Displaying publications 1 - 20 of 481 in total

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  1. Molla AH, Fakhru'l-Razi A, Abd-Aziz S, Hanafi MM, Roychoudhury PK, Alam MZ
    Bioresour Technol, 2002 Dec;85(3):263-72.
    PMID: 12365494
    Twenty seven filamentous fungal strains representing five genera; Aspergillus, Penicillium, Trichoderma, Myriodontium and Pleurotus were isolated from four sources; domestic wastewater sludge cake (SC) from IWK (Indah Water Konsortium) wastewater treatment plant, palm oil mill effluent compost from Sri Ulu palm Oil Processing Mill, compost of plant debris, and fungal fruiting bodies from a rotten wood stump. Thirty-three strains/isolates were tested for their ability to convert domestic wastewater sludge into compost by assessing biomass production and growth rate on sludge enriched media. The strains/isolates Aspergillus niger, SS-T2008, WW-P1003 and RW-P1 512 produced the highest dry biomass at higher sludge supplemented culture media from their respective group (Aspergillus, Trichoderma, Penicillium and Basidiomycetes, respectively). This implied these strains are better adapted for growth at higher sludge rich substances, and subsequently may be efficient in bioconversion/biodegradation of sludge. The fungi isolated from ecological closely related sources were more amendable to adaptation in a sludge rich culture media.
  2. Najafpour GD, Shan CP
    Bioresour Technol, 2003 Jan;86(1):91-4.
    PMID: 12421015
    Kinetic studies of the enzymatic hydrolysis of molasses were conducted using glucoamylase. Central Sugar Refinery SDN BHD contains 13-20% glucose. The molasses was diluted and the kinetic experiments were conducted at 67 degrees C with 100-1000 mg/l of glucoamylase. The glucose contents of the molasses were enhanced after hydrolysis of molasses solution with 1000 mg/l glucoamylase. A Lineweaver-Burk plot was obtained based on enzyme kinetic data. The rate constant, Km and maximum reaction rate, Vmax for 500 mg/l of glucoamylase were 100 mmol/l (18 g/l) and 5 mmol/l min (0.9 g/l min), respectively. The maximum reaction rate, Vmax for 1000 mg/l of glucoamylase was doubled, to 100 mmol/l (18 g/l) and the rate constant, Km was the same for 500 mg/l of glucoamylase. The substrate inhibition model was noncompetitive based on the resulting Lineweaver-Burk plot for enzyme concentration of 500 and 1000 mg/l.
  3. Daud WM, Ali WS
    Bioresour Technol, 2004 May;93(1):63-9.
    PMID: 14987722
    A series of experiments were conducted to compare the pore development in palm-shell and coconut-shell-based activated carbons produced under identical experimental conditions. Carbonization and activation processes were carried out at 850 degrees C using a fluidized bed reactor. Within the range of burn-off studied, at any burn-off, the micropore and mesopore volumes created in palm-shell-based activated carbon were always higher than those of coconut-shell-based activated carbon. On macropore volume, for palm-shell-based activated carbon, the volume increased with increase in burn-off up to 30% and then decreased. However, for coconut-shell-based activated carbon, the change in macropore volume with burn-off was almost negligible but the absolute macropore volume decreased with burn-off.
  4. Najafpour G, Younesi H, Syahidah Ku Ismail K
    Bioresour Technol, 2004 May;92(3):251-60.
