How can ammonia nitrogen and total phosphorus levels be reduced like this?
Thread Content
Currently, a system for treating rural domestic wastewater with a capacity of 80 tons per day is under debugging. The inlet water quality shows COD levels of 272 mg/L, ammonia nitrogen at 98.33 mg/L, and total phosphorus at 4.997 mg/L. The outlet water quality has COD levels of 26.4 mg/L, ammonia nitrogen at 28.31 mg/L, and total phosphorus at 2.846 mg/L. The treatment process used is A/O contact oxidation. I think it’s already quite good that the ammonia nitrogen level can be reduced to below 30, but since an inspection is coming up soon and the level needs to be below 10, it’s a bit difficult for me. That’s why I’m asking the experts here if there are any good methods. Actually, I have studied many nitrogen and phosphorus removal processes, and I discovered a method in which adding magnesium salts can cause precipitates to form with ammonia and phosphate ions. However, I have never used this method before, so I’m not sure how feasible it is
“A method was discovered in which adding a magnesium salt can result in the formation of a precipitate with ammonia and phosphate ions; however, the solubility product of the resulting compound is not very low, which makes it difficult to achieve both acceptable levels of ammonia nitrogen and phosphorus content. What is the acceptable level for ammonia nitrogen? There are many methods, such as modified zeolite adsorption and gas-phase membrane ammonia removal.
1. The A/O process does not possess the capability to remove nitrogen or phosphorus; it can only remove either one of them； 2. In the case of biological nitrogen removal, determine whether the nitrogen load in the biochemical tank and the air volume meet the requirements for nitrogen removal ； Generally speaking, once nitrifying bacteria are cultivated, ammonia nitrogen levels tend to meet the required standards, but this is not necessarily the case for total nitrogen ； 3. There are many chemical methods for phosphorus removal, and the amount of chemicals used is also high; factors such as the cost of adding these chemicals need to be taken into consideration. Personal opinion, for reference only
It’s possible, but the cost is too high:):):)
First, add Ca(OH)2 for phosphorus removal, then proceed to A/O process for ammonia nitrogen removal.
The removal rate of ammonia nitrogen has reached 70%; judging from the COD level of the influent water, the organic load should not be high. It’s already quite good that the ammonia nitrogen level has reached this figure, and it will be difficult to increase the biochemical removal rate of ammonia nitrogen any further. It is possible to add alkali before the water enters to raise the pH for aeration and stripping, or to add sodium hypochlorite to the effluent using the breakpoint method to remove ammonia nitrogen.