2.3 Sludge pre-treatment
The feedstocks were subjected to combined microwave and hydrogen peroxide treatment. The sludge was initially heated at 80 °C by microwave irradiation at 660 W for 2 minutes to curtail catalase activity in the microbial fraction of MWAS; catalase breaks down H2O2 into water and molecular oxygen inhibiting the oxidative effect of pre-treatment 24. Followed by, the addition of hydrogen peroxide (1% w/w H2O2/TS) at room temperature with constant mixing. The sludge was again microwave irradiated at 660W for 3 minutes in a laboratory-scale microwave oven, with an intermittent break to avoid water evaporation. The treated and untreated mixed sludge samples were inoculated with 10% DS making up to an operating volume of 500 ml.