Experimental Design for Optimizing the Removal of Heavy Metals Ability from Wastewater by Ficus Benjamina
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Excessive and cumulative release of toxic metals from industrial effluents due to rapid industrialization has posed hazard to aquatic ecosystem integrity and environmental/ human health. The inadequacy and high cost of traditional metal treatment technologies coupled with the imposition of stricter environmental regulations and guidelines for industrial point source discharges have increased the demand for economically feasible alternative methods. Application of natural and abundant sorption material known as biosorbents comprising microbial biomass, agriculture waste, and industrial waste biomass, has gained international attention in scientific world as a low-cost and effective method for The removal of heavy metals from waste water. However, this method has not been able to gain the attention of industry for large-scale applications thus far. This research was aimed to further evaluate the potential of biosorption performance of Cd2+ and Pb2+ from aqueous solutions using readily available dried plant biomasses namely: Ficus benjamina. The objectives of this work are as following: i) to investigate the effects of pH, temperature and initial concentration, ii) determine the factors impacting the biosorption process besides interaction between factors using full factorial design, iii) To validate the result optimization model for the removal of Cd2+ and Pb2+ from real industrial wastewater. The removal of Cd2+ and Pb2+ was studied separately, using the factorial design 23. The three factors considered are pH, temperature and metal ion concentration at two markedly different levels: pH (2.0 and 6.0), Temp (20°C and 45°C) and metal ion concentration (Cd2+: 5 and 300 mg l-1; Pb2+: 10 and 500 mg l-1). The experiments were carried out in a batch type reactor system with 0.2g of biosorbent (dead dried biomass of Ficus Benjamina), 50 ml of Cd2+ and Pb2+ solutions , and the blending rate (300 rpm)and. The removal efficiencies of both ions during an exposition time of 6 h were then evaluated. The results were statistically analyzed using analysis of variance to define the most important process variables affecting the metal removal efficiency. The most significant effects for Cd2+ are pH and X while The largest effect of the main factors in Pb2+ biosorption was ascribed to initial metal ion concentration(X). The best percentage removal of Cd2+ was 81.2% at pH=6, Temp=45°C and X= 5mg/l but the best percentage of Pb2+ was 81.4% at pH=2, Temp=20°C and X=10mg/l. When applying these optimum conditions on real wastewater sample collected from El Mahmoudia channel, affected by Industrial, agricultural and sewage discharges. The best Removal results were 99.9% for Cd2+ and 92.4% for Pb2+. These results indicated that Ficus Benjamina can be used as a low cost adsorbent for the removal of heavy metals from waste water.