Displaying publications 41 - 60 of 214 in total

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  1. Sources, mechanisms, and fate of steroid estrogens in wastewater treatment plants: a mini review
    Ting YF, Praveena SM
    Environ Monit Assess, 2017 Apr;189(4):178.
    PMID: 28342046 DOI: 10.1007/s10661-017-5890-x
    Steroid estrogens, such as estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2), are natural and synthetic hormones released into the environment through incomplete sewage discharge. This review focuses on the sources of steroid estrogens in wastewater treatment plants (WWTPs). The mechanisms and fate of steroid estrogens throughout the entire wastewater treatment system are also discussed, and relevant information on regulatory aspects is given. Municipal, pharmaceutical industry, and hospitals are the main sources of steroid estrogens that enter WWTPs. A typical WWTP comprises primary, secondary, and tertiary treatment units. Sorption and biodegradation are the main mechanisms for removal of steroid estrogens from WWTPs. The fate of steroid estrogens in WWTPs depends on the types of wastewater treatment systems. Steroid estrogens in the primary treatment unit are removed by sorption onto primary sludge, followed by sorption onto micro-flocs and biodegradation by microbes in the secondary treatment unit. Tertiary treatment employs nitrification, chlorination, or UV disinfection to improve the quality of the secondary effluent. Activated sludge treatment systems for steroid estrogens exhibit a removal efficiency of up to 100%, which is higher than that of the trickling filter treatment system (up to 75%). Moreover, the removal efficiency of advance treatment systems exceeds 90%. Regulatory aspects related to steroid estrogens are established, especially in the European Union. Japan is the only Asian country that implements a screening program and is actively involved in endocrine disruptor testing and assessment. This review improves our understanding of steroid estrogens in WWTPs, proposes main areas to be improved, and provides current knowledge on steroid estrogens in WWTPs for sustainable development.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  2. A review on the advanced leachate treatment technologies and their performance comparison: an opportunity to keep the environment safe
    Show PL, Pal P, Leong HY, Juan JC, Ling TC
    Environ Monit Assess, 2019 Mar 18;191(4):227.
    PMID: 30887225 DOI: 10.1007/s10661-019-7380-9
    Landfill application is the most common approach for biowaste treatment via leachate treatment system. When municipal solid waste deposited in the landfills, microbial decomposition breaks down the wastes generating the end products, such as carbon dioxide, methane, volatile organic compounds, and liquid leachate. However, due to the landfill age, the fluctuation in the characteristics of landfill leachate is foreseen in the leachate treatment plant. The focuses of the researchers are keeping leachate from contaminating groundwater besides keeping potent methane emissions from reaching the atmosphere. To address the above issues, scientists are required to adopt green biological methods to keep the environment safe. This review focuses on the assorting of research papers on organic content and nitrogen removal from the leachate via recent effective biological technologies instead of conventional nitrification and denitrification process. The published researches on the characteristics of various Malaysian landfill sites were also discussed. The understanding of the mechanism behind the nitrification and denitrification process will help to select an optimized and effective biological treatment option in treating the leachate waste. Recently, widely studied technologies for the biological treatment process are aerobic methane oxidation coupled to denitrification (AME-D) and partial nitritation-anammox (PN/A) process, and both were discussed in this review article. This paper gives the idea of the modification of the conventional treatment technologies, such as combining the present processes to make the treatment process more effective. With the integration of biological process in the leachate treatment, the effluent discharge could be treated in shortcut and novel pathways, and it can lead to achieving "3Rs" of reduce, reuse, and recycle approach.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  3. Management of tannery waste effluents towards the reclamation of clean water using an integrated membrane system: A state-of-the-art review
    Kumar R, Basu A, Bishayee B, Chatterjee RP, Behera M, Ang WL, et al.
    Environ Res, 2023 Jul 15;229:115881.
