Displaying publications 1 - 20 of 31 in total

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  1. A review of the treatment technologies for hexavalent chromium contaminated water
    Ramli NN, Kurniawan SB, Ighalo JO, Mohd Said NS, Marsidi N, Buhari J, et al.
    Biometals, 2023 May 20.
    PMID: 37209220 DOI: 10.1007/s10534-023-00512-x
    The toxicity of hexavalent chromium (Cr(VI)) present in the environment has exceeded the current limits or standards and thus may lead to biotic and abiotic catastrophes. Accordingly, several treatments, including chemical, biological, and physical approaches, are being used to reduce Cr(VI) waste in the surrounding environment. This study compares the Cr(VI) treatment approaches from several areas of science and their competence in Cr(VI) removal. As an effective combination of physical and chemical approaches, the coagulation-flocculation technique removes more than 98% of Cr(VI) in less than 30 min. Most membrane filtering approaches can remove up to 90% of Cr(VI). Biological approaches that involve the use of plants, fungi, and bacteria also successfully eliminate Cr(VI) but are difficult to scale up. Each of these approaches has its benefits and drawbacks, and their applicability is determined by the research aims. These approaches are also sustainable and environmentally benign, thus limiting their effects on the ecosystem.
  2. Effective microbes for simultaneous bio-oxidation of ammonia and manganese in biological aerated filter system
    Abu Hasan H, Abdullah SR, Kofli NT, Kamarudin SK
    Bioresour Technol, 2012 Nov;124:355-63.
    PMID: 22995166 DOI: 10.1016/j.biortech.2012.08.055
    This study determined the most effective microbes acting as ammonia-oxidising (AOB) and manganese-oxidising bacteria (MnOB) for the simultaneous removal of ammonia (NH(4)(+)-N) and manganese (Mn(2+)) from water. Two conditions of mixed culture of bacteria: an acclimatised mixed culture (mixed culture: MC) in a 5-L bioreactor and biofilm attached on a plastic medium (stages of mixed culture: SMC) in a biological aerated filter were isolated and identified using Biolog MicroSystem and 16S rRNA sequencing. A screening test for determining the most effective microbe in the removal of NH(4)(+)-N and Mn(2+) was initially performed using SMC and MC, respectively, and found that Bacillus cereus was the most effective microbe for the removal of NH(4)(+)-N and Mn(2+). Moreover, the simultaneous NH(4)(+)-N and Mn(2+) removal (above 95% removal for both NH(4)(+)-N and Mn(2+)) was achieved using a biological aerated filter under various operating conditions. Thus, the strain could act as an effective microbe of AOB and a MnOB for the simultaneous removal of NH(4)(+)-N and Mn(2+).
  3. Utilization of palm empty fruit bunch for the production of biodiesel from Jatropha curcas oil
    Yaakob Z, Sukarman IS, Narayanan B, Abdullah SR, Ismail M
    Bioresour Technol, 2012 Jan;104:695-700.
    PMID: 22113069 DOI: 10.1016/j.biortech.2011.10.058
    Transesterification reaction of Jatropha curcas oil with methanol was carried out in the presence of ash generated from Palm empty fruit bunch (EFB) in a heterogeneous catalyzed process. The ash was doped with KOH by impregnation to achieve a potassium level of 20 wt.%. Under optimum conditions for the EFB-catalyzed (65 °C, oil/methanol ratio of 15, 90 min, 20 wt.% EFB ash catalyst) and the KOH-EFB-catalyzed reactions (65 °C, oil/methanol ratio of 15, 45 min, 15 wt.% of KOH doped EFB ash), biodiesel (>98%) with specifications higher than those stipulated by European biodiesel quality standard EN 14214 was obtained.
  4. Arsenic toxicity on Ludwigia octovalvis in spiked sand
    Titah HS, Abdullah SR, Mushrifah I, Anuar N, Basri H, Mukhlisin M
    Bull Environ Contam Toxicol, 2013 Jun;90(6):714-9.
    PMID: 23595348 DOI: 10.1007/s00128-013-0996-5
    Wilting, especially of the leaves, was observed as an initial symptom of arsenate [As(V)] to Ludwigia octovalvis (Jacq.) P. H. Raven. The plants tolerated As(V) levels of 39 mg kg⁻¹ for as long as 35 days of exposure. After 91 days, the maximum concentration of As uptake in the plant occurred at As(V) concentration of 65 mg kg⁻¹ while As concentration in the stems, roots and leaves were 6139.9 ± 829.5, 1284.5 ± 242.9 and 1126.1 ± 117.2 mg kg⁻¹, respectively. In conclusion, As(V) could cause toxic effects in L. octovalvis and the plants could uptake and accumulate As in plant tissues.
  5. Lead (Pb) removal from contaminated water using constructed wetland planted with Scirpus grossus: Optimization using response surface methodology (RSM) and assessment of rhizobacterial addition
    Tangahu BV, Sheikh Abdullah SR, Basri H, Idris M, Anuar N, Mukhlisin M
    Chemosphere, 2022 Mar;291(Pt 3):132952.
    PMID: 34798103 DOI: 10.1016/j.chemosphere.2021.132952
