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Evaluation of a wetland system designed to meet stringent phosphorus discharge requirements
Author(s) -
Adler Paul R.,
Summerfelt Steven T.,
Glenn D. Michael,
Takeda Fumiomi
Publication year - 1996
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143096x127839
Subject(s) - effluent , phosphorus , nutrient , wetland , biomass (ecology) , environmental science , nitrate , limiting , zoology , constructed wetland , chemistry , environmental engineering , agronomy , sewage treatment , ecology , biology , mechanical engineering , organic chemistry , engineering
In this study, a wetland system was created and managed to increase plant removal of influent phosphorus (P). This was accomplished by making P the most limiting nutrient, by enhancing mass transfer of P to the root surface and by harvesting the shoot biomass to regenerate the nutrient removal capacity of the wetland. A mixture of grass species that are tolerant of wet conditions (66% Reed canary grass) was grown in long (3.66‐m) and narrow (0.l‐m) troughs containing silica sand. Four replicates of three depths of sand (1.3, 2.5, and 5.1 cm) were investigated at a hydraulic loading rate between 1 500 and 1 800 m 3 /ha · d. Removal of P was greater than 90% in all treatments, and P was reduced from 0.480 mg/L to less than 0.001 mg/L in the 5.1‐cm‐deep sand treatment. The treatments removed approximately 40% of the influent nitrate (22 mg/L in; 13 mg/L out). Nutrient removal occurred 24 hours a day with small diurnal fluctuations. Grass was harvested biweekly by cutting to a uniform 7.6‐cm height. Comparison of the actual amount of nutrients removed in the harvested biomass with that calculated from differences between influent and effluent concentrations showed that approximately 50% of the N and approximately 80% of the P were removed from the effluent in the biweekly grass clippings.