Genome-level insights into the operation of an on-site biological wastewater treatment unit reveal the importance of storage time

Genome-level insights into the operation of an on-site biological wastewater treatment unit reveal the importance of storage time

Biochemistry

Tanks (containers)

Polycyclic aromatic hydrocarbons

Wastewater treatment

Degradation

Effluents

Biological water treatment

Effluent treatment

Reclamation

Genes

Activated sludge process

On-site wastewater treatment systems are gaining popularity in areas where centralized wastewater treatment is not available. In the current case study a domestic activated sludge system was investigated, where treated effluent was stored in a short-term (1 week turn-over time) and a long-term (over 23 months) storage tank and was then used for irrigation. This design provided a unique opportunity to assess the chemical and microbial changes of the effluent upon storage. Long-term storage greatly improved both the chemical quality and the degradation efficiency of most organic micropollutants examined, including petroleum hydrocarbons and the pesticide diethyltoluamide. Taxonomic profile of the core microbiome of the effluent was also influenced upon storage. Relative abundance values of the members of Azoarcus and Thauera genera, which are important in degrading polycyclic aromatic hydrocarbons compounds, clearly indicated the biodegrading activity of these microbes across samples. The abundance of xenobiotics degradation functions correlated with the observed organic micropollutant degradation values indicating efficient microbial decomposition of these contaminants. Functions related to infectious diseases also had the highest abundance in the short-term storage tank corresponding well with the relative abundance of indicator organisms and implying to the significance of storage time in the elimination of pathogens. Based on these results, small, on-site wastewater treatment systems could benefit from long-term storage of wastewater effluent. 2020 The Authors

766

Science of the Total Environment

2021

Knisz, J.

Shetty, P.

Wirth, R.

Maroti, G.

Karches, T.

Dalko, I.

Balint, M.

Vadkerti, E.

Biro, T.

journalArticle

489697

10.1016/j.scitotenv.2020.144425