Effect of bulking materials and mixing ratios on concentration of nutrients during composting of raw faecal sludge from peri-urban areas

Composting of raw faecal sludge (FS) poses many difficulties due to its high moisture content (MC), high wet bulk density and low carbon to nitrogen ratio. The aim of this study were to (1) examine the suitability of bulking materials (BMs) and (2) investigate the effect of bulking material and mixing ratio on concentration of nutrients during composting of raw FS compost. Raw FS and BMs (wood chips and maize cobs) were sampled from three peri-urban communities. The raw FS showed an initial high MC (73%) which was greater than that required to start a compost process (55–65%). The results showed that the total carbon and nitrogen contents of all the experiments decreased at the end of the composting process. Composted materials at the end of the experiment showed lower concentrations of available phosphorus and potassium in all the experiments than the initial substrate materials. Experimental trial, Maize cob (1:2) is the most preferred due to the fact that it contained more nitrogen, phosphorus, potassium and also carbon which are essential nutrients for plant growth and for improving on the soil organic matter content.