The response of nitrous oxide emissions to different operating conditions in activated sludge wastewater treatment plants in Southeastern Brazil.

The continuous measurements of NO emissions from the aeration tanks of three activated sludge wastewater treatment plants (WWTPs) operated with biological nitrogen removal (BNR) and non-BNR were performed during the different operating conditions of several parameters, such as aeration, dissolved oxygen (DO) profiling and organic shock loading (with landfill leachate). The nitrification process is the main driving force behind NO emission peaks. There are indications that the variation of the air flow rate influenced NO emissions; high NO emissions denote over-aeration conditions or incomplete nitrification, with accumulation of NO concentrations.

Factors controlling nitrous oxide emissions from a full-scale activated sludge system in the tropics.

Despite interest in characterizing nitrous oxide (N2O) emissions from wastewater treatment plants (WWTPs) in several parts of the globe, there are few studies in tropical zones. This study focus on the contribution of the scientific knowledge of anthropogenic nitrogen greenhouse gas emissions to climate change in tropical countries, investigating factors controlling N2O emissions in a non-biological nitrogen removal municipal WWTP. In terms of operational parameters, dissolved oxygen (DO) concentrations displayed a biphasic impact on N2O production and emission, with the highest emission at DO of 2.

Fate of organochlorine (14)C-dicofol in a lab-scale wastewater treatment.

The fate of organochlorine (14)C-dicofol in activated sludge process was investigated. Results showed that the major part of radioactivity remained adsorbed on biological sludge. Consequently, its final disposal deserves special attention.