Why has the aerobic tank for wastewater become cloudy?
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Our wastewater biological treatment system: previously, the water in the two aerobic tanks was quite clear, though slightly whitish in color. Recently, however, the water in these aerobic tanks has become turbid, with flocculent sediment present. When performing sludge sedimentation tests, only 20 ml of sediment was obtained in a 500 ml measuring cylinder – not much sediment at all – yet the water in the aerobic tanks still appears turbid. I’m not sure what the cause might be; could it be that the airflow from the fans has increased, or is there some other reason? Thank you!
Why hasn’t anyone knowledgeable come to give some guidance?
Could you provide more details on the operational data?
For example, COD, BOD, pH, water temperature, and MLSS of inlet and outlet water
The COD of the wastewater before entering the anaerobic stage was around 4000 ppm, while the COD of the water coming out of the anaerobic tank was about 1300 ppm. Subsequently, the water moved on to aerobic tank 1 and then aerobic tank 2; the COD of the wastewater by the time it reached aerobic tank 2 was below 500 ppm. The pH value throughout the entire wastewater treatment process remained around 8. The steam heating in the anaerobic tank controls the water temperature at 30 degrees.
The pH value is a bit high; generally, around 7.5 is ideal