Publication: Removal of organic pollutants from humic acid extracted leachate by combined copper sulphate and crosslinked oil palm trunk starch coagulation
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Date
2022-04-01
Authors
Ahmed, Zaber
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Abstract
Landfilling is the preferred solution worldwide for overwhelming sold waste
management because of operational simplicity and cost-effectiveness. However, the
producing leachate is a typical dilemma of this method. Leachate encompasses
concentrated refractory organics (humic and fulvic acid) and is toxic. Hence, this study
investigated a blended mechanism to treat leachate, i.e., humic acid extracted leachate
treatment by combined coagulation-flocculation process with copper sulphate and
natural oil palm trunk starch to eliminate the organic pollutants from stabilized
leachate. The humic acid was recovered from raw leachate through microfiltrationcentrifugation,
and starch (OPTS) was extracted from the oil palm trunk by applying
the optimized bisulphite steeping method. The best yield of starch was improved
further by applying a crosslinking technique (C-OPTS). The performance of CuSO4,
OPTS, C-OPTS, and the combination (CuSO4-OPTS, CuSO4-COPTS), were
examined individually using the humic acid extracted leachate. Experimental
conditions were optimised by using RSM. The study reported 1380 mg/L of humic
acid recovery, and 13.54% yield of OPTS. The combined application of CS-OPTS and
CS-COPTS increased the removal efficiencies significantly. CS-COPTS ensured
64.5% COD, 86.79% colour, and 54.79% UV254 removal (at pH=7, CuSO4=4 g/L, COPTS=
1.5 g/L), which eventually reduced 56% of CuSO4 dosage. As a result, this
blended mechanism removed 77% COD, 91% colour and 71% UV254 ultimately from
the initial concentration of raw leachate. According to the ANOVA for CS-COPTS,
the R2 values were 0.91, 0.93, 0.93 and predicted R2 are 0.85, 0.88, 0.89 for colour,
COD and UV254, respectively. Therefore, better sludge and floc formation through
particle bridging were obtained from CS-COPTS application. Hence the combination
of copper sulphate and C-OPTS can be suggested as an effective process for organics
removal from humic acid extracted leachate.