Removal of Diuron and Hexazinone from Public Water Supply Using a Filter System

The intensive use of pesticides, such as the herbicides diuron and hexazinone, leads to a concern about the preservation of the water quality of the water resources destined for human consumption. Currently, conventional water treatment techniques do not have high capacity to remove herbicides; therefore, the need to study other techniques arises. The present study aimed to evaluate the efficiency of the removal of diuron and hexazinone herbicides present in water through a commercial filtration system. The study was carried out in a filtration system composed of the following sequence of filters: sand filter and coconut shell activated granular carbon, polypropylene filter 20 mm, activated carbon filter with silver salts, polypropylene filter 5 mm and reverse osmosis. The affluent contained an initial concentration of 12.06 mg mL-1 of hexazinone and 37.70 mg mL-1 of diuron. The samples were collected in all filters and subjected to the analysis of turbidity and presence of herbicides by high performance liquid chromatography. The filter set removed 99.31; 99.84 and 99.99% of water turbidity, hexazinone and diuron respectively at the end of the system. After the filtration process, the treated water presented adequate quality for public supply and human consumption. The technique employed in this study is easy to operate and has a low acquisition and maintenance cost. RESUMO: O uso intensivo de pesticidas, como os herbicidas diuron e hexazinone, levam a uma preocupação quanto à preservação da qualidade da água dos recursos hídricos destinados ao consumo humano. Atualmente, as técnicas convencionais de tratamento de água não possuem alta capacidade de remover os herbicidas; portanto, surge a necessidade de estudar outras técnicas. O presente estudo teve por objetivo avaliar a eficiência de remoção dos herbicidas diuron e hexazinone presentes na água, através de um sistema de filtração comercial. O estudo foi realizado em um sistema de filtração composto pela seguinte sequência de filtros: filtro de areia e carvão granular ativado de casca de coco, filtro polipropileno de 20 mm, filtro de carvão ativado com sais de prata, filtro de polipropileno de 5 mm e osmose reversa. O afluente continha uma concentração inicial de 12,06 mg mL-1 de hexazinone e 37,70 mg mL-1 de diuron. As amostras foram coletadas em todos os filtros e submetidas à análise de turbidez e presença dos herbicidas por cromatografia líquida de alta eficiência. O conjunto de filtros removeu 99,3