# Coupling Nitrogenous Organic Wastewater Treatment and Biorefinery via N‐Cycling Bacterium

## TL;DR

This paper introduces a new biorefinery strategy using a bacterium to treat nitrogen-rich wastewater while producing a valuable bioplastic.

## Contribution

The study introduces a novel biorefinery process using Paracoccus sp. ZQW-1 for simultaneous wastewater treatment and PHB production.

## Key findings

- Paracoccus sp. ZQW-1 produces 7.71 g L−1 of PHB using NMP as a nitrogen source.
- The process enables non-sterile PHB production by suppressing microbial competitors with NMP.
- The strategy is applicable to various nitrogenous wastewaters like pyridine and N,N-dimethylformamide.

## Abstract

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.

The vast reservoir of nitrogenous organic pollutants in industrial wastewaters can serve as untapped carbon‐nitrogen resources. This study employs the newly discovered Paracoccus sp. ZQW‐1 as a versatile chassis to simultaneously achieve N‐methylpyrrolidone (NMP) wastewater depuration and polyhydroxybutyrate (PHB) synthesis. Ingeniously, the selective pressure of NMP can suppress microbial competitors, thereby enabling efficient PHB production under non‐sterile conditions.