Displaying publications 1 - 20 of 46 in total

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  1. Ong SY, Zainab-L I, Pyary S, Sudesh K
    Appl Microbiol Biotechnol, 2018 Mar;102(5):2117-2127.
    PMID: 29404644 DOI: 10.1007/s00253-018-8788-9
    Polyhydroxyalkanoate (PHA) is a family of microbial polyesters that is completely biodegradable and possesses the mechanical and thermal properties of some commonly used petrochemical-based plastics. Therefore, PHA is attractive as a biodegradable thermoplastic. It has always been a challenge to commercialize PHA due to the high cost involved in the biosynthesis of PHA via bacterial fermentation and the subsequent purification of the synthesized PHA from bacterial cells. Innovative enterprise by researchers from various disciplines over several decades successfully reduced the cost of PHA production through the efficient use of cheap and renewable feedstock, precisely controlled fermentation process, and customized bacterial strains. Despite the fact that PHA yields have been improved tremendously, the recovery and purification processes of PHA from bacterial cells remain exhaustive and require large amounts of water and high energy input besides some chemicals. In addition, the residual cell biomass ends up as waste that needs to be treated. We have found that some animals can readily feed on the dried bacterial cells that contain PHA granules. The digestive system of the animals is able to assimilate the bacterial cells but not the PHA granules which are excreted in the form of fecal pellets, thus resulting in partial recovery and purification of PHA. In this mini-review, we will discuss this new concept of biological recovery, the selection of the animal model for biological recovery, and the properties and possible applications of the biologically recovered PHA.
    Matched MeSH terms: Waste Products/analysis*
  2. Ryan PG
    Mar Pollut Bull, 2013 Apr 15;69(1-2):128-36.
    PMID: 23415747 DOI: 10.1016/j.marpolbul.2013.01.016
    A size and distance-based technique was used to assess the distribution, abundance and composition of floating marine debris in the northeast Indian Ocean. Densities of floating litter (>1 cm) were greater and more variable in the Straits of Malacca (578±219 items km(-2)) than in oceanic waters of the Bay of Bengal (8.8±1.4 items km(-2)). The density of debris in the Straits was correlated with terrestrial vegetation, and peaked close to urban centres, indicating the predominance of land-based sources. In the Bay of Bengal, debris density increased north of 17°N mainly due to small fragments probably carried in run-off from the Ganges Delta. The low densities in the Bay of Bengal relative to model predictions may result from biofouling-induced sinking and wind-driven export of debris items. Standardised data collection protocols are needed for counts of floating debris, particularly as regards the size classes used, to facilitate comparisons among studies.
    Matched MeSH terms: Waste Products/analysis*
  3. Fung WY, Yuen KH, Liong MT
    J Agric Food Chem, 2011 Aug 10;59(15):8140-7.
    PMID: 21711050 DOI: 10.1021/jf2009342
    This study explored the potential of soluble dietary fiber (SDF) from agrowastes, okara (soybean solid waste), oil palm trunk (OPT), and oil palm frond (OPF) obtained via alkali treatment, in the nanoencapsulation of Lactobacillus acidophilus . SDF solutions were amended with 8% poly(vinyl alcohol) to produce nanofibers using electrospinning technology. The spinning solution made from okara had a higher pH value at 5.39 ± 0.01 and a higher viscosity at 578.00 ± 11.02 mPa·s (P < 0.05), which resulted in finer fibers. FTIR spectra of nanofibers showed the presence of hemicellulose material in the SDF. Thermal behavior of nanofibers suggested possible thermal protection of probiotics in heat-processed foods. L. acidophilus was incorporated into the spinning solution to produce nanofiber-encapsulated probiotic, measuring 229-703 nm, visible under fluorescence microscopy. Viability studies showed good bacterial survivability of 78.6-90% under electrospinning conditions and retained viability at refrigeration temperature during the 21 day storage study.
    Matched MeSH terms: Waste Products/analysis*
  4. Shuokr Qarani Aziz, Hamidi Abdul Aziz, Mohammed Jk Bashir, Mohd Suffian Yusoff
    Waste Manag Res, 2011 Aug;29(8):880-7.
