Composting paper and grass clippings with anaerobically treated palm oil mill effluent

Purpose The purpose of this study is to investigate thecomposting performance of anaerobically treated palm oilmill effluent (AnPOME) mixed with paper and grassclippings.Methods Composting was conducted using a laboratoryscale system for 40 days. Several parameters were determined:temperature, mass reduction, pH, electrical conductivity,colour, zeta potential, phytotoxicity and finalcompost nutrients.Results The moisture content and compost mass werereduced by 24 and 18 %, respectively. Both final compostpH value and electrical conductivity were found to increasein value. Colour (measured as PtCo) was not suitable as amaturity indicator. The negative zeta potential valuesdecreased from -12.25 to -21.80 mV. The phytotoxicityof the compost mixture was found to decrease in valueduring the process and the final nutrient value of thecompost indicates its suitability as a soil conditioner.Conclusions From this study, we conclude that the additionof paper and grass clippings can be a potential substrateto be composted with anaerobically treated palm oilmill effluent (AnPOME). The final compost produced issuitable for soil conditioner.