The effect of activated organic sludge on the process and quality of composting palm oil empty fruit bunches

Empty fruit bunches (EFB) has been the second biggest contributor of waste produced by the Malaysian palm oil industries in which the disposal methods lack of sustainability such as dumping into landfills, incinerating, soil mulching, and boiler fuel. Therefore, EFB composting is introduced as one of the handling methods that could benefit the agriculture industry due to its effective ways of material recovery by natural ways and its ability to reduce greenhouse gas emissions as well as its economic feasibility. However, composting EFB alone is not as effective as co-composting it with other organic wastes. Hence, this study focused on co-composting EFB with activated organic sludge (AOS) to provide an alternative nitrogen source for the composting process. This study is to determine the effect of various compost ratio of EFB and AOS on the compost process and quality by using the compost ratio of 1:1, 2:3, and 1:3 w/w and to investigate the effect of turning the compost samples in the composting process by having a turning and non-turning batch of each compost ratio stated. During composting process, parameters such as the carbon to nitrogen (C/N) ratio, moisture content, pH value, temperature, and total bacterial count (TBC) are measured to determine the best compost ratio either with or without turning to achieve the lowest C/N ratio. Amongst the six compost samples, the compost 1:3 (with turning) has recorded to have the best conditions. The temperature and microbial growth profile has shown that the compost 1:3 (with turning) has recorded the highest temperature for microbial degradation to take place at 36.07 ° C and the highest microbial activity with the bacterial count of 4.9 × 10¹² cfu/g. By the 6^th week (day 42) of composting period, the compost 1:3 (with turning) has reached maturation with the C/N ratio of 10.5 which is the lowest amongst other compost batches. In addition, the pH levels are within the alkaline range and the moisture content remained in the 55-65% range. Hence, the compost 1:3 (with turning) is the most suitable to be used as soil conditioner.