Showing papers by "Hamidi Abdul Aziz published in 2010"

Variability of Parameters Involved in Leachate Pollution Index and Determination of LPI from Four Landfills in Malaysia

Abstract: Landfill sites are potential sources of human and environmental hazards. Leachate produced form these waste dumping sites is heterogeneous and exhibits huge temporal and seasonal variations. Leachate pollution index (LPI) provides an overall pollution potential of a landfill site. The parameters required to calculate LPI from a landfill site are discussed in terms of their variations over time, and their significance has been highlighted in the context of LPI. The LPI values of two semiaerobic and two anaerobic landfill sites in Malaysia have been calculated in this study. Pulau Burung Landfill Site (PBLS) was found to have the highest LPI score while Ampang Jajar Landfill Site (AJLS) showed the lowest LPI as compared to other landfills. It is concluded that LPI value can be used as a tool to assess the leachate pollution potential from landfill sites particularly at places where there is a high risk of leachate migration and pollution of groundwater.

Effect of Initial Oil Concentration and Dispersant on Crude Oil Biodegradation in Contaminated Seawater

Abstract: The effects of initial oil concentration and the Corexit 9500 dispersant on the rate of bioremediation of petroleum hydrocarbons were investigated with a series of ex-situ seawater samples. With initial oil concentrations of 100, 500, 1,000 and 2,000 mg/L, removal of total petroleum hydrocarbons (TPHs) with dispersant were 67.3%, 62.5%, 56.5% and 44.7%, respectively, and were 64.2%, 55.7%, 48.8% and 37.6% without dispersant. The results clearly indicate that the presence of dispersant enhanced crude oil biodegradation. Lower concentrations of crude oil demonstrated more efficient hydrocarbon removal. Based on these findings, bioremediation is not recommended for crude oil concentrations of 2,000 mg/L or higher.

Influence of Fenton reagent oxidation on mineralization and decolorization of municipal landfill leachate.

Abstract: This study evaluated the effectiveness of Fenton's technique for the treatment of semi-aerobic landfill leachate collected from Pulau Burung Landfill Site (PBLS), Penang, Malaysia. The Fe2 + or Fe3 + as catalyst and H2O2 as oxidizing agent are commonly used for the classical Fenton's reaction. In present study, the effect of operating conditions such as pH, reaction time, molar ratio, agitation rate, feeding mode and Fenton reagent concentrations which are important parameters that affect the removal efficiencies of Fenton method were investigated. Under the most favorable conditions, the highest removals of 58.1 and 78.3% were observed for COD and color, respectively. In general, the best operating conditions were pH = 3, Fe = 560 mg L−1, H2O2 = 1020 mg L−1, H2O2/Fe2 + molar ratio = 3, agitation rate = 400 rpm and reaction time = 120 minutes. The results highlighted that stepwise addition of Fenton's reagent was more effective than adding the entire volume in a single step. Excessive hydrogen peroxide an...

Enhancement Biodegradation of n-alkanes from Crude Oil Contaminated Seawater

Abstract: The aim of this research was to optimize bioremediation of seawater samples spiked with 1000 mg/L crude oil for removal of n-alkanes (C12H26 to C34H70). Bioaugmentation experiments were performed at laboratory scale: each bioreactor contained 250 ml dispersed crude-oil-contaminated seawater, indigenous acclimatized microorganism and nitrogen and phosphorus at concentrations based on central composite design (CCD) calculations. Three independent variables, time, nitrogen and phosphorus, were investigated and the experimental data obtained were fitted to a second-order polynomial mathematical model with multiple regressions. The obtained Model F-value of 97.12 and probability F

The Effectiveness of Silica Sand in Semi-Aerobic Stabilized Landfill Leachate Treatment

Abstract: This study examines the suitability of natural silica sand as a low-cost adsorbent for the removal of ammoniacal nitrogen and heavy metals, particularly iron and zinc, from semi-aerobic stabilized landfill leachate. Leachate samples were collected from the Pulau Burung landfill site (PBLS) in Penang, Malaysia. The above-mentioned contaminants are highlighted in this study because of their unsafe concentrations at PBLS. The effects of shaking time, settling time, and silica sand dosage on the study parameter removal efficiencies were investigated to predict the performance of the process. The adsorptions of ammoniacal nitrogen, iron, and zinc were judiciously described by Langmuir and Freundlich isotherm models. The optimum removal efficiencies of ammoniacal nitrogen, iron, and zinc obtained were 51%, 44.4%, and 39.2%, respectively, with a shaking time of 90 min, a settling time of 60 min, and with a dosage of 60 g (0.5 kg/L) of silica sand. Based on the coefficient of determination (R2) values obtained from Langmuir and Freundlich isotherm models, ammoniacal nitrogen, iron, and zinc adsorption were better fitted to the Freundlich model.

Ex-situ Bioremediation of Crude Oil in Soil, a Comparative Kinetic Analysis

Abstract: Weathered crude oil (WCO) removals in shoreline sediment samples were monitored for 60 days in bioremediation experimentation. Experimental modeling was carried out using statistical design of experiments. At optimum conditions maximum of 83.13, 78.06 and 69.92% WCO removals were observed for 2, 16 and 30 g/kg initial oil concentrations, respectively. Significant variations in the crude oil degradation pattern were observed with respect to oil, nutrient and microorganism contents. Crude oil bioremediation were successfully described by a first-order kinetic model. The study indicated that the rate of hydrocarbon biodegradation increased with decrease of crude oil concentrations.

