Raw sewage treatment by a single-stage vertical flow constructed wetland: a case study in Brazil

This paper evaluates the performance of raw domestic sewage treatment by a single-stage vertical-flow constructed wetland (VFCW) installed in Northeastern Brazil, where sanitation coverage is low. Biological and physicochemical parameters were monitored for 1 year to evaluate the system's performance. The impact of factors such as operational cycle and filter media on VFCW pollutant removal efficiencies was investigated. The means of removal efficiencies of chemical oxygen demand (COD), biological oxygen demand (BOD), and ammonia were 74.2, 87.9, and 82.1%, respectively. A statistically significant influence (p < 0.05) of substrate material on COD and ammonia removal efficiency was found. Ceramic construction waste media achieved the best performances compared with the traditionally used material and concrete construction waste. Operational cycles of 3.5/7 and 7/14 days of the feeding/resting period did not present a statistically significant influence (p < 0.05) on pollutant removal efficiencies. The single-stage VFCW pilot plant achieved a better global treatment performance than other VFCW reported in the literature; however, it showed a limitation in removing TS. The reduced installation costs, in addition to operation and maintenance simplicity, indicate a potential for single-stage VFCW applicability in the sewage treatment of housing units and small communities in Brazil and possibly in other developing countries in tropical areas.