Hydrothermal pre-treatment of hospital food waste for efficient bio-methane generation

Abstract

Municipal solid waste management (MWM) in Malaysia has become a challenging task in recent years due to the growth of population, industrialization and an increase in quantity and variation in the types of waste generated. Major solid waste generated in Malaysia is organic waste which includes mainly food waste from households, food processing facilities, markets, food and beverages industry and hospitals. Therefore, it is crucial to identify ways to manage food waste (FW) properly and improve the energy recovery efficiency. This paper is aimed to study the impact of pre-treatment on food waste from Hospital Pakar Sultanah Fatimah (HPSF) as a method to decompose FW faster and to determine the potential of bio-methane generation. A compositional study showed that total solid waste generated was 2,301 kg with 67% waste from lunch followed by 31% from breakfast sessions daily. Hydrothermal pre-treatment was done using a Multipurpose Recycling Machine (MRM) at 1.6MPa for 15 minutes followed by anaerobic digestion with and without the inoculum addition. Un-treated FW with inoculum was used as control in this experiment. It was found out that at a controlled pH of 7, hydrothermal pre-treatment and addition of inoculum i.e. cow manure played an important role in anaerobic digestion process for enhancement of bio-methane production. It significantly reduced the lag phase by 4 days and produced biogas faster compared to nontreated FW and hence, increased the biogas volume up to 638.53 mL compared to 504.08 mL in non-treated FW at the same experimental conditions. Therefore, this study signified that hydrothermal pretreatment is an effective and a beneficial technique added to the waste through the generation of biogas energy.