    PMID: 14766158
    Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilized cell reactor (ICR) was successfully carried out to improve the performance of the fermentation process. The fermentation set-up was comprised of a column packed with beads of immobilized cells. The immobilization of S. cerevisiae was simply performed by the enriched cells cultured media harvested at exponential growth phase. The fixed cell loaded ICR was carried out at initial stage of operation and the cell was entrapped by calcium alginate. The production of ethanol was steady after 24 h of operation. The concentration of ethanol was affected by the media flow rates and residence time distribution from 2 to 7 h. In addition, batch fermentation was carried out with 50 g/l glucose concentration. Subsequently, the ethanol productions and the reactor productivities of batch fermentation and immobilized cells were compared. In batch fermentation, sugar consumption and ethanol production obtained were 99.6% and 12.5% v/v after 27 h while in the ICR, 88.2% and 16.7% v/v were obtained with 6 h retention time. Nearly 5% ethanol production was achieved with high glucose concentration (150 g/l) at 6 h retention time. A yield of 38% was obtained with 150 g/l glucose. The yield was improved approximately 27% on ICR and a 24 h fermentation time was reduced to 7 h. The cell growth rate was based on the Monod rate equation. The kinetic constants (K(s) and mu(m)) of batch fermentation were 2.3 g/l and 0.35 g/lh, respectively. The maximum yield of biomass on substrate (Y(X-S)) and the maximum yield of product on substrate (Y(P-S)) in batch fermentations were 50.8% and 31.2% respectively. Productivity of the ICR were 1.3, 2.3, and 2.8 g/lh for 25, 35, 50 g/l of glucose concentration, respectively. The productivity of ethanol in batch fermentation with 50 g/l glucose was calculated as 0.29 g/lh. Maximum production of ethanol in ICR when compared to batch reactor has shown to increase approximately 10-fold. The performance of the two reactors was compared and a respective rate model was proposed. The present research has shown that high sugar concentration (150 g/l) in the ICR column was successfully converted to ethanol. The achieved results in ICR with high substrate concentration are promising for scale up operation. The proposed model can be used to design a lager scale ICR column for production of high ethanol concentration.
  5. Wan Rosli WD, Law KN, Zainuddin Z, Asro R
    Bioresour Technol, 2004 Jul;93(3):233-40.
    PMID: 15062817
    Caustic pulping of oil-palm frond-fiber strands was conducted following a central composite design using a two-level factorial plan involving three pulping variables (temperature: 160-180 degrees C, time: 1-2 h, alkali charge: 20-30% NaOH). Responses of pulp properties to the process variables were analyzed using a statistical software (DESIGN-EXPERT). The results indicated that frond-fiber strands could be pulped with ease to about 35-45% yield. Statistically, the reaction time was not a significant factor while the influences of the treatment temperature and caustic charge were in general significantly relative to the properties of the resultant pulps.
  6. Loh TC, Lee YC, Liang JB, Tan D
    Bioresour Technol, 2005 Jan;96(1):111-4.
    PMID: 15364088
    Vermicomposting is commonly adopted for the treatment of livestock organic wastes. In the present study, two types of livestock manure were used for culturing of the earthworm, Eisenia foetida. Each treatment group consisted of six replicates and worm vermicasts were examined after 5 weeks. The concentrations of total C, P and K in goat manure vermicasts were higher than those in cattle manure vermicasts. Cattle vermicasts had a higher N content than goat vermicasts but the C:N ratio of fresh manure was higher than that of vermicasts for both materials. Earthworm biomass and reproductive performance, in terms of number of worms after 5 weeks of experiment, were higher in cattle manure than in goat manure. The cocoon production per worm in cattle manure was higher than in goat manure. However, the hatchability of cocoons was not affected by manure treatments. In conclusion, cattle manure provided a more nutritious and friendly environment to the earthworms than goat manure.
  7. Ngah WS, Ab Ghani S, Kamari A
    Bioresour Technol, 2005 Mar;96(4):443-50.
    PMID: 15491825
    A batch adsorption system was applied to study the adsorption of Fe(II) and Fe(III) ions from aqueous solution by chitosan and cross-linked chitosan beads. The adsorption capacities and rates of Fe(II) and Fe(III) ions onto chitosan and cross-linked chitosan beads were evaluated. Chitosan beads were cross-linked with glutaraldehyde (GLA), epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE) in order to enhance the chemical resistance and mechanical strength of chitosan beads. Experiments were carried out as function of pH, agitation period, agitation rate and concentration of Fe(II) and Fe(III) ions. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Equilibrium data agreed very well with the Langmuir model. The kinetic experimental data correlated well with the second-order kinetic model, indicating that the chemical sorption was the rate-limiting step. Results also showed that chitosan and cross-linked chitosan beads were favourable adsorbers.
  8. Rahman RN, Geok LP, Basri M, Salleh AB
    Bioresour Technol, 2005 Mar;96(4):429-36.
    PMID: 15491823
    The physical factors affecting the production of an organic solvent-tolerant protease from Pseudomonas aeruginosa strain K was investigated. Growth and protease production were detected from 37 to 45 degrees C with 37 degrees C being the optimum temperature for P. aeruginosa. Maximum enzyme activity was achieved at static conditions with 4.0% (v/v) inoculum. Shifting the culture from stationary to shaking condition decreased the protease production (6.0-10.0% v/v). Extracellular organic solvent-tolerant protease was detected over a broad pH range from 6.0 to 9.0. However, the highest yield of protease was observed at pH 7.0. Neutral media increased the protease production compared to acidic or alkaline media.
