Biotreatment and bioassessment of heavy metal removal by sulphate reducing bacteria in fixed bed reactors.
In this work a batch-optimised mixture (w/w %: 6% leaves, 9% compost, 3% Fe(0), 30% silica sand, 30% perlite, 22% limestone) was investigated in a continuous fixed bed column reactor for the treatment of synthetic acid-mine drainage (AMD). A column reactor was inoculated with sulphate-reducing bacteria and fed with a solution containing sulphate and heavy metals (As(V), Cd, Cr(VI), Cu and Zn). At steady state, sulphate abatement was 50+/-10%, while metals were totally removed. A degradation rate constant (k) of 0.015+/-0.001h(-1) for sulphate removal was determined from column data by assuming a first order degradation rate. Reduction of AMD toxicity was assessed by using the nematode Caenorhabditis elegans as a test organism. A lethality assay was performed with the toxicants before and after the treatment, showing that only 5% of the animals were still alive after 48h in presence of the contaminants, while the percentage increased to 73% when the nematodes were exposed to the solution eluted from the column.
Cruz Viggi
C
C
Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy. carolina.cruzviggi@uniroma1.it
Pagnanelli
F
F
Cibati
A
A
Uccelletti
D
D
Palleschi
C
C
Toro
L
L
D000818:Animals; D019149:Bioreactors / Q000382:microbiology*; D017173:Caenorhabditis elegans / Q000187:drug effects; D019216:Metals, Heavy / Q000378:metabolism* / Q000633:toxicity; D013431:Sulfates / Q000378:metabolism*; D016999:Sulfur-Reducing Bacteria / Q000378:metabolism*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity
D019216:Metals, Heavy; D013431:Sulfates; D014874:Water Pollutants, Chemical