Intensification of biogas production using pretreatment based on hydrodynamic cavitation

• First depiction of the use of hydrodynamic cavitation for intensification of biogas.
• Use of wheat straw as a sustainable raw material for biofuel production.
• Evaluation of combination of hydrodynamic cavitation with chemical treatment.
• Investigation into effect of important operating parameters.
• Almost 100% increase in the biogas production under optimised treatment.

The present work investigates the application of hydrodynamic cavitation (HC) for the pretreatment of wheat straw with an objective of enhancing the biogas production. The hydrodynamic cavitation reactor is based on a stator and rotor assembly. The effect of three different speeds of rotor (2300, 2500, 2700 rpm), wheat straw to water ratios (0.5%, 1% and 1.5% wt/wt) and also treatment times as 2, 4 and 6 min have been investigated in the work using the design of experiments (DOE) approach. It was observed that the methane yield of 31.8 ml was obtained with untreated wheat straw whereas 77.9 ml was obtained with HC pre-treated wheat straw confirming the favourable changes during the pre-treatment. The combined pre-treatment using KOH and HC gave maximum yield of biogas as 172.3 ml. Overall, it has been established that significant enhancement in the biogas production can be obtained due to the pretreatment using HC which can also be further intensified by combination with chemical treatment.