Biosorption of Lead (Pb2+) from Industrial Effluent using Green Algae

Heavy metal pollution is one of the most serious environmental problems being faced by the world today. Biosorption has emerged as a cost-effective and efficient alternative technology for removal of heavy metals. The potential of three immobilized algae species for removal of Lead (Pb2+) from industrial effluent was analysed through batch studies. Algal bloom water samples were obtained from fish ponds in Prof. Olu Odeyemis Farm, Ilesa. Effluent was collected from industrial discharge system around IleIfe (Nigeria). Algae were isolated from the effluent samples using pour plate technique on Allen and Bristol agar media at pH 7.1. The identity of the algae isolates was established using Identification guide to Freshwater and Terrestrial algae. Algae were immobilized with 1.5 % calcium alginate and the beads of approximately 3mm were formed using peristaltic pump. Biosorption batch studies was carried out by the addition of 150 beads into 100ml solution (50 ml of wastewater and 50 ml of media) in 250ml conical flask at 100rpm, room temperature and pH 3, 5 and 7. Concentration of Lead (Pb2+) was determined in 2 days interval using atomic absorption spectrophotometer at 0.04mg/l detection limit. The algal isolates were identified as Synochromonas elaeochrus, Scenedesmus facatus chodat and Aphanizomenon flos-aquae. The percentage removal of Lead (Pb2+) by Synochromonas elaeochrus, Scenedesmus facatus chodat and Aphanizomenon flos-aquae varies with pH and time. At pH 5, Synochromonas elaeochrus had the best percentage removal rate (100 %) (that is not detectable in the effluent) while Scenedesmus facatus chodat and Aphanizomenon flos-aquae performed best at (100 %) pH 3 and 5 over the period of time. At pH 7, the percentage removal of Lead (Pb2+) decreases with time for all algae species. At pH 3, Scenedesmus facatus chodat and Aphanizomenon flos-aquae performed better by complete (100 %) removal of Lead (Pb2+) starting from day 1 while Synochromonas elaeochrus completely (100 %) remove Lead (Pb2+) starting from day 3. Since the algae isolates showed appreciable sorption of the metal, they can be used for biosorption of metals from industrial effluent prior to its discharge to avoid environmental pollution.