Treatment of wastewater with high COD and ammonia nitrogen
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Help: There is wastewater now, 40 cubic meters per day； It contains about 5% urethophene, as well as methanol and formaldehyde; the COD level is 100,000. Meanwhile, the ammonia nitrogen content is very high, exceeding 3,000 mg/l (and it may be even higher based on conservative estimates). The solution I came up with is: since urethane needs to be decomposed into formaldehyde and NH3. So, first dilute it 10 times, then oxidize formaldehyde and methanol, followed by NH3 stripping, and finally send it for biochemical treatment. I’m not sure if this approach will work This post was last edited by princessdidi on 2009-4-19 12:04]
While the author’s method can indeed meet the requirements for biochemical treatment by treating high-concentration wastewater, diluting it ten times first before processing would increase the volume of wastewater and thus raise the costs associated with biochemical treatment. I think it would be more economical to first use methods such as oxidation to reduce the concentration of NH3, and then carry out a smaller degree of dilution before sending the wastewater to biochemical treatment; only by properly controlling the pre-treatment steps can optimal economic efficiency be achieved.
Are you saying to treat NH3-N with chemicals first? Is that feasible?
I’m very glad to be here, dear seniors and colleagues, to exchange ideas and make progress together! :）:)
40 cubic meters per day: that’s a considerable amount of water. It contains about 5% urethane: it should have considerable value for recycling. It contains methanol and formaldehyde, with a COD value of 100,000; methanol and ammonia evaporate more easily than water, while at low concentrations formaldehyde is less volatile than water (unless under high temperature and pressure). At the same time, the ammonia nitrogen level is very high, exceeding 3000 mg/l (and it may be even higher according to conservative estimates); this is not difficult to handle. Therefore, this method of treating aqueous solutions should not involve adding water or oxidizing agents; rather, it should be a \"subtraction\" process, one that involves separating, concentrating, and purifying the useful substances. If there are no other anions in the aqueous solution, ammonia should exist mainly in the form of free ammonia. Normal-pressure distillation can be used first (ammonia and formaldehyde will further react to form uretone); if there is an excess of ammonia, ammonia, methanol, and a portion of water vaporize from the top of the tower, while the liquid at the bottom of the tank consists mainly of concentrated uretone along with a small amount of formaldehyde. The liquid at the bottom of the tank can be concentrated to about 40% using conventional low-temperature multi-effect evaporation (or our more efficient and energy-saving membrane-assisted multi-stage multi-effect evaporation), after which allantoin is crystallized. If the water evaporated contains a high level of formaldehyde (>0.5%), its reuse can be considered. The aqueous solution vaporized from the top of the tower, which contains methanol, a small amount of formaldehyde, and ammonia, can be further distilled; the wastewater containing only trace amounts of formaldehyde can be discharged or reused. Concentrated ammonia can be used as a raw material for the production of urotropin, while methanol can find other applications. For further discussion, please contact: yjqin1@yahoo.com or yqin@chembrane.com
Recycling methods can be employed. Due to the high salt content and the toxicity of formaldehyde gas, it is best to remove formaldehyde and methanol first, before dealing with the recovery and reuse of urotropin. Multi-effect evaporation should work for this; IPGood is an expert in this area, so you can ask him.
Ammonia nitrogen can be treated with hypochlorous acid. This post was last edited by li*ch1968 on 2009-4-20 19:41]