Biological, chemical and mathematical sciences

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    Treatment of poultry slaughterhouse wastewater using integrated anaerobic-aerobic sequencing batch reactor
    (Universiti Teknologi Malaysia, 2018) Rajab, Ahmed Rahomi
    Poultry slaughterhouse industries produce relatively high quantity of wastewater. This effluent is classified as a high-strength wastewater causing environmental deterioration if it is discharged without proper treatment especially for organics, ammoniacal nitrogen (NH3-N), including fat, oil, and grease (FOG) contaminants. A review was carried out to determine the research gap and to gain more insight on treatment system using two regimes (anaerobic and aerobic) processes in sequence for high-rate bioreactors which act as one unit in an integrated manner with physical separation and utilizing merely suspended growth system. Thus, a new configuration bioreactor called integrated anaerobic-aerobic sequencing batch reactor (IAASBR) was proposed and investigated to achieve the aforementioned targets. This study comprises of four parts: the first part characterized the poultry slaughterhouse wastewater (PSW) generated in Malaysia by selection of three poultry slaughterhouses. The second part dealt with choosing the best volumetric anaerobic/aerobic ratio (Van/Va) for the proposed IAASBR that has achieved the best organics and NH3-N removal efficiencies. Subsequently, the third part investigated the IAASBR’s endurance for maximum organic loading rate (OLR). Lastly, the ability of the proposed configuration for the simultaneous biological total nitrogen (TN) and phosphate (PO43-) removal from PSW was investigated. The characteristics of PSWs displayed high fluctuation in their pollution levels between the three selected factories and within the same plant itself (for example total chemical oxygen demand (TCOD) concentration was in the range of 940-3400 mg/L with an average 1940 ± 680 mg/L). The average removal efficiency for the best ratio (Van/Va = 2) measured as the TCOD, soluble chemical oxygen demand (SCOD), NH3-N, FOG, and total suspended solids were 97% ± 2%, 95% ± 3%, 98% ± 1.3%, 90% ± 11%, and 96% ± 3% respectively. The laboratory comparison test revealed that IAASBR configuration has enhanced the sludge settleability for aerobic sequencing batch reactor (SBR) more than the conventional SBR by emerging a new phenomenon called “Water Inflation Phenomenon (WIPh)”. IAASBR could tolerate the shock loading occurrence and handle OLR up to 4.5 kg(TCOD)/m3 d, producing a high-quality effluent complying with the standards for industrial’s effluents. In the aspect of renewable energy, the anaerobic SBR produced a reasonable quantity of biogas 0.10-0.21 L/d Lr (26-28°C) with methane (CH4) composition of 69%. This configuration exhibited low overall removal efficiencies for TN and PO43- by 38% and 6%, respectively. Furthermore, the main features of this IAASBR configuration are elimination of the inhibitory effect for FOG constituent’s concentration up to 370 mg/L and high removal efficiencies of organics and NH3-N with less aeration exertion (economical aspect) in addition of biogas production. In conclusion, the proposed bioreactor configuration exhibits a high performance, steady, and flexibility under different operation conditions along the 17 months period of this research
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    Development and characterization of sago based pervaporation membranes for the recovery of mixed cesium and potassium formate brines
    (Universiti Teknologi Malaysia, 2018) Zamrud, Zafifah