    PMID: 37084947 DOI: 10.1016/j.envres.2023.115881
    Tanning and other leather processing methods utilize a large amount of freshwater, dyes, chemicals, and salts and produce toxic waste, raising questions regarding their environmental sensitivity and eco-friendly nature. Total suspended solids, total dissolved solids, chemical oxygen demand, and ions such as chromium, sulfate, and chloride turn tannery wastewater exceedingly toxic for any living species. Therefore, it is imperative to treat tannery effluent, and existing plants must be examined and upgraded to keep up with recent technological developments. Different conventional techniques to treat tannery wastewater have been reported based on their pollutant removal efficiencies, advantages, and disadvantages. Research on photo-assisted catalyst-enhanced deterioration has inferred that both homogeneous and heterogeneous catalysis can be established as green initiatives, the latter being more efficient at degrading organic pollutants. However, the scientific community experiences significant problems developing a feasible treatment technique owing to the long degradation times and low removal efficiency. Hence, there is a chance for an improved solution to the problem of treating tannery wastewater through the development of a hybrid technology that uses flocculation as the primary treatment, a unique integrated photo-catalyst in a precision-designed reactor as the secondary method, and finally, membrane-based tertiary treatment to recover the spent catalyst and reclaimable water. This review gives an understanding of the progressive advancement of a cutting-edge membrane-based system for the management of tanning industrial waste effluents towards the reclamation of clean water. Adaptable routes toward sludge disposal and the reviews on techno-economic assessments have been shown in detail, strengthening the scale-up confidence for implementing such innovative hybrid systems.
    Matched MeSH terms: Waste Disposal, Fluid/methods
  4. Optimization of coagulation-flocculation process for palm oil mill effluent using response surface methodology
    Ahmad AL, Ismail S, Bhatia S
    Environ Sci Technol, 2005 Apr 15;39(8):2828-34.
    PMID: 15884382
    The coagulation-flocculation process incorporated with membrane separation technology will become a new approach for palm oil mill effluent (POME) treatment as well as water reclamation and reuse. In our current research, a membrane pilot plant has been used for POME treatment where the coagulation-flocculation process plays an important role as a pretreatment process for the mitigation of membrane fouling problems. The pretreated POME with low turbidity values and high water recovery are the main objectives to be achieved through the coagulation-flocculation process. Therefore, treatment optimization to serve these purposes was performed using jar tests and applying a response surface methodology (RSM) to the results. A 2(3) full-factorial central composite design (CCD) was chosen to explain the effect and interaction of three factors: coagulant dosage, flocculent dosage, and pH. The CCD is successfully demonstrated to efficiently determine the optimized parameters, where 78% of water recovery with a 20 NTU turbidity value can be obtained at the optimum value of coagulant dosage, flocculent dosage, and pH at 15 000 mg/L, 300 mg/L, and 6, respectively.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  5. Preparation, characterization, and dye removal study of activated carbon prepared from palm kernel shell
    García JR, Sedran U, Zaini MAA, Zakaria ZA
    Environ Sci Pollut Res Int, 2018 Feb;25(6):5076-5085.
    PMID: 28391459 DOI: 10.1007/s11356-017-8975-8
    Palm oil mill wastes (palm kernel shell (PKS)) were used to prepare activated carbons, which were tested in the removal of colorants from water. The adsorbents were prepared by 1-h impregnation of PKS with ZnCl2 as the activating agent (PKS:ZnCl2 mass ratios of 1:1 and 2:1), followed by carbonization in autogenous atmosphere at 500 and 550 °C during 1 h. The characterization of the activated carbons included textural properties (porosity), surface chemistry (functional groups), and surface morphology. The dye removal performance of the different activated carbons was investigated by means of the uptake of methylene blue (MB) in solutions with various initial concentrations (25-400 mg/L of MB) at 30 °C, using a 0.05-g carbon/50-mL solution relationship. The sample prepared with 1:1 PKS:ZnCl2 and carbonized at 550 °C showed the highest MB adsorption capacity (maximum uptake at the equilibrium, q max = 225.3 mg MB / g adsorbent), resulting from its elevated specific surface area (BET, 1058 m2/g) and microporosity (micropore surface area, 721 m2/g). The kinetic experiments showed that removals over 90% of the equilibrium adsorptions were achieved after 4-h contact time in all the cases. The study showed that palm oil mill waste biomass could be used in the preparation of adsorbents efficient in the removal of colorants in wastewaters.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  6. Analysing the accuracy of machine learning techniques to develop an integrated influent time series model: case study of a sewage treatment plant, Malaysia
    Ansari M, Othman F, Abunama T, El-Shafie A
    Environ Sci Pollut Res Int, 2018 Apr;25(12):12139-12149.
