Pilot-Scale Polyhydroxyalkanoate Production from Paper Mill Wastewater: Process Characteristics and Identification of Bottlenecks for Full-Scale Implementation

摘要

In this study, the suitability of paper industry wastewater for production of polyhydroxyalkanoate (PHA) was investigated in a pilot reactor in an industrial setting. The pilot plant was designed as a three-step process comprising (1)anaerobic fermentation for maximization of the volatile fatty acid (VFA) concentration, (2)enrichment of PHA-producing biomass, and (3)accumulation for maximization of the PHA content of the biomass. After fermentation, the paper mill process water contained a VFA fraction of 78% on a chemical oxygen demand (COD) basis. The length of the feast phase in the enrichment process stabilized at 45min +/- 4min after 18days of operation. At the end of the feast phase all VFA was consumed and the PHA content of the volatile suspended solids (VSS) was 0.50gPHA/gVSS +/- 0.05gPHA/gVSS. The acquired microbial community was dominated by Plasticicumulans acidivorans, a PHA-producing microorganism previously found to dominate VFA-fed laboratory reactors. The maximum PHA content achieved after accumulation was 0.70 to 0.80g PHA/g VSS. An overall PHA yield of 34% on a COD basis was achieved. Improving the VFA fraction in the product spectrum of the fermentation and minimization of acid and base consumption for pH control were identified as major bottlenecks.