  9. Alias Z, Tan IK
    Bioresour Technol, 2005 Jul;96(11):1229-34.
    PMID: 15734309
    In early attempts to isolate palm oil-utilising bacteria from palm oil mill effluent (POME), diluted liquid samples of POME were spread on agar containing POME as primary nutrient. 45 purified colonies were screened for intracellular lipids by staining with Sudan Black B. Of these, 10 isolates were positively stained. The latter were grown in a nitrogen-limiting medium with palm olein (a triglyceride) or saponified palm olein (salts of fatty acids) as carbon source. None of the isolates grew in the palm olein medium but all grew well in the saponified palm olein medium. Of the latter however, only one isolate was positively stained with Nile Blue A, indicating the presence of PHA. This method did not successfully generate bacterial isolates which could metabolise palm olein to produce PHA. An enrichment technique was therefore developed whereby a selective medium was designed. The latter comprised minerals and palm olein (1% w/v) as sole carbon source to which POME (2.5% v/v) was added as the source of bacteria. The culture was incubated with shaking at 30 degrees C for 4 weeks. Out of seven isolates obtained from the selective medium, two isolates, FLP1 and FLP2, could utilise palm olein for growth and production of the homopolyester, poly(3-hydroxybutyrate). FLP1 is gram-negative and is identified (BIOLOG) to have 80% similarity to Burkholderia cepacia. When grown with propionate or valerate, FLP1 produced a copolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate).
  10. Rahman IA, Saad B, Shaidan S, Sya Rizal ES
    Bioresour Technol, 2005 Sep;96(14):1578-83.
    PMID: 15978990
    Phosphoric acid (H(3)PO(4)) and sodium hydroxide (NaOH) treated rice husks, followed by carbonization in a flowing nitrogen were used to study the adsorption of malachite green (MG) in aqueous solution. The effect of adsorption on contact time, concentration of MG and adsorbent dosage of the samples treated or carbonized at different temperatures were investigated. The results reveal that the optimum carbonization temperature is 500 degrees C in order to obtain adsorption capacity that is comparable to the commercial activated carbon for the husks treated by H(3)PO(4). It is interesting to note that MG adsorbed preferably on carbon-rich than on silica rich-sites. It is found that the behaviour of H(3)PO(4) treated absorbent followed both the Langmuir and Freundlich models while NaOH treated best fitted to only the Langmuir model.
  11. Hashim R, How LS, Kumar RN, Sulaiman O
    Bioresour Technol, 2005 Nov;96(16):1826-31.
    PMID: 16051090
    The flame retardancy of medium density fiberboard (MDF) made from mixture of rubberwood fibers and recycled old corrugated containers was studied. Aluminum trihydroxide (ATH) was used as a fire retardant additive and mixed with the fibers to manufacture experimental MDF panels using wet process. Phenol formaldehyde (PF) resin in liquid, 2% based on oven dry weight of fibers, was used along with 0%, 10%, 15% and 20% of ATH. The flame retardant test was done using the limiting oxygen index (LOI) test. The other properties investigated include internal bond strength, thickness swelling and water absorption. The results showed that ATH loading increased as the LOI of MDF increased. This demonstrated that ATH could improved the fire retardant property of MDF at sufficient loading. An increase in concentration of ATH showed an increase in the IB values of MDF made without resin. MDF panels made without resin showed a progressive increase in internal bond as the composition of recycled old corrugated containers fiber increased. Addition of resin improved internal bond strength and reduced thickness swelling, and water absorption. Thickness swelling of panel increased as the composition of recycled old corrugated containers fiber increased. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) showed that there is indication of ATH and resin filling the void space in between fibers.
  12. Zulkali MM, Ahmad AL, Norulakmal NH
    Bioresour Technol, 2006 Jan;97(1):21-5.
    PMID: 15963716
    The effects of initial concentration of lead, temperature, biomass loading and pH were investigated for an optimized condition of lead uptake from the aqueous solution. The optimization process was analyzed using Central Composite Face-Centered Experimental Design in Response Surface Methodology (RSM) by Design Expert Version 5.0.7 (StatEase, USA). The design was employed to derive a statistical model for the effect of parameters studied on the removal of lead ion from aqueous solution. The coefficient of determination, R2 was found to be 92.36%. The initial concentration of 50.0 mg/L, temperature of 60 degrees C, biomass loading of 0.2 g and pH of 5.0 had been found to be the optimum conditions for the maximum uptake of lead ions in 98.11% batch mode. Under the optimum conditions, the lead uptake was attained to be circa 8.60 mg/g.
