Performance of wetland systems in the treatment of sewage generated at an educational institution, after a recession period

Abstract

Education institutions are potential generators of large volumes of domestic sewage. Studies of natural systems for effluent treatment have shown good efficiency and low cost compared to traditional systems. This makes them suitable for various segments of society, including educational institutions. A characteristic shared by most educational institutions is that they have the same academic calendars that include a long period of recess when, in many cases, the flow of sewage systems drops to almost zero, causing damage to both macrophytes in sewage bed and their associated microorganisms. This study aimed to evaluate the efficiency of a wetland system in an educational institution, after the recess period. It was observed for 45 days if there were signs of natural recovery, without any intervention. After this period, 15 seedlings of Thypha sp. were planted in the sewage bed, and analyses were performed for 45 additional days. The system efficiency in reducing turbidity, NH3, NO3- and phosphorus was, respectively, 63.0%, 21.7%, 31.1% and 20.3%, and for BOD, COD and thermotolerant coliforms, the average efficiency was 46.0%, 29.7% and 44.0%, respectively. If considered only the period after planting the results improved, with the following results: turbidity = 78.2%, 38.0% = NH3, NO3- = 53.2% = 25.6% phosphorus, BOD = 66, 2% = 36.5% COD and thermotolerant coliform = 60.7%. The results demonstrated the importance of vegetation bed for the efficiency of such treatment system.

Keywords

• wetlands
• domestic sewage
• environmental sanitation
• wastewater