Research Publications

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Open Access
Column Study for Adsorption of Copper and Cadmium Using Activated Carbon Derived from Sewage Sludge
(hindawi.com., 2022-03-22) Al-mahbashi, N; Kutty, S. R. M; Jagaba, A. H; Al-Nini, A; Ali, M; Saeed, A. A. H; Ghaleb, A. A. S; Rathnayake, U
mong the water-polluting substances, heavy metals stand out due to their carcinogenic and toxic effects on the creatures and environment. This study aimed to scrutinize the effectiveness of sewage sludge-based activated carbon in the removal of copper and cadmium from aqueous solutions in column study. Detection of breakthrough curves and related parameters was conducted by varying bed depths (3, 6, and 9 cm). The solution with an initial metal concentration (IMC) of 100 ppm was pumped to the column at a flow rate of 2 mL/min. In the process of copper removal, the breakthrough points for depths 3 cm, 6 cm, and 9 cm were achieved at 10 min, 15 min, and 60 min, respectively, whereas breakthrough points of similar depths in cadmium removal process were achieved at 5 min, 10 min, and 30 min, respectively. Adsorption kinetics were analyzed using the Adams–Bohart, Yoon–Nelson, and Thomas kinetics models. The Adams–Bohart model described only the initial part of breakthrough curves. The Thomas model represented the adsorption process with coefficients of determination (R2) ranging between 0.90–0.95 for cadmium removal and 0.89–0.96 for copper removal, while the coefficients of determination of Yoon–Nelson ranged between 0.89–0.94 for cadmium and 0.95–0.97 for copper. Yoon–Nelson was fitted well with copper removal data, while removal of cadmium data was best described by the Thomas model. This study demonstrated that using sewage sludge-based activated carbon to remove heavy metals is an alternative, more cost-effective option to reach the objectives of sustainable development.
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Metal Recovery from Printed Circuit Boards through Biotechnology
(Faculty of Humanities and Sciences - SLIIT, 2021-03-26) Alwis, M.A.M.A.; Nishshanka, N.A.K.Y.A.; Mirissage, M.S.A.S.N.; Fernando, W.R.S.; Perera, D.S.M.; Fernando, W.P.E.M.
The increase of e-waste generated through electrical and electronic equipment has led to vast exploitation in recent years as they have increased the risk of destruction of both life and the environment. The end-of-life PCBs represent one of the most significant wastes in this category. PCBs contain a high amount of Cu and Zn with concentrations around 25% and 2% respectively. Pyrometallurgical treatments and hydrometallurgical treatments are the most common methods used for PCB recycling at present. Bio-hydrometallurgical strategies have been identified as a successful alternative for the existing methods as they reduce the economic costs and are more environmentally friendly. The poster introduces a sustainable bioleaching process by using two bacteria Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans. This developed technology allows to obtain a high PCB concentration and to reduce the metal toxicity on the bacteria metabolism. Ferric iron was used as the oxidant to leach Cu and Zn. The best conditions were when At. ferrooxidans was used at 30ºC, with a solid concentration of 5% (w/v) with 10g/L of Fe2+ for 9 days. The carbon footprint assessment proved the environmental advantage of the process. The bioleaching treatment which was the most efficient method according to the analyzation explained that the amount of raw material reduction that results in decreasing the bioreactor size and lowering the energy requirement could be facilitated by increasing the PCB concentration. Through this process, the environmental impact could be decreased up to 4 times compared to the existing bioleaching processes.

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