Over the past decade, we have seen cases where petrochemical whole effluent tests are compromised by higher than expected effluent nitrite. In most wastewater treatment systems, ammonia oxidation to nitrite is the rate limiting step and nitrite is quickly converted into less toxic nitrate. The solution has been to add nitrite oxidizing cultures (NOB) when effluent nitrite levels start to increase. Until now, there has been no answers on trigger events that create the NOB activity problem. This past month, I noticed an interesting article in Environmental Science & Technology Journal. The paper by Dr. Sylvia Schaefer and Dr. James Hollibaugh covers their research into temperature decouples ammonium and nitrite oxidation in coastal waters. While coastal waters are not wastewater treatment plants, they have some interesting findings.
In coastal waters, with sufficient oxygen and mixing, when temperatures increase to between 20 - 30 Deg C, NOB oxidizing bacteria start to lag behind the AOB - resulting in nitrite buildup. The full abstract is available here: http://pubs.acs.org/doi/abs/10.1021/acs.est.6b03483
I intend on reviewing data from industrial and municipal wastewater treatment facilities to see if we have a similar phenomenon occurring during periods with high water temperatures. If we could identify trigger conditions, actions can be taken to prevent the nitrite increase before effluent quality is impacted.
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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