    Lead (Pb) is one of the toxic heavy metals that pollute the environment as a result of industrial activities. This study aims to optimize Pb removal from water by using horizontal free surface flow constructed wetland (HFSFCW) planted with Scirpus grossus. Optimization was conducted using response surface methodology (RSM) under Box-Behnken design with the operational parameters of initial Pb concentration, retention time, and aeration. Optimization results showed that 37 mg/L of initial Pb concentration, 32 days of retention time, and no aeration were the optimum conditions for Pb removal by using the systems. Validation test was run under two different conditions, namely, non-bioaugmented and bioaugmented with rhizobacteria (Bacillus cereus, B. pumilus, B. subtilis, Brevibacillus choshinensis, and Rhodococcus rhodochrous). Results of the validation test showed that Pb removal in water achieved 99.99% efficiency with 0.2% error from the RSM prediction, while the adsorption of Pb by plants reached 5160.18 mg/kg with 10.6% error from the RSM prediction. The bioaugmentation of the five rhizobacterial species showed a slight improvement in Pb removal from water and Pb adsorption by plants. However, no significant improvement was achieved (p 
  6. Integrating phytoremediation and mycoremediation with biosurfactant-producing fungi for hydrocarbon removal and the potential production of secondary resources
    Ahmad J, Marsidi N, Sheikh Abdullah SR, Hasan HA, Othman AR, Ismail N', et al.
    Chemosphere, 2024 Feb;349:140881.
    PMID: 38048826 DOI: 10.1016/j.chemosphere.2023.140881
    Treatment of petroleum-contaminated soil to a less toxic medium via physical and chemical treatment is too costly and requires posttreatment. This review focuses on the employment of phytoremediation and mycoremediation technologies in cleaning hydrocarbon-contaminated soil which is currently rare. It is considered environmentally beneficial and possibly cost-effective as it implements the synergistic interaction between plants and biosurfactant producing mycorrhiza to degrade hydrocarbon contaminants. This review also covers possible sources of hydrocarbon pollution in water and soil, toxicity effects, and current technologies for hydrocarbon removal and degradation. In addition to these problems, this review also discusses the challenges and opportunities of transforming the resultant treated sludge and treating plants into potential by-products for a higher quality of life for future generations.
  7. Optimizing refuse-derived fuel production from scheduled wastes through Aspen plus simulation
    Zubir MA, Kamyab H, Vasseghian Y, Hashim H, Zhi OM, Abdullah SR, et al.
    Environ Res, 2024 Mar 11;251(Pt 2):118617.
    PMID: 38467362 DOI: 10.1016/j.envres.2024.118617
    This study aims to improve the quality of fuel with high calorific value namely Sfuel - a commercial high-quality refuse-derived fuel (RDF) from hazardous waste via modifying the process design and operating parameters of thermal conversion process. The study analyses key parameters of RDF quality, such as calorific value and heavy metal content, before and after process modifications based on the combination of experimental and simulation using Aspen Plus. In this study, the temperature and pressure of the simulation system are varied from 100 to 700 °C and from 1 to 5 bar, respectively. Findings indicate that there are a total of eleven heavy metals and 179 volatile compounds in the "Sfuels". The quality of the targeted product is greatly improved by the metal evaporation at high temperatures and pressures. However, the calorific value of RDF significantly decreases at 700 °C due to a large amount of the carbon content being evaporated. Although the carbon content at high temperatures is significantly lost, the heat from the vapour stream reactor outlet, which is reused to preheat the nitrogen gas stream supplied to the system, reduces energy consumption while improving the thermal conversion efficiency of the system. Besides, low pressure along with high temperature are not the optimal conditions for quality Sfuels improvement by thermal conversion. Results also indicate that electric heating is more economically efficient than natural gas heating.
  8. Performance evaluation of a granular activated carbon-sequencing batch biofilm reactor pilot plant system used in treating real wastewater from recycled paper industry
    Muhamad MH, Sheikh Abdullah SR, Mohamad AB, Rahman RA, Kadhum AA
    Environ Technol, 2012 Apr-May;33(7-9):915-26.
    PMID: 22720416
