Pre-treating anaerobic mixed microflora with waste frying oil: A novel method to inhibit hydrogen consumption

摘要

Highlights•Waste frying oil was successfully used as an inhibitor for H2consumption during dark fermentation of mixed cultures.•Methane production in pre-treated cultures decreased significantly.•Duration of pre-treatment and concentration of waste frying oil affected H2production.•Volatile fatty acids accumulation increased with waste frying oil concentration.AbstractAn innovative method was introduced to inhibit methanogenic H2consumption during dark fermentative hydrogen production by anaerobic mixed cultures. Waste frying oil was used as an inhibitor for hydrogenotrophic methanogens. Simultaneous effect of waste frying oil concentrations (0–20 g/L) and initial pH (5.5, 6.5 and 7.5) on inhibition of methanogenic H2consumption and enhancement of H2accumulation were investigated using glucose as substrate. Enhanced hydrogen yields with decreased methane productions were observed with increasing the waste frying oil concentrations. On average, CH4productions from glucose in the cultures received 10 g/L WFO were reduced by 88%. Increased WFO concentration up to 20 g/L led to negligible CH4productions and in turn enhanced H2yields. Hydrogen yields of 209.26, 195.35 and 185.60 mL/g glucoseaddedwere obtained for the cultures pre-treated with 20 g/L waste frying oil with initial pH of 5.5, 6.5 and 7.5 respectively. H2production by pre-treated cultures was also studied using a synthetic food waste. Anaerobic mixed cultures were pre-treated with 10 g/L WFO and varying durations (0, 24 and 48 h). A H2yield of 71.46 mL/g VS was obtained for cultures pre-treated with 10 g/L WFO for 48 h that was 475% higher than untreated control. This study suggests a novel and inexpensive approach for suppressing hydrogenotrophic methanogens during dark fermentative H2production.