    PMID: 29455350 DOI: 10.1007/s11356-018-1438-z
    The function of a sewage treatment plant is to treat the sewage to acceptable standards before being discharged into the receiving waters. To design and operate such plants, it is necessary to measure and predict the influent flow rate. In this research, the influent flow rate of a sewage treatment plant (STP) was modelled and predicted by autoregressive integrated moving average (ARIMA), nonlinear autoregressive network (NAR) and support vector machine (SVM) regression time series algorithms. To evaluate the models' accuracy, the root mean square error (RMSE) and coefficient of determination (R2) were calculated as initial assessment measures, while relative error (RE), peak flow criterion (PFC) and low flow criterion (LFC) were calculated as final evaluation measures to demonstrate the detailed accuracy of the selected models. An integrated model was developed based on the individual models' prediction ability for low, average and peak flow. An initial assessment of the results showed that the ARIMA model was the least accurate and the NAR model was the most accurate. The RE results also prove that the SVM model's frequency of errors above 10% or below - 10% was greater than the NAR model's. The influent was also forecasted up to 44 weeks ahead by both models. The graphical results indicate that the NAR model made better predictions than the SVM model. The final evaluation of NAR and SVM demonstrated that SVM made better predictions at peak flow and NAR fit well for low and average inflow ranges. The integrated model developed includes the NAR model for low and average influent and the SVM model for peak inflow.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  7. Enhancement of simultaneous batik wastewater treatment and electricity generation in photocatalytic fuel cell
    Khalik WF, Ho LN, Ong SA, Voon CH, Wong YS, Yusuf SY, et al.
    Environ Sci Pollut Res Int, 2018 Dec;25(35):35164-35175.
    PMID: 30328543 DOI: 10.1007/s11356-018-3414-z
    The objective of this study was to investigate several operating parameters, such as open circuit, different external resistance, pH, supporting electrolyte, and presence of aeration that might enhance the degradation rate as well as electricity generation of batik wastewater in solar photocatalytic fuel cell (PFC). The optimum degradation of batik wastewater was at pH 9 with external resistor 250 Ω. It was observed that open circuit of PFC showed only 17.2 ± 7.5% of removal efficiency, meanwhile the degradation rate of batik wastewater was enhanced to 31.9 ± 15.0% for closed circuit with external resistor 250 Ω. The decolorization of batik wastewater in the absence of photocatalyst due to the absorption of light irradiation by dye molecules and this process was known as photolysis. The degradation of batik wastewater increased as the external resistor value decreased. In addition, the degradation rate of batik wastewater also increased at pH 9 which was 74.4 ± 34.9% and at pH 3, its degradation rate was reduced to 19.4 ± 8.7%. The presence of aeration and sodium chloride as supporting electrolyte in batik wastewater also affected its degradation and electricity generation. The maximum absorbance of wavelength (λmax) of batik wastewater at 535 nm and chemical oxygen demand gradually decreased as increased in irradiation time; however, batik wastewater required prolonged irradiation time to fully degrade and mineralize in PFC system.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  8. Integrated adsorption-solar photocatalytic membrane reactor for degradation of hazardous Congo red using Fe-doped ZnO and Fe-doped ZnO/rGO nanocomposites
    Ong CB, Mohammad AW, Ng LY
    Environ Sci Pollut Res Int, 2019 Nov;26(33):33856-33869.
    PMID: 29943245 DOI: 10.1007/s11356-018-2557-2
    In this work, synergistic effect of solar photocatalysis integrated with adsorption process towards the degradation of Congo red (CR) was investigated via two different approaches using a photocatalytic membrane reactor. In the first approach, sequential treatments were conducted through the adsorption by graphene oxide (GO) and then followed by photocatalytic oxidation using Fe-doped ZnO nanocomposites (NCs). In the second approach, however, CR solution was treated by photocatalytic oxidation using Fe-doped ZnO/rGO NCs. These nanocomposites were synthesized by a sol-gel method. The NCs were characterized by X-ray diffraction (XRD), photoluminescence (PL), Fourier transmission infrared (FTIR), ultraviolet-visible (UV-vis) spectroscopy, and field emission scanning electron microscopy (FESEM). It was observed that Fe-doped ZnO could enhance the photoactivity of ZnO under solar light. When Fe-doped ZnO were decorated on GO sheets, however, this provided a surface enhancement for adsorption of organic pollutants. The photocatalytic performances using both approaches were evaluated based on the degradation of CR molecules in aqueous solution under solar irradiation. Nanofiltration (NF) performance in terms of CR residual removal from water and their fouling behavior during post-separation of photocatalysts was studied. Serious flux declined and thicker fouling layer on membrane were found in photocatalytic membrane reactor using Fe-doped ZnO/rGO NCs which could be attributed to the stronger π-π interaction between rGO and CR solution.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  9. Bioremediation of palm oil mill effluent (POME) using indigenous Meyerozyma guilliermondii
    Ganapathy B, Yahya A, Ibrahim N
    Environ Sci Pollut Res Int, 2019 Apr;26(11):11113-11125.