    A pilot scale granular activated carbon-sequencing batch biofilm reactor with a capacity of 2.2 m3 was operated for over three months to evaluate its performance treating real recycled paper industry wastewater under different operational conditions. In this study, dissolved air floatation (DAF) and clarifier effluents were used as influent sources of the pilot plant. During the course of the study, the reactor was able to biodegrade the contaminants in the incoming recycled paper mill wastewater in terms of chemical oxygen demand (COD), adsorbable organic halides (AOX; specifically 2,4-dichlorophenol (2,4-DCP)) and ammoniacal nitrogen (NH3-N) removal efficiencies at varying hydraulic retention times (HRTs) of 1-3 days, aeration rates (ARs) of 2.1-3.4 m3/min and influent feed concentration of 40-950 mg COD/l. Percentages of COD, 2,4-DCP and NH3-N removals increased with increasing HRT, resulting in more than 90% COD, 2,4-DCP and NH3-N removals at HRT values above two days. Degradation of COD, 2,4-DCP and NH3-N were seriously affected by variation of ARs, which resulted in significant decrease of COD, 2,4-DCP and NH3-N removals by decreasing ARs from 3.4 m3/min to 2.1 m3/min, varying in the ranges of 24-80%, 6-96% and 5-42%, respectively. In comparison to the clarifier effluent, the treatment performance of DAF effluent, containing high COD concentration, resulted in a higher COD removal of 82%. The use of diluted DAF effluent did not improve significantly the COD removal. Higher NH3-N removal efficiency of almost 100% was observed during operation after maintenance shutdown compared to normal operation, even at the same HRT of one day due to the higher dissolved oxygen concentrations (1-7 mg/l), while no significant difference in COD removal efficiency was observed.
  9. Cytotoxicity evaluation of ketoprofen found in pharmaceutical wastewater on HEK 293 cell growth and metabolism
    Zulkarnain NN, Anuar N, Johari NA, Sheikh Abdullah SR, Othman AR
    Environ Toxicol Pharmacol, 2020 Nov;80:103498.
    PMID: 32950717 DOI: 10.1016/j.etap.2020.103498
    Inefficient ketoprofen removal from pharmaceutical wastewater may negatively impact the ecosystem and cause detrimental risks to human health. This study was conducted to determine the cytotoxicity effects of ketoprofen on HEK 293 cell growth and metabolism, including cyclooxygenase-1 (COX-1) expression, at environmentally relevant concentrations. The cytotoxic effects were evaluated through the trypan blue test, DNS assay, MTT assay, and the expression ratio of the COX-1 gene. The results of this study show insignificant (p > 0.05) cytotoxic effects of ketoprofen on cell viability and cell metabolism. However, high glucose consumption rates among the treated cells cause an imitation of the Warburg effect, which is likely linked to the development of cancer cells. Apart from that, the upregulation of COX-1 expression among the treated cells indicates remote possibility of inflammation. Although no significant cytotoxic effects of ketoprofen were detected throughout this study, the effects of prolonged exposure of residual ketoprofen need to be evaluated in the future.
  10. Fulltext Cell-based influenza vaccine: current production, halal status assessment, and recommendations towards Islamic-compliant manufacturing
    Zulkarnain NN, Anuar N, Abd Rahman N, Sheikh Abdullah SR, Alias MN, Yaacob M, et al.
    Hum Vaccin Immunother, 2021 07 03;17(7):2158-2168.
    PMID: 33539195 DOI: 10.1080/21645515.2020.1865044
    Influenza virus is a life-threatening pathogen that infects millions of people every year, with annual mortality in the hundreds of thousands. The scenario for controlling infection has worsened with increasing numbers of vaccine hesitancy cases reported worldwide due to objections on safety, religious and other grounds. Uses of haram (impermissible) and mashbooh (doubtful) ingredients in vaccine production has raised doubts among Muslim consumers and consequently stimulated serious vaccine hesitancy. To address this major problem, we have reviewed and recommended some alternatives appropriate for manufacturing cell-based influenza vaccine which comply with Islamic laws and consumers' needs. Intensive assessments of current influenza vaccine production in both scientific and Islamic views have led to the identification of four main ingredients deemed impermissible in novel sharia-compliant (approved by Islamic laws) vaccine manufacturing. Only some of these impermissible components could be replaced with halal (permissible) alternatives, while others remain impermissible due to unavailability and unsuitability.
  11. Fulltext Design, Operation and Optimization of Constructed Wetland for Removal of Pollutant
    Rahman ME, Bin Halmi MIE, Bin Abd Samad MY, Uddin MK, Mahmud K, Abd Shukor MY, et al.
    Int J Environ Res Public Health, 2020 Nov 11;17(22).
    PMID: 33187288 DOI: 10.3390/ijerph17228339
