Influences of volatile solid concentration, temperature and solid retention time for the hydrolysis of waste activated sludge to recover volatile fatty acids

▸ Waste activated sludge was fermented at 50 °C, 23.78 gVSS/L and uncontrolled pH. ▸ When SRT of reactor was two days, VFA yield was 5699.43 mgCOD/L more than other ways. ▸ Iso-valeric acid, acetic acid and n-butyric acid were the dominant VFA produced. ▸ Long-chain fatty acids were beneficial for forming more PHV in mixed VFA.