    Natural polymeric membranes being low cost, environmentally friendly and abundant in nature have proven their potential in pervaporative dehydration of organics. In this study, the efficiency of separation of mixed cesium and potassium (CsKFo) brines was evaluated at different membrane preparation conditions using sago starch (SS) and pervaporation (PV) operation conditions. Response surface methodology (RSM) was used to optimize the membrane preparation conditions and pervaporation operating conditions on flux and pervaporation separation index (PSI). Sago based pervaporation membranes showed excellent physicochemical properties after poly(vinyl) alcohol (PVA) blending, glutaraldehyde (GTA) crosslinking and heat treatment. The optimum preparation conditions for sago based membranes were found to be at 50 wt. % of SS in the blend, crosslinked with 1.0 wt. % GTA and heat treated at 150 °C with the highest flux and PSI of 228.03 g/m²h and 79.30 x 104, respectively. The optimum PV operating conditions were at 98% of CsKFo in feed and operated at 53 °C of feed temperature with the highest flux and PSI being 261.38 g/m²h and 277.42 x 105, respectively. The apparent activation energy for permeation (Ep) and activated diffusion (ED) calculated from the Arrhenius equation for water were smaller (Ep = 22.06 kJ/mol,ED = 22.17 kJ/mol) than CsKFo (Ep = 48.99 kJ/mol, ED = 48.98 kJ/mol) suggesting that the water molecules were easily permeated across the membrane and required less energy to diffuse through. The findings demonstrated that PV has potential for the complete recovery of CsKFo brines, which in turn benefits the oil and gas industry. This research also provides findings for extended application of SS biocomposite particularly as hydrophilic membranes
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    Hydrogen production from steam reforming of phenol over supported nickel-cobalt catalyst
    (Universiti Teknologi Malaysia, 2017) Nabgan, Walid
    This thesis presents the results of a study of catalytic phenol steam reforming with the aim of hydrogen production using bimetallic nickel-cobalt (Ni-Co) supported on cerium oxide, zirconium dioxide (ZrO2), lanthanum oxide, gamma alumina, and alpha alumina catalysts. Phenol has been selected as a reactant due to the high amount of phenol in bio-oil and is a potential renewable feedstock for hydrogen production. The high cost of noble based catalysts, low activity and performance of non-noble based catalysts, deactivation of catalysts by coke formation, and high temperature requirements for complete phenol conversion are the problems of the previous research. The aim of this research is to develop a highly active and stable catalyst for hydrogen production from the steam reforming of phenol. The physical and chemical properties of the catalysts were characterized in terms of their surface area, crystallinity, reducibility, acidity, basicity, and coke formation. Five prepared catalysts were screened by using a micro-reactor fixed bed at a temperature of 650 °C and atmospheric pressure. The effect of Ni to Co ratio on hydrogen production from phenol steam reforming reaction was then investigated. This was followed by parametric study on the process involving five factors, namely temperature (A), feed flow rate (B), catalyst amount (C), presence of Ni and Co (D), as well as concentration of phenol (E), and the two responses were phenol conversion (Y1) and hydrogen (Y2). The optimum catalytic performance was found to be for the Ni-Co/ZrO2 catalyst with 81.9% of phenol conversion and 80.7% of hydrogen yield at 650 °C. The effect of Ni to Co metal ratio study showed that the 75 wt.% Ni-25 wt.% Co supported on ZrO2 catalyst displayed a superior catalytic activity among all the ratios. The parametric analysis showed that five variables (A, B, C, D and E) and interactions among AE, BE and DE produced significant effects on Y1 and Y2. In the kinetic study, the results suggested that the surface reaction was the rate limiting step by assuming non-dissociative adsorption of phenol and steam using this catalyst. Hence, it is concluded that bimetallic Ni-Co supported on ZrO2 catalyst is able to produce high hydrogen yield and has the potential to tackle the catalyst deactivation by coke.
