Investigating the performance of internet of things based anaerobic digestion of food waste

Abstract

A pilot scale decentralised Continuously Stirred Tank Reactor (CSTR) was designed, developed and installed, with 675 L working volume, to treat food waste generated from the Asian Institute of Technology (AIT) campus community. The reactor was operated in mesophilic, anaerobic and wet condition with feedstock as food waste of 10% Total Solids (TS) content. This study aims for performance evaluation of food waste anaerobic digestion and development of remote monitoring system suitable for centralised monitoring of decentralised anaerobic digestion plants. The performance of the reactor was remotely monitored with the installation of pH, Temperature and Oxidation Reduction Potential (ORP) electrodes connected with the Programmable Logic Controller (PLC). The quality of biogas produced was monitored by online biogas analyzer system. The CSTR was operated with three different Organic Loading Rates (OLR) viz., 1, 2 and 3 kg of volatile solids per cubic meter of digester per day (kg VS/m3.d) to evaluate performance of the food waste digestion and biogas production. The average biogas yield was 0.75, 0.62 and 0.52 cubic meter per kilogram of volatile solids (m3/kg VS), with average methane yield of 0.42, 0.33 and 0.27 m3/kg VS at OLR of 1, 2 and 3 kg VS/m3.d respectively. Furthermore, it was observed that the average reduction in total solids was 70.7, 66.5 and 54.98% and average reduction in volatile solids was 78.3, 72 and 67% at OLR of 1, 2 and 3 kg VS/m3.d respectively. Internet of Things (IoT) enabled remote monitoring on real time basis and aided the centralised operator to improve the process performance resulting in better operation and maintenance of the decentralised anaerobic digestion systems.