Title: Influence of fresh and aged palm oil-mill effluents on soil biochemical and microbial properties in humid tropical environments

Authors: Daniel Onyedikachi Ugwu; Prisca Oluchi Ogumba; Parker Elijah Joshua; Sunday Ewele Obalum; Obioma Uzoma Njoku

Addresses: Department of Medical Biochemistry, Faculty of Basic Medical Sciences, David Umahi Federal University of Health Sciences, Uburu, 491105, Ebonyi State, Nigeria; Department of Biochemistry, Faculty of Biological Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria ' Department of Soil Science and Land Resources Management, College of Crop and Soil Sciences, Michael Okpara University of Agriculture, Umudike, PMB 7267 Umuahia, Abia State, Nigeria; Department of Soil Science, Faculty of Agriculture, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria ' Department of Biochemistry, Faculty of Biological Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria ' Department of Soil Science, Faculty of Agriculture, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria ' Department of Biochemistry, Faculty of Biological Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria

Abstract: Effects of fresh and aged palm oil-mill effluents (POME) on enzyme and microbial activities of a sandy-loam soil in a tropical environment were investigated. The soil was amended with fresh and aged (6-12 months old) POME at 0%, 25%, 50%, 75%, and 100%, and soil enzyme and microbial activities determined weekly over a 28-day period. All concentrations of both POME types increased soil dehydrogenase activity over the control (0%). Catalase activity was decreased by fresh POME over the 28-day period while increased by higher concentrations of aged POME after day 14. Lipase activity generally decreased at all fresh POME concentrations while increased at higher aged POME concentrations. Soil microbial biomass C-N-P always increased steadily with POME concentration, being more evident with aged than fresh POME. Natural fermentation of freshly discharged POME under aerobic conditions with time can ameliorate its toxicity and inhibitory effects on soil enzymatic activity, leading to increased soil microbial biomass.

Keywords: fresh POME; aged POME; agro-waste management; natural fermentation; soil enzymatic activities; dehydrogenase activity; catalase activity; lipase activity; soil microbial biomass; agro-environmental quality.

DOI: 10.1504/IJEWM.2026.155088

International Journal of Environment and Waste Management, 2026 Vol.40 No.3, pp.275 - 294

Received: 21 Jun 2024
Accepted: 16 Jun 2025
Published online: 27 Jul 2026 *

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