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Journal of Water, Sanitation and Hygiene for Development Vol 2 No 3 pp 133–145 © IWA Publishing 2012 doi:10.2166/washdev.2012.047 Removal of cyanobacteria by slow sand filtration for drinking waterSilvano Porto Pereira, Fabiana de Cerqueira Martins, Lenora Nunes Ludolf Gomes, Manoel do Vale Sales and Valter Lúcio De PáduaDepartment of Hydraulic and Environmental Engineering, Federal University of Ceará, Campus do Pici, Bloco 713, Fortaleza, Brazil CEP 60451-970 E-mail: silvanopereira@terra.com.br and Water and Sewage Company of Ceará (CAGECE), Av. Dr. Lauro Vieira Chaves, 1030 Vila União, Fortaleza, Brazil CEP 60422-901Department of Sanitary and Environmental Engineering, Federal University of Minas Gerais, Antonio Carlos 6627, Bloco 1(4), Pampulha Belo Horizonte, Brazil CEP 31270-901 Department of Civil and Environmental Engineering, University of Brasília, Campus Universitário Darcy Ribeiro, Brazil CEP 70910-900 ABSTRACT Potential problems arising from the presence of cyanobacteria in water intended for human consumption have been reported by several researchers. Regarding water treatment plants, intact cells of cyanobacteria should be removed to avoid the release of cyanotoxins due to cell lysis. Water treatment techniques with different degrees of complexity can be employed but, whenever possible, the method of easiest installation, operation and maintenance should be selected, especially for non-industrialized countries and rural communities. In this context, research was carried out to evaluate the efficiency of slow sand filtration to treat water from Gavião reservoir in the city of Pacatuba, Ceara, Brazil, which has exhibited phytoplankton density of approximately 105 cells/mL with a prevalence of cyanobacteria representing over 90% of total cells. The results have demonstrated that slow sand filtration can be used to achieve water purification that meets federal standards. However, it was established that filtration through beds of gravel (prefilter) before the slow sand filtration is essential. The removal of phytoplankton reached values of approximately 97% and the filter run duration was more than 70 days. Furthermore, the slow sand filter was very efficient in removing total coliforms, with removal of up to 99.98%. Keywords: cyanobacteria; drinking water; pre-filtration; slow sand filtration 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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