@article{Teka_Gessesse_Welday_2023, title={Comparing the bio-fertilizer quality of co-composted municipal organic wastes of different mix ratio: evidence from Tigray, northern Ethiopia}, volume={13}, url={https://oiccpress.com/international-journal-of-recycling-of-organic-waste-in-agriculture/article/comparing-the-bio-fertilizer-quality-of-co-composted-municipal-organic-wastes-of-different-mix-ratio-evidence-from-tigray-northern-ethiopia/}, DOI={10.57647/j.ijrowa.2024.1301.11}, abstractNote={Purpose: There is an increasing trend of using sewage sludge co-composting to produce bio-fertilizers for use in agriculture. However, existing studies on the quality of the produced compost came out with contradicting results, which hinder its sustainable utilization. Hence, this study aimed at assessing the quality of sludge based compost for agricultural use. Method: Four treatments, T1 (70% sludge, 15.3% wheat straw and 14.7% cattle manure), T2 (50% sludge, 14.8% wheat straw and 35.2% cattle manure), T3 (30% sludge, 20% wheat straw and 50% cattle manure) and T4 (20% sludge, 14.2% wheat straw and 65.8% cattle manure) having three replications were arranged in a randomized complete design. Matured compost samples, composted for 90 days, were analyzed for nutrient contents, pathogens and heavy metals concentration. Results: The nitrogen content of the produced compost was in the range of 1.74–2.0%, which is higher than the recommended 0.3%. It was significantly higher in the T1 treatment, a 0.24% increase compared to the T4 treatment. However, the phosphorous (202−222 ppm) and potassium (1801−2357 ppm) contents were classified into the very low category. Both elements were higher in the T4 treatment, a 9.9% and 31% increase, respectively as compared to that of T1. Furthermore, all treatments were free of the major disease causing bacteria and characterized by a very low heavy metal concentration. Conclusion: Overall, municipal sludge co-composting has yielded a bio-fertilizer with both pathogen-free and safe levels of heavy metal concentrations. However, further research is required to enhance the poor phosphorous and potassium contents.   Research Highlights ·        Nt in the co-composted sludge was 1.74 – 2.0%, which is higher than the recommended 0.3%. ·        Nt in treatment T1 increased by 0.24% compared to the T4 treatment. ·        The highest phosphorous and potassium values were recorded on the T4 treatment. ·        All treatments were free of the major disease causing bacteria. ·        All treatments were characterized by a very low heavy metal concentration.  }, number={1}, journal={International Journal of Recycling of Organic Waste in Agriculture}, publisher={OICC Press}, author={Teka, Kassa and Gessesse, Tigist. A. and Welday, Yemane}, year={2023}, month={Nov.}, keywords={Compost, Heavy metals, Agriculture, Sludge waste, Nutrient content, Pathogen} }