PERFORMANCE OF PRECAST ANAEROBIC DIGESTION TANK COMBINED WITH A FOOD WASTE DISPOSER SYSTEM. A CASE STUDY OF HOUSEHOLD FOOD WASTE IN THAILAND

The actual sizes of precast anaerobic digestion tanks (600 dm(3)) combined with food waste disposer systems (PAD-FWD) were selected to investigate efficiency under actual use conditions. The effects of organic loading rates (OLRs) and the presence of linear alkylbenzene sulfonate (LAS) surfactants in dishwashing liquid on the organic removal efficiency and biogas generation of PAD-FWD were studied. According to the findings, the PAD-FWD at an OLR of 0.13 kg VS/(m(3).day) and hydraulic retention time (HRT) of 12 days could be applied to treat food waste without adding any nutrients to the system to effectively produce biogas. Under operating conditions of the LAS concentration of 63.4 mg/dm(3), PAD-FWD was able to reach a steady-state condition with a performance similar to the system without added LAS. The quality of effluent from the PAD-FWD system was unable to meet the effluent standard for households; thus, this effluent should be collected for treatment in a secondary wastewater treatment plant (WTP) before release into the environment. The effluent quality at an OLR of 0.13 kg VS/(m(3).day) was in the range of the influent properties of the central WTP, which ensures that the pollutants in the effluent do not increase the overall burden on the WTP. The bio-sludge from PAD-FWD was not a sufficient nutrient source for the growing plants. However, the germination index (GI) of the effluent at an OLR of 0.13 kg VS/(m(3).day) did meet the fertilizer standard. The results of this study can be applied to develop self-management of food waste technology to encourage the separation of food waste at the origin within households.