Bio-refinery of organic pollutants for wastewater reclamation

Abstract

With rapid development of global climate change and resource scarcity, the demand for sustainable wastewater reclamation technologies is growing rapidly. Alginate like exopolymers (ALE) are value-added biopolymers that can be recovered from excess biomass. In this study, a novel biopolymer value-driven moving bed biofilm reactor (bMBBR) was constructed to achieve high-efficiency conversion of organics to Alginate like exopolymers (ALE). The results revealed that excellent COD and low NH4+-N reduction could be achieved, with the reduction efficiencies of 87.7 ± 0.6 % and 12.6 ± 0.8 %, respectively. It is indicated that high-rate organics conversion and blockage of nitrification activity for energy saving could be simultaneous achieved in this process. Additionally, the superior settleability (SVI30 < 80 mL/g) and functional genera related to extracellular polymeric substances (EPS) secretion were observed, making it promising for ALE recovery from residual biomass. The yields of ALE extraction from biofilm and suspended biomass ranged of 232.9–381.5 mg/g VSS. The property analyses demonstrated that the biopolymer had a similarity functional group between two samples and commercial alginate. Meanwhile, the profit evaluation results suggested that the net profit could be reached of 0.54 CNY/kg SS in the present study, which was higher than that of conventional waste activated sludge (−1.92 CNY/kg SS). Moreover, the economic value of ALE (0.38 CNY/m3 wastewater treated) was also 2.93 times of that obtained from CH4 (0.13 CNY/m3 wastewater treated). In general, the present study provides a prove of concept that bio-refinery of organics into value-added biopolymers could offer a promising direction towards next generation of sustainable wastewater treatment plants.