    PMID: 21242179 DOI: 10.1177/0734242X10387462
    Solid waste collection and disposal are among the most vital services provided to about 700 770 residents of the city of Erbil in northern Iraq. As such, proper waste management systems that consider both the quantity and composition of domestic solid waste are strongly required to address the increasing amount of solid waste. Unfortunately, these essential data are not easily available. The present study sought to gather data on the quantity and composition of domestic solid waste collected from different quarters in Erbil, and the feasibility of recycling these wastes. The solid waste generation rate (GR), uncompacted density, and weight percentages of combustible and incombustible materials were determined based on the collected materials (i.e., food, plastic, paper, metal, glass and cloth). The results show that the average GR and uncompacted density were 0.654 kg capita(-1) day(-1) and 175.72 kg m(-3), respectively. The weight percentages of food, plastic, paper, metal, glass, and cloth as components of domestic solid waste were 79.34, 6.28, 5.9, 3.6, 3.42 and 1.45%, respectively.
    Matched MeSH terms: Waste Products/analysis*
  5. Boey PL, Maniam GP, Hamid SA
    Bioresour Technol, 2009 Dec;100(24):6362-8.
    PMID: 19666218 DOI: 10.1016/j.biortech.2009.07.036
    A recent rise in crab aquaculture activities has intensified the generation of waste shells. In the present study, the waste shells were utilized as a source of calcium oxide to transesterify palm olein into methyl esters (biodiesel). Characterization results revealed that the main component of the shell is calcium carbonate which transformed into calcium oxide when activated above 700 degrees C for 2 h. Parametric studies have been investigated and optimal conditions were found to be methanol/oil mass ratio, 0.5:1; catalyst amount, 5 wt.%; reaction temperature, 65 degrees C; and a stirring rate of 500 rpm. The waste catalyst performs equally well as laboratory CaO, thus creating another low-cost catalyst source for producing biodiesel. Reusability results confirmed that the prepared catalyst is able to be reemployed up to 11 times. Statistical analysis has been performed using a Central Composite Design to evaluate the contribution and performance of the parameters on biodiesel purity.
    Matched MeSH terms: Waste Products/analysis*
  6. Khan MA, Ngabura M, Choong TS, Masood H, Chuah LA
    Bioresour Technol, 2012 Jan;103(1):35-42.
    PMID: 22055093 DOI: 10.1016/j.biortech.2011.09.065
    Biosorption potential of mustard oil cake (MOC) for Ni(II) from aqueous medium was studied. Spectroscopic studies showed possible involvement of acidic (hydroxyl, carbonyl and carboxyl) groups in biosorption. Optimum biosorption was observed at pH 8. Contact time, reaction temperature, biosorbent dose and adsorbate concentration showed significant influence. Linear and non-linear isotherms comparison suggests applicability of Temkin model at 303 and 313 K and Freundlich model at 323K. Kinetics studies revealed applicability of Pseudo-second-order model. The process was endothermic and spontaneous. Freundlich constant (n) and activation energy (Ea) values confirm physical nature of the process. The breakthrough and exhaustive capacities for 5 mg/L initial Ni(II) concentration were 0.25 and 4.5 mg/g, while for 10 mg/L initial Ni(II) concentration were 4.5 and 9.5 mg/g, respectively. Batch desorption studies showed maximum Ni(II) recovery in acidic medium. Regeneration studies by batch and column process confirmed reutilization of biomass without appreciable loss in biosorption.
    Matched MeSH terms: Waste Products/analysis*
  7. Goudarzi M, Mir N, Mousavi-Kamazani M, Bagheri S, Salavati-Niasari M
    Sci Rep, 2016 09 01;6:32539.
    PMID: 27581681 DOI: 10.1038/srep32539
    In this work, two natural sources, including pomegranate peel extract and cochineal dye were employed for the synthesis of silver nanoparticles. The natural silver complex from pomegranate peel extract resulted in nano-sized structures through solution-phase method, but this method was not efficient for cochineal dye-silver precursor and the as-formed products were highly agglomerated. Therefore, an alternative facile solid-state approach was investigated as for both natural precursors and the results showed successful production of well-dispersed nanoparticles with narrow size distribution for cochineal dye-silver precursor. The products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray microanalysis (EDX), and Transmission Electron Microscopy (TEM).
