Shamsul Rahman Mohamed Kutty

Landfill leachate treatment by electrochemical oxidation

This study investigated the electrochemical oxidation of stabilized leachate from Pulau Burung semi-aerobic sanitary landfill by conducting laboratory experiments with sodium sulfate Na(2)SO(4) (as electrolyte) and graphite carbon electrodes. The control parameters were influent COD, current density and reaction time, while the responses were BOD removal, COD removal, BOD:COD ratio, color and pH. Na(2)SO(4) concentration was 1 g/L. Experiments were conducted based on a three-level factorial design and response surface methodology (RSM) was used to analyze the results. The optimum conditions were obtained as 1414 mg/L influent COD concentration, 79.9 mA/cm(2) current density and 4 h reaction time. This resulted in 70% BOD removal, 68% COD removal, 84% color removal, 0.04 BOD/COD ratio and 9.1 pH. Electrochemical treatment using graphite carbon electrode was found to be effective in BOD, COD and color removal but was not effective in increasing the BOD/COD ratio or enhancing biodegradability of the leachate. The color intensity of the treated samples increased at low influent COD and high current density due to corrosion of electrode material.

Kinetic modeling and half life study on bioremediation of crude oil dispersed by Corexit 9500

Hydrocarbon pollution in marine ecosystems occurs mainly by accidental oil spills, deliberate discharge of ballast waters from oil tankers and bilge waste discharges; causing site pollution and serious adverse effects on aquatic environments as well as human health. A large number of petroleum hydrocarbons are biodegradable, thus bioremediation has become an important method for the restoration of oil polluted areas. In this research, a series of natural attenuation, crude oil (CO) and dispersed crude oil (DCO) bioremediation experiments of artificially crude oil contaminated seawater was carried out. Bacterial consortiums were identified as Acinetobacter, Alcaligenes, Bacillus, Pseudomonas and Vibrio. First order kinetics described the biodegradation of crude oil. Under abiotic conditions, oil removal was 19.9% while a maximum of 31.8% total petroleum hydrocarbons (TPH) removal was obtained in natural attenuation experiment. All DCO bioreactors demonstrated higher and faster removal than CO bioreactors. Half life times were 28, 32, 38 and 58 days for DCO and 31, 40, 50 and 75 days for CO with oil concentrations of 100, 500, 1000 and 2000 mg/L, respectively. The effectiveness of Corexit 9500 dispersant was monitored in the 45 day study; the results indicated that it improved the crude oil biodegradation rate.

Application of statistical experimental methodology to optimize bioremediation of n-alkanes in aquatic environment.

Response surface methodology (RSM) was employed to optimize nitrogen and phosphorus concentrations for removal of n-alkanes from crude oil contaminated seawater samples in batch reactors. Erlenmeyer flasks were used as bioreactors; each containing 250 mL dispersed crude oil contaminated seawater, indigenous acclimatized microorganism and different amounts of nitrogen and phosphorus based on central composite design (CCD). Samples were extracted and analyzed according to US-EPA protocols using a gas chromatograph. During 28 days of bioremediation, a maximum of 95% total aliphatic hydrocarbons removal was observed. The obtained Model F-value of 267.73 and probability F<0.0001 implied the model was significant. Numerical condition optimization via a quadratic model, predicted 98% n-alkanes removal for a 20-day laboratory bioremediation trial using nitrogen and phosphorus concentrations of 13.62 and 1.39 mg/L, respectively. In actual experiments, 95% removal was observed under these conditions.

Feasibility study of biodiesel production using lipids of Hermetia illucens larva fed with organic waste

Hermetia illucens larvae by nature are a decomposer which fed on organic wastes. This study explores the potential of producing biodiesel using lipids from H. illucens larvae. Three types of organic wastes (sewage sludge, fruit waste and palm decanter cake from oil palm mill) were selected based on considerable generation and disposal concern in the area of study as well as lack of investigations as feed for Hermetia illucens larvae in current literatures. Growth rate of the larvae was determined with studying the changes in the biomass per day. H. illucens larvae fed with fruit waste and palm decanter cake have shown growth rates of 0.52±0.02 and 0.23±0.09 g d(-1), respectively. No positive sign of growth were observed in the larvae fed with treated sewage sludge (-0.04±0.01 g d(-1)). Biodiesel as fatty acid methyl ester (FAME) was synthesized by transesterification of the larvae lipid using sulphuric acid as catalyst in methanol. FAME produced was ascertained using ATR-FTIR spectroscopy and GC-MS. The main compositions of fatty acid were found to be C12:0, C16:0 and C18:1n9c. Fatty acid composition of C12:0 fed with fruit waste, sewage sludge and palm decanter was found to be most abundant in the larvae lipid. The amount of C12:0 obtained was 76.13%, 58.31% and 48.06%, respectively. In addition, fatty acid of C16:0 was attained at 16.48% and 25.48% fed with sewage sludge and palm decanter, respectively. Based on the findings, FAME derived from larvae lipids is feasible to be used for biodiesel production.

Adsorptive Removal of Reactive Yellow 15 from Aqueous Solution by Coconut Coir Activated Carbon

Activated carbon was prepared from coconut coir and its ability to adsorb Reactive Yellow 15 (RY15) dye examined. Batch adsorption tests showed that the extent of dye adsorption depended on the initial dye concentration, the contact time and the pH value of the solution. Equilibrium adsorption was attained within 240 min, with maximum adsorption occurring at a pH value of 2. The adsorption capacity of the activated carbon towards the dye was evaluated and compared with that of a commercial activated carbon. Equilibrium adsorption data for the coconut coir activated carbon (CCAC) and the commercial activated carbon (CAC) were well described by the Langmuir and Freundlich isotherm models, and indicated the higher adsorption capacity of CCAC. The adsorption of RY15 by CCAC and CAC followed pseudo-second-order kinetics. The results indicate that activated carbon prepared from coconut coir is more effective than CAC for the adsorption of RY15. Hence, CCAC would be a suitable substitute for CAC in the removal of Reactive dyes from aqueous solution.

Response surface analysis and modeling of n-alkanes removal through bioremediation of weathered crude oil.

Central composite design (CCD) and response surface methodology (RSM) were employed to optimize four important variables, i.e. amounts of oil, bacterial inoculum, nitrogen and phosphorus, for the removal of selected n-alkanes during bioremediation of weathered crude oil in coastal sediments using laboratory bioreactors over a 60 day experimentation period. The reactors contained 1 kg soil with different oil, microorganisms and nutrients concentrations. The F Value of 26.89 and the probability value (P < 0.0001) demonstrated significance of the regression model. For crude oil concentration of 2, 16 and 30 g per kg sediments and under optimized conditions, n-alkanes removal was 97.38, 93.14 and 90.21% respectively. Natural attenuation removed 30.07, 25.92 and 23.09% n-alkanes from 2, 16 and 30 g oil/kg sediments respectively. Excessive nutrients addition was found to inhibit bioremediation.

Polycyclic aromatic hydrocarbon removal from petroleum sludge cake using thermal treatment with additives

Petroleum sludge is a hazardous waste that contains various organic compounds including polycyclic aromatic hydrocarbons (PAHs) which have carcinogenic–mutagenic and toxic characteristics. This study focuses on the thermal treatment (indirect heating) of petroleum sludge cake for PAH degradation at 250, 450, and 650 °C using Ca(OH)2+NaHCO3 as an additive. The treatment was conducted in a rotary drum electric heater. All experiments were carried out in triplicate. Concentrations of the 16 priority PAHs in gas (absorbed on Amberlite XAD-4 adsorbent), particulate (on quartz filter) and residue phases were determined using gas chromatography-mass spectrometry (GC-MS). The samples were extracted with acetonitrile by ultra-sonication prior to GC-MS analysis. The use of additive was beneficial and a temperature of 450 °C was suitable for PAH degradation. Low levels of PAH emissions, particularly carcinogenic PAH and toxic equivalent concentration (ΣTEC), were observed in gas, particulate and residue phases after treatment.

Treatment of Wastewater Using an Integrated Submerged Attached Growth System

The performance of a single sludge integrated attached growth system comprising of an aerobic and anoxic tanks in biological nutrient removal was evaluated in treating synthetic wastewater simulating medium strength domestic wastewater. An aero-packer and bio-balls were installed in the aeration and anoxic tank occupying about 40% and 25% of both tanks respectively. The efficiency of the integrated attached growth system was evaluated on the removal of chemical oxygen demand (COD), ammonia removal (NH3), nitrate removal (NO3), total suspended solids removal (TSS) and biochemical oxygen demand removal (BOD5). Effluent results show that the integrated attached growth system had a removal efficiency of 97.8% (COD), 97.5% (NH3), 87.5% (NO3), 97% (TSS) and 97.1% (BOD). These results support the viability of an integrated system in mitigating the enormous challenges of a conventional wastewater treatment.

Lipid for biodiesel production from attached growth Chlorella vulgaris biomass cultivating in fluidized bed bioreactor packed with polyurethane foam material

The potential to grow attached microalgae Chlorella vulgaris in fluidized bed bioreactor was materialized in this study, targeting to ease the harvesting process prior to biodiesel production. The proposed thermodynamic mechanism and physical property assessment of various support materials verified polyurethane to be suitable material favouring the spontaneous adhesion by microalgae cells. The 1-L bioreactor packed with only 2.4% (v/v) of 1.00-mL polyurethane foam cubes could achieve the highest attached growth microalgae biomass and lipid weights of 812±122 and 376±37mg, respectively, in comparison with other cube sizes. The maturity of attached growth microalgae biomass for harvesting could also be determined from the growth trend of suspended microalgae biomass. Analysis of FAME composition revealed that the harvested microalgae biomass was dominated by C16-C18 (>60%) and mixture of saturated and mono-unsaturated fatty acids (>65%), satiating the biodiesel standard with adequate cold flow property and oxidative stability.

Biomass as Low-Cost Adsorbents for Removal of Heavy Metals from Aqueous Solution: A Review of Some Selected Biomass

Low cost adsorbents have become a major area of consideration to many researchers due to the expense nature of the available activated carbon. Although commercial activated carbon is the most sufficient and efficiently used carbon for the removal of heavy metals ions coming from wastewater, it is faced with a lot of setback such as; the higher the quality of the activated carbon the more expensive it is, the regeneration of the used carbon tends to be very difficult especially in large volume. Due to this different biomass from agricultural by-products have been investigated to replace the commercial activated carbon and most of the findings have indicated a significant removal in terms of heavy metals in synthetic aqueous solution. This study have looked into and reviewed the various low cost adsorbents that have been employed for the treatment of wastewater laden with heavy metals.