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Lead and Zinc Removal by Laboratory‐Scale Constructed Wetlands
Author(s) -
Song Ying,
Fitch Mark,
Burken Joel,
Nass Linda,
Chilukiri Somnath,
Gale Nord,
Ross Chad
Publication year - 2001
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 - 10.2175/106143001x138660
Subject(s) - effluent , wetland , ceriodaphnia dubia , environmental chemistry , wastewater , environmental engineering , environmental science , sulfate , constructed wetland , chemistry , ecology , toxicity , acute toxicity , biology , organic chemistry
Constructed wetlands have the potential to trap and remove metals in mine wastewater. To determine the effectiveness of constructed wetlands for treating selected heavy metals in neutral mine effluent typical of lead mines, eight laboratory‐scale constructed wetlands were set up to treat a synthetic, slightly alkaline, mine water containing 34.2 mg/L sulfate (SO 4 2− ), 50 μg/L lead (Pb), and 300 μg/L zinc (Zn). After 45 days, one of the wetlands was switched to treat a synthetic smelter effluent with a much greater load of SO 4 2− , sodium (Na + ), and Pb. Temperature, hydraulic loading, and substrate composition typically did not affect treatment efficiency. The pH of the effluent was reduced from 8.0 to 8.5 to near neutral. The average removal in the eight wetlands was 90% for Pb and 72% for Zn. In wetlands operating on synthetic mine water, SO 4 2− was completely removed, likely by conversion to sulfide by sulfate‐reducing bacteria. In the wetland operating on synthetic smelter effluent, only approximately 25% of 6 g/L influent sulfate was removed, and a breakthrough period of 4 days for Na + was observed. Whole effluent toxicity assays on undiluted wetland effluent from wetlands treating mine and smelter water had 100% survival of fathead minnows and Daphnia magnia . Survival of Ceriodaphnia dubia was zero in undiluted effluent, but 75 to 100% survival was observed when the effluent was diluted to one‐half strength.