What are the reasons for the increase in COD and TP in pig farming wastewater in the aerobic tank?
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Pig farm wastewater, AO process. Process flow: primary sedimentation – anaerobic stage – aerobic tank 1 – secondary sedimentation – aerobic tank 2 – secondary sedimentation. The main issue now is that ammonia nitrogen levels are continuously decreasing, while COD and TP levels are rising in the aerobic secondary tanks (COD is over 300 and TP is 30 in the middle sedimentation tank; COD is over 500 and TP is over 40 in the aerobic secondary tank). The DO in aerobic tank 1 is 2.5, and the DO in aerobic tank 2 is 7. In recent days, the DO level in the two aerobic tanks has been set at 4.5, while COD and TP levels remain unchanged compared to before. I need expert advice!
Don’t understand; waiting for an expert to answer. 66666666666
Generally, in the aerobic zone, phosphorus-accumulating bacteria accumulate phosphorus. Due to the high oxygen levels in these two tanks, the growth rate of microorganisms increases; however, the lack of available carbon sources leads to the death of these microorganisms or the consumption of their own substances, as a result of which COD and TP levels in the tanks become high.
It’s wastewater from a pig farm again! My colleagues are all unwilling to do it, saying that working on such a project would mean ruining several sets of clothes:D
The poster has provided limited information. But the DO level in the aerobic secondary tank is too high. Such a high DO level in this tank is likely due to excessive aeration, which can cause the activated sludge flocs to break apart, resulting in high SS levels in the effluent, as well as increased TP and COD levels ； Additionally, it’s possible that the microbial activity in Tank 2 is low, preventing it from consuming DO, which results in high DO levels. If this is the case, trying to transfer the sludge from the intermediate sedimentation tank to Tank 2 could be an option.
The first phosphorus cannot be removed through biochemical processes; therefore, the total phosphorus level should remain constant and not increase. If COD levels rise while ammonia nitrogen levels decrease, COD is generally not supposed to increase; please conduct more tests. If COD levels rise, ammonia nitrogen levels hardly decrease.