The fate of nitrogen through algal treatment of landfill leachate

Nitrogen was tracked though an algae-based landfill leachate remediation system. This system was designed to remove nutrients from the liquid waste via nitrogen assimilation into new algae biomass. While the nitrogen removal pathway of bio-assimilation was present, it was not the only nitrogen removal pathway in the treatment system. Weekly measurements of the dissolved inorganic nitrogen (ammonia-N, nitrate-N, and nitrite-N) and the nitrogen content of the biomass were used to track nitrogen transformation pathways during this yearlong study. During a major part of the study (83.4% of the observed weeks), all nitrogen could not be accounted for in the dissolved inorganic nitrogen or biomass portions of the system. It is hypothesized that some of the unaccounted-for nitrogen was lost due to volatilization of gaseous nitrogen species. Based upon characteristic distribution of measured dissolved inorganic nitrogen and the nitrogen content of the biomass for each week and prior metagenomic analysis of the microbial community in the treatment system, we have postulated potential scenarios of the fate of nitrogen in this algae-based wastewater treatment system. Further research is needed to identify all pathways of nitrogen conversion in algae-based wastewater remediation systems and verify our proposed scenarios.