    Matched MeSH terms: Waste Products/analysis
  8. Lim SL, Wu TY
    J Agric Food Chem, 2016 Mar 2;64(8):1761-9.
    PMID: 26844586 DOI: 10.1021/acs.jafc.6b00531
    The valorization process involves transforming low-value materials such as wastes into high-value-added products. The current study aims to determine the potential of using a valorization process such as vermicomposting technology to convert palm oil mill byproduct, namely, decanter cake (DC), into organic fertilizer or vermicompost. The maturity of the vermicompost was characterized through various chemical and instrumental characterization to ensure the end product was safe and beneficial for agricultural application. The vermicomposting of DC showed significantly higher nutrient recovery and decreases in C:N ratio in comparison with the controls, particularly in the treatment with 2 parts DC and 1 part rice straw (w/w) (2DC:1RS). 2DC:1RS vermicompost had a final C:N ratio of 9.03 ± 0.12 and reasonably high levels of calcium (1.13 ± 0.05 g/kg), potassium (25.47 ± 0.32 g/kg), magnesium (4.87 ± 0.19 g/kg), sodium (7.40 ± 0.03 g/kg), and phosphorus (3.62 ± 0.27 g/kg). In addition, instrumental characterization also revealed a higher degree of maturity in the vermicompost. Ratios of 2921:1633 and DTG2:DTG3 also showed significant linear correlations with the C:N ratio, implying that those ratios could be used to characterize the progression of vermicompost maturity during the valorization process of DC.
    Matched MeSH terms: Waste Products/analysis*
  9. Haslinda WH, Cheng LH, Chong LC, Noor Aziah AA
    Int J Food Sci Nutr, 2009;60 Suppl 4:232-9.
    PMID: 19449278 DOI: 10.1080/09637480902915525
    Flour was prepared from peeled and unpeeled banana Awak ABB. Samples prepared were subjected to analysis for determination of chemical composition, mineral, dietary fibre, starch and total phenolics content, antioxidant activity and pasting properties. In general, flour prepared from unpeeled banana was found to show enhanced nutrition values with higher contents of mineral, dietary fibre and total phenolics. Hence, flour fortified with peel showed relatively higher antioxidant activity. On the other hand, better pasting properties were shown when banana flour was blended with peel. It was found that a relatively lower pasting temperature, peak viscosity, breakdown, final viscosity and setback were evident in a sample blended with peel.
    Matched MeSH terms: Waste Products/analysis
  10. Ang TN, Ngoh GC, Chua AS
    Bioresour Technol, 2013 May;135:116-9.
    PMID: 23138072 DOI: 10.1016/j.biortech.2012.09.045
    The performance of alkalis (NaOH and Ca(OH)2) and acids (H2SO4, HCl, H3PO4, CH3COOH, and HNO3) in the pretreatment of rice husk was screened, and a suitable reagent was assessed for subsequent optimization using response surface methodology. From the assessment, HCl that hydrolysed rice husk well was optimized with three parameters (HCl loading, pretreatment duration, and temperature) using Box-Behnken Design. The optimized condition (0.5% (w/v) HCl loading, 125 °C, 1.5 h) is relatively mild, and resulted in ~22.3mg TRS/ml hydrolysate. The reduced model developed has good predictability, where the predicted and experimental results differ by only 2%. The comprehensive structural characterization studies that involved FT-IR, XRD, SEM, and BET surface area determination showed that the pretreated rice husk consisted mainly of cellulose and lignin. Compared to untreated rice husk, pretreated rice husk possessed increased pore size and pore volume, which are expected to be beneficial for fungal growth during fermentation.
    Matched MeSH terms: Waste Products/analysis*
  11. Chai EW, H'ng PS, Peng SH, Wan-Azha WM, Chin KL, Chow MJ, et al.
    Environ Technol, 2013 Sep-Oct;34(17-20):2859-66.
