Hydrolysis, acidification and dewaterability of waste activated sludge under alkaline conditions: Combined effects of NaOH and Ca(OH)2

- Combined use of NaOH and Ca(OH)2 enabled high VFA production.
- Combined use of NaOH and Ca(OH)2 enabled good sludge dewaterability.
- Combined use of NaOH and Ca(OH)2 decreased the costs for VFA production.
- Ca2+ may inhibit protein hydrolysis and decrease VFA production.
- The NaOH to Ca(OH)2 ratio did not exert influences on solubilisation of WAS.