    PMID: 30788704 DOI: 10.1007/s11356-019-04334-8
    Despite being a key Malaysian economic contributor, the oil palm industry generates a large quantity of environmental pollutant known as palm oil mill effluent (POME). Therefore, the need to remediate POME has drawn a mounting interest among environmental scientists. This study has pioneered the application of Meyerozyma guilliermondii with accession number (MH 374161) that was isolated indigenously in accessing its potential to degrade POME. This strain was able to treat POME in shake flask experiments under aerobic condition by utilising POME as a sole source of carbon. However, it has also been shown that the addition of suitable carbon and nitrogen sources has significantly improved the degradation potential of M. guilliermondii. The remediation of POME using this strain resulted in a substantial reduction of chemical oxygen demand (COD) of 72%, total nitrogen of 49.2% removal, ammonical nitrogen of 45.1% removal, total organic carbon of 46.6% removal, phosphate of 60.6% removal, and 92.4% removal of oil and grease after 7 days of treatment period. The strain also exhibited an extracellular lipase activity which promotes better wastewater treatment. Additionally, Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) analyses have specifically shown that M. guilliermondii strain can degrade hydrocarbons, fatty acids, and phenolic compounds present in the POME. Ultimately, this study has demonstrated that M. guilliermondii which was isolated indigenously exhibits an excellent degrading ability. Therefore, this strain is suitable to be employed in the remediation of POME, contributing to a safe discharge of the effluent into the environment.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  10. Optimization of decolorization of palm oil mill effluent (POME) by growing cultures of Aspergillus fumigatus using response surface methodology
    Neoh CH, Yahya A, Adnan R, Abdul Majid Z, Ibrahim Z
    Environ Sci Pollut Res Int, 2013 May;20(5):2912-23.
    PMID: 23054764 DOI: 10.1007/s11356-012-1193-5
    The conventional treatment process of palm oil mill effluent (POME) produces a highly colored effluent. Colored compounds in POME cause reduction in photosynthetic activities, produce carcinogenic by-products in drinking water, chelate with metal ions, and are toxic to aquatic biota. Thus, failure of conventional treatment methods to decolorize POME has become an important problem to be addressed as color has emerged as a critical water quality parameter for many countries such as Malaysia. Aspergillus fumigatus isolated from POME sludge was successfully grown in POME supplemented with glucose. Statistical optimization studies were conducted to evaluate the effects of the types and concentrations of carbon and nitrogen sources, pH, temperature, and size of the inoculum. Characterization of the fungus was performed using scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and Brunauer, Emmet, and Teller surface area analysis. Optimum conditions using response surface methods at pH 5.7, 35 °C, and 0.57 % w/v glucose with 2.5 % v/v inoculum size resulted in a successful removal of 71 % of the color (initial ADMI of 3,260); chemical oxygen demand, 71 %; ammoniacal nitrogen, 35 %; total polyphenolic compounds, 50 %; and lignin, 54 % after 5 days of treatment. The decolorization process was contributed mainly by biosorption involving pseudo-first-order kinetics. FTIR analysis revealed that the presence of hydroxyl, C-H alkane, amide carbonyl, nitro, and amine groups could combine intensively with the colored compounds in POME. This is the first reported work on the application of A. fumigatus for the decolorization of POME. The present investigation suggested that growing cultures of A. fumigatus has potential applications for the decolorization of POME through the biosorption and biodegradation processes.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  11. The use of date palm as a potential adsorbent for wastewater treatment: a review
    Ahmad T, Danish M, Rafatullah M, Ghazali A, Sulaiman O, Hashim R, et al.
    Environ Sci Pollut Res Int, 2012 Jun;19(5):1464-84.
