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Water Science & Technology Vol 65 No 11 pp 1939–1945 © IWA Publishing 2012 doi:10.2166/wst.2012.090 Organic biowastes blend selection for composting industrial eggshell by-product: experimental and statistical mixture designMicaela A. R. Soares, Sandra R. Andrade, Rui C. Martins, Margarida J. Quina and Rosa M. Quinta-FerreiraCernas – Natural Resources, Environment and Society Research Centre, Coimbra College of Agriculture of Polytechnic Institute of Coimbra, Bencanta 3040-316 Coimbra, Portugal E-mail: msoares@esac.ptCIEPQPF- Research Centre on Chemical Processes Engineering and Forest Products, Chemical Engineering Department of University of Coimbra, Pólo II – Rua Sílvio Lima, 3030-790 Coimbra, Portugal ABSTRACT Composting is one of the technologies recommended for pre-treating industrial eggshells (ES) before its application in soils, for calcium recycling. However, due to the high inorganic content of ES, a mixture of biodegradable materials is required to assure a successful procedure. In this study, an adequate organic blend composition containing potato peel (PP), grass clippings (GC) and wheat straw (WS) was determined by applying the simplex-centroid mixture design method to achieve a desired moisture content, carbon: nitrogen ratio and free air space for effective composting of ES. A blend of 56% PP, 37% GC and 7% WS was selected and tested in a self heating reactor, where 10% (w/w) of ES was incorporated. After 29 days of reactor operation, a dry matter reduction of 46% was achieved and thermophilic temperatures were maintained during 15 days, indicating that the blend selected by statistical approach was adequate for composting of ES. Keywords: composting; eggshell waste; mixture design eProduct: Buy this article for £24.00 (IWA MEMBER PRICE: £18.00) All prices include VAT. For customers where VAT should not be applied, the VAT amount will be removed upon payment |
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