Co-Composting of Sewage Sludge with Food Waste Using Bin Composter

Abstract

Optimization of sludge composting has been analysed by co-composting of sewage sludge with food waste by using a bin composter with regular aeration. Two bin composting experiments were set up to study the effect of different mixing ratios of food waste from the wet market to sewage sludge from Al Hadhbah waste water treatment plant which is located in Tripoli on some physical and chemical characteristics of the resulted compost. The selected ratios were 1:2 (A) and 1:3 (B) of food waste to sewage sludge respectively. Composting was conducted for 100 days and the sampling from the mixtures was performed each five days. Temperature (T), pH, electrical conductivity (EC), total organic carbon contents (TOC %) and total nitrogen contents (TN %) were monitored during the composting. The ratio of C/N, inorganic residual material (ash content) and nutrient changes as represented by potassium (K %) and phosphorus (P %) contents was also determined. The compost produced in this study has a favorable ratio of C/N (13.43 for compost A and 14. 32 for compost B). With significant amount of nutrients (TN %, K%, P%) The results of analysis of variance (ANOVA) revealed a significant effect of elapsed composting time (at the probability level of 0.05) on T, pH, TOC%, K% and P%. The effect of composting ratio was insignificant (at the probability level of 0.05) on T, TOC %, TN %, C/N and P%. The multiple comparison results using Tukey’s test showed significance difference between the mean values of EC and K% among the composting ratio at the confidence level of 95%. Generally, the compost ratio of 1:2 was found to be the most suitable for use as organic fertilizer