In this laboratory-scale study, earthworms were introduced as biodegraders of palm oil mill effluent (POME), which is a wastewater produced from the wet process of palm oil milling. POME was absorbed into amendments (soil or rice straw) in different ratios as feedstocks for the earthworm, Eudrilus eugeniae. The presence of earthworms led to significant increases in pH, electrical conductivity, and nutrient content but decreases in the C/N ratio (0.687-75.8%), soluble chemical oxygen demand (19.7-87.9%), and volatile solids (0.687-52.7%). However, earthworm growth was reduced in all treatments by the end of the treatment process. Rice straw was a better amendment/absorbent relative to soil, with a higher nutrient content and greater reduction in soluble chemical oxygen demand with a lower C/N ratio in the vermicompost. Among all treatments investigated, the treatment with 1 part rice straw and 3 parts POME (w/v) (RS1:3) produced the best quality vermicompost with high nutritional status.
Matched MeSH terms: Water Pollutants, Chemical/chemistry
The ability of non-living biomass of an arsenic-hypertolerant Bacillus cereus strain SZ2 isolated from a gold mining environment to adsorb As (III) from aqueous solution in batch experiments was investigated as a function of contact time, initial As (III) concentration, pH, temperature and biomass dosage. Langmuir model fitted the equilibrium data better in comparison to Freundlich isotherm. The maximum biosorption capacity of the sorbent, as obtained from the Langmuir isotherm, was 153.41 mg/g. The sorption kinetic of As (III) biosorption followed well the pseudo-second-order rate equation. The Fourier transform infrared spectroscopy analysis indicated the involvement of hydroxyl, amide and amine groups in As (III) biosorption process. Field emission scanning electron microscopy-energy dispersive X-ray analysis of the non-living B. cereus SZ2 biomass demonstrated distinct cell morphological changes with significant amounts of As adsorbed onto the cells compared to non-treated cells. Desorption of 94 % As (III) was achieved at acidic pH 1 showing the capability of non-living biomass B. cereus SZ2 as potential biosorbent in removal of As (III) from arsenic-contaminated mining effluent.
Matched MeSH terms: Water Pollutants, Chemical/chemistry
The presence of endocrine disruptors in source water is of great concern because of their suspected adverse effects on humans, even when present at very low levels. As the main source of potable water supply, rivers in Malaysia are highly susceptible to contamination by various endocrine disruptors originating from anthropogenic activities. In this study, the contamination levels of 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) and its metabolites and di-(2-ethylhexyl) phthalate (DEHP) in rivers of Selangor were examined using gas chromatography-mass spectrometry. Samples were collected from sites representing source water for 18 drinking water treatment plants in Selangor between July 2008 and July 2009. DDT and its metabolites were detected in only 14% of the 192 samples analysed at levels ranging from 0.6 to 14.6 ng/L. Meanwhile DEHP was detected in 96.8% of the samples at levels ranging from below quantitation level (18 ng/L) to 970 ng/L. The detected levels of DDTs and DEHP were lower than the WHO and Malaysian Guidelines for Drinking Water Quality. Data obtained from this study should also serve as a reference point for future surveillance on these endocrine disruptors.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH3-N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m(3) ozone, 1g/1g COD0/S2O8(2-) ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH3-N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O3/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S2O8(2-) only, to evaluate its effectiveness. The combined method (i.e., O3/S2O8(2-)) achieved higher removal efficiencies for COD, color, and NH3-N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
Fe-doped titanium dioxide (TiO(2)) nanotubes were prepared using sol-gel followed by hydrothermal methods and characterized using various methods. The sonocatalytic activity was evaluated based on oxidation of Rhodamine B under ultrasonic irradiation. Iron ions (Fe(3+)) might incorporate into the lattice and intercalated in the interlayer spaces of TiO(2) nanotubes. The catalysts showed narrower band gap energies, higher specific surface areas, more active surface oxygen vacancies and significantly improved sonocatalytic activity. The optimum Fe doping at Fe:Ti=0.005 showed the highest sonocatalytic activity and exceeded that of un-doped TiO(2) nanotubes by a factor of 2.3 times. It was believed that Fe(3+) doping induced the formation of new states close to the valence band and conduction bands and accelerated the separation of charge carriers. Leached Fe(3+) could catalyze Fenton-like reaction and led to an increase in the hydroxyl radical (OH) generation. Fe-doped TiO(2) nanotubes could retain high degradation efficiency even after being reused for 4 cycles with minimal loss of Fe from the surface of the catalyst.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC) analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC). The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO and 100 ppm of p-cresol. P-cresol photocatalytic degradation was favorable in the pH range of 6-9. The detected intermediates were 4-hydroxy-benzaldehyde and 4-methyl-1,2-benzodiol. TOC studies show that 93% of total organic carbon was removed from solution during irradiation time. Reusability shows no significant reduction in photocatalytic performance in photodegrading p-cresol.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
