Evaluation of Effluent Treatment Practices in Textile Dyeing and Finishing Plants in Kano State

Textile dyeing and finishing effluents contain complex mixtures of synthetic dyes, surfactants, fixing agents, and salt that require appropriate treatment before discharge to prevent environmental contamination of receiving water bodies. This study evaluates the effluent treatment practices employed by dyeing and finishing plants operating in Kano State, North West Nigeria, assessing compliance with national effluent discharge standards. Wastewater samples were collected from twelve dyeing plants at effluent outlet points and analysed for biochemical oxygen demand, chemical oxygen demand, total suspended solids, colour, pH, and heavy metal content. Plant operational records on treatment system capacity, treatment steps, and maintenance protocols were obtained. Laboratory analysis results were compared against the National Environmental Standards and Regulations Enforcement Agency standard limits for textile effluents. Results indicate that only four of twelve plants operated biological treatment systems, with the remainder relying on sedimentation and dilution. Chemical oxygen demand of untreated discharge averaged 1840 mg/L, exceeding the 40 mg/L national limit by 46-fold. Colour removal in plants without biological treatment averaged only 18 percent, resulting in visually coloured discharge into drainage channels. Heavy metal analysis identified chromium exceedance in three plants using mordant dyeing methods. The study recommends urgent regulatory enforcement action, subsidised effluent treatment plant construction for small dyeing operators, and cleaner production training programmes for the Kano textile dyeing sector to achieve environmental compliance with national discharge standards. Keywords: textile effluent, dyeing plants, Kano State, environmental compliance, water pollution