Assessment of aeration procedures on windrow composting process efficiency: A case on municipal solid waste in Sri Lanka

Abstract

Windrow is the most commonly used aerobic digestion technique for the biodegradable fraction of Municipal Solid Waste (MSW). High labor cost, long lead time and taking up of valuable land space are the major constrains of windrow composting. The present study was planned to assess the efficiency of the process via altering of aeration procedure. Fifteen piles each with triplicates were constructed using pre-sorted MSW. Three different aeration procedures were designed using Poly Vinyl Chloride (PVC) pipes with 4” diameter and 2m length at two steps. Pipes were set 10cm above the ground horizontally (Treatment 1), vertically (Treatment: 2) with 3 pipes and both horizontally and vertically (Treatment: 3) with 4 pipes. No pipes were used for Controls. All piles were subject to turn once a week. For each pile, volatile solid and total nitrogen were monitored once a week while temperature was measured daily. The quality of resultant compost was evaluated according to Sri Lanka Standard (SLS) 1246:2003. Results revealed that Treatment: 1 performed better consuming the shortest lead time. The highest heat generation, total nitrogen, bulk density difference and the lowest maturing time were recorded from Treatment: 1. The results further indicated that potassium and phosphorous (as oxides) of resultant compost produced from all piles were below the SLS specifications. Thus, present study suggests Treatment: 1 in future compost production in local authorities at small scale as it reduces labor cost by three eighth and process lead time by three weeks.