 2000 oxidation ditch. In the past year, the ammonia nitrogen in the incoming water has been increasing, about 250, and the ammonia nitrogen removal rate is about 30%-40%. What impact does the increase in ammonia nitrogen have on system operation? What should be done? If the ammonia nitrogen in the incoming water is controlled at 80, what can be done to achieve the standard?Answer: Do you want to confirm whether the nitrification conditions such as sludge load and alkalinity are met? If these basic conditions are met, the amount of oxygen in the aerobic zone can be increased, and the internal reflux gate can be opened wider. The purpose is to increase the DO in the front of the anoxic zone, so that part of the anoxic zone also has a certain nitrification function.58．Question: How to determine the hydrolysis and acidification residence time? What standards are used to determine the degree and effect of hydrolysis and acidification of sewage?Answer: The acidification time must be determined through operation tests. Generally speaking, when the pH of the acidification tank effluent decreases and the BOD/COD ratio increases, it means that acidification is effective.59．Question: Our factory adopts the CASS process. The concentration of the incoming water has increased from an average COD of 250 ppm last year to an average of about 350 ppm now. At the same time, the suspended solids in the incoming water are also much higher than last year. The treatment cycle is 4 hours, with intermittent aeration, and the method is to aerate for 2 hours while feeding water. When the concentration of the incoming water is not so high, the treatment method is basically to feed water for 1 hour and aerate for 1 hour. At the end of the aeration stage, DO basically remains above 2ppm, but the color of activated sludge is still black. The amount of water in each batch of water does not change significantly. The previous method has been used for more than half a month. After treatment, the effluent is still around 150ppm, the suspended matter is 50~60ppm, the sludge is black, the flocculation of activated sludge is poor, the structure is loose, and it is difficult to see native microorganisms. MLSS is 1700ppm, and the water BOD is around 120.Answer: My initial judgment is that the aeration time is not enough. The reason is: after the inlet water concentration increased, you adopted a non-limited aeration method. On the surface, it seems that the aeration time is increased by one hour. In fact, this is not the case, because the water inlet period Most of the time, due to the low water level, the utilization rate of oxygen is very low. More importantly, due to the increased load, the biochemical process has not been completed at the end of the aeration stage of the previous cycle. In the static sedimentation stage, the sludge anaerobia is aggravated, and the Although aeration is taking place during the water inflow stage of a cycle, the aeration during this period is actually only the recovery or partial recovery of sludge activity, and the actual biochemical reaction time does not increase much.The basic idea of ​​process adjustment is correct. Suggestions: (1) Rotate the sludge in each tank until the color of the mud initially turns brown and then add water for aeration; also confirm whether the nitrogen or phosphorus is enough? Because when the COD concentration of the incoming water increases, the nutrient ratio may become imbalanced. I'm just speculating from the surface, for reference only.60．Question: Pharmaceutical wastewater contains sulfate 3000-4000, Cl-3000-4000, COD 3000-4000. I want to put fillers in the hydrolysis and acidification tank, but the small test found that it is quite difficult to put the film. I don’t know whether it is the improper selection of fillers or the high Cl- reason? The environmental protection company said that if Cl- exceeds 3000, the filler will not be able to film.Answer: Such Cl- concentration will affect the biofilm culture speed, but if the film can still be hung, it is best to introduce activated sludge or anaerobic sludge, which can increase the film hanging speed. From the perspective of fillers, soft fillers are the easiest to film, followed by elastic fillers. Semi-soft fillers are worse, but elastic fillers are easy to ball up and should be used with caution.