Bacteria for Wastewater Odour Control

Every wastewater treatment plant has to deal with the challenge of odour control at some point or the other. The extent of foul smell varies depending on the geographical and environmental parameters around the effluent treatment plant. Today with the widespread use of social media, wastewater treatment plants cannot afford to attract unwanted attention and possibly regulatory fines due to local complaints.

The odour from the wastewater treatment plants, apart from being a nuisance to those residing around and working at the plant, can also be at times a health hazard for the community. It is critical to identify the source of the foul odour at the effluent treatment plant and address the issue.

In this example, one of the Common Effluent Treatment Plants in Maharashtra successfully isolated the source of foul odour and treated it biologically using Evobac and Evobac ANB. The foul odour came primarily from the collection tank and the aeration chambers. The settling tank too was emanating a foul odour with bubbling seen continuously in the tank.

The collection tank had very high levels of organic content. The generic bacteria were quickly consuming the dissolved oxygen and turning the collection tank anaerobic. The sulphur present in the tank was being converted to H₂S gas. The collection tank smelled heavily of hydrogen sulfide, sulfur dioxide, and mercaptans. The collection tank received a dose of Evobac ANB. Facultative anaerobic bacteria in Evobac ANB started rapidly breaking down organic and assimilating them at low oxygen levels. The sulphur assimilation process of these anoxic bacteria trapped the free sulphur and prevented the formation of H₂S gas in an anoxic environment.

The aerobic bacteria in Evobac took care of the odours in the aeration tank. We observed a rapid drop in COD and BOD levels coupled with the elimination of odours due to ammonia, skatoles, amines and indoles in wastewater. The judicious application of aerobic and anaerobic bacteria eliminated foul odours right at the source in the effluent treatment plant.

The improved clarity of the treated water and the near absence of any foul odour from the wastewater treatment plant was a remarkable proof of what the right bacteria mix can achieve when applied correctly.