Ozonation, combined with the Fenton process (O(3)/H(2)O(2)/Fe(2+)), was used to treat matured landfill leachate. The effectiveness of the Fenton molar ratio, Fenton concentration, pH variance, and reaction time were evaluated under optimum operational conditions. The optimum removal values of chemical oxygen demand (COD), color, and NH(3)-N were found to be 65%, 98%, and 12%, respectively, for 90 min of ozonation using a Fenton molar ratio of 1 at a Fenton concentration of 0.05 mol L(-1) (1700 mg/L) H(2)O(2) and 0.05 mol L(-1) (2800 mg/L) Fe(2+) at pH 7. The maximum removal of NH(3)-N was 19% at 150 min. The ozone consumption for COD removal was 0.63 kg O(3)/kg COD. To evaluate the effectiveness, the results obtained in the treatment of stabilized leachate were compared with those obtained from other treatment processes, such as ozone alone, Fenton reaction alone, as well as combined Fenton and ozone. The combined method (i.e., O(3)/H(2)O(2)/Fe(2+)) achieved higher removal efficiencies for COD, color, and NH(3)-N compared with other studied applications.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
The effective removal of o-cresol is currently both an environmental and economic challenge. ZnO is not only an efficient photocatalyst but is also cost effective, as its photoabsorption can extend from the ultraviolet (UV) to the visible range thereby allowing the use of inexpensive visible light sources, such as sunlight. The principal objective of the present work is to investigate the visible light-driven removal of o-cresol from aqueous solution in the presence of 1.0 wt% Mn-doped ZnO. To measure the efficiency ofphotodegradation, the variables studied included the amount ofphotocatalyst, concentration of o-cresol, pH and irradiation time. The concentration ofo-cresol and residual organic carbon was monitored using a UV-visible spectrophotometer, ultra high-pressure liquid chromatography and a total organic carbon analyser. The optimum conditions under which the photodegradation of o-cresol was most favourable corresponded to 1.5 g/l ZnO, 35 ppm o-cresol and pH 9. The ZnO-1 wt% Mn photoprocess has demonstrated reusability for more than three times, which warrants its scale-up from laboratory- to in industrial-scale application.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
A new heterogeneous catalyst for sonocatalytic degradation of amaranth dye in water was synthesized by introducing titania into the pores of zeolite (NaY) through ion exchange method while Fe (III) was immobilized on the encapsulated titanium via impregnation method. XRD results could not detect any peaks for titanium oxide or Fe(2)O(3) due to its low loading. The UV-vis analysis proved a blue shift toward shorter wavelength after the loading of Ti into NaY while a red shift was detected after the loading of Fe into the encapsulated titanium. Different reaction variables such as TiO(2) content, amount of Fe, pH values, amount of hydrogen peroxide, catalyst loading and the initial dye concentration were studied to estimate their effect on the decolorization efficiency of amaranth. The maximum decolorization efficiency achieved was 97.5% at a solution pH of 2.5, catalyst dosage of 2 g/L, 20 mmol/100 mL of H(2)O(2) and initial dye concentration of 10 mg/L. The new heterogeneous catalyst Fe/Ti-NaY was a promising catalyst for this reaction and showed minimum Fe leaching at the end of the reaction.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
Sorbent materials based on a hydrazone Schiff base compound, C(14)H(11)BrN(4)O(4), were prepared either by immobilizing the ligand into sol-gel (SG1) or bonding to silica (SG2). The sorbent materials were characterized by FT-IR, EDX, SEM, TEM, and TGA. The sorption characteristics of a matrix of eight transition metal ions (Ag(+), Cu(2+), Co(2+), Ni(2+), Fe(3+), Pb(2+), Zn(2+), and Mn(2+)) using batch method were studied. Several key parameters that affected the extraction efficiency such as pH, contact time, metal ions concentration, and gel size (for SGl) were investigated and optimized. Under the optimized conditions, the physically immobilized hydrazone sorbent (SG1) exhibits highest selectivity towards Ag(+) ions, while the chemically bonded hydrazone sorbent (SG2) exhibits high extraction for all metal ions tested. However, for practical applications such as the removal and preconcentration of Ag(+), the physically immobilized sorbent (SG1) is preferred.
