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Beneficiation of Agri-Industry Effluents
Expanded Title:In view of the large volumes of fruit processing wastewaters, the feasibility of wastewater beneficiation depends largely on the concentrations of valuable by-products present and the efficiency of the extraction processes that can be applied. Apple and citrus wastewaters were obtained and were characterised and found to be unexpectedly dilute but did contain phenolics and sugars. Significant levels of antioxidant activity were observed. It is recommended that membrane-based concentration of the wastewaters be utilised as the first step in treatment. Particularly, it would be recommended to include a greater diversity of membranes, including polyamide membranes which would be more resistant to microbial digestion. The greater the degree of concentration achieved in the first step, the smaller the volumes of wastewater to be treated in subsequent steps. Of the adsorbents tested, it is recommended that either PVPP or activated carbon be used for the adsorption of phenolics. Ethanol is the recommended solvent for elution from either PVPP or activated carbon. More work is required to improve elution efficiencies since eluting a more concentrated antioxidant solution with a smaller volume of ethanol would be preferable. The addition of solid fruit waste to the wastewater was found to be a useful approach to increasing the carbon content of the water. Enzymatic pretreatment of the solid waste is recommended as this method releases sugars from solid apple waste with high or low sugar concentrations and is therefore well suited to a range of apples from different cultivars and at different stages of ripening. While fermentation of the sugars to ethanol by Saccharomyces cerevisiae was shown to be possible, for cost efficient recovery, a goal concentration of 40 g/l ethanol in solution would be needed; below this level, the distillation costs involved in recovering the ethanol, would be prohibitive. A distillation unit operation will be necessary in the proposed process, both for concentration of ethanol after fermentation and for concentration of phenolic extracts but through optimisation of all unit processes.
Date Published:01/03/2013
Document Type:Research Report
Document Subjects:Wastewater Management - Domestic, Wastewater Management - Industrial
Document Keywords:Municipality
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:1937-1-12
ISBN No:978-1-4312-0239-3
Authors:Burton SG; Mupure CK; Horne KA; Jones S; Welz P
Project No:K5/1937
Originator:WRC
Organizations:Biocatalysis and Technical Biology Research Group, Cape Peninsula University of Technology
Document Size:1 734 KB
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