Abstract:
Biotransformation of brewery sludge and Lantana camara is a double interest, as it converts industrial waste in to useful product and helps to control invasive weeds. The objective of this study was to evaluate vermicomposting technology in the biotransformation of brewery sludge (BS) and Lantana biomass in to valuable product. Fresh (BS) was obtained from the waste water treatment plant of Harar brewery factory, which is located in Harar city. Lantana camara (LC) was collected from the premises of Haramaya University main campus. Fifty young earthworm species (Eisenia fetida) were obtained from the vermicomposting site of Raree, Haramaya University. Dried BS and LC were sampled before composting process. The combinations were with earthworm (WE) and without earthworm (WW) in BS and LC, 75 BS: 25 LC, 50 BS: 50 LC, 25 BS: 75 LC with earthworm respectively. After 90 days compost samples were taken from each treatment to analyze total nitrogen (TN), total phosphorus (TP), total potassium (TK), total organic carbon (TOC) and heavy metals analysis in soil chemistry laboratory of Haramaya University. TOC, TN, and heavy metals were analyzed by Walkley and Black method, Bremmer and Mulvaney method, and Wet digestion method respectively. Data analysis was carried out using R software (version 4.1.2). At the end of vermicomposting, heavy metals content increased but the concentrations were below the maximum permissible limits, which indicates that the compost can be used for agricultural purpose without any risk. Vermicomposting resulted in reduction of pH and TOC, whereas increase in TN, TP, TK, and EC compared with the initial level. Vermicomposting increased the amount of nutrient content compared with the conventional compost in different treatments. Earthworms were unable to survive in 100 % BS but 50 BS: 50 LC treatments was most suitable combination for earthworm growth. The results imply that vermicomposting alters the concentration of nutrients and metals but further research is required to strengthen the recent findings with respect to environmentally safe utilization of bio transformed BS and LC.
