Impact of Soap Factory Wastewater on Soil Physicochemical Properties: a Study of Cape Coast Industrial Area in Ghana

Abstract

Analysis of physicochemical properties of soil samples from Cape Coast Industrial area, Ghana influenced by discharge of soap factory effluent for 43 years was conducted. A control profile excavated 1 km away provided the basis for comparison of results from the contaminated site. A two-way data comparison was done. Changes within the same soil profile were compared. Analogous profile levels of the contaminated and control profiles were also compared. Sixteen (16) soil properties were evaluated in this experiment. Results of the study showed that the cation exchange capacity of soil and concentrations of nitrogen, phosphorus and potassium in the soil increased significantly following 43 years of effluent discharge. Organic matter content was also significantly higher in the contaminated soil than in the control soil, especially in the top 30 cm depth. The soil can be considered as a sodic soil as the exchangeable sodium percentage (ESP) in the contaminated soil exceeded the established minimum of 15 % for sodic soils while the electrical conductivity (EC) in the same soil was less than 4 dS m^-1). The impact of the sodic condition on soil structure (dispersion and slacking of clay soil particle) resulted in the development of compact soil of high bulk density throughout the soil profile.