Synergistic improvement of short-chain fatty acid production from waste activated sludge via anaerobic fermentation by combined plasma-calcium peroxide process

In this study, the combination of dielectric barrier discharge plasma (DBD) with calcium peroxide (CaO2) achieved significant synergistic effects in promoting hydrolysis of waste activated sludge (WAS) and short-chain fatty acid (SCFA) production during anaerobic fermentation. Compared with the control, DBD/CaO2 pretreatment increased SCFA production by 116 %, acetic acid ratio by 39 %, and sludge reduction by 30 % under the optimal conditions (discharge power = 76.5 W, CaO2 dosage = 0.05 g/g VSS). Mechanism investigations elucidated that DBD/CaO2 enhanced the generation of center dot OH, O-1(2), and center dot O-2(-), synergistically promoted decomposing extracellular polymeric substances (EPS), lysing cells, releasing biodegradable substances, and enhancing acetic acid-enriched SCFA accumulation from fermentation. Meanwhile, Illumina MiSeq sequencing analysis revealed that the enrichment of hydrolytic and SCFAs-forming bacteria and the decrease in SCFAs-consuming bacteria by DBD/CaO2 treatment also contributed. This work provides an effective method to boost the SCFA production from WAS fermentation.

Automated summary

The combination of dielectric barrier discharge plasma with calcium peroxide was found to significantly enhance the hydrolysis of waste activated sludge and the production of short-chain fatty acids. This was achieved by promoting the decomposition of extracellular polymeric substances, lysing cells, and releasing biodegradable substances. Additionally, the treatment increased the abundance of hydrolytic and SCFAs-forming bacteria, while decreasing the abundance of SCFAs-consuming bacteria.