Abstract
Common conventional biological treatment methods fail to decolorize palm oil mill effluent (POME). The present study focused on using the abundant palm oil mill boiler (POMB) ashes for POME decolorization. The POMB ashes were subjected to microwave irradiation and chemical treatment using H2SO4. The resultant adsorbents were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analyses. The adsorption efficiency was evaluated at various pH levels (2–8.5), adsorption dosages (3–15 g) in 200 mL, and contact times (1–5 h). The microwave-irradiated POMB-retained ash recorded the highest color removal of 92.31%, for which the best conditions were pH 2, 15 g adsorbent dosage in 200 mL, and 5 h of contact time. At these best treatment conditions, the color concentration of the treated effluent was analyzed using the method proposed by the American Dye Manufacturers Institute (ADMI). The color concentration was 19.20 ADMI, which complies with the Malaysia discharge standard class A. The Freundlich isotherm model better fit the experimental data and had a high R2 of 0.9740. Based on these results, it can be deduced that microwave-irradiated POMB-retained ash has potential applications for POME decolorization via a biosorption process.
Highlights
Malaysia contributes over 29% of world palm oil production and 37% of world exports [1]
The results of the analysis exceeded the standard limit except the pH value (8.5), which was within the acceptable limit
In comparison with reports in the literature, this study showed that chemically activated carbon is more susceptible to oxidation than physically activated carbon; as such, the former has a greater tendency to produce a large number of acidic oxygen functional groups on the surface of the resultant sorbent [67]
Summary
Malaysia contributes over 29% of world palm oil production and 37% of world exports [1]. This method requires no chemical or biological reagents and solely depends on microbial metabolic activities [9] This treatment method remarkably remediates the COD and BOD, but color removal has remained a challenge, as it is unable to meet the discharge standard. In order to meet the color discharge limit, several alternative treatment methods have been attempted by researchers This includes membrane filtration [10,11], growing culture [4,12,13], electrocoagulation and oxidation [14,15,16], and adsorption using activated carbon (AC) [17,18,19]. The results of the experimental data were fitted with Freundlich and Langmuir isotherm models
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