Studies on Effect of Peracetic Acid Pretreatment on Anaerobic Fermentation Biogas Production from Sludge

To enhance anaerobic fermentation biogas production, excess sludge from Hanxi waste water plant of Wuhan City was first pretreated by peracetic acid (PAA), then anaerobic digested for 20 days in 35degC. An anaerobic digestion process without pretreatment was conducted as reference for comparison purpose. The results showed that organic matter dissolved from sludge after PAA pretreatment, soluble chemical oxygen demand (SCOD) increased 99, 227, 261 and 277%, mixed liquor suspended solid (MLSS) reduced 20.0, 25.0, 27.0 and 28.8%, according to the PAA concentration of 0.011, 0.027, 0.133, 0.266%. At the PAA concentration of 0.011%, there was almost no PAA or H₂O₂ left in excess sludge solution after 12h´reaction, so it wouldn´t disturb the following anaerobic fermentation. After the anaerobic fermentation for 20 days, the total biogas production of PAA pretreated sludge enhanced 72% than that of the raw sludge, and the MLSS reduction ratio was 31%, which was conducive to reclaim the energy and decrease the excess sludge.