Enhancing Faecal Sludge Compost Quality by Co-Composting with Rice Husk as Binding Agent.

Abstract

Rice husk and feacal sludge poses waste management challenges, which result in Sanitation or environmental consequences in Ghana. Feacal sludge is rich in nitrogen (N) and phosphorus (P) while rice husk is rich in potassium (K) and organic carbon (OC). As such co-composting these two bio-wastes could be useful for applications in agriculture while minimizing the environmental consequences associated with the disposal of these wastes at landfills. This study aimed to enhance rice husk compost by co-composting with feacal sludge. The University of Skill Training and Entrepreneurial Development (AAMUSTED) Mampong campus was the place of study. A composting experiment was done by mixing Rice husk (R) and Faecal sludge (F) in the ratios: RF (1:0.5), RF (1:1), and RF (1:2) by volume in a complete randomized design. The aerobic composting method was used for the treatment and was turned weekly, to enhance decomposition. Results of the study showed that raw rice husk was low in total N (0.47%), P (0.05 %), Total Coliform (2.3 x103 CFUg-l), and feacal coliform (nil CFUg-l) compared to raw feacal sludge which was high in N (3.15 %), P(0.79 %), Tot. coliform (2.4x1017 CFUg-l) and feacal coliform (4.2 x1013 CFUg-l) . The OC (45.03%) content, C: N ratio (95), and K (1.26%) of rice husk were very high unlike that of feacal-sludge: OC (32.66%), C: N (10.36) and K (0.81%). At the end of the composting experiment, RF (1:2) recorded the highest total N (21000 mg/kg) and P (9300 mg/kg) followed by RF (1:1) (16000 N mg/kg; 6800 P mg/kg) and RF (1:0.5) (1400 N mg/kg; 4200 P mg/kg). On the contrary, the highest total K among the mixing ratios was recorded in RF (1:0.5) (10000 mg/kg) followed by RF (1:1) (9300) and RF (1:2) (7400). The highest mineralized NPK was observed in RF (1:2)(2900 N mg/kg; 1581 P mg/kg; 2072 K mg/kg) followed by RF(1:1)(2400 N mg/kg; 680 P mg/kg; 1581 K mg/kg) and RF(1:0.5)(1260 N mg/kg; 210 P mg/kg; 1400 K mg/kg). Concerning pathogen load, RF (1:2) recorded the highest total and feacal coliform (7.38 in log units; 6.38 in log units) followed by RF (1:1) (6.63 total coliform in log units; 5.32 feacal in log units) and the least being RF (1:0.5) (4.38 total coliform in log units; 3.63 feacal coliform in log units). RF (1:2) was identified as the mixing ratio that gave the best compost among the co-composting treatments based on total NPK, mineralized NPK, and other nominal factors at the end of the co-compost experiment. It was therefore recommended that Rice husk be co-composted with feacal sludge in a ratio of 1:2.