    PMID: 22207239 DOI: 10.1007/s11356-011-0709-8
    BACKGROUND: In tropical countries, the palm tree is one of the most abundant and important trees. Date palm is a principal fruit grown in many regions of the world. It is abundant, locally available and effective material that could be used as an adsorbent for the removal of different pollutants from aqueous solution.

    REVIEW: This article presents a review on the role of date palm as adsorbents in the removal of unwanted materials such as acid and basic dyes, heavy metals, and phenolic compounds. Many studies on adsorption properties of various low cost adsorbent, such as agricultural waste and activated carbons based on agricultural waste have been reported in recent years.

    CONCLUSION: Studies have shown that date palm-based adsorbents are the most promising adsorbents for removing unwanted materials. No previous review is available where researchers can get an overview of the adsorption capacities of date palm-based adsorbent used for the adsorption of different pollutants. This review provides the recent literature demonstrating the usefulness of date palm biomass-based adsorbents in the adsorption of various pollutants.

    Matched MeSH terms: Waste Disposal, Fluid/methods*
  12. Mycoremediation--a prospective environmental friendly technique of bioseparation and dewatering of domestic wastewater sludge
    Molla AH, Fakhru'l-Razi A
    Environ Sci Pollut Res Int, 2012 Jun;19(5):1612-9.
    PMID: 22134862 DOI: 10.1007/s11356-011-0676-0
    INTRODUCTION: Environmental safe and friendly management and disposal of wastewater sludge is a problem of every treatment plant throughout the world. Bioseparation and dewaterability of raw domestic wastewater sludge were evaluated for proper management and disposal by mycoremediation, i.e., using prior grown 2% (v/v) spore suspension of filamentous fungal (Mucor hiemalis Wehmer) broth inoculation, which were grown in 2% (w/v) solution of malt extract and wheat flour for 48-60 h in orbital shaker.

    DISCUSSION: Within 2-3 days of treatment application, encouraging results were achieved in total dry solids (TDS), total suspended solid (TSS), turbidity, chemical oxygen demand (COD), specific resistance to filtration (SRF), and pH due to fungal treatment in recognition of bioseparation and dewaterability of wastewater sludge compared to control. The significant reduction of TDS was remarked at fungal biomass (FB) in wheat flour (WF) treatment. The removal of TSS, turbidity, COD, and SRF were observed 96.0%, 99.4%, 92.6%, and 97.6%, respectively, in supernatant at 5 days by FB in WF. The SRF measuring the dewaterability was decreased with maximum (0.26 × 10(-12) mg/kg) equivalent to 95.5% at 2 days in FB in WF also. FB in WF broth is a potential, environmental friendly, comparatively low-cost biological technique which might play the significant role for bioremediation and bioseparation of domestic wastewater sludge. The present technique may bring a dynamic change in treatment of wastewater in future.

    Matched MeSH terms: Waste Disposal, Fluid/methods*
  13. Enhancement of anaerobic digestibility of waste activated sludge using photo-Fenton pretreatment
    Heng GC, Isa MH, Lim JW, Ho YC, Zinatizadeh AAL
    Environ Sci Pollut Res Int, 2017 Dec;24(35):27113-27124.
    PMID: 28963706 DOI: 10.1007/s11356-017-0287-5
    Biological treatments, such as activated sludge process, are common methods to treat municipal and industrial wastewaters. However, they produce huge amounts of waste activated sludge (WAS). The excess sludge treatment and disposal are a challenge for wastewater treatment plants due to economic, environmental, and regulatory factors. In this study, photo-Fenton pretreatment (oxidation using hydrogen peroxide and iron catalyst aided with UV light) was optimized using response surface methodology (RSM) and central composite design (CCD) to determine the effects of three operating parameters (H2O2 dosage, H2O2/Fe2+ molar ratio, and irradiation time) on disintegration and dewaterability of WAS. MLVSS removal, capillary suction time (CST) reduction, sCOD, and EPS were obtained as 70%, 25%, 12,000 mg/L, and 500 mg/L, respectively, at the optimal conditions, i.e., 725 g H2O2/kg TS, H2O2/Fe2+ molar ratio 80, and irradiation time 40 min. Two batch-fed completely mixed mesophilic anaerobic digesters were then operated at 15-day solid retention time (SRT) and 37 ± 0.5 °C to compare the digestibility of untreated and photo-Fenton pretreated sludge in terms of volatile solids (VS) reduction, COD removal, and biogas production at steady-state operations. Photo-Fenton pretreatment followed by anaerobic digestion of WAS was very effective and yielded 75.7% total VS reduction, 81.5% COD removal, and 0.29-0.31 m3/kg VSfed·d biogas production rate, compared to 40.7% total VS solid reduction, 54.7% COD removal, and 0.12-0.17 m3/kg VSfed·d biogas production rate for control. Thus, photo-Fenton can be a useful pretreatment step in sludge management.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  14. Sono assisted electrocoagulation process for the removal of pollutant from pulp and paper industry effluent
    Asaithambi P, Aziz ARA, Sajjadi B, Daud WMABW
    Environ Sci Pollut Res Int, 2017 Feb;24(6):5168-5178.