    Constructed wetlands (CWs) are affordable and reliable green technologies for the treatment of various types of wastewater. Compared to conventional treatment systems, CWs offer an environmentally friendly approach, are low cost, have fewer operational and maintenance requirements, and have a high potential for being applied in developing countries, particularly in small rural communities. However, the sustainable management and successful application of these systems remain a challenge. Therefore, after briefly providing basic information on wetlands and summarizing the classification and use of current CWs, this study aims to provide and inspire sustainable solutions for the performance and application of CWs by giving a comprehensive review of CWs' application and the recent development of their sustainable design, operation, and optimization for wastewater treatment. To accomplish this objective, thee design and management parameters of CWs, including macrophyte species, media types, water level, hydraulic retention time (HRT), and hydraulic loading rate (HLR), are discussed. Besides these, future research on improving the stability and sustainability of CWs are highlighted. This article provides a tool for researchers and decision-makers for using CWs to treat wastewater in a particular area. This paper presents an aid for informed analysis, decision-making, and communication. The review indicates that major advances in the design, operation, and optimization of CWs have greatly increased contaminant removal efficiencies, and the sustainable application of this treatment system has also been improved.
  12. Phytotoxicity of wastewater containing lead (Pb) effects Scirpus grossus
    Tangahu BV, Abdullah SR, Basri H, Idris M, Anuar N, Mukhlisin M
    Int J Phytoremediation, 2013;15(8):814-26.
    PMID: 23819277
    Phytoremediation is an environment-friendly and cost-effective method to clean the environment of heavy metal contamination. A prolonged phytotoxicity test was conducted in a single exposure. Scirpus grossus plants were grown in sand to which the diluted Pb (NO3)2 was added, with the variation of concentration were 0, 100, 200, 400, 600, and 800 mg/L. It was found that Scirpus grossus plants can tolerate Pb at concentrations of up to 400 mg/L. The withering was observed on day-7 for Pb concentrations of 400 mg/L and above. 100% of the plants withered with a Pb concentration of 600 mg/L on day 65. The Pb concentration in water medium decreased while in plant tissues increased. Adsorption of Pb solution ranged between 2 to 6% for concentrations of 100 to 800 mg/L. The Bioaccumulation Coefficient and Translocation Factor of Scirpus grossus were found greater than 1, indicating that this species is a hyperaccumulator plant.
  13. Phytoremediation of wastewater containing lead (Pb) in pilot reed bed using Scirpus grossus
    Tangahu BV, Abdullah SR, Basri H, Idris M, Anuar N, Mukhlisin M
    Int J Phytoremediation, 2013;15(7):663-76.
    PMID: 23819266
    Phytoremediation is a technology to clean the environment from heavy metals contamination. The objectives of this study are to threat Pb contaminated wastewater by using phytoremediation technology and to determine if the plant can be mention as hyperaccumulator. Fifty plants of Scirpus grossus were grown in sand medium and 600 L spiked water in various Pb concentration (10, 30 and 50 mg/L) was exposed. The experiment was conducted with single exposure method, sampling time on day-1, day-14, day-28, day-42, day-70, and day-98. The analysis of Pb concentration in water, sand medium and inside the plant tissue was conducted by ICP-OES. Water samples were filtered and Pb concentration were directly analyzed, Pb in sand samples were extracted by EDTA method before analyzed, and Pb in plant tissues were extracted by wet digestion method and analyzed. The results showed that on day-28, Pb concentration in water decreased 100%, 99.9%, 99.7%, and the highest Pb uptake by plant were 1343, 4909, 3236 mg/kg for the treatment of 10, 30, and 50 mg/L respectively. The highest BC and TF were 485,261 on day-42 and 2.5295 on day-70 of treatment 30 mg/L, it can be mentioned that Scirpus grossus is a hyperaccumulator.
  14. Fulltext The Effect of a Combined Intermittent Fasting Healthy Plate Intervention on Anthropometric Outcomes and Body Composition Among Adults With Overweight and Obesity: Nonrandomized Controlled Trial
    Abdullah SR, Wan Mohd Zin RM, Azizul NH, Sulaiman NS, Khalid NM, Mohd Salim Mullahi Jahn RJ, et al.
    JMIR Form Res, 2024 Apr 10;8:e51542.
    PMID: 38598283 DOI: 10.2196/51542
    BACKGROUND: Adult obesity and overweight pose a substantial risk to global public health and are associated with various noncommunicable diseases. Although intermittent fasting (IF) is increasingly used as a relatively new dietary strategy for weight loss, the effectiveness of 2 days per week of dry fasting remains unknown.