Matched MeSH terms: Water Pollutants, Chemical/chemistry
Landfill leachate is one of the most recalcitrant wastes for biotreatment and can be considered a potential source of contamination to surface and groundwater ecosystems. In the present study, Fenton oxidation was employed for degradation of stabilized landfill leachate. Response surface methodology was applied to analyze, model and optimize the process parameters, i.e. pH and reaction time as well as the initial concentrations of hydrogen peroxide and ferrous ion. Analysis of variance showed that good coefficients of determination were obtained (R2 > 0.99), thus ensuring satisfactory agreement of the second-order regression model with the experimental data. The results indicated that, pH and its quadratic effects were the main factors influencing Fenton oxidation. Furthermore, antagonistic effects between pH and other variables were observed. The optimum H2O2 concentration, Fe(II) concentration, pH and reaction time were 0.033 mol/L, 0.011 mol/L, 3 and 145 min, respectively, with 58.3% COD, 79.0% color and 82.1% iron removals.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
In this research, two types of sequencing batch reactors (SBRs) with 8 h of cycle times, namely non-powdered activated carbon (NPAC-SBR) and powdered activated carbon (PAC-SBR), were used for the treatment of raw leachates at Kulim and Pulau Burung landfill sites. To test the performance of SBRs, phenols, total iron, zinc, ammonia, nitrite, nitrate, color, suspended solids, chemical oxygen demand, biochemical oxygen demand, and total dissolved salts removal efficiencies and sludge volume index (SVI) were studied at both sites. The rates of phenols removal, for instance in NPAC-SBRs and PAC-SBRs at Kulim, were 25% and 55%, respectively, whereas those at Pulau Buring were 94.81% and 97.75%, respectively. PAC as adsorbent in PAC-SBRs enhanced the removal efficiencies of the aforementioned pollutants from leachates at both sites. In addition, PAC as adsorbent decreased the SVI values at Kulim (59.7 mL/g) and Pulau Burung (91.4 mL/g) leachates and improved the nitrification and denitrification processes.
Matched MeSH terms: Water Pollutants, Chemical/chemistry
This paper describes the sorption of Pb(ll) from aqueous solution. Oil palm empty fruit bunch (OPEFB) fiber was first grafted with poly(methylacrylate) and then treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid (PHA) grafted OPEFB. Sorption of Pb(ll) by PHA-OPEFB was maximum at pH 5. The sorption followed the Langmuir model with maximum capacityof 125.0 mg g-1 at 25 degrees C. The sorption process was exothermic, as shown by the negative value of enthalpy change, Delta H0. The free energy change (DeltaG0) for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Pb(ll) sorption followed a second order kinetic model.
Matched MeSH terms: Water Pollutants, Chemical/chemistry
The performances of HZSM-5 and transition metal-loaded HZSM-5 (Mn, Cu, Fe, Ti) catalysts during catalytic ozonation of phenol have been investigated. It was observed the performance order for removal of phenol and COD was Mn/HZSM-5 > Fe/HZSM-5 > Cu/HZSM-5 > Ti/HZSM-5 > HZSM-5. The presence of metals on HZSM-5 enhanced the phenol removal capability of HZSM-5. Mn loading on HZSM-5 was optimized due to its high phenol removal capability amongst metal-loaded HZSM-5 catalysts. Experimental results suggested that low amount of Mn loading on HZSM-5 was sufficient for HZSM-5 to act as catalyst and adsorbent. A maximum of 95.8 wt% phenols and 70.2 wt% COD were removed over 2 wt% Mn/HZSM-5 in 120 min. It was supposed that transition metals mainly acted as ozone decomposers due to their multiple oxidation states that enhanced the ozonation of phenol.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
Many coagulants, mainly inorganic, are widely used in conventional water and wastewater treatment. Recent studies reported the occurrence of some chronic diseases associated with residual coagulant in treated wastewater. The use of alternative coagulants which are biodegradable and environmentally friendly could alleviate the problem associated with these diseases. This work investigates the capability of Jatropha curcas seed and presscake (the residue left after oil extraction) to reduce the turbidity of wastewater through coagulation. The coagulant was prepared by dissolving Jatropha curcas seed and presscake powder into solution. Then jar tests were conducted on kaolin solution as the model wastewater. The Jatropha seed was found to be an effective coagulant with more than 96% of turbidity removal at pH 1-3 and pH 11-12. The highest turbidity removal was recorded at pH 3 using a dosage of 120 mg/L. The flocs formed using Jatropha were observed to be bigger and to sediment faster when compared with flocs formed using alum. The turbidity removal was high (>98%) at all turbidities (100 NTU to 8000 NTU), suggesting its suitability for a wide range of industrial wastewater. The performance of Jatropha presscake after extraction of oil was also comparable to the fresh seed and alum at highly acidic and highly alkaline conditions. The addition of Jatropha did not significantly affect the pH of the kaolin samples after treatment and the sludge volume produced was less in comparison to alum. These results strongly support the use of Jatropha curcas seed and presscake as a potential coagulant agent.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