    PMID: 27221586 DOI: 10.1007/s11356-016-6909-5
    In the present work, the efficiency of the sonication, electrocoagulation, and sono-electrocoagulation process for removal of pollutants from the industrial effluent of the pulp and paper industry was compared. The experimental results showed that the sono-electrocoagulation process yielded higher pollutant removal percentage compared to the sonication and electrocoagulation process alone. The effect of the operating parameters in the sono-electrocoagulation process such as electrolyte concentration (1-5 g/L), current density (1-5 A/dm(2)), effluent pH (3-11), COD concentration (1500-6000 mg/L), inter-electrode distance (1-3 cm), and electrode combination (Fe and Al) on the color removal, COD removal, and power consumption were studied. The maximum color and COD removal percentages of 100 and 95 %, respectively, were obtained at the current density of 4 A/dm(2), electrolyte concentration of 4 g/L, effluent pH of 7, COD concentration of 3000 mg/L, electrode combination of Fe/Fe, inter-electrode distance of 1 cm, and reaction time of 4 h, respectively. The color and COD removal percentages were analyzed by using an UV/Vis spectrophotometer and closed reflux method. The results showed that the sono-electrocoagulation process could be used as an efficient and environmental friendly technique for complete pollutant removal.
    Matched MeSH terms: Waste Disposal, Fluid/methods
  15. A mini-review on rare earth metal-doped TiO2 for photocatalytic remediation of wastewater
    Saqib NU, Adnan R, Shah I
    Environ Sci Pollut Res Int, 2016 Aug;23(16):15941-51.
    PMID: 27335012 DOI: 10.1007/s11356-016-6984-7
    Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  16. Decolorization of palm oil mill effluent using growing cultures of Curvularia clavata
    Neoh CH, Lam CY, Lim CK, Yahya A, Ibrahim Z
    Environ Sci Pollut Res Int, 2014 Mar;21(6):4397-408.
    PMID: 24327114 DOI: 10.1007/s11356-013-2350-1
    Agricultural wastewater that produces color are of environmental and health concern as colored effluent can produce toxic and carcinogenic by-products. From this study, batch culture optimization using response surface methods indicated that the fungus isolated from the pineapple solid waste, Curvularia clavata was able to decolorize sterile palm oil mill effluent (POME) which is mainly associated with polyphenol and lignin. Results showed successful decolorization of POME up to 80 % (initial ADMI [American Dye Manufacturing Index] of 3,793) with 54 % contributed by biosorption and 46 % by biodegradation after 5 days of treatment. Analysis using HPLC and GC-MS showed the degradation of color causing compound such as 3-methoxyphenyl isothiocynate and the production of new metabolites. Ecotoxicity test indicated that the decolorized effluent is safe for discharge. To determine the longevity of the fungus for a prolonged decolorization period, sequential batch decolorization studies were carried out. The results showed that lignin peroxidase and laccase were the main ligninolytic enzymes involved in the degradation of color. Carboxymethyl cellulase (CMCase) and xylanase activities were also detected suggesting possible roles of the enzymes in promoting growth of the fungus which consequently contributed to improved decolorization of POME. In conclusion, the ability of C. clavata in treating color of POME indicated that C. clavata is of potential use for decolorization and degradation of agricultural wastewater containing polyphenolic compounds.
    Matched MeSH terms: Waste Disposal, Fluid/methods
  17. Application of zeolite-activated carbon macrocomposite for the adsorption of Acid Orange 7: isotherm, kinetic and thermodynamic studies
    Lim CK, Bay HH, Neoh CH, Aris A, Abdul Majid Z, Ibrahim Z
    Environ Sci Pollut Res Int, 2013 Oct;20(10):7243-55.
