Showing papers in "Journal of water process engineering in 2014"
TL;DR: In this article, a review summarises the known facts about the fouling processes and cleaning procedures and details of the most successful physical and chemical cleaning combinations for one-stage and multi-stage UF membrane cleaning.
Abstract: Ultrafiltration (UF) is one of the best options for both one-stage and as part of multi-stage water and wastewater purification. This review summarises the known facts about the fouling processes and cleaning procedures and details of the most successful physical and chemical cleaning combinations. The optimum cleaning is closely linked to the nature of the fouling. Precise knowledge of both the fouling type (organic, inorganic, or biological) and the fouling mechanism (gel formation, adsorption, deposition, pore blockage, or cake formation) is the key to success in UF membrane cleaning.
588 citations
TL;DR: In this paper, the applicability of carbon nanoparticles made from vine wood as an inexpensive adsorbent for the removal of Amoxicillin, Cephalexin, Tetracycline and Penicillin G from aqueous solutions was shown.
Abstract: The present study shows the applicability of carbon nanoparticles made from vine wood as an inexpensive adsorbent for the removal of Amoxicillin, Cephalexin, Tetracycline and Penicillin G from aqueous solutions. The activation of carbon nanoparticles was studied by aqueous solutions of NaOH, KOH, ZnCl 2 , NaCl and HNO 3 . The removal efficiency ( R %) of pollutants showed that NaOH can be used as an efficient, low-cost and environmentally friendly activator ( R % = 74–88). Infrared spectroscopy, XRD pattern, BET and BJH methods and scanning electron microscope (SEM) images were used to characterize the prepared carbon. The area and pore volume of activated carbon were obtained as 13.397 m 2 /g and 54.79 cm 3 /g, respectively. The SEM images showed a high porosity for activated carbon. Removal of antibiotics from aqueous samples was carried out using a modular method. The optimized parameters of pH 2, an amount of adsorbent of 0.4 g/L, a concentration of antibiotic solution of 20 mg L −1 , a contact time of 8 h and a temperature of 45 °C were obtained in a modular way. Kinetic studies confirmed that the adsorption followed second-order reaction kinetics. Thermodynamic studies revealed that the process was spontaneous and endothermic. The reusability of sorbent was achieved by using of NaOH (5 w/w%) solution and recovery time of 4 h.
301 citations
TL;DR: A review of the implementation of membrane technology for produced water treatment could contribute to the knowledge required for the increased introduction of scaled-up membrane technology in the petroleum industry as discussed by the authors, which encompasses the capabilities and performance optimization possibilities of microfiltration, ultrafiltration and nanofiltration membranes.
Abstract: This review provides insight into the implementation of membrane technology in the petroleum industry for treating produced water that is generated from conventional oilfields in upstream and downstream processes. The ever-evolving and increasingly stringent regulatory standards for discharging produced water pose colossal environmental and economic implications because the bulk of this produced water is disposed into the environment. Thus, a review of the implementation of membrane technology for produced water treatment could contribute to the knowledge required for the increased introduction of scaled-up membrane technology in the petroleum industry. This review encompasses the capabilities and performance optimization possibilities of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membranes. The level of applications that these membrane technologies might attain within the petroleum industry were determined, and these implementations were correlated with the purpose, performance efficiency, treatment system configurations, necessary pretreatment procedures, quality of treated produced water, fouling occurrence and control, foulants, cleaning procedures, raw produced water content, potential challenges with corresponding applied solutions, and economic factors. This review also maps current and future trends and provides a perspective on the outlook for advances in novel membrane applications for produced water treatment.
288 citations
TL;DR: A comprehensive overview of current knowledge of draw solutes in terms of recovery from water is provided in this paper, where a variety of existing recovery methods developed so far to overcome the recovery barriers, including thermal separation, membrane separation, precipitation, stimuli response, combined processes, and direct use without recovery are presented.