Conventional aerobic and low-rate anaerobic processes such as pond and open-tank systems have been widely used in wastewater treatment. In order to improve treatment efficacy and to avoid greenhouse gas emissions, conventional treatment can be upgraded to a high performance anaerobic granular-sludge system. The anaerobic granular-sludge systems are designed to capture the biogas produced, rendering a potential for claims of carbon credits under the Kyoto Protocol for reducing emissions of greenhouse gases. Certified Emission Reductions (CERs) would be issued, which can be exchanged between businesses or bought and sold in international markets at the prevailing market prices. As the advanced anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they render more carbon credits than other conventional anaerobic systems. In addition to efficient waste degradation, the carbon credits can be used to generate revenue and to finance the project. This paper presents a scenario on emission avoidance based on a methane recovery and utilization project. An example analysis on emission reduction and an overview of the global emission market are also outlined.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
The potential of Pleurotus ostreatus spent mushroom compost (PSMC) as a green biosorbent for nickel (II) biosorption was investigated in this study. A novel approach of using the half-saturation concentration of biosorbent to rapidly determine the uptake, kinetics and mechanism of biosorption was employed together with cost per unit uptake analysis to determine the potential of this biosorbent. Fifty per cent nickel (II) biosorption was obtained at a half-saturation constant of 0.7 g biosorbent concentration, initial pH in the range of 4-8, 10 min contact time, 50 mL 50 mg/L nickel (II) initial concentration. The experimental data were well fitted with the Langmuir isotherm model and the maximum nickel (II) biosorption was 3.04 mg/g. The results corresponded well to a second pseudo order kinetic model with the coefficient of determination value of 0.9999. Based on FTIR analysis, the general alkyl, hydroxyl or amino, aliphatic alcohol and carbonyl functional groups of biosorbent were involved in the biosorption process. Therefore, biosorption of nickel (II) must involve several mechanisms simultaneously such as physical adsorption, chemisorption and ion exchange. Cost comparison for PSMC with Amberlite IRC-86 ion exchange resin indicates that the biosorbent has the potential to be developed into a cost effective and environmentally friendly treatment system.
Matched MeSH terms: Water Pollutants, Chemical/chemistry
This study investigated the reaction kinetics and degradation mechanism of parabens (methylparaben, ethylparaben, propylparaben and butylparaben) during ozonation. Experiments were performed at pH 2, 6 and 12 to determine the rate constants for the reaction of protonated, undissociated and dissociated paraben with ozone. The rate constants for the reaction of ozone with dissociated parabens (3.3 × 10(9)-4.2 × 10(9)M(-1)s(-1)) were found to be 10(4) times higher than the undissociated parabens (2.5 × 10(5)-4.4 × 10(5)M(-1)s(-1)) and 10(7) times higher than with the protonated parabens (1.02 × 10(2)-1.38 × 10(2)M(-1)s(-1)). The second-order rate constants for the reaction between parabens with hydroxyl radicals were found to vary from 6.8 × 10(9) to 9.2 × 10(9)M(-1)s(-1). Characterization of degradation by-products (DBPs) formed during the ozonation of each selected parabens has been carried out using GCMS after silylation. Twenty DBPs formed during ozonation of selected parabens have been identified. Hydroxylation has been found to be the major reaction for the formation of the identified DBPs. Through the hydroxylation reaction, a variety of hydroxylated parabens was formed.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non-linear Langmuir isotherm for chitosan, chitosan-GLA and chitosan-alginate beads in single metal system were 34.98, 14.24 and 60.27 mg/g, respectively. However, the adsorption capacity of Pb(II) ions were reduced in the binary metal system due to the competitive adsorption between Pb(II) and Cu(II) ions. Based on the ion exchange study, the release of Ca2+, Mg2+, K+ and Na+ ions played an important role in the adsorption of Pb(II) ions by all three adsorbents but only at lower concentrations of Pb(II) ions. Infrared spectra showed that the binding between Pb(II) ions and the adsorbents involved mostly the nitrogen and oxygen atoms. All three adsorbents showed satisfactory adsorption capacities and can be considered as an efficient adsorbent for the removal of Pb(II) ions from aqueous solutions.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
The removal of Reactive Black 5 dye in an aqueous solution by electrocoagulation (EC) as well as addition of flocculant was investigated. The effect of operational parameters, i.e. current density, treatment time, solution conductivity and polymer dosage, was investigated. Two models, namely the artificial neural network (ANN) and the response surface method (RSM), were used to model the effect of independent variables on percentage of dye removal. The findings of this work showed that current density, treatment time and dosage of polymer had the most significant effect on percentage of dye removal (p<0.001). In addition, interaction between time and current density, time and dosage of polymer, current density and dosage of polymer also significantly affected the percentage of dye removal (p=0.034, 0.003 and 0.024, respectively). It was shown that both the ANN and RSM models were able to predict well the experimental results (R(2)>0.8).
Matched MeSH terms: Water Pollutants, Chemical/chemistry*