Utilização de plantas de bambu no tratamento de esgoto sanitário pelo sistema de alagados construídos

Abstract

This study aimed to evaluate the efficiency of three species of bamboo (Guadua angustifolia, Phyllostachys aurea and Phyllostachys bambusoides) in the sanitary sewage treatment, with a vertically downward sub-surface flow constructed wetlands, in Goiânia, GO, Brazil. Sewage from a university was applied to asbestos cement water tanks with 1,000 liters volume capacity, filled with oxisol above a 0.26 m drainage layer of gravel # 3. Bamboo seedlings were planted in nine tanks and three tanks remained without plants (controls). The wastewater was captured at the initial part of a facultative pond and applied to the surface of the treatment tanks, three times a day, using a timer controlled pump. It was used a hydraulic retention time (HRT) of 2.3 days during 150 days and a HRT of 5.2 days for 360 days. Inside the treatment tanks, the wastewater was maintained two inches below the substrate surface. For a period of twelve months sewage samples were collected before and after passing through each treatment tank. The samples were submitted to laboratory testing for determination of chemical oxygen demand, biochemical oxygen demand, ammonia nitrogen and phosphates. The evapotranspiration rate of each treatment was measured, their efficiencies in removing the sewage pollutant load were calculated and the behavior of plants in treatment tanks were observed. The results were submitted to F and Tukey (5% of probability) tests. In general, the specie G. angustifolia showed greater efficiency in removing the pollution load of all attributes. There was a higher removal of BOD and phosphate at HRT of 5.2 days. The HRT of 2.3 days was better on removing ammonia nitrogen.