EFFECT OF PICRALIMA NITIDA STEM BARK RESIDUE AS ADSORBENT IN DOMESTIC WASTEWATER (SULLAGE) TREATMENT
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Abstract
The rising issue of domestic wastewater pollution, mainly from heavy metals and organic pollutants, poses significant risks to public health and environmental sustainability in Nigeria. Traditional treatment methods are often costly and energy-intensive, emphasising the need for affordable, eco-friendly alternatives. This study investigated the use of Picralima nitida stem bark residue as a sustainable biosorbent for removing iron (Fe3⁺), zinc (Zn²⁺), chemical oxygen demand (COD), and total dissolved solids (TDS) from domestic wastewater. The research focused on evaluating the adsorption efficiency, identifying optimal conditions, modelling the underlying mechanisms, and comparing the cost-effectiveness to commercial activated carbon. The study conducted an experimental investigation using batch adsorption tests in controlled laboratory conditions. P. nitida bark residue was washed, oven-dried, ground, and chemically activated before analysis. The adsorbent was characterised through Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface analysis. Parameters such as dosage, contact time, temperature, and pH were systematicallys varied to evaluate performance. Additionally, Langmuir and the Freundlich isotherm models were employed to interpret the equilibrium data. A cost analysis was also performed to assess the economic viability of the adsorbent. The results indicated that adsorption efficiency increased with longer contact time and stabilised after 90 minutes. The highest removal rates were 100% for Fe3⁺, 99.60% for Zn²⁺, 98.90% for COD, and 89.97% for TDS at near-neutral pH and ambient temperature. The equilibrium data conformed to the Langmuir isotherm (R² = 0.9940), indicating monolayer adsorption. Economically, the treatment cost was ₦19.50 per litre, which is roughly 30–40% lower than that of commercial activated carbon. The study concludes that Picralima nitida stem bark residue is an effective, cost-efficient, and sustainable biosorbent for domestic wastewater treatment, supporting Nigeria’s initiatives in sustainable waste utilisation and SDG 6 (Clean Water and Sanitation).
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