Organic and nitrogenous pollutants removal paths in vegetation activated sludge process (V-ASP) for decentralized wastewater treatment by using stable isotope technique

The organics (C) and nitrogenous (N) pollutants removal paths by functional units in vegetation-activated sludge process (V-ASP) were investigated by using stable isotope probing and high-throughput sequencing for the first time. V-ASP system displayed superior treatment performance compared to conventional activated sludge system, as manifested by its greater C and N removal efficiencies, higher abundance of denitrifying and heterotrophic functional Genus, and better resistance to low temperature. Isotope δ¹³C and δ¹⁵N were continuously accumulated in plant roots allocated in the V-ASP, where suspended sludge demonstrated obviously higher C and N enrichment rates compared to the rhizosphere sludge. The mass balance estimation showed that bacterial dissimilation was the dominant removal paths for C (54.13%) and N (47.53%). The underlying pollutants removal paths evidenced the advantageous of V-ASP that is a high feasible and promising approach for decentralized wastewater treatment process.