  13. Vikineswary S, Abdullah N, Renuvathani M, Sekaran M, Pandey A, Jones EB
    Bioresour Technol, 2006 Jan;97(1):171-7.
    PMID: 15967661
    A comparative study on solid substrate fermentation (SSF) of sago 'hampas', oil palm frond parenchyma tissue (OPFPt) and rubberwood sawdust with Pycnoporus sanguineus for laccase production was carried out. Optimal mycelial growth of Pyc. sanguineus was observed on all the substrates studied over a 21 days time-course fermentation. Laccase productivity was highest during degradation of sago 'hampas' and OPFPt and a range from 7.5 to 7.6 U/g substrate on the 11th day of fermentation compared to degradation of rubberwood sawdust with a maximum laccase productivity of 5.7 U/g substrate on day 11 of SSF. Further optimization of laccase production was done by varying the inoculum age, density and nitrogen supplementation. SSF of OPFPt by Pyc. sanguineus gave maximum productivity of laccase of 46.5 U/g substrate on day 6 of fermentation with a 30% (w/w) of 4 weeks old inoculum and 0.92% nitrogen in the form of urea supplemented in the substrate. The extraction of laccase was also optimized in this study. Recovery of laccase was fourfold higher at 30.6 U/g substrate on day 10 of SSF using unadjusted tap water at pH 8.0 as extraction medium at 25+/-2 degrees C compared to laccase recovery of 7.46 U/g substrate using sodium acetate buffer at pH 4.8 at 4 degrees C. Further optimization showed that laccase recovery was increased by 50% with a value of 46.5 U/g substrate on day 10 of SSF when the extraction medium was tap water adjusted to pH 5.0 at 25+/-2 degrees C.
  14. Iluyemi FB, Hanafi MM, Radziah O, Kamarudin MS
    Bioresour Technol, 2006 Feb;97(3):477-82.
    PMID: 16216731
    Palm kernel cake (PKC), an agro-industrial by-product used extensively in the animal feed industry, has limited use in fish feeds due to its high fiber and low protein contents. In this study, PKC was processed under solid state culture conditions with five fungal strains and the effect of this fungal culturing on the amino acid, fatty acid, cellulose and hemicellulose fractions was evaluated. Fungal strains used were Sclerotium rolfsii, Trichoderma harzianum, Trichoderma longiobrachiatum, Trichoderma koninggi and Aspergillus niger. Fungal growth was carried out at 50% moisture level and 1% inoculum level for 7 days. A significant increase in protein content from 18.76% to 32.79% was obtained by growing T. longibrachiatum on PKC. Cellulose level decreased significantly from 28.31% to 12.11% for PKC cultured with T. longibrachiatum, and hemicellulose from 37.03% to 19.01% for PKC cultured with A. niger. Fungal culturing of PKC brought about an increase in the level of unsaturated- and a decrease in the level of the saturated-fatty acids.
  15. Sannasi P, Kader J, Ismail BS, Salmijah S
    Bioresour Technol, 2006 Mar;97(5):740-7.
    PMID: 16324841
    This paper reports the sorption of three metallic ions, namely Cr(VI), Cu(II) and Pb(II) in aqueous solution by a consortium culture (CC) comprising an acclimatised mixed bacterial culture collected from point and non-point sources. Metal sorption capability of growing and non-growing cells at initial pH of between 3 and 8 in the 1-100mg/L concentration range were studied based on Q(max) and K(f) values of the Langmuir and linearised Freundlich isotherm models, respectively. Maximal metal loading was generally observed to be dependent on the initial pH. Growing cells displayed significant maximal loading (Q(max)) for Pb(II) (238.09 mg/g) and Cu(II) (178.87 mg/g) at pH 6 and at pH 7 for Cr(VI) (90.91 mg/g) compared to non-growing cells (p < 0.05). At the pH range of 6-8, growing cells showed higher loading capacity compared to non-growing cells i.e. 38-52% for Cr, 17-28% for Cu and 3-17% for Pb. At lower metal concentrations and at more acidic pH (3-4) however, non-growing cells had higher metal loading capacity than growing cells. The metal sorption capacity for both populations were as follows: Pb(II) > Cu(II) > Cr(VI).
