Spent Labisia pumilia as a bulking agent for palm oil mill sludge composting

Abstract

This paper aims to explore the potential use of herbal residue, spent Labisia pumilia (SLP) (also known as Kacip Fatimah) as a bulking agent for palm oil mill effluent sludge (POMES) composting to obtain biofertilizer. Natural aerobic decomposition through the passive aeration approach was implemented by using the bin-composting technique. POMES and SLP mixture were placed in three compost bins with a different weight ratio of 1:3, 1:1 and 3:1. Throughout the experimental period, samples were regularly taken out for physical analysis i.e. pH, temperature and moisture content. On day 90, samples were analyzed for nutrients analysis. The result indicated that ratios 1:1 and 1:3 illustrated typical pH and temperature profiles; meanwhile, ratio 3:1 vice versa for pH profiles. An in-depth analysis of the nutrients composition summarized that the C/N ratio for all mixture samples is within the standard limit for mature compost, and nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) are sufficient to utilize as a biofertilizer. In conclusion, it is feasible to utilize SLP as a bulking agent to improve palm oil mill sludge composting and eventually produce biofertilizer. Thus, it offers an alternative in handling solid waste from palm oil mills.