ASSESSMENT OF HEAVY METAL CONCENTRATIONS AND PHYSICOCHEMICAL PROPERTIES OF EFFLUENT FROM NUMAN ABATTOIR: IMPLICATIONS FOR ENVIRONMENTAL HEALTH AND REGULATORY COMPLIANCE IN NORTHEASTERN NIGERIA

Abstract

A study was conducted to evaluate the physicochemical parameters and heavy metal concentrations in effluent samples from Numan Abattoir (NAB) in Adamawa State, Northeastern Nigeria, comparing them against World Health Organization (WHO) drinking water quality guidelines and Nigerian Standard for Drinking Water Quality (NSDWQ, SON, 2019): Implications for Environmental Health and Regulatory Compliance in Northeastern Nigeria. The specific objectives were to: determine the physicochemical characteristics including pH, temperature, conductivity, TDS, DO, BOD, and COD of effluent samples; quantify the concentrations of cadmium, chromium, iron, lead, and manganese; compare measured values against established regulatory standards; and discuss implications for environmental management and public health protection. The abattoir produces large amounts of wastewater containing organic pollutants and heavy metals that can pose risks to the environment and public health if not adequately treated before discharge. In this study the physicochemical parameters and heavy metal concentrations in effluent samples from Numan Abattoir (NAB ) in Adamawa, Nigeria were collected from the NAB wastewater discharge point on three separate occasions  (NAB _WW1, NAB _WW2, NAB _WW3) using standard sampling protocols, evaluated and compared with the World Health Organization (WHO) and National Environmental Standards and Nigerian Standard for Drinking Water Quality (NSDWQ, SON, 2019) permissible limits. The effluent samples, NAB _WW1, NAB _WW2, NAB _WW3 were analyzed for pH, temperature, conductivity and total dissolved solids (TDS) using pH/conductivity meter (Jenway 430), dissolved oxygen (DO), biological oxygen demand (BOD) and chemical oxygen demand (COD) using DR Spectrometer and concentrations of cadmium (Cd), chromium (Cr), iron (Fe), lead (Pb) and manganese (Mn) using Atomic Absorption Spectrometer (model AA240FS Varian). Results revealed significant non-compliance with both WHO and NSDWQ standards across multiple parameters. pH values ranged from 8.28± 0.0071 to 10.11± 0.0100, with NAB _WW1 and NAB _WW3 exceeding permissible limits, indicating alkaline conditions. Dissolved oxygen levels (1.2 to 1.2± 0.1000 mg/L) were critically below the minimum requirement, reflecting severe organic pollution. Iron concentrations (6.934 ± 0.0003 to 47.095 ± 0.0019 mg/L) exceeded limits by 23 to 157 times, with NAB _WW1 showing exceptionally elevated levels. Manganese concentrations (0.934 ± 0.0010 to 1.282 ± 0.0013 mg/L) exceeded guidelines by 9 to 13 times. Cadmium levels (0.007 ± 0.0003 to 0.009 ± 0.0005 mg/L) exceeded limits by 2.3 to 3.0 times. Chromium and lead were undetectable. COD values for NAB _WW3 (24± 1.0000 mg/L) substantially exceeded permissible limits, indicating high chemical oxygen demand. These findings highlight critical environmental and public health concerns, necessitating urgent implementation of wastewater treatment interventions, enhanced regulatory enforcement, and adoption of sustainable abattoir waste management practices to protect receiving water bodies and surrounding communities. These findings can help regulators such as NSDWQ review national discharge limits, enforce stricter monitoring, and the methodology provides a replicable framework for other beverage industries in Nigeria to assess their environmental performance. Moreover, the results provide important information to local communities and public health officials to promote sound environmental management and protect downstream water users from potential heavy metal exposure.