Potential Use Of Some Agricultural Wastes Biosorbents For The Removal Of Some Heavy Metals From Wastewater

Abstract

In this study the adsorption behavior of spent tea (Camellia sinensis L.) leaves waste (TW) and sugarcane (Saccharum officinarum L.) bagasse (SB) in clarification of industrial wastewater of heavy metals was investigated. Batch experiment has been employed for the adsorption of Pbfrom aqueous solutions in vitro. The efficiency of those two waste products was studied by using the effect of contact time, pH, the adsorbent dosage and the concentration of heavy metals to obtain the optimum conditions to produce highly removal with low cost process. Kinetic studies showed that maximum removal of lead, copper and nickel ions takes place at pH 5.5, 6 and 4 respectively and the equilibrium time was attained after 60 min. Adsorption parameters were determined using both Langmuir and Freundlich isotherms. Analysis of TW and SB indicated the presence of a relatively high level of cellulose, hemicelluloses, lignin, fibers, phenolic compounds, proteins and minerals. Such molecules, which are identified as active biosorbent for a wide range of heavy metals, may participate effectively in clarification of wastewater from these hazardous pollutants. The results of infrared spectroscopy and scanning electron microscopy indicated the presence of ionisable functional groups, which can be replaced with metal ions, playing a crucial role in the efficiency of TW and SB as biosorbent of heavy metals. The results of analysis of TW- and SB-treated wastewater revealed marked reduction in its content of Feand Cr compared with raw untreated water. Investigating the feasibility of reusing wastewater pre-treated with TW or SB in certain agricultural aspects revealed their competency in this respect where a significant increase in % of germination, % of emerged seedlings and major growth attributes of parsley (Petroselinum crispum Mill) plants were obtained in response to irrigation with TW- and SB-treated wastewater, compared with irrigation with wastewater. Tea leaves waste and sugarcane bagasse via adsorption of heavy metals pollutant of wastewater, had relieve the syndrome of oxidative stress in parsley plants induced in response to exposition to heavy metal stress as it is evident from activity level of antioxidant enzymes as catalase, peroxidase and superoxide dismutase. Via this and other ways, TW and SB succeed in reversal of the manifest growth inhibition prevailed in parsley plants subjected to stress induced by their irrigation with wastewater.