Estudo da utilização da goma xantana como auxiliar no processo de floculação em tratamento de água para abastecimento

Abstract

The conventional water treatment involves the addition of chemicals to the water in order to remove impurities and maintain the quality parameters according to the required law. Aluminum sulfate is the most commonly used coagulant chemicals due to low cost, but the use of this coagulant has been questioned because there is evidence that the aluminum residues in water are related to Alzheimer's and Parkinson's diseases. These residues are also accumulated in the sludge, which may cause problems with the final disposition of that. Alternatively, natural polymers have been used as aids coagulation, flocculation and filtration, and have achieved satisfactory results because they reduce the need for large amounts of primary coagulant and produce a more biodegradable sludge. Xanthan gum is a natural polymer, anionic, non-toxic and biodegradable, which can be used as flocculation aids for water treatment. The present study aimed to determine the optimal concentrations of xanthan gum combined with lower concentrations of aluminum polychloride to ensure the reduction of primary coagulant and treated water quality. All tests were performed in Jar Test, and for raw water and treated water were made physical-chemical and bacteriological characterization. For parameters of color and turbidity, the removing was 94.8% and 99.7%, respectively. The removing of thermotolerant coliforms obtained a reduction of 100%, and total coliforms was 98.8%. Xanthan gum was effective as an aid flocculant combined with aluminum polychloride.