Abstract: Recently, there has been an increasing use of forward osmosis (FO) technique for energy-efficient water treatment, leading to significant public concerns. One key know-how to make FO practical is developing an ideal draw solute characterized by high water flux, low reverse solute flux, and easy recovery. The recovery of draw solutes takes a significant energy cost in FO technology implementation. To this end, it is necessary to enhance the understanding of how different kinds of draw solutes are regenerated during the dewatering process. This review aims to provide a comprehensive overview of current knowledge of draw solutes in terms of recovery from water. A variety of existing recovery methods developed so far to overcome the recovery barriers, including thermal separation, membrane separation, precipitation, stimuli–response, combined processes, and direct use without recovery are presented. Discussions on the advantages and limits of the existing recovery methods are made based on acquired knowledge from the literature. Future directions for the effective and energy-efficient recovery of draw solutes are also provided. Information summarized in the paper further highlights the potential applications of the FO process.
159 citations
TL;DR: In this paper, all the available processes to remove cadmium from aqueous solution have been listed and the broad range of research work done by researchers in this field has been evaluated.
Abstract: Cadmium(II) is a highly toxic element and can cause a serious threat to living organisms. It is listed as an carcinogen by IARC and US EPA and stringent limits have been set for it in industrial wastewater (discharged into water bodies containing cadmium) as well as in drinking water. Therefore, an efficient and economic process to remove cadmium from aqueous solution is a pressing need. In this paper, all the available processes to remove cadmium from aqueous solution have been listed and the broad range of research work done by researchers in this field has been evaluated. The operational conditions of various processes have been briefly discussed. About 218 published studies are reviewed in this paper in order to provide insight into efficient and economic processes for the removal of cadmium. From the study, it is evident that adsorption, especially Biosorption, has been used by most of the researchers during the last few decades and it has proved to be a very efficient and economic process. But a lack of recent work has been observed in the area of precipitation and coagulation which could otherwise be an economic and convenient method.
152 citations
TL;DR: In this article, the authors investigated the feasibility of crystal violet dye (CV + ) onto acid-activated bentonite clay, entrapped in a polymeric matrix of calcium alginate bead examined in this work.
Abstract: Adsorption feasibility of crystal violet dye (CV + ) onto acid-activated bentonite clay, entrapped in a polymeric matrix of calcium alginate bead examined in this work. Operational parameters have been investigated, isotherms were analyzed using non-linear regression model and data obtained optimized by Box–Behnken model. Pseudo- n th order fits well with the kinetic data obtained, and the reaction order n was found to be between 0.925 and 3.269. Desorption tests showed that the recovery of CV + decreased from 92.39 to 84.59% in the tenth cycle. The maximum adsorptions of crystal violet onto alginate/acid activated bentonite beads (A-AAB), alginate/bentonite beads (AB), and acid activated bentonite clay (AAB) were 582.4, 498.2 and 229 mg dye g −1 respectively. The thermodynamic parameters indicate that the adsorption process of CV + is endothermic and more effective at high temperatures.
152 citations
TL;DR: In this paper, the adsorption mechanism of the cationic methylene blue dye to the abundant and inexpensive lignite as an adsorbent from aqueous solutions was investigated as a function of ionic strength, pH, temperature, initial dye concentration, contact time and stirring speed.
