Essay On Wastes

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Waste universally is a direct consequence of all human activities. Wastes are generally classified into three categories according to the status that they are existed: solid, liquid and gaseous wastes and into three main categories according to the sources that they are generated: industrial, agricultural and agro-industrial wastes. Continuous accumulation of wastes poses a serious environmental problem. There are a number of different options available for the treatment and management of waste including prevention, minimisation, re-use, recycling, energy recovery, disposal and landfilling. Leather industry has been categorized as one of the highly polluting industries. Solid wastes generated in leather industries contribute mainly skin trimmings,…show more content…
Various treatment methods have been developed. Basic hydrolysis, such as using Ca(OH)2 with steam or NaOH/KOH at elevated temperature and/or pressure, CaO or MgO at moderate temperatures were used for recycle amino acids and peptides, isolation of protein fractions and chrome recovery [Ferreira et al., 2010, Alves Dos Reis, M. and Beleza, V. (1991; Taylor et al., 1993; Haiming et al., 2009 and Marcilla et al., 2011]. Recently, we used alkaline hydrolysis (CaO or KOH) and enzymatic hydrolysis (protease or trypsin) to produce leather protein hydrolysates (LPHs) from chrome-containing leather waste (CCLW) and evaluated their antioxidant and metal chelating activities. Our results showed that LPH obtained by CaO had the highest values for degree of hydrolysis (46.86%), total free amino acids (246.65 mg/g waste) and Fe+2 chelating activity (85.54% at concentration 0.20 mg/ml) compared with the other treatments. The LPH obtained by enzymatic hydrolysis possessed the higher DPPH scavenging and Cu2+ chelating activities than LPH obtained by alkaline hydrolysis. We concluded that the alkaline hydrolysis (especially by CaO) is a suitable and economically beneficial method to produce LPH. The LPH is an economic and natural source of amino acids and good antioxidant and metal chelating agents in plant and animal nutrition
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