Comparative Assessment of Raw and Peroxide-Aeration Recycled Cassava Effluent on Soil Heavy Metal Content

This research investigates the levels of heavy metal contamination in soils exposed to raw and peroxide-aeration recycled cassava processing effluent and potential impact on soil quality and environmental health. Cassava processing effluent treated using the peroxide-aeration treatment method in a fabricated pilot scale plant. The treated effluent was thereafter subjected to potted experiment to determine its effect on heavy metal contamination at different concentrations (25, 50, 75 and 100%), groundwater as well as raw effluent. The treatment was applied on 10 kg soil pots at the rate of 0.9 L/day over a period of 90 days. Heavy metal content in the soil was analysed using recommended laboratory methods. The maximum values of Cr, Ni, Fe, Pb and Zn ion pollution reduction of 85.00, 86.29, 71.69, 57.03 and 88.73% respectively was recorded during the treatment, it was however observed that there was a total removal of heavy metals when the treated effluent was supplied at 25% concentration. Cr, Ni and Fe concentration in the soil after the treatment were however observed to be not significantly (p > 0.05) different for control, 25 and 50% treated effluent concentrations. Enrichment factor (EF) of heavy metals in the soil ranged from 1.01 to 2.73 showing that the considered heavy metal concentrations measured were due to a combination of both the soil parent material and the cassava processing wastewater. The study concludes that treatment at 25% concentration resulted in the best attenuation of heavy metal pollution soil although higher concentrations also gave acceptable pollution levels.