Reed beds: constructed wetlands for municipal wastewater treatment plant sludge dewatering

Abstract

Reed beds are an alternative technology wastewater treatment system that mimic the biogeochemical processes inherent in natural wetlands. The purpose of this project was to determine the effectiveness of a reed bed sludge treatment system (RBSTS) in southern New England after a six-year period of operation by examining the concentrations of selected metals in the reed bed sludge biomass and by determining the fate of solids and selected nutrients. Parameters assessed in both the reed bed influent and effluent: total suspended solids, biochemical oxygen demand, nitrate-nitrogen and total phosphorus. In addition, the following metals were studied in the reed bed influent, effluent and Phragmites plant tissue and the sludge core biomass: boron, cadmium, chromium, copper, iron, lead, manganese, molybdenum, nickel, and zinc. The removal efficiencies for sludge dewatering, total suspended solids and biochemical oxygen demand were all over 90%. Nitrate and total phosphorus removal rates were 90% and 80% respectively. Overall metals removal efficient was 87%. Copper was the only metal in the sludge biomass that exceeded the standards set by the Massachusetts Department of Environmental Protection for land disposal of sludge. The highest metal concentrations, for the most part, tended to be in the lower tier of the sludge profile. The exception was boron, which was more concentrated in the middle tier of the sludge profile. The data and results presented in this paper support the notion that reed bed sludge treatment systems and the use of reed beds provide an efficient and cost effective alternative for municipal sludge treatment.

Effect of plant species on water quality at the outlet of a sludge treatment wetland

“…These results are consistent with other studies that have shown removal efficiency superior to 90% at the outlet of sludge treatment wetlands (Burgoon et al, 1997;Begg et al, 2001;Wang et al, 2009). However, due to the extremely high pollutant content of the sludge, even a removal rate of 90% can result in an outflow with a relatively high amount of pollutants.…”

Seasonal Changes of Shoot Nitrogen Concentrations and15N/14N Ratios in Common Reed in a Constructed Wetland

“…Ex Steudel] is a perennial grass that occurs in a wide range of habitats, including inland and coastal salt-affected marshes (Lissner and Schierup, 1997). Because of its plasticity to changes in environmental conditions and high productivity, P. australis has been extensively planted in artificial wetlands constructed for the purification of contaminated water (Zurayk et al, 1997;Kern and Idler, 1999;Begg et al, 2001). Because constructed wetlands are being actively managed to enhance their functions such as removal of pollutants and providing wildlife habitats, maintaining the productivity of P. australis is crucial to the success of the constructed wetlands (Kern and Idler, 1999;Begg et al, 2001).…”

Feasibility study of faecal sludge treatment by constructed wetlands in Sahelian context: Experiments with Oryza longistaminata and Sporobolus pyramidalis species in Ouagadougou

“…Plants play a key role in constructed wetland systems. Phragmites Australis is the species most commonly used in this type of process (Begg et al, 2001;Pempkowiak and Obarska-Pempkowiak, 2002;Nassar et al, 2006;Stefanakis et al, 2014). However, other plants can be adapted such as Phalaris arundinacea, Scirpus lacustris, Typha latifolia, Typha angustifolia, Echinochloas pyramidalis (Kadlec et al, 2000;Koottatep et al, 2005;Kengne et al, 2008).…”