    OBJECTIVE: This study aims to evaluate the effectiveness of a combined dry IF and healthy plate (IFHP) and healthy plate (HP) intervention in improving anthropometric outcomes and body composition.

    METHODS: This nonrandomized controlled trial involved 177 adults who were overweight and obese. Among them, 91 (51.4%) were allocated to the IFHP group and 86 (48.6%) were allocated to the HP group. The overall study duration was 6 months (October 2020 to March 2021). The intervention was divided into 2 phases: supervised (3 months) and unsupervised (3 months). The data were collected at baseline, after the supervised phase (month 3), and after the unsupervised phase (month 6). Anthropometric (weight, height, waist circumference, and hip circumference) and body composition (body fat percentage, body fat mass, skeletal muscle mass, and visceral fat area) data were measured at all 3 data collection points. Sociodemographic data were obtained using a questionnaire at baseline.

    RESULTS: Most participants were female (147/177, 83.1%) and Malay (141/177, 79.7%). After 3 months, there were significant reductions in weight (difference -1.68; P.05).

    CONCLUSIONS: A combined IFHP intervention was effective in improving anthropometric outcomes and body composition in adults with overweight and obesity.

    INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.2196/33801.

  15. Fulltext Investigating Genetic and Other Determinants of First-Onset Myocardial Infarction in Malaysia: Protocol for the Malaysian Acute Vascular Events Risk Study
    Chowdhury R, Noh MFM, Ismail SR, van Daalen KR, Kamaruddin PSNM, Zulkiply SH, et al.
    JMIR Res Protoc, 2022 Feb 10;11(2):e31885.
    PMID: 35142634 DOI: 10.2196/31885
    BACKGROUND: Although the burden of premature myocardial infarction (MI) is high in Malaysia, direct evidence on the determinants of MI in this multi-ethnic population remains sparse.

    OBJECTIVE: The Malaysian Acute Vascular Events Risk (MAVERIK) study is a retrospective case-control study established to investigate the genomic, lipid-related, and other determinants of acute MI in Malaysia. In this paper, we report the study protocol and early results.

