Potential of sewage sludge as energy recovery via gasification process

Sewage sludge is a valuable resource and of considerable interest which has recently been exploited for its potential as an energy recovery. Sewage sludge gasification is an alternative and promising approach to find a continuous and reliable resource of disposal of the constant supply of sewage sludge, hence it is the attractive way of handling waste management. It is important to move towards the development of a sustainable energy solution to fulfil the present and future energy requirements and reduce the dependency on non-renewable resources. Therefore, the main aim of this study was to investigate the characteristics of sewage sludge collected from Gadong wastewater treatment plant to ensure its possibility for gasification conversion process. Proximate analysis, ultimate analysis, heating value and Energy Dispersive X-Ray Analysis (EDX) were performed. Results showed that the sewage sludge contains 2.70 wt. % moisture contents, 36.9 wt. % volatile matter, 63.0 wt. % ash contents and 7.77 wt. % fixed carbon with a heating value of 8.04 MJ/kg. Thermogravimetric and derivative thermogravimetric (TGA and DTG) analyses were examined to investigate the decomposition behaviour of sewage sludge under nitrogen (N2) and oxygen (O2) conditions at heating rates of 50.00°C to 900.00°C at 10.00°C/min for both conditions. The TG/DTG curves were compared to provide an inclusive description of the three different stages of thermal decomposition in all conditions. The overall conclusion based on experimental studies is that the characteristics and thermal analyses of sewage sludge are suitable as an energy recovery feedstock for the gasification process.