Dewatered Sludge Utilization from Leachate Treatment Plant (LTP) for Composting at Supit Urang Landfill, Malang

The Leachate Treatment Plant (LTP) at Supit Urang Landfill produces a by-product of dewatered sludge that has not been utilized optimally and according to its potential. Sludge is a highly organic material that agriculture can reuse as a fertilizer or soil conditioning agent. However, its potential heavy metals possess environmental risks. Currently, sludge from the dewatering process is disposed of in landfills. Sludge left open without further handling will potentially be a source of environmental pollution that will cause unpleasant odors. This study aims to identify how to utilize sludge as raw material for compost mixtures. The approach applied in this research was quantitative with an experimental design. Sludge was mixed with ready-made compost and EM4 solution. Composting is carried out with three different ratios of sludge and compost, which consist of (w/w) 1:1 (M1), 1:2 (M2), and 1:3 (M3). The addition of EM4 solution (10% of the mixture weight) was used to enhance the efficiency of the composting process. The result revealed that after 21 days, the quality of co-composting sludge and ready-made compost met the requirements of SNI 19-7030-2004. The best results were obtained in mixture M3 (C-Org = 17.92%, Ntotal = 1.71%, Ptotal = 0.80%, Ktotal = 1.33%, C/N-ratio = 10.38, Cd = 2.47 mg.kg-1, Hg = 0.0 mg.kg-1). These findings suggest that sludge has the potential to be used as raw material for compost mixtures. Keywords: composting, dewatered sludge, EM4, heavy metals.