Control of sulfide and methane production in anaerobic sewer systems by means of Downstream Nitrite Dosage. biofilm metagenome

The aim of this study is to test the effectiveness of Downstream Nitrite Dosage (DNO2D) in pressured sewer systems to reduce the production of sulfide (H2S) and methane (CH4) and to assess its effects on the microbial composition of sewer biofilms. The work was carried out in a laboratory system previously demonstrated to mimic the main features of sewer rising main. The work has been carried out in three different periods: system setup, nitrite addition and system recovery. Different normal functioning and batch tests were carried out during the three experimental periods to determine the changes produced by nitrite in the last section of the pipe. Biofilm samples were collected to assess changes in the composition of the bulk and active fractions of microbial communities through pyrotag sequencing of both 16S rRNA and its gene, respectively. This work provides valuable insights of DNO2D effects on both H2S and CH4 production and allows a useful comparison with downstream nitrate dosage (DND) that help to identify the main advantages and limitations of each strategy.