    METHODS: By June 2019, we had enrolled approximately 2500 patients with their first MI and 2500 controls without cardiovascular disease, who were frequency-matched by age, sex, and ethnicity, from 17 hospitals in Malaysia. For each participant, serum and whole blood have been collected and stored. Clinical, demographic, and behavioral information has been obtained using a 200-item questionnaire.

    RESULTS: Tobacco consumption, a history of diabetes, hypertension, markers of visceral adiposity, indicators of lower socioeconomic status, and a family history of coronary disease were more prevalent in cases than in controls. Adjusted (age and sex) logistic regression models for traditional risk factors indicated that current smoking (odds ratio [OR] 4.11, 95% CI 3.56-4.75; P30 kg/m2; OR 1.19, 95% CI 1.05-1.34; P=.009) were associated with MI in age- and sex-adjusted models.

    CONCLUSIONS: The MAVERIK study can serve as a useful platform to investigate genetic and other risk factors for MI in an understudied Southeast Asian population. It should help to hasten the discovery of disease-causing pathways and inform regionally appropriate strategies that optimize public health action.

    INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/31885.

  16. Optimized conditions for phytoremediation of diesel by Scirpus grossus in horizontal subsurface flow constructed wetlands (HSFCWs) using response surface methodology
    Al-Baldawi IA, Sheikh Abdullah SR, Abu Hasan H, Suja F, Anuar N, Mushrifah I
    J Environ Manage, 2014 Jul 1;140:152-9.
    PMID: 24762527 DOI: 10.1016/j.jenvman.2014.03.007
    This study investigated the optimum conditions for total petroleum hydrocarbon (TPH) removal from diesel-contaminated water using phytoremediation treatment with Scirpus grossus. In addition, TPH removal from sand was adopted as a second response. The optimum conditions for maximum TPH removal were determined through a Box-Behnken Design. Three operational variables, i.e. diesel concentration (0.1, 0.175, 0.25% Vdiesel/Vwater), aeration rate (0, 1 and 2 L/min) and retention time (14, 43 and 72 days), were investigated by setting TPH removal and diesel concentration as the maximum, retention time within the given range, and aeration rate as the minimum. The optimum conditions were found to be a diesel concentration of 0.25% (Vdiesel/Vwater), a retention time of 63 days and no aeration with an estimated maximum TPH removal from water and sand of 76.3 and 56.5%, respectively. From a validation test of the optimum conditions, it was found that the maximum TPH removal from contaminated water and sand was 72.5 and 59%, respectively, which was a 5 and 4.4% deviation from the values given by the Box-Behnken Design, providing evidence that S. grossus is a Malaysian native plant that can be used to remediate wastewater containing hydrocarbons.
  17. Comparative performance of free surface and sub-surface flow systems in the phytoremediation of hydrocarbons using Scirpus grossus
    Al-Baldawi IA, Abdullah SR, Suja F, Anuar N, Mushrifah I
    J Environ Manage, 2013 Nov 30;130:324-30.
    PMID: 24113536 DOI: 10.1016/j.jenvman.2013.09.010
    Two types of flow system, free surface flow (FSF) and sub-surface flow (SSF), were examined to select a better way to remove total petroleum hydrocarbons (TPH) using diesel as a hydrocarbon model in a phytotoxicity test to Scirpus grossus. The removal efficiencies of TPH for the two flow systems were compared. Several wastewater parameters, including temperature (T, °C), dissolved oxygen (DO, mgL(-1)), oxidation-reduction potential (ORP, mV), and pH were recorded during the experimental runs. In addition, overall plant lengths, wet weights, and dry weights were also monitored. The phytotoxicity test using the bulrush plant S. grossus was run for 72 days with different diesel concentrations (1%, 2%, and 3%) (Vdiesel/Vwater). A comparison between the two flow systems showed that the SSF system was more efficient than the FSF system in removing TPH from the synthetic wastewater, with average removal efficiencies of 91.5% and 80.2%, respectively. The SSF system was able to tolerate higher diesel concentrations than was the FSF system.
