The Sanitation Company of the Federal District (CAESB) is responsible for the treatment and distribution of water in the municipality of Sobradinho-DF. Part of the supply is accomplished through the abstraction of water from two sources, Ribeirão Contagem and Córrego Paranoazinho, with flow rates varying between 100 and 160 l / s. For ETA Contagem, CAESB, after technical studies, opted for the implementation of a coagulation type water treatment plant, direct upward filtration, disinfection and fluoridation, despite the wellspring having good quality water. Another important feature of this plant is the high degree of automation with which it was designed, in order to reduce the workforce of operation.
The technology selected was the one of direct filtration ascending, due to the good quality of the fountains. In this system, the coagulated water passes through a loading chamber and then enters the lower part of the filter, passes through the drainage system, the support layer and the sand, being collected in ducts or perforated tubes, located in the upper part of the filter unit. There will be six filters operating in parallel, fully automated.
After disinfection, the water will proceed to the distribution tanks. The water sources in the Brasília region present water with low turbidity but with the presence of a significant amount of algae, which makes treatment difficult and requires a well adjusted operation and a properly trained team. H2O Engenharia was contracted for the commissioning, training of personnel and start up of the plant Fieldwork was developed for an extended period of time and the adjustment of the automation part was quite delicate requiring an integrated work of equipment, mechanical, electrical, automation and process suppliers in order to achieve the expected results.
A água de contralavagem deste sistema também é tratada, pois a legislação brasileira impôe uma disposição adequada para o resíduo sólido a ser gerado. O processo de tratamento empregado para esta água, consiste em adensamento através de flotação por ar dissolvido seguido de desaguamento por centrifugação. A água separada neste processo é reciclada na própria Estação de Tratamento.
A equipe da H2O Engenharia acompanhou a instalação dos equipamentos, a montagem do laboratório, os testes com água e a equipe de automação durante seis(6) meses. Após a conclusão do comissionamento foi realizado um treinamento para os funcionários da CAESB que estarão ligados direta ou indiretamente com a operação da ETA Contagem.