Implications of Nitrate Dosage in anaerobic sewers to control sulfide and methane emissions. biofilm metagenome

The aim of the study is to determine the effects of Downstream Nitrate Dosage on sewer biofilms with regards to sulfide oxidation and, for the first time, on methane production. The work was carried out in a laboratory main sewer system previously validated to mimic the main features of anaerobic sewer rising mains. The DND testing involved three phases, namely: the baseline phase, the dosage phase during which NO3- was added to the downstream section of the pipe, and a recovery phase, during which the performance of the pipe was monitored subsequent to the termination of the dosage. The work provides further information on the optimal dosage of nitrate for H2S and CH4 control, both at process and microbiological levels. The production of nitrogen-related greenhouse gas, nitrous oxide (N2O), was also monitored to evaluate a potential greenhouse gas effect of the DND strategy. Besides, the changes in biofilm bacterial and archaeal communities exposed to nitrate were investigated by 454-pyrosequencing over the study period.