    PMID: 24527651
    In Malaysia, large amounts of organic materials, which lead to disposal problems, are generated from agricultural residues especially from palm oil industries. Increasing landfill costs and regulations, which limit many types of waste accepted at landfills, have increased the interest in composting as a component of waste management. The objectives of this study were to characterize compost feedstock properties of common organic waste materials available in Malaysia. Thus, a ratio modelling of matching ingredients for empty fruit bunches (EFBs) co-composting using different organic materials in Malaysia was done. Organic waste materials with a C/N ratio of < 30 can be applied as a nitrogen source in EFB co-composting. The outcome of this study suggested that the percentage of EFB ranged between 50% and 60%, which is considered as the ideal mixing ratio in EFB co-composting. Conclusively, EFB can be utilized in composting if appropriate feedstock in term of physical and chemical characteristics is coordinated in the co-composting process.
    Matched MeSH terms: Waste Products/analysis*
  12. Tai WY, Tan JS, Lim V, Lee CK
    Biotechnol Prog, 2019 05;35(3):e2781.
    PMID: 30701709 DOI: 10.1002/btpr.2781
    The high cost of cellulases remains the most significant barrier to the economical production of bio-ethanol from lignocellulosic biomass. The goal of this study was to optimize cellulases and xylanase production by a local indigenous fungus strain (Aspergillus niger DWA8) using agricultural waste (oil palm frond [OPF]) as substrate. The enzyme production profile before optimization indicated that the highest carboxymethyl cellulose (CMCase), filter paper (FPase), and xylanase activities of 1.06 U/g, 2.55 U/g, and 2.93 U/g were obtained on day 5, day 4, and day 5 of fermentation, respectively. Response surface methodology was used to study the effects of several key process parameters in order to optimize cellulase production. Of the five physical and two chemical factors tested, only moisture content of 75% (w/w) and substrate amount of 2.5 g had statistically significant effect on enzymes production. Under optimized conditions of 2.5 g of substrate, 75% (w/w) moisture content, initial medium of pH 4.5, 1 × 106 spores/mL of inoculum, and incubation at ambient temperature (±30°C) without additional carbon and nitrogen, the highest CMCase, FPase, and xylanase activities obtained were 2.38 U/g, 2.47 U/g, and 5.23 U/g, respectively. Thus, the optimization process increased CMCase and xylanase production by 124.5 and 78.5%, respectively. Moreover, A. niger DWA8 produced reasonably good cellulase and xylanase titers using OPF as the substrate when compared with previous researcher finding. The enzymes produced by this process could be further use to hydrolyze biomass to generate reducing sugars, which are the feedstock for bioethanol production.
    Matched MeSH terms: Waste Products/analysis
  13. Prasetyoko D, Ramli Z, Endud S, Hamdan H, Sulikowski B
    Waste Manag, 2006;26(10):1173-9.
    PMID: 16274981
    White rice husk ash (RHA), an agriculture waste containing crystalline tridymite and alpha-cristobalite, was used as a silica source for zeolite Beta synthesis. The crystallization of zeolite Beta from RHA at 150 degrees C in the presence of tetraethylammonium hydroxide was monitored by XRD, FTIR and (29)Si MAS NMR techniques. It was found that zeolite Beta started to form after 12h and the complete crystallization of zeolite Beta phase was achieved after 2d. XRD, (29)Si MAS NMR and solid yield studies indicate that the transformation mechanism of silica present in RHA to zeolite Beta involves dissolution of the ash, formation of an amorphous aluminosilicate after 6h of crystallization, followed by dissolution in the mother liquor and final transformation to pure zeolite Beta crystals.
    Matched MeSH terms: Waste Products/analysis*
  14. Auta HS, Emenike CU, Fauziah SH
    Environ Int, 2017 May;102:165-176.
    PMID: 28284818 DOI: 10.1016/j.envint.2017.02.013
    The presence of microplastics in the marine environment poses a great threat to the entire ecosystem and has received much attention lately as the presence has greatly impacted oceans, lakes, seas, rivers, coastal areas and even the Polar Regions. Microplastics are found in most commonly utilized products (primary microplastics), or may originate from the fragmentation of larger plastic debris (secondary microplastics). The material enters the marine environment through terrestrial and land-based activities, especially via runoffs and is known to have great impact on marine organisms as studies have shown that large numbers of marine organisms have been affected by microplastics. Microplastic particles have been found distributed in large numbers in Africa, Asia, Southeast Asia, India, South Africa, North America, and in Europe. This review describes the sources and global distribution of microplastics in the environment, the fate and impact on marine biota, especially the food chain. Furthermore, the control measures discussed are those mapped out by both national and international environmental organizations for combating the impact from microplastics. Identifying the main sources of microplastic pollution in the environment and creating awareness through education at the public, private, and government sectors will go a long way in reducing the entry of microplastics into the environment. Also, knowing the associated behavioral mechanisms will enable better understanding of the impacts for the marine environment. However, a more promising and environmentally safe approach could be provided by exploiting the potentials of microorganisms, especially those of marine origin that can degrade microplastics.

