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Articles by A.L. Ahmad
Total Records ( 8 ) for A.L. Ahmad
  A.L. Ahmad and C.Y. Chan
  Malaysia is the largest producer of palm oil, the processing of oil palm Fresh Fruit Bunches (FFB) has resulted large amount Palm Oil Mill Effluent (POME). The highly polluting POME is identified as the major stumbling block to the development of palm oil industry in Malaysia. Hence, an integrated membrane process with physical-chemical treatment had been successfully achieved for treatment of POME. The role of membrane was explored significantly; where the chemical treated POME was further treated using ultrafiltration and reverse osmosis membrane. The concept of sustainable development in palm oil industries is achieved by recovering and recycling the crystal clear water and sludge as organic fertilizer from POME back to its process and plantations using the innovative membrane treatment. Consequently, zero discharge is achieved by eliminating the discharge of POME into the rivers.
  N.A. Abdullah Sani , A.L. Ahmad and S.H.S. Zein
  Defect-free SrCo0.8Fe0.2O3 perovskite-dispersed titania (perovskite-titania) membrane was successfully prepared by sol-gel method combined with wet impregnation process. In this experiment, titania membrane was immersed in a perovskite solution, dried and calcined to obtain perovskite dispersed in titania membrane. The phase composition and membrane morphology of the membrane were characterized by thermogravimetric analysis (TGA), X-Ray Diffraction (XRD) spectroscopy, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The TEM result demonstrated that perovskite particles were well-dispersed among the titania particles. The SEM analysis showed that a uniform membrane approximately 0.5 μm thick on titania support was obtained after multiple coatings and calcination at 400°C. O2 and N2 permeability across the perovskite-titania membrane was measured to investigate membrane performance. From the permeability result, both gases appeared to decrease as the operating temperature increased, indicating that surface diffusion gradually reduced. The separation of O2 from its binary mixtures containing N2 was possible because the value of separation factor N2/O2 was slightly higher than the theoretical Knudsen diffusion.
  N.R. Sajuni , A.L. Ahmad and V.M. Vadivelu
  Biological filtration in the broadest sense includes any filtration technique that utilizes biological (living) organisms to remove impurities from the wastewater. Filter media selection is critical in the operation to achieve effluent quality requirements. The most important is to choose the correct types of filter media. Laboratory studies were conducted to evaluate the optimum ammonia removal performance using four different types of filter media (Ceramic Ring A, Ceramic Ring B, Japanese Filter Mat and Filter Wool) at different ammonia loading rates of 20 until 120 mg L-1. Ceramic Ring A has been found to give the best performance with respect to their efficiency of ammonia removal because of high surface area and characteristic roughness. In general, nitrification is most efficient at pH levels ranging from about 7.5 to 9.0. Water temperature was kept between (27 and 30°C). Nitrification efficiency is slower at lower temperatures.
  A.L. Ahmad , C.Y. Chan , S.R. Abd Shukor and M.D. Mashitah
  Carotenes is one of the most important vitamin A precursor in human nutrition which has numerous advantages. Palm Oil Mill Effluent (POME) is wastewater which consists of carotenes in the oil and grease content. Therefore, adsorption chromatography is used to separate the carotenes from the oil and grease in POME. Several types of adsorbents, temperatures and mass loading were studied in the experiments. The 40°C and oil:adsorbent ratio of 1:5 was recommended to be the most suitable temperature and mass loading for separation of carotenes by adsorption chromatography. Silica gel also shows better quality of adsorbent in separation of carotenes in hexane fractions.
  W.J.N. Fernando , HuaChin Low and A.L. Ahmad
  Experiments of convective drying on thin slices (0.5 cm) of banana, cassava and pumpkin were carried out under three air temperatures of 85, 90 and 95°C at constant 2 m sec-1 of air velocity with and without application of infrared in the drying process. The drying characteristics included diffusion coefficient and activation energy were evaluated under the influence of the infrared radiation. Tutuncu model was used in order to evaluate the effective diffusion coefficient and activation energies of samples under different values of parameters of temperature and infrared conditions during drying. The results indicate that the effective diffusion coefficients increased with increasing of the air temperature and increase in the infrared radiation. The diffusion coefficient values were found to be between 1.85x10-9 to 7.02x10-9 m2 sec-1 for banana, 1.18x10-9 to 6.16x10-9 m2 sec-1 for cassava and 1.12x10-9 to 3.64x10-9 m2 sec-1 for pumpkin respectively for lowest temperature of 85°C and no infrared radiation to highest temperature of 95°C and highest infrared of 200 W. The activation energies were found to be between 15.89-19.75 kJ mol-1 for banana, 26.44-32.85 kJ mol-1 for cassava and 27.83-29.26 kJ mol-1 for pumpkin respectively for the same condition.
  A.L. Ahmad , Z.H. Ban and B.S. Ooi
  Shear stress on the membrane surface has been proven very important in reducing concentration polarization and cake layer formation in membrane processes. This paper investigates the effect of rotation of membrane channels with high viscous feed solution on the membrane shear stress using Computational Fluid Dynamics (CFD). This study focus on two small membrane channels separated with corrugated spacer. The inner membrane was 39 mm and outer membrane was 41.5 mm from the axis of rotation. The feed solution viscosity used for the simulation was 0.0025 Pa•s and the inlet feed velocity was 2 m sec-1. The membrane shear stress is found out to be increasing with rotation speed. The shear stress on the outer membrane is also higher than inner membrane. There are three forces acting on the fluid flow in the membrane channels, namely pressure force, centrifugal force and tangential force. The rotation of the corrugated membrane channels can be applied to the spiral wound membrane module so that the membrane shear stress can be increased.
  A.L. Ahmad , N. Ideris , B.S. Ooi , S.C. Low and A. Ismail
  This study was aimed to study the influence of different PVDF membrane morphology on the adsorption of single proteins. Porous, symmetric PVDF membranes were prepared from PVDF/NMP solution by the phase inversion process. In this paper, the influence of polymer concentration in the 10.0-22.0 wt.% interval for the batchwise protein adsorption of BSA was investigated. The effect of polymer concentration on pore size distribution and surface morphology has been studied under capillary flow porometer and Scanning Electron Microscopy (SEM) respectively, which were further supported with the porosity test. All the synthesized membranes have a small range of pore size distribution with the decreased in pore size as the polymer concentration increased. It was found the membrane made of semi-crystalline PVDF showed a significant morphology change. For membrane performance, protein binding capacity showed the highest protein being retained at an optimum membrane formulation.
  S. Ismail , I. Idris , Y.T. Ng and A.L. Ahmad
  Aluminum sulfate or alum is traditionally used as a coagulant in wastewater treatment since it has proven its effectiveness in the removal suspended solid. In the current study, coagulation process is used as a pre-treatment to remove the high content of the suspended solids for membrane distillation treatment in raw Palm Oil Mill Effluent (POME) at high temperature. The performance in term of percentage suspended solids removal was evaluated to identify the optimum conditions for each of temperatures (30, 50, 60, 70 and 80°C). The operating parameters for the coagulation process which are coagulant dosages (1-6 g L-1) and pH (4-8). The optimum temperature for coagulation process was found at 50°C with pH (6.5) and coagulant dosage (4 g L-1). Thus, these finding shows it can be used as pretreatment before further treat by membrane distillation (MD) treatment.
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