Effect of sodium chloride on polyhydroxyalkanoate production from food waste fermentation leachate under different organic loading rate

Polyhydroxyalkanoate (PHA) production integrated with anaerobic digestion is promising for food waste recycle. However, effect of salinity and high organic load in waste fermentation leachate (FWFL) on PHA production is unknown. Effects of sodium chloride (NaCl, 0, 5.0, 10.0 and 15.0 g/L) and organic loading rate (OLR, 1350 and 8433 mg COD/(L·d)) on the enrichment of PHA-accumulating microorganisms and PHA accumulation using FWFL were investigated in this research. Stable operation and obvious effect were observed under lower OLR with increasing NaCl concentration, but effect of NaCl was concealed by the inhibition caused by high OLR. Paracoccus was the dominant bacteria in all treatments with NaCl. Microbial community at low OLR and 5.0 g/L NaCl had the best performance reflected by kinetic parameters. Real FWFL with different NaCl concentrations was used in batch assays to verify the optimized enrichment strategy, reaching the maximum PHA content of 33.4% at 2.5 g/L NaCl.