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Purification of Fuel and Nitrate Contaminated Ground Water Using a Free Water Surface Constructed Wetland Plant
Author(s) -
Machate Thomas,
Heuermann Elisabeth,
Schramm KarlWerner,
Kettrup Antonius
Publication year - 1999
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1999.00472425002800050034x
Subject(s) - environmental chemistry , scirpus , typha , nitrate , chemistry , surface water , hydraulic retention time , environmental engineering , environmental science , wetland , wastewater , ecology , organic chemistry , biology
Contaminated ground water from a former coke plant site was purified in a free water surface (FWS) constructed wetland plant during a 3‐mo short‐term experiment. The pilot plant (total surface area 27 m 2 ) was filled with a 1 m thick lava‐gravel substrate planted with cattail ( Typha spp.) and bulrush ( Scirpus lacustris ). Major contaminants were low to moderate concentrations of polycyclic aromatic hydrocarbons (PAH 50–9000 µg L −1 according to USEPA, 1‐methylnaphthalene 2–1900 µg L −1 , 2‐methylnaphthalene 3–4300 µg L −1 ), BTEX (10–450 µg L −1 ), nitrate (60 mg L −1 as N), and nitrite (7 mg L −1 as N). The wetland was dosed at hydraulic loading rates of q A = 4.8 and 9.6 cm d −1 with a hydraulic residence time (HRT) of 13.7 and 6.8 d. The surface removal rates of PAH were between 98.8 and 1914 mg m −2 d −1 . Efficiency was always >99%. Extraction of lava gravel showed that approx. 0.4% of the applied PAH were retained on the substratum. The ratio of ∑2,3‐ring PAH and ∑4,5,6‐ring PAH showed a shift from 1:0.11 in water (influent) to 1:2.5 in lava (Tank 1). The removal of BTEX was >99%, but might be in part due to volatilization. The efficiency in the removal of nitrate was 91% (2.47–3.34 g m −2 d −1 ) and of nitrite was 97% (0.034–0.036 g m −2 d −1 ). Purification performance was not influenced by hydraulic loading rates or after die‐back of the macrophytes.