Production of a bioflocculant using old polyester fibre as a fermentation feedstock and its use in treatment of polyester alkali-peeling wastewater

Abstract Old polyester fibre (OPF) was used for the first reported microbial flocculant (MBF) production by Diaphorobacter nitroreducens R9. Pretreatment of OPF was performed by different bases individually. The optimal pretreatment conditions were determined by total organic carbon (TOC) content of hydrolysate supernatants. Although all alkaline OPF-hydrolysate culture media were investigated for MBF production, KOH hydrolysate produced the highest yield. The influence of KOH OPF-hydrolysate culture condition factors were applied throughout the response surface methodology, and the optimal conditions with the maximum MBF yield (4.02 g/L) were 33.5 °C, pH 9.5, and hydrolysate TOC (4.416 g/L). Furthermore, the MBF was applied to treat polyester alkali-peeling wastewater (PAPW) for the first time, and the highest removal efficiency was achieved when 1.0 g/L MBF was added to PAPW. In general, this contribution reveals that KOH OPF-hydrolysate could be used as a potential inexpensive carbon source for production of MBF by sustainable processes that could reduce environmental pollution.