    CAPSULE: The concentration, distribution sources and fate of microplastics in the global marine environment were discussed, so also was the impact of microplastics on a wide range of marine biota.

    Matched MeSH terms: Waste Products/analysis*
  15. Naganathan S, Razak HA, Hamid SN
    Waste Manag Res, 2010 Sep;28(9):848-60.
    PMID: 20852000 DOI: 10.1177/0734242X09355073
    Incineration of industrial waste produces large quantities of bottom ash which are normally sent to secured landfill, but is not a sustainable solution. Use of bottom ash in engineering applications will contribute to sustainability and generate revenue. One way of using the industrial waste incineration bottom ash is in controlled low-strength material (CLSM). Use of bottom ash in CLSM has problems related to bleeding and excessive strength development and so an additive has to be used to control bleeding and strength development. The main objective of this research is to study the effect of kaolin addition on the performance of CLSM made using industrial waste incineration bottom ash. CLSM mixes were made with bottom ash, cement, and refined kaolin. Various tests were performed on the CLSM in fresh and hardened states including compressive strength, water absorption, California bearing ratio (CBR) and the tests for concentration of leachable substances on the bleed and leachate. The compressive strength of CLSM tested ranged from 0.11 to 9.86 MPa. CBR values ranged from 6 to 46, and water absorption values from 12 to 36%. It was shown that the addition of kaolin delayed the initial setting time of CLSM mixtures, reduced bleeding, lowered the compressive strength, and increased the values of water absorption, sorption, and initial surface absorption. The CLSM tested did not have corrosivity. It was shown that the hardened CLSM was non hazardous, and the addition of kaolin increased the concentration of heavy metals and salts in the bleed and leachate.
    Matched MeSH terms: Waste Products/analysis*
  16. Tanimu MI, Mohd Ghazi TI, Harun MR, Idris A
    Appl Microbiol Biotechnol, 2015 May;99(10):4509-20.
    PMID: 25761621 DOI: 10.1007/s00253-015-6486-4
    Foaming problem which occurred occasionally during food waste (FW) anaerobic digestion (AD) was investigated with the Malaysian FW by stepwise increase in organic loading (OL) from 0.5 to 7.5 g VS/L. The FW feedstock with carbon to nitrogen (C/N) ratio of 17 was upgraded to C/N ratio of 26 and 30 by mixing with other wastes. The digestion which was carried out at 37 °C in 1-L batch reactors showed that foam formation initiated at OL of 1.5 g VS/L and was further enhanced as OL of feedstock was increased. The digestion foaming reached its maximum at OL of 5.5 g VS/L and did not increase further even when OL was increased to 7.5 g VS/Ld. Increase in the C/N ratio of feedstock significantly enhanced the microbial degradation activity, leading to better removal of foam causing intermediates and reduced foaming in the reactor by up to 60%.
    Matched MeSH terms: Waste Products/analysis*
  17. Hosseini SM, Abdul Aziz H
    Bioresour Technol, 2013 Apr;133:240-7.
    PMID: 23428821 DOI: 10.1016/j.biortech.2013.01.098
    The effects of thermochemical pretreatment and continuous thermophilic conditions on the composting of a mixture of rice straw residue and cattle manure were investigated using a laboratory-scale composting reactor. Results indicate that the composting period of rice straw can be shortened to less than 10 days by applying alkali pre-treatment and continuous thermophilic composting conditions. The parameters obtained on day 9 of this study are similar to the criteria level published by the Canadian Council of Ministers of the Environment. The moisture content, organic matter reduction, pH level, electrical conductivity, total organic carbon reduction, soluble chemical oxygen demand reduction, total Kjeldahl nitrogen, carbon-to-nitrogen ratio, and germination index were 62.07%, 16.99%, 7.30%, 1058 μS/cm, 17.00%, 83.43%, 2.06%, 16.75%, and 90.33%, respectively. The results of this study suggest that the application of chemical-biological integrated processes under thermophilic conditions is a novel method for the rapid degradation and maturation of rice straw residue.
