02606cas|a2200241 i 450000500170000000800410001703500150005810000310007324500850010426000520018930000140024149000270025550001580028250200580044052015200049865000470201870000380206570000450210370000450214871000470219381000590224085600650229920260817162845.0050499s1994    th  uzm rtt  00|  a1eng d  a.b100875641 aThayalakumaran, Nagalingam10aApplication of constructed wetlands to the treatment of a heavy metal wastewater  aBangkok :bAsian Institute of Technology,c1994  a99 leaves1 aThesis ;vno. EV-94-31  aA thesis submitted in · partial fulfillment of the requirements for the degree of Master of  Engineering, School of Environment, Resources & Development  aThesis (M.Eng.) - Asian Institute of Technology, 1994  aVarious industrial activities such as electroplating and metal finishing generate tons of  metallic pollutants into the air and water bodies. There are a number of techniques available  for the removal of heavy metals from wastewaters. Electroplating industries produce Cr and  Ni wastewaters. Because constructed wetlands are cost-effective and energy-efficient, they  were used to investigate efficiencies in treating an electroplating wastewater.  One pilot-scale and three lab-scale constructed wetland units were constructed at the  Environmental Research Station, AIT campus where cattail plants were grown. These  constructed wetlands were fed with mixtures of the electroplating wastewater and a domestic  wastewater and maintained at a hydraulic retention time of 7 days. Physico-chemical  parameters such as pH, SCOD, TSS, DO and influent and effluent heavy metal concentrations  were measured at three days interval.  Heavy metal removal efficiencies of more than 99 3 were observed in pilot-scale unit  even when the influent heavy metal concentrations were 25 mg/l. The heavy metals were  removed mainly by precipitation and adsorption. The soil adsorbed more Cr and Ni than the  plants. The Cr and Ni ions were strongly held by the root cells showing high concentrations  in the roots. Cr was more strongly chelated in the root than Ni. Ni fed wetland plants showed  some phytotoxic effects. In the pilot-scale unit, removal efficiencies of SCOD, TSS, TKN  were more than 64, 89 and 85 3 respectively. 0aSewagexPurificationxHeavy metals removal0 aChongrak Polprasert,eChairperson0 aSamorn Muttamara,eExamination Committee1 aUmita, Teruyuki, eExamination Committee2 aGovernment of Finland, eScholarship Donor2 aAsian Institute of Technology.tThesis ;vno. EV-94-31  3Full-Textuhttp://203.159.5.9/ait-thesis/detail.php?q=B15821