    PMID: 23653315 DOI: 10.1007/s11356-013-1725-7
    In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer-Emmett-Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet-visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution.
    Matched MeSH terms: Waste Disposal, Fluid/methods
  18. Solar photocatalytic degradation of mono azo methyl orange and diazo reactive green 19 in single and binary dye solutions: adsorbability vs photodegradation rate
    Ong SA, Min OM, Ho LN, Wong YS
    Environ Sci Pollut Res Int, 2013 May;20(5):3405-13.
    PMID: 23114839 DOI: 10.1007/s11356-012-1286-1
    The objective of this study was to examine the effects of adsorbability and number of sulfonate group on solar photocatalytic degradation of mono azo methyl orange (MO) and diazo Reactive Green 19 (RG19) in single and binary dye solutions. The adsorption capacity of MO and RG19 onto the TiO₂ was 16.9 and 26.8 mg/g, respectively, in single dye solution, and reduced to 5.0 and 23.1 mg/g, respectively, in the binary dye solution. The data obtained for photocatalytic degradation of MO and RG19 in single and binary dye solution were well fitted with the Langmuir-Hinshelwood kinetic model. The pseudo-first-order rate constants of diazo RG19 were significant higher than the mono azo MO either in single or binary dye solutions. The higher number of sulfonate group in RG19 contributed to better adsorption capacity onto the surface of TiO₂ than MO indicating greater photocatalytic degradation rate.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  19. Ozonation of metoprolol in aqueous solution: ozonation by-products and mechanisms of degradation
    Tay KS, Rahman NA, Abas MR
    Environ Sci Pollut Res Int, 2013 May;20(5):3115-21.
    PMID: 23054788 DOI: 10.1007/s11356-012-1223-3
    This study investigated the degradation pathway of metoprolol, a widely used β-blocker, in the ozonation via the identification of generated ozonation by-products (OPs). Structure elucidation of OPs was performed using HPLC coupled with quadrupole time-of-flight high-resolution mass spectrometry. Seven OPs were identified, and four of these have not been reported elsewhere. Identified OPs of metoprolol included aromatic ring breakdown by-products; aliphatic chain degraded by-products and aromatic ring mono-, di-, and tetrahydroxylated derivatives. Based on the detected OPs, metoprolol could be degraded through aromatic ring opening reaction via reaction with ozone (O3) and degradation of aliphatic chain and aromatic ring via reaction with hydroxyl radical (•OH).
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  20. Assessment of sewage sludge bioremediation at different hydraulic retention times using mixed fungal inoculation by liquid-state bioconversion
    Rahman RA, Molla AH, Fakhru'l-Razi A
    Environ Sci Pollut Res Int, 2014 Jan;21(2):1178-87.
    PMID: 23881591 DOI: 10.1007/s11356-013-1974-5
    Sustainable, environmental friendly, and safe disposal of sewage treatment plant (STP) sludge is a global expectation. Bioremediation performance was examined at different hydraulic retention times (HRT) in 3-10 days and organic loading rates (OLR) at 0.66-7.81 g chemical oxygen demand (COD) per liter per day, with mixed filamentous fungal (Aspergillus niger and Penicillium corylophilum) inoculation by liquid-state bioconversion (LSB) technique as a continuous process in large-scale bioreactor. Encouraging results were monitored in treated sludge by LSB continuous process. The highest removal of total suspended solid (TSS), turbidity, and COD were achieved at 98, 99, and 93%, respectively, at 10 days HRT compared to control. The minimum volatile suspended solid/suspended solid implies the quality of water, which was recorded 0.59 at 10 days and 0.72 at 3 days of HRT. In treated supernatant with 88% protein removal at 10 days of HRT indicates a higher magnitude of purification of treated sludge. The specific resistance to filtration (SRF) quantifies the performance of dewaterability; it was recorded minimum 0.049 × 10(12) m kg(-1) at 10 days of HRT, which was equivalent to 97% decrease of SRF. The lower OLR and higher HRT directly influenced the bioremediation and dewaterability of STP sludge in LSB process. The obtained findings imply encouraging message in continuing treatment of STP sludge, i.e., bioremediation of wastewater for environmental friendly disposal in near future.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
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