Micro-particle-clay aided microporous support for removal of hydrocarbon toxicity from petroleum refinery wastewater in single-slope solar distillation

Abstract

The removal of toxic hydrocarbon pollutants is not sustainable via conventional treatment technology. This research investigates the feasibility of a solar distillation (SSD) system to eliminate soluble hydrocarbon salts, stubborn organics, and separation of oil emulsion from petroleum refinery wastewater (PRW). The PRW collected from the petroleum refinery facility and hydrophilic micro-particle clay (MP-clay) samples were characterized following the ASTM and SEM techniques. The treatment process for the removal of total dissolved salts (TDS), biological oxygen demand (BOD), and separation of oil emulsion was monitored in the SSD still using MP-clay aided microporous filter support, at varying MP-clay concentrations (0.5–3.5 mg/L), pH (6.6–7.3), temperature (27–80 ⁰C), and exposure time (1–18hrs) respectively. The results showed MP-clay as self-assembled monolayers on microporous support with a 98 % reduction in BOD concentration under optimum conditions: pH of 7.3, contact time of 9 hours, and MP-clay concentration of 3.2 mg/L. The TDS concentration decreased by 94 % at the optimal exposure time (15hrs) and temperature (48 ⁰C) in SSD still. The investigation also examined the recyclability of MP-clay for oil content accumulation and water separation. The findings demonstrated MP-clay on reuse retained 90.5 % of its activity in water separation and established MP-clay can be operated to the optimum of 3 cycles, each lasting 60 minutes. After this period, reactivity loss becomes severe owing to lipase leakage and substrate obstruction. The research findings will help harness solar energy for environmentally friendly and cost-effective PRW remediation.