On the removal of total nitrogen and total phosphorus in reclaimed water reuse systems
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The wastewater from the sewage treatment plant enters the primary lift pump room, where it mixes thoroughly with sodium hypochlorite, thereby effectively reducing the ammonia nitrogen content in the wastewater. After being lifted to the activated sand filter, it mixes with polyaluminum chloride; subsequent filtration through a sand filter removes the suspended solids in the wastewater, effectively eliminating phosphorus and solid particles as well. The water after filtration enters the ozone contact tank, where it is treated with ozone to achieve sterilization, decolorization, oxidation, and deodorization; this process effectively reduces the levels of COD, BOD, color, and E. coli in the wastewater, while also controlling the emission of odors. The quality standards for the output water correspond to Class V surface water standards. Since our reclaimed water reuse system has just been put into operation, none of the employees have any experience. In the past two days, both the total nitrogen and total phosphorus levels have been significantly above the acceptable limits. Regarding total phosphorus, I believe increasing the dosage of polyaluminum chloride might help improve the situation. As for the degradation of total nitrogen, I have no idea at all; reclaimed water is different from sewage, and denitrification cannot be used to remove total nitrogen. Worse still, with an inlet total nitrogen level of 40 mg/L, the outlet total nitrogen level reached 60 mg/L. I would be very grateful if all the teachers could help analyze how to control the levels of total nitrogen and total phosphorus, as well as the underlying principles behind this. Thank you very much
Ozone can be tried to remove total nitrogen; it should work well
As for total phosphorus, it can be removed using chemical methods; it can be eliminated by adding lime. For total nitrogen, it depends on whether it’s nitrate? Ammonia nitrogen again? If it’s nitrates, it’s quite troublesome; at present, the only ways to remove nitrates completely are denitrification or evaporating and crystallizing the nitrates. But it raises the issue of what to do with the crystalline salts, which is quite troublesome ； If it is ammonia nitrogen, it is relatively easier to treat, for example by forming struvite ； Or resin adsorption can also be used, but this is for the transfer of ammonia nitrogen ； Whatever the method, it has one goal: to convert organic matter into carbon dioxide and nitrogen into nitrogen gas, returning them to nature. This is true zero emissions.
This post was last edited by sunshineda_VGMP on 2018-5-31 09:13. Reuse systems for treated water have high requirements regarding water quality, as they need to meet the standards for treated water quality. Requirements such as those related to total nitrogen and total phosphorus, mentioned by the original poster, can only be ensured through testing. To measure total phosphorus and total nitrogen, a spectrophotometer is required, one that enables rapid analysis in order to obtain the necessary values. This allows for adjustments to the reagents used at various stages of the treatment process, so that they remain within the specified limits.
What was said on the 3rd floor is correct; it seems that your current industrial processes do not remove total nitrogen. Ammonium nitrogen can only be converted into nitrate nitrogen