  16. Katayon S, Noor MJ, Asma M, Ghani LA, Thamer AM, Azni I, et al.
    Bioresour Technol, 2006 Sep;97(13):1455-60.
    PMID: 16213137
    Moringa oleifera is a plant whose seeds have coagulation properties for treating water and wastewater. In this study the coagulation efficiency of Moringa oleifera kept in different storage conditions were studied. The Moringa oleifera seeds were stored at different conditions and durations; open container and closed container at room temperature (28 degrees C) and refrigerator (3 degrees C) for durations of 1, 3 and 5 months. Comparison between turbidity removal efficiency of Moringa oleifera kept in refrigerator and room temperature revealed that there was no significant difference between them. The Moringa oleifera kept in refrigerator and room temperature for one month showed higher turbidity removal efficiency, compared to those kept for 3 and 5 months, at both containers. The coagulation efficiency of Moringa oleifera was found to be dependent on initial turbidity of water samples. Highest turbidity removals were obtained for water with very high initial turbidity. In summary coagulation efficiency of Moringa oleifera was found independent of storage temperature and container, however coagulation efficiency of Moringa oleifera decreased as storage duration increased. In addition, Moringa oleifera can be used as a potential coagulant especially for very high turbidity water.
  17. Sulaiman O, Hashim R, Wahab R, Ismail ZA, Samsi HW, Mohamed A
    Bioresour Technol, 2006 Dec;97(18):2466-9.
    PMID: 16524726
    Studies were carried out on heat treatment of bamboo species Gigantochloa scortechinii Gamble using palm oil. The samples were laminated and glued. The adhesion results showed that the delamination of glue line increased as the temperature and duration of oil heat treatment increased. Maximum load and shear strength of the glue line reduced as the heat treatment become more severe. It was found that the palm oil used as the heating medium penetrated in some parts of the cell wall as well as in the cell lumen of the bamboo.
  18. Issabayeva G, Aroua MK, Sulaiman NM
    Bioresour Technol, 2006 Dec;97(18):2350-5.
    PMID: 16321520
    The performance of a commercially available palm shell based activated carbon to remove lead ions from aqueous solutions by adsorption was evaluated. The adsorption experiments were carried out at pH 3.0 and 5.0. The effect of malonic and boric acid presence on the adsorption of lead ions was also studied. Palm shell activated carbon showed high adsorption capacity for lead ions, especially at pH 5 with an ultimate uptake of 95.2mg/g. This high uptake showed palm shell activated carbon as amongst the best adsorbents for lead ions. Boric acid presence did not affect significantly lead uptake, whereas malonic acid decreased it. The diffuse layer surface complexation model was applied to predict the extent of adsorption. The model prediction was found to be in concordance with the experimental values.
  19. Aziz HA, Alias S, Adlan MN, Faridah, Asaari AH, Zahari MS
    Bioresour Technol, 2007 Jan;98(1):218-20.
    PMID: 16386895
    A study was conducted to investigate the efficiency of coagulation and flocculation processes for removing colour from a semi-aerobic landfill leachate from one of the landfill sites in Malaysia. Four types of coagulant namely aluminium (III) sulphate (alum), ferric (III) chloride, ferrous (II) sulphate and ferric (III) sulphate were studied using standard jar test apparatus. Results indicated that ferric chloride was superior to the other coagulants and removed 94% of colour at an optimum dose of 800 mg/l at pH 4. The effect of coagulant dosages on colour removal showed similar trend as for COD, turbidity and suspended solids. This suggested that colour in landfill leachate was mainly contributed by organic matters with some insoluble forms that exhibited turbidity and suspended solids readings. The results from this study suggested that ferric chloride could be a viable coagulant in managing colour problems associated with landfill leachate.
  20. Adinata D, Wan Daud WM, Aroua MK
    Bioresour Technol, 2007 Jan;98(1):145-9.
    PMID: 16380249
    Palm shell was used to prepare activated carbon using potassium carbonate (K2CO3) as activating agent. The influence of carbonization temperatures (600-1000 degrees C) and impregnation ratios (0.5-2.0) of the prepared activated carbon on the pore development and yield were investigated. Results showed that in all cases, increasing the carbonization temperature and impregnation ratio, the yield decreased, while the adsorption of CO2 increased, progressively. Specific surface area of activated carbon was maximum about 1170 m2/g at 800 degrees C with activation duration of 2 h and at an impregnation ratio of 1.0.
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