Yee-Shian Wong

Degradation of cationic and anionic dyes in coagulation–flocculation process using bi-functionalized silica hybrid with aluminum-ferric as auxiliary agent

Cationic dye (methylene blue) and anionic dye (methyl orange) degradation in the coagulation process was demonstrated. The key material was a natural coagulant–laterite soil dominated by a silica component, while aluminum-ferric ions acted as an auxiliary agent in the degradation process. Charge neutralization, electrical double layer compression and sweeping flocculation were the mechanisms in the decolorization reaction. These results provided a new insight into effective dye degradation using a new class of natural coagulant–natural resources (laterite soil). The complex molecular structure of methylene blue and methyl orange was degraded into smaller hydrocarbon forms, accompanied by the formation of silsesquioxane. The silsesquioxane was the final product of degradation with promising flocculation and low volume sludge. Lastly, a comparison of the aluminum-based coagulant and a laterite soil natural coagulant shows a clear vision of the performance for both types of coagulant.

Suspended growth kinetic analysis on biogas generation from newly isolated anaerobic bacterial communities for palm oil mill effluent at mesophilic temperature

The anaerobic degradation of palm oil mill effluent (POME) was carried out under mesophilic temperature in an anaerobic suspended growth closed bioreactor (ASGCB). Monod model was applied to describe the kinetic analysis of POME at different organic loading rates (OLR) in the range of 2.75–8.2 g TCOD per L per day. The hydraulic retention time (HRT) ranged between 8 and 24 days. The TCOD removal efficiency achieved was between 89.66% and 79.83%. The evaluated kinetic coefficients were: growth yield, YG (0.357 g VSS per g TCOD), specific biomass decay rate, b (0.07 per day), maximum specific biomass growth rate, μmax (0.27 per day), saturation constant for substrate, Ks (25.03 g TCOD per L), critical retention time, ΘC (3.72 day) and methane yield, YCH4 (0.34 L CH4 per TCODremoved). Besides, new fermentative anaerobic bacteria isolated from POME were identified as Escherichia fergusonii, Enterobacter asburiae, Enterobacter cloacae, Desulfovibrio aerotolerans, Desulfobulbus propionicus, Fusobacterium nucleatum, Paenibacillus pabuli, Bacillus subtilis, Methanobacterium sp., Methanosaeta concilii, Methanofollis tationis, Methanosarcina mazei and Methanosarcina acetivorans using 16S rDNA.

Catalytic thermolysis in treating Cibacron Blue in aqueous solution: Kinetics and degradation pathway.

A thermal degradation pathway of the decolourisation of Reactive Cibacron Blue F3GA (RCB) in aqueous solution through catalytic thermolysis is established. Catalytic thermolysis is suitable for the removal of dyes from wastewater as it breaks down the complex dye molecules instead of only transferring them into another phase. RCB is a reactive dye that consists of three main groups, namely anthraquinone, benzene and triazine groups. Through catalytic thermolysis, the bonds that hold the three groups together were effectively broken and at the same time, the complex molecules degraded to form simple molecules of lower molecular weight. The degradation pathway and products were characterized and determined through UV-Vis, FT-IR and GCMS analysis. RCB dye molecule was successfully broken down into simpler molecules, namely, benzene derivatives, amines and triazine. The addition of copper sulphate, CuSO4, as a catalyst, hastens the thermal degradation of RCB by aiding in the breakdown of large, complex molecules. At pH 2 and catalyst mass loading of 5 g/L, an optimum colour removal of 66.14% was observed. The degradation rate of RCB is well explained by first order kinetics model.

Integrated photocatalytic and sequencing batch reactor (SBR) treatment system for degradation of phenol

This study will examine the efficiency of the simultaneous photocatalytic and biodegradation process in the same treatment reactor. The sequencing batch reactor or also known as SBR is an effective wastewater treatment method that has been applied widely. SBR system has become an alternative method for industrial wastewater treatment with high concentration of chemical oxygen demand (COD), and phenolic compound. In order for the photocatalytic process to occur, ZnO nanoparticles immobilized onto sponge were introduced to the reactor. It was observed that the COD value were decreased, indicated that the simultaneous biodegradation and photodegradation process in functional. The effect of ZnO nanoparticles on the production and composition of extracellular polymeric substances (EPS) and the physiochemical stability of activated sludge in hybrid growth type SBR were monitored. The percentages of removal are varied with different concentration of ZnO nanoparticles. The highest COD removal recorded is 31.5% wi...

Comparison the performance of carbon plate and Pt-loaded carbon in photocatalytic fuel cell (PFC) process

The objective of this study is to compare the performance of cathode electrode in photocatalytic fuel cell (PFC) system under UV light irradiation. The initial concentration 10 mg/L of Reactive Black 5 (RB5) with carbon plate (CP) and Pt-loaded carbon (Pt/C) as cathode reduced to 2.052 and 0.549 mg/L, respectively, after 24 h irradiated by UV light. The value for open circuit voltage, Voc, short-circuit current density, Jsc and maximum power density, Pmax for CP was 0.825 V, 0.00035 mA/cm2 and 0.000063 mW/cm2, respectively, meanwhile Voc, Jsc and Pmax for Pt/C was 1.15 V, 0.0015 mA/cm2 and 0.000286 mW/cm2, respectively, by varying external resistor value from 300 kΩ to 10 Ω. The degradation of RB5 and generation of electricity with Pt/C as cathode showed greater performance than CP.

Pilot scale single chamber up-flow membrane-less microbial fuel cell for wastewater treatment and electricity generation

Pilot scale up-flow membrane-less microbial fuel cell (UFML-MFC) was constructed to study feasibility of the bioreactor for simultaneous degradation of organic substance and electricity generation. The performance of the UFML-MFC was evaluated with different anode electrode (cube carbon felt and stacked carbon felt) in terms of voltage output, chemical oxygen demand (COD) and Coulombic efficiency (CE). Carbon flake were used as cathode in the UFML-MFC. UFML-MFC was operated in three stages where included batch-fed, end of batch fed and semi-continuous. The Cube carbon felt as anode have the better performance in terms of voltage output and electricity generation in all 3 stages. Maximum voltage output was 0.311 ± 0.004 V at 75% of COD reduction and thus CE was 0.15%. The result shows the operational mode is the key to improve the voltage output and also COD reduction.