    Matched MeSH terms: Waste Products/analysis*
  18. Dieng H, Tan Yusop NS, Kamal NN, Ahmad AH, Ghani IA, Abang F, et al.
    J Agric Food Chem, 2016 May 11;64(18):3485-91.
    PMID: 27115536 DOI: 10.1021/acs.jafc.6b01157
    Dengue mosquitoes are evolving into a broader global public health menace, with relentless outbreaks and the rise in number of Zika virus disease cases as reminders of the continued hazard associated with Aedes vectors. The use of chemical insecticides-the principal strategy against mosquito vectors-has been greatly impeded due to the development of insecticide resistance and the shrinking spectrum of effective agents. Therefore, there is a pressing need for new chemistries for vector control. Tea contains hundreds of chemicals, and its waste, which has become a growing global environmental problem, is almost as rich in toxicants as green leaves. This paper presents the toxic and sublethal effects of different crude extracts of tea on Aedes albopictus. The survival rates of larvae exposed to tea extracts, especially fresh tea extract (FTE), were markedly lower than those in the control treatment group. In addition to this immediate toxicity against different developmental stages, the extracts tested caused a broad range of sublethal effects. The developmental time was clearly longer in containers with tea, especially in those with young larvae (YL) and FTE. Among the survivors, pupation success was reduced in containers with tea, which also produced low adult emergence rates with increasing tea concentration. The production of eggs tended to be reduced in females derived from the tea treatment groups. These indirect effects of tea extracts on Ae. albopictus exhibited different patterns according to the exposed larval stage. Taken together, these findings indicate that tea and its waste affect most key components of Ae. albopictus vectorial capacity and may be useful for dengue control. Reusing tea waste in vector control could also be a practical solution to the problems associated with its pollution.
    Matched MeSH terms: Waste Products/analysis
  19. Gan S, Ng HK, Ooi CW, Motala NO, Ismail MA
    Bioresour Technol, 2010 Oct;101(19):7338-43.
    PMID: 20435468 DOI: 10.1016/j.biortech.2010.04.028
    In this work, the esterification of free fatty acids (FFA) in waste cooking oil catalysed by ferric sulphate was studied as a pre-treatment step for biodiesel production. The effects of reaction time, methanol to oil ratio, catalyst concentration and temperature on the conversion of FFA were investigated on a laboratory scale. The results showed that the conversion of FFA reached equilibrium after an hour, and was positively dependent on the methanol to oil molar ratio and temperature. An optimum catalyst concentration of 2 wt.% gave maximum FFA conversion of 59.2%. For catalyst loadings of 2 wt.% and below, this catalysed esterification was proposed to follow a pseudo-homogeneous pathway akin to mineral acid-catalysed esterification, driven by the H(+) ions produced through the hydrolysis of metal complex [Fe(H(2)O)(6)](3+) (aq).
    Matched MeSH terms: Waste Products/analysis*
  20. Wan-Mohtar WAAQI, Halim-Lim SA, Kamarudin NZ, Rukayadi Y, Abd Rahim MH, Jamaludin AA, et al.
    J Food Sci, 2020 Oct;85(10):3124-3133.
    PMID: 32860235 DOI: 10.1111/1750-3841.15402
    In a commercial oyster mushroom farm, from 300 g of the total harvest, only the cap and stem of the fruiting body parts are harvested (200 g) while the unused lower section called fruiting-body-base (FBB) is discarded (50 g). A new antioxidative FBB flour (FBBF) conversion to mixed-ratio chicken patty was recently developed which converts 16.67% of FBB into an edible flour. At the initial stage, pretreatments of FBBF were optimized at particle size (106 µm) and citric acid concentration (0.5 g/100 mL) to improve flour antioxidant responses. Such pretreatments boosted total phenolic content (2.31 ± 0.53 mg GAE/g) and DPPH (51.53 ± 1.51%) of pretreated FBBF. Mixed-ratio chicken patty containing FBBF (10%, 20%, 30%) significantly (P
    Matched MeSH terms: Waste Products/analysis*
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