  18. Application of response surface methodology (RSM) for optimisation of COD, NH3-N and 2,4-DCP removal from recycled paper wastewater in a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR)
    Muhamad MH, Sheikh Abdullah SR, Mohamad AB, Abdul Rahman R, Hasan Kadhum AA
    J Environ Manage, 2013 May 30;121:179-90.
    PMID: 23542216 DOI: 10.1016/j.jenvman.2013.02.016
    In this study, the potential of a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR) for removing chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N) and 2,4-dichlorophenol (2,4-DCP) from recycled paper wastewater was assessed. For this purpose, the response surface methodology (RSM) was employed, using a central composite face-centred design (CCFD), to optimise three of the most important operating variables, i.e., hydraulic retention time (HRT), aeration rate (AR) and influent feed concentration (IFC), in the pilot-scale GAC-SBBR process for recycled paper wastewater treatment. Quadratic models were developed for the response variables, i.e., COD, NH3-N and 2,4-DCP removal, based on the high value (>0.9) of the coefficient of determination (R(2)) obtained from the analysis of variance (ANOVA). The optimal conditions were established at 750 mg COD/L IFC, 3.2 m(3)/min AR and 1 day HRT, corresponding to predicted COD, NH3-N and 2,4-DCP removal percentages of 94.8, 100 and 80.9%, respectively.
  19. Simultaneous removal of AOX and COD from real recycled paper wastewater using GAC-SBBR
    Osman WH, Abdullah SR, Mohamad AB, Kadhum AA, Rahman RA
    J Environ Manage, 2013 May 30;121:80-6.
    PMID: 23524399 DOI: 10.1016/j.jenvman.2013.02.005
    A lab-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR), a combined adsorption and biological process, was developed to treat real wastewater from a recycled paper mill. In this study, one-consortia of mixed culture (4000-5000 mg/L) originating from recycled paper mill activated sludge from Kajang, Malaysia was acclimatized. The GAC-SBBR was fed with real wastewater taken from the same recycled paper mill, which had a high concentration of chemical oxygen demand (COD) and adsorbable organic halides (AOX). The operational duration of the GAC-SBBR was adjusted from 48 h to 24, 12 and finally 8 h to evaluate the effect of the hydraulic retention time (HRT) on the simultaneous removal of COD and AOX. The COD and AOX removals were in the range of 53-92% and 26-99%, respectively. From this study, it was observed that the longest HRT (48 h) yielded a high removal of COD and AOX, at 92% and 99%, respectively.
  20. Isotherm equilibria of Mn²⁺ biosorption in drinking water treatment by locally isolated Bacillus species and sewage activated sludge
    Hasan HA, Abdullah SR, Kofli NT, Kamarudin SK
    J Environ Manage, 2012 Nov 30;111:34-43.
    PMID: 22813857 DOI: 10.1016/j.jenvman.2012.06.027
    Manganese (Mn(2+)) is one of the inorganic contaminant that causes problem to water treatment and water distribution due to the accumulation on water piping systems. In this study, Bacillus sp. and sewage activated sludge (SAS) were investigated as biosorbents in laboratory-scale experiments. The study showed that Bacillus sp. was a more effective biosorbent than SAS. The experimental data were fitted to the Langmuir (Langmuir-1 & Langmuir-2), Freundlich, Temkin, Dubinin-Radushkevich (D-R) and Redlich-Peterson (R-P) isotherms to obtain the characteristic parameters of each model. Mn(2+) biosorption by Bacillus sp. was found to be significantly better fitted to the Langmuir-1 isotherm than the other isotherms, while the D-R isotherm was the best fit for SAS; i.e., the χ(2) value was smaller than that for the Freundlich, Temkin, and R-P isotherms. According to the evaluation using the Langmuir-1 isotherm, the maximum biosorption capacities of Mn(2+) onto Bacillus sp. and SAS were 43.5 mg Mn(2+)/g biomass and 12.7 mg Mn(2+)/g biomass, respectively. The data fitted using the D-R isotherm showed that the Mn(2+) biosorption processes by both Bacillus sp. and SAS occurred via the chemical ion-exchange mechanism between the functional groups and Mn(2+) ion.
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