Coupling Nitrogenous Organic Wastewater Treatment and Biorefinery via N-Cycling Bacterium

The pathway toward circular economy fundamentally overthrows the perspective on wastewater, from a mere waste to a stream encompassing retrievable resources. Nevertheless, reliable and cost-effective technologies for resource recovery from refractory nitrogenous organic wastewaters (NOWs) are very scarce. Therefore, this study proposes an innovative strategy that couples the bioremediation of NOWs with sustainable production of polyhydroxybutyrate (PHB). Specifically, this study employs the newly discovered Paracoccus sp. ZQW-1 as a "sustainable cell factory", which exhibits outstanding PHB production capabilities using N-methylpyrrolidone (NMP) as the specific nitrogen source. Ingeniously, the selective pressure of NMP eliminates the sterilization requirement in PHB biorefinery processes. Capitalizing on this advantage, the conceptual demonstration of simultaneous non-sterile PHB production (7.71 g L^-1) and steady-state wastewater depuration is successfully conducted in a 3-L bioreactor. More encouragingly, this paradigm has been successfully applied to the valorization of diverse NOWs (e.g., pyridine and N, N-dimethylformamide), demonstrating its general applicability. Therefore, this study provides a valuable reference for upcycling other NOWs (e.g., aziridine, acridine, pyrrole, and indole). Additionally, life-cycle assessment and techno-economic analysis validate the environmental and economic sustainability of this biorefinery process. Overall, this study proposes an innovative biorefinery strategy and offers a forward-looking trajectory for sustainable wastewater valorization.