Drying Technology
Ⅰ
Q: In the ordinary activated sludge process, sludge expansion will occur during the treatment of municipal sewage, with SVI>400, so it is planned to install an anaerobic selector at the front part of the aeration tank. Since there is little experience in this area, I want to find out if there is anything wrong with setting the selector larger? Now we set the anaerobic selector to account for 25% of the total biochemical tank volume, and the contact time between the return sludge and the sewage is about 1 hour.
Answer:
1. Municipal sewage swells in filament form, which is not very common, because the composition of municipal sewage is reasonable, unlike industrial wastewater with a single composition, which is more prone to swelling.
2. Adding an anaerobic tank at the front stage is indeed a better method to control filamentous bacteria.
3. From the perspective of craftsmanship alone, it is better to set a larger one! From the information you provide, the residence time of the biochemical tank is 4 hours, which seems to be a little shorter. If the sludge load is high, it is recommended to enlarge the anaerobic selector.
Ⅱ
Q: Why is the effluent of the sedimentation tank green in the process of sewage treatment? The water in the pond is also green. The two reasons should be similar, right?
Answer: The pond water is green and in most cases caused by algae. In the case of wastewater, even if the treated water meets the discharge standards, there will be swimming algae such as chlorella, which will make the water colored. In addition, due to the color of the source water, it is also common for the effluent to be colored, such as colored wastewater from printing and dyeing plants and coating wastewater from paper mills.After the sludge is concentrated and mechanically dehydrated, there is still a high water content. In order to reduce the moisture content of the sludge entering the boiler and increase the calorific value of the sludge, the sludge needs to be dried. By drying, the moisture in the dewatered sludge can be further evaporated to avoid or reduce the auxiliary fuel consumption and reduce the heat loss of the boiler exhaust. Therefore, the treatment and disposal technology combined with incineration can maximize the reduction and resource utilization of sludge, and has a good application prospect.
Ⅲ
Q: Our current sewage can temporarily meet the standard, but this is because our pipe network is still under construction, so a large part of the current inflow is groundwater discharged during the construction of the pipe network, and a small part of domestic sewage is only from a university. So the BOD of influent is very low. Our design water intake is 25,000 tons/day, but the current water intake cannot meet the process requirements of continuous water intake and continuous water output. The current daily water intake is about 8,000 cubic meters. Now if you ignore the SV30, the sewage can meet the standard, but there seems to be no sludge in the aeration tank. When the pipe network construction is completed in March or April, most of the sewage in the city will be incorporated. There is no sludge, and I am very worried about the failure. When I reach the target, if SV30 can have 10%, I am not so worried, but now 2 months have passed, it is still only 2%, and after baking in a iron furnace, I found that the organic content only accounts for about 20% of the SV30 sludge. The rest are all inorganic substances or inert substances. It is really doubtful whether such sludge is effective for the sewage coming in in March or April.
Answer:
1. Investigation work still needs to be carried out. For example, after the completion of your peripheral pipe network, the water intake and water quality need first-hand reference materials so that you can control your biochemical system to meet the water intake.
2. I think you don’t have to increase mlss now. In fact, it's very difficult for you to increase. If possible, after confirming the time for the completion of the pipe network and the water intake, add a large amount of additional organic matter to the wastewater (the specific dosage is determined according to the planned incoming water volume and concentration) to increase the mlss. Industrial methanol is relatively cheap and can be considered.
3. If the cost is not economical, there is no need to add additional organics. Just wait for the water and cultivate slowly slowly. I think it will not exceed the standard for a few days if it is done properly!
Ⅳ
Q: Now we are starting and debugging the sewage treatment plant. It was in good condition, but the pH of the intake water was changed yesterday (the sewage pipe was cascaded with hydrochloric acid and it ran for about 20 hours), which caused the secondary sedimentation tank to run mud and the effluent was muddy. At present, the pH of the inlet water is normal, the pH of the aeration tank is about 6.5, and the pH of the secondary settling tank is about 4.8. I have stopped the water inflow and backflow. Can the system be restored? How to proceed in the next step? Please advise. In the current commissioning stage, the sewage inflow is 100M3/h, the COD is 50mg/l, and the water temperature is about 15 degrees.
Answer:
1. You run for 20 hours, so you can run mud.
2. The PH is low, it is wrong not to enter the water! It is recommended to keep the water in.
3. The reflux can be adjusted smaller.
4. Under normal circumstances, the water output may deteriorate in a short time, but it can be recovered. After the normal water intake, it can basically return to normal within 2 to 3 days.
5. For the impact of the biochemical system, it is best to use a microscope to observe the activity of the metazoan to understand. As long as this part of the organism is not disintegrated, there is usually no problem in recovering in a short time.
Ⅴ
Q: Our plant uses oxidation ditch process. Recently, the COD of the effluent is not up to the standard (the standard is 100), the SV has dropped, but the effluent is clear, and the DO is almost the same as usual (about 0.4), and the ammonia nitrogen is a bit high (but it has always been a little high). Can you help analyze what caused it? The second-stage aeration tank has mud bleaching phenomenon (AB method), the aeration volume is not large, and the DO is not high. Maybe the sludge is aging?
Answer:
1. From the data you provided, it seems that the dissolved oxygen is too low, which may inhibit the normal proliferation of normal bacteria. Properly increase to 1.5, I think it's better!
2. The second-stage aeration tank has mud bleaching phenomenon (AB method), the aeration volume is not large, the DO is not high, and the sludge may be aging, but the sludge aging and aeration volume are not large, and the DO is not high and not too large Of the relationship. The reasons for the aging of the sludge and the effluent and floating mud, you can look at some of the exchanges in front of this site! I believe some answers will be found!