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    Cracking of low density polyethylene dissolved in benzene to liquid fuels using zeolite-based catalysts
    (Universiti Teknologi Malaysia, 2016) Wong, Syie Luing
    Researchers proposed numerous solutions to plastic pollution, with the hope to tackle the intractable problems brought by plastic especially to mankind and environment. One of the proposed methods of solving the problem is the conversion of plastic waste to chemicals and fuels through pyrolysis and cracking. However, previous studies focused on polymer cracking in a batch process, which resulted in the wide distribution of the products. Thus, there is a need to develop polymer cracking process in continuous mode and improve the product quality by using a suitable catalyst. The aim of this research is to investigate on catalytic cracking of low density polyethylene (LDPE) in a fixed bed reactor into liquid fuel. LDPE was dissolved in different solvents with similar solubility parameter and the most suitable solvent was selected. The catalytic cracking was then carried out on the LDPE solution using a fixed bed reactor at atmospheric pressure. Parent zeolites and nickel-impregnated zeolites were screened as catalysts for the cracking of LDPE. The change in product composition at different reaction conditions was also studied, and a plausible reaction mechanism was proposed. This was followed by parametric study of the process involving five factors, namely temperature (A), catalyst mass (B), feed flow rate (C), N2 flow rate (D), as well as concentration of LDPE solution (E), and the two responses were LDPE conversion (Y1) and liquid yield (Y2). Two level full factorial design was used to evaluate the factors. It was found that benzene is the most suitable solvent for LDPE dissolution. Catalytic cracking of the LDPE solution produced C1-C8 hydrocarbons in all runs. During the catalyst screening, zeolite Z2 (ZSM-5 zeolite, Si/Al: 1000) was found to be the most promising catalyst, as it was able to obtain high LDPE conversion (99.93%), high liquid yield (92.28%) and low coke formation (0.02%). The parametric analysis showed that four out of five factors (A, B, C and D) produced significant effects on Y1 and Y2. On the other hand, factor E was statistically insignificant on the responses. Analysis on products composition showed that cracking of LDPE over zeolite Z2 produced a high amount of aliphatic branched-chain compounds, together with the moderate amount of cyclic compounds (C7-C12). The reaction conditions also led to alkylation of benzene by the cracking products from LDPE. It is suggested that the catalytic cracking of LDPE is dominated by free radical mechanism, while the influence of carbenium ion mechanism is less pronounced due to low acidity of the catalyst. Hence, it is concluded that catalytic cracking of dissolved LDPE in fixed bed reactor with zeolite Z2 is able to convert LDPE into liquid fuel in gasoline range and has the potential to tackle the plastic pollution
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    Catalytic conversion of glycerol to olefins over modified ZSM-5 zeolite catalysts
    (Universiti Teknologi Malaysia, 2014) Zakaria, Zaki Yamani
    Glycerol, an alcohol and oxygenated chemical byproduct from biodiesel production, has enormous potential to be converted into higher value-added fuels and chemicals. Due to the alarming excessive production of glycerol worldwide that have triggered environmental concerns, and the importance of olefins in the industry, it is therefore essential to explore the process of glycerol-to-olefin (GTO) in greater depth. This is mainly due to the fact that no dedicated study concerning GTO has been performed. In this present research, the activity and yield towards light olefin in the glycerol steam reforming process was tested and analyzed using zeolite ZSM-5 catalysts modified with selected metals across the periodic table and characterized using X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR), Temperature Programmed Desorption (TPD) and Temperature Programmed Reduction (TPR). Then GTO process involving the best performing catalyst, Cu/ZSM-5, yielding light olefin of 16.3% was further optimized using Response Surface Methodology (RSM) to obtain the most optimum operating condition. The best olefin selectivity and yield were 22.87% and 17.68%, respectively. Multi-Response Objective Genetic Algorithm (MRO-GA) was then performed to give optimum olefin selectivity of 22.06% and yield of 17.84% at the following optimum conditions: T=923K, WHSV=116.54hr-1 and glycerol concentration=26.91%. The reaction kinetic analysis revealed fractional positive values for the order of reaction for products whilst calculated reaction activation energy was 51.88 kJ/mol and pre-exponential constant was 3720.9 mmol.m-2s-1. A reaction model and the reaction mechanism consisting 18 reactions on the catalyst acid surface single-site based on Langmuir-Hinshelwood model were then generated. Thermodynamic analysis was also carried out to investigate the trend of light olefin yield as a function of temperature, pressure and glycerol to water ratio (GWR). The thermodynamic analysis revealed that light olefin formation is minute and occured at temperatures between 873 to 1073K for various GWR. The effect of co-feeding with CO2 shows more encouraging results towards light olefin formation. At thermoneutral point, optimum C2H4 production occurred at 778.44 K (GWR 2:1 and P=1 Bar). In conclusion, GTO offers viable, sustainable and environmental friendly technology for green olefins production from renewable resources, and concerted efforts should be geared to explore its potential