Abstract: The adsorption mechanism of the cationic methylene blue dye to the abundant and inexpensive lignite as an adsorbent from aqueous solutions was investigated as a function of ionic strength, pH, temperature, initial dye concentration, contact time and stirring speed. The adsorption capacity increased with the increasing temperature, initial dye concentration, pH and ionic strength, although it was not affected by the stirring speed. The value of zeta potential decreased with the increasing pH. Experimental adsorption data were modelled by different equilibrium isotherms such as Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (D–R), BET, Halsey, Harkins–Jura, Smith and Henderson isotherms. The adsorption process fitted well to pseudo-second-order kinetics and the Langmuir model. Activation energy of the adsorption processes was found to be 49.81 kJ mol −1 initial dye concentration of 80 mg L −1 using the Arrhenius equation, indicating the strong electrostatic interactions between the adsorbent and dye. The isosteric enthalpy and entropy changes were calculated as 58.19 kJ mol −1 and −0.186 kJ mol −1 K −1 , respectively, indicating that the adsorption process was endothermic and the orderliness of the adsorption system slightly decreases with adsorption of methylene blue molecules to the lignite surface. FT-IR results revealed that several functional groups on the coal surface are responsible for methylene blue adsorption. The observed differences in the reflection of the SEM images of lignite and methylene blue adsorbed lignite are due to the presence of methylene blue, which was adsorbed. BET isotherm and nitrogen-adsorption–desorption isotherms analysis results implied that lignite is a heteroporous material exhibiting microporous properties.
118 citations
TL;DR: In this paper, a graphene oxide (GO)/BiOBr composite was successfully synthesized, using a simple two-step process, and the tetragonal phase of BiOBr was incorporated into GO sheets, and was employed as a photocatalyst for the degradation of rhodamine-B (RhB) and methylene blue (MB) under visible light.
Abstract: A graphene oxide (GO)/BiOBr composite was successfully synthesized, using a simple two-step process. The tetragonal phase of BiOBr was incorporated into GO sheets, and was employed as a photocatalyst for the degradation of rhodamine-B (RhB) and methylene blue (MB) under visible light. The synthesized composites have been characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-rays analysis (EDAX), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopic (XPS) studies. The decomposition and degradation of the dyes were visualized by UV–Visible spectroscopy, by decrease in the intensity of absorbance and concentration, substantiated by TOC analysis. The mechanism of photocatalytic effect of GO/BiOBr composite has been also discussed. The degradation efficiency of GO–BiOBr (5%) composite towards MB & RhB was found to be 98% and 95% respectively, when compared to 40% and 50% using pure BiOBr.
105 citations
TL;DR: In this article, a composite composed of polyaniline and silica gel was successfully prepared via in situ polymerization, which was used as an adsorbent for the removal of Cr(VI) ions from the aqueous solutions.
Abstract: In this study, a composite composed of polyaniline and silica gel was successfully prepared via in situ polymerization. The prepared polyaniline/silica gel (PANI/SiO 2 ) composite was used as an adsorbent for the removal of Cr(VI) ions from the aqueous solutions. Structure and morphology of the composite were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX). A batch adsorption system was applied to study the ability of the adsorbent to remove Cr(VI) ions from aqueous solution. Results revealed that the PANI/SiO 2 composite requires minimum contact time as 60 min, pH 4.2, a dosage of 0.1 g and 50 mg/L as an initial concentration of Cr(VI) ions for the maximum removal capacity at 303 K. Langmuir and Freundlich adsorption isotherm models were studied to describe isotherm constants. The Cr(VI) ion uptake by the composite follows Freundlich isotherm. The maximum Cr(VI) ion adsorption capacity of PANI/SiO 2 composite was found to be 63.41 mg/g at 303 K. Thermodynamic parameter studies concluded that the nature of Cr(VI) ion adsorption was spontaneous and endothermic. The kinetic study revealed that the adsorption of Cr(VI) ions by the composite follows the pseudo-second-order and pore diffusion models. The mechanism was mainly driven by both ion exchange and adsorption coupled reduction.
100 citations
TL;DR: In this article, a coagulation process using ferric chloride was employed as a pre-treatment process for landfill leachate and Fenton process was applied for degradation of the leachates.
Abstract: Landfill leachate is a complex mixture containing toxic and recalcitrant substances with considerably low BOD 5 /COD indicating the necessity and difficulty of its treatment. Amongst treatment processes, integrated separating-destructive processes are promising ones. In this way, suspended and colloidal particles get separated in a separating process while the soluble fraction undergoes a destructive process; probