| Summary: | 碩士 === 國立成功大學 === 環境工程研究所 === 82 === Physical-chemical processes, including chemical coagulation,
granular activated carbon (GAC) adsorption and electrochemical
oxidation, were used to investigate the feasibility for the
treatment of refractory landfill leachate. The raw landfill
leachate contained high strength of COD and ammonium with the
concentrations of 2700 mg/l and 1800 mg/l, respectively.
Besides, the BOD/COD ratio was only 0.1, and the transparency
was only 2.5 cm. Among these three processes,chemical
coagulation could remove about 60% COD under the conditions of
pH 6 anddosage of 3000 mg/l ferric chloride. The GAC adsorption
phenomena of the landfill leachate carried out for 24 hours at
pH 7 and 25℃ could be described adequately by the Freundich
isotherm, and the adsorptive capacity was only 30 mg-COD/g-GAC
at the equilibrium concentration of 500 mg/l COD.
Electrochemical oxidation process exhibited good efficacy for
the treatment of landfill leachate, and both COD and ammonium
removal efficiencies were increased with the increase of
operating current density and addition of chloride. After 3
hour electrolysis with the addition of 3000 mg/l chloride, COD
and ammonium could be removed 59% and 92%, respectively. From
gel permeation chromatography (GPC) analysis results, it
discovered that theabove three processes could remove specific
group of organic matters in landfill leachate. Chemical
coagulation could mainly remove the organicmatters with
molecular weight(MW) higher than 15000, while GAC adsorption
was effective for the removal of organicmatters with low
molecular weight (MW<5000). Electrochemical oxidation could
removeboth high and low MW organic matters, but the destruction
of high MW organic matters was much facile. Using chemical
coagulation c/o electrochemical oxidation as the pre-treatment
before GAC adsorption, the adsorptive capacity of landfill
leachate was improved due to the increase of low MW matters
fraction in
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