Physico-Chemical Treatment of Anaerobic Landfill Leachate Using Activated Carbon and Zeolite: Batch and Column Studies

Abstract: Leachate generated from one of the old landfills in Malaysia contains high concentrations of colour, COD, iron and ammoniacal. The ability of activated carbon-zeolite mixtures as an adsorbent was investigated in this research. Results of the batch experiments indicated that more than 522.2 mg/g of colour, 52.63 mg/g of iron, 232.6 mg/g of COD and 21.01 mg/g of ammoniacal nitrogen were removed by a mixture of activated carbon and zeolite. Results of the column studies indicated that more than 70% of colour and ammoniacal nitrogen, 80% of COD and 90% of iron were removed on the first five days.

Municipal solid waste management in Benghazi (Libya): current practices and challenges.

Abstract: This paper provides an overview of the current solid waste management (SWM) practices in Benghazi, Libya and suggests solutions to some of the major problems regarding the matter. There have been several crucial issues faced by the city of Benghazi (the second capital city in Libya) on SWM, including limited documentation on the generation, handling, management, and disposal of waste. The existing solid waste-management system is affected by unfavourable economic, institutional, legislative, technical, and operational constraints. The collection process is deficient in terms of manpower and vehicle availability. There is no treatment provided to the wastes dumped into an open land at Ganfoudah site after collection. Lack of suitable facilities and inadequate management and technical skills, improper bin collection, and route planning are among the issues resulting in poor collection and transportation of municipal solid wastes. The MSW management should be improved in terms of effectiveness of the MSW collection, transportation, and treatment. More effective efforts are also needed by involving the public in policymaking, development of service plans, implementation of future waste-management programs, and decision-making regarding landfill siting.

Chemical oxidation of treated textile effluent by hydrogen peroxide and fenton process

Abstract: In this study the possibility to apply the oxidation process for treating textile effluents, by using hydrogen peroxide and Fenton process was evaluated through determining the color and chemical oxygen demand (COD) removal. The experimental variables studied include the dosages of hydrogen peroxide and iron salts, oxidation time and pH value. The result showed that oxidation process using hydrogen peroxide alone is inefficient in COD and color removal, since only 25 % of COD removal and 21.3 % of color removal were obtained at 100 mg/L H2O2 dosage, pH 5 and 60 minutes contact time. Fenton process is normally used in textile wastewater treatment. However, in Malaysia, it is a new technology applied for treatment of textile effluents. Results obtained from this study showed that Fenton process is efficient in removing color. The color removal reaches a maximum of 90% at reaction time of 30 minutes under the action of the Fenton reagent. Although the COD removal is not very effective using Fenton process, in this study it still complies standard B in Environmental Quality Act, 1974. The percentage of COD removal obtained from this experiment is 67.1 % and the concentration is 85 mg/L under 125 mg/L H2O2 dosage, 3 mg/L Fe 2+ dosage and pH 4. From this study one may conclude that Fenton process for the treatment of textile effluent favors rather the removal of color than of COD.

Electrochemical treatment of semi-aerobic landfill leachate using Response Surface Methodology (RSM).

Abstract: This research investigated the effectiveness of electrochemical treatment in treating semi-aerobic landfill leachate. The electrolytic reactor assembly included a pair of aluminium electrodes, a power supply and NaCl as electrolyte. The interactive effects of initial COD, current density and reaction time on treated leachate quality were studied. Regression equations were developed using design-expert software and results were analysed using response surface methodology. At optimum conditions (2000 mg/L initial COD, about 17 mA/cm² current density, 4 h reaction time and 1 g/l NaCl), SCOD removal, BOD removal and colour removal were estimated to be 82.2, 81.5 and 95%, respectively.

A review of heavy metal pollution and potential removal techniques in malaysia

Abstract: The objective of the paper is to present information concerning sources if heavy metals to waste, harmful effects of heavy metals, the problems posed by the disposal and recycling of heavy metals and heavy metal containing products, and to assess the options for substituting the heavy metals. In recent years, some heavy metals such as cadmium, lead, zinc, nickel, copper and chromium (III) or their compounds have been used extensively by various industries thus leading to sharp increase in the contamination especially of water. Because of their toxicity, the presence of any of these metals in excessive quantities will interfere with many beneficial uses of the water. As a result, the standard B discharge limit of these metals under Environmental Quality Act 1974 of Malaysia, (Sewage and Industrial Effluents) 1979 are kept below 1.0 mg/l in which the standard for Cd is 0.02 mg/l, 0.50 mg/l for Pb, 1.0 mg/l each for Zn, Ni, Cu and Cr (III). Despite of their potential toxicity, many of these metals are widely used, particularly by industries, which rely on solutions of the metallic ions. This paper reviews heavy metals pollution in Malaysia and potential removal techniques, which may be suitable to overcome the problem.