Reduction of cod, apparent colour and turbidity from landfill leachate by coagulation and Fenton process
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Date
2009
Authors
Talebi, Amir
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Abstract
A study using coagulation and Fenton oxidation methods have been carried out for the
reduction of COD, apparent colour and turbidity from municipal solid waste (MSW)
landfill leachate, generated from Pulau Burung landfill site located in Pulau Pinang.
The characteristics of the leachate are chemical oxygen demand (COD) and apparent
colour as well as turbidity is 3450 mg/L, 6260 Pt.Co, and 160 N.T.U, respectively.
Aluminum sulfate (Al2(SO4)3·18H2O) and ferrous sulphate (FeSO4·7H2O) have been
chosen as coagulants and hydrogen peroxide (30%-H2O2) has been used for Fenton
oxidation. Sodium hydroxide and sulfuric acid has been used for pH adjustment. Jar test
method was conducted to evaluate the effect of coagulant dosage and pH on coagulation
process. For each single section, central composite designs (CCD) with two
independent variables are used in order to optimize the relevant process. Based on
optimization for coagulation with aluminium sulphate, the maximum reduction for all
responses was achieved at the dosage of 15 g/L and pH 5.10. The selected combinations
of the two variables resulted in 33.13% COD, 74.78% apparent colour and 35.93%
turbidity reductions. For coagulation by ferrous sulphate, the maximum reduction for all
responses was achieved at the dosage of 10 g/L FeSO4 and pH 11.7. The selected
combinations of the two variables resulted in 21.54% COD reduction, 41.84%
apparent colour removal, and 31.20 % turbidity reduction. The maximum reductions of
responses for Fenton oxidatopn process occurs at FeSO4 dosage 12.8 g/L and H2O2
concentration of 747.8 mg/L. The selected combinations of the two variables resulted in
68% COD reduction, 81% apparent colour removal and 86% turbidity reduction.
Consequently, a combination of both methods (coagulation and Fenton) has been
carried out, in order to determine the efficiency of mixed method on COD, apparent
colour and turbidity reductions. Results revealed that the optimum Fenton solution for
samples which have been pre-treated with aluminum sulfate coagulant was achieved at
H2O2 (800 mg/L) and FeSO4 (more than 6 g/L and less than 8 g/L). On the other hand, it
was discovered that higher COD reduction was achieved by the use of low dosages of
FeSO4 and H2O2 for samples which were coagulated by ferrous sulfate, in comparison
with the use of the same levels of individual Fenton oxidation.
Description
Master
Keywords
Industrial technology , Landfill leachate , Fenton process