Study of an eco-efficient method for wastewater treatment and safe agricultural reuse: Effect of influent splitting rates on effluent quality parameters

In this study, an eco-efficient scheme (EES) that is both selective and environmentally viable is proposed and compared to a conventional activated sludge scheme (CAS). The results showed an optimal process operation and a significant difference (p < 0.001) in organic load and nutrient removal efficiencies between CAS and EES. Moreover, statistical analysis based on variance and principal component analysis highlighted a significant positive correlation between influent/effluent wastewater parameters, performance indicators and adopted process configuration. Thus, the average concentrations of activated sludge biomass were 3.11 +/- 0.48 g(TSS).L-1 and 2.51 +/- 0.37 g(VSS).L-1, and the volatile suspended solids (VSS) to average total suspended solids (TSS) ratio, which indicates the rate of active fraction of activated sludge biomass and the degree of mineralization, was approximately 81%+/- 2%, suggesting the optimal development of activated sludge biomass in the bioreactor. Furthermore, chemical oxygen demand and 5-day biological oxygen demand removal efficiencies in CAS were 94% and 97% versus 55% and 66% in EES, respectively. Nitrogen abatement in terms of total Kjeldahl nitrogen and NH4+ performed by CAS was approximately 85% and 86%, respectively, and by EES 41% and 40%, respectively. Phosphorus abatements were comparable in both CAS and EES. The effluent hygienic quality parameters after disinfection conformed to applied standards for safe reuse. For agricultural purposes and environmental and socio-economic considerations, we must consider further ecological methods. Selecting organic matter and nutrients can also provide hygienic effluent; therefore, the eco-efficient process constitutes a promising eco-friendly technology.