The wastewater discharged after testing is yellow; what is the solution?
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Currently, we have a project for treating rural domestic wastewater, using an AO + biological filter treatment process. The inlet COD level is 500+, ammonia nitrogen level is 100+, and total phosphorus level is 10+. It is currently in the debugging phase; the effluent is quite yellow and contains insects, as well as having high quality parameters. May I ask the experts where the problem lies and what the solutions are?
It is normal to see small red insects in the secondary sedimentation tank; they are the precursors of mosquitoes. That small red insect is called a red worm. Activated sludge is used to cultivate bacteria. If it is a yellow color with suspended particles, trying to add activated carbon might work. If it is the color of water, it will be yellow; in that case, considering strengthening the decolorization treatment with oxidants during preprocessing might be a good option. .
One issue is related to the incoming water; in the case of domestic wastewater, anaerobic and hypoxic conditions occur as it passes through the pipes, which causes the water to turn black. It is normal for the effluent to be slightly yellow at this time； One reason is related to the improper dosage of coagulants, primarily the improper use of iron salt coagulants. It could also be due to some other process-related reasons.
The sludge from the biochemical system should be acclimated first; as for the color, proper decolorization is essential – for example, activated carbon can be used specifically for decolorization. As for the insects, they can simply be removed whenever necessary. It’s fine once the water flowing into the main sedimentation tank has been coagulated.