Effects of mixed carbon sources in wood enzyme hydrolysate on microbial intracellular and extracellular polymers

In order to achieve efficient conversion of woody biomass resources and improve the sustainable development of non-food biobased materials, this paper investigated the effects of mixed carbon sources of wood enzyme hydrolysate on the microbial intracellular polymer polyhydroxystreptate(PHA) and extracellular polymer EPS during the domestication of mixed strains of activated sludge, and analysed the relationship between PHA, EPS and the properties of domesticated sludge. The results showed that the addition of sodium acetate, a co-substrate carbon source, mimicked filamentous bacterial overgrowth and sludge swelling, and favoured the growth of PHA-synthesizing bacteria. The elevated content of extracellular polymer PS in the domestication system of wood enzyme hydrolysate was the main factor leading to poor sludge performance and sludge swelling, and the addition of sodium acetate could reduce the content of PN and PS. Mixed carbon sources resulted in maximum PHA content(491.8 mg CDO/L) as well as a high HV monomer percentage(HV∶HB = 10∶90). Correlation analysis proved that increasing sludge concentration and preventing sludge swelling while promoting EPS synthesis were effective ways to further accumulate PHA.