Markos et al_2024 Physico-chemical Characterization of Domestic Sludge of Hawassa Industry Park and evaluation of its potential use as fertilizer

Abstract

The use of domestic sewage on cultivable soils may increase agricultural yield in underdeveloped countries; nevertheless, the environmental dangers must be properly examined and addressed. This research was undertaken to determine the physical and chemical characteristics of domestic sludge from Hawassa Industrial Park in Ethiopia and assess its potential applicability as organic fertilizer for crop production and a source of major nutrients to reduce environmental problems with their disposal, which is valuably replace synthesized fertilizer. For this purpose, five domestic sludge samples were collected in consecutive five days a week and the samples were analyzed at the College of Agriculture soil laboratory of Hawassa University. Descriptive statistics and regression analysis were conducted to separate the mean differences between the treatments. The research revealed that organic carbon, total nitrogen, and available phosphorus contents were high in all samples compared with the maximum attainable values of soils. These results are good indicators that the sludge could improve the soil's physical properties. The analyses also revealed that the sludge is slightly alkaline (pH>7.4) and with low electrical conductivity (EC, 2.06 mS/cm). The result of analyses in terms of heavy metals (Zn, Cu, Cd, Pb, Ni, and Cr) showed that the heavy metals in the domestic sludge are below the Ethiopian standard and FAO limits. In general, the majority of the physical and chemical properties revealed that the sludge is suitable for agricultural purposes. However, further research should be conducted on the effect of sludge on crop parameters, especially on the tissues of crops.