ABSTRACT
Pollutant removal performance in solid matrix, subsurface flow constructed wetland systems depends upon the maintenance of hydraulic conductivity sufficient to allow interaction of effluent with the matrix. Solids loading, removal performance, and in-system accumulation have been investigated in a number of large-scale, subsurface flow constructed wetland systems and in a rapid-sand filter system. A large-scale investigation of constructed wetland systems for sewage effluent treatment was established in late 1983 and remains on-going at the University of Western Sydney-Hawkesbury, Richmond, New South Wales. During the study, aquatic macrophyte systems have been evaluated with respect to treatment performance for a number of effluent constituents, including nitrogen, phosphorus, biochemical oxygen demand, suspended solids, and bacteria. Large rock filters in a California study also exhibited clogging at solids loading rates comparable to those applied to the sand filters and macrophyte systems. Particular attention would need to be given to achieving an inlet solids loading of approximately 40 g/m2/day.
