Bioremediation of Industrial Solid Wastes

Abstract

Aims: Use of Pleurotus ostreatus as a veritable tool in the bioremediation of empty fruit bunches, pulp and paper wastes from respective industries.    Place and Duration of Study: Samples of pure culture Pleurotus ostreatus was obtained from National Roots Crops Research Institute Laboratory Umudike, Umuahia and  transported to the laboratory of Starline Nigeria Group of Companies Aba, both in Abia state, Nigeria  where it was used to carry out experimental work from July to September, 2013. Methodology:  The two substrates (empty fruit bunch (EFB) and paper pulp wastes) were dried in the sun for one week and further dried in Gallen Kamp hot box oven (DGH-9053A) at 50ºC  for 4hours. Samples were ground, sieved and powder obtained used for proximate composition determination. Approximately 1cm2 blocks of pure culture of Pleurotus ostreatus mycelium previously collected and maintained on Malt extract agar (MEA) was used to inoculate sterilized wheat grain already soaked in water for 36hours, mixed with 2.5% calcium carbonate and 1% gypsum during spawn preparation. The empty fruit bunches and paper wastes were reduced to smaller sizes of 2-5cm. The respective substrates were mixed with lime and soaked in water for 4h to obtain moisture level of 70%. The substrates (2kg) was bagged in heat resistant polythene and sterilized for 3hours at 80°C. Approximately 40g individual sterilized substrate was inoculated with 2% spawn adopting multilayered technique. After inoculation, holes were made on the bags to ensure aeration, kept inside a disinfected room at 25-28ºC. When Pleurotus mycelium had completely colonized the substrates, bags were removed, colonized substrate transferred to sunlight illuminated room at 28°C, moisture content of 75-85% and adequate watering of the mushroom for 21 days. The process was repeated in combinations of other substrates like wheat, straw and sorghum respectively with each of the substrates (EFB and Paper Waste); all prepared at 70:30% ratio respectively. Results: Among the different treatments, Empty fruit bunch gave maximum yield of 201.5g/kg of substrate on 14th day and total yield of 675.1g/kg of dry substrate. The nutritional content of Pleurotus ostreatus grown on different substrate and substrate combination ranges from 83.5-91.4% moisture, 18.3-23.5% protein and 6.04-6.86% ash contents. The combination of EFB + sorghum best supported the bioremediation process of Empty fruit bunch. Conclusion: Pleurotus ostreatus could serve as bioremediation tool for industrial solid wastes like EFB and paper. It can also alleviate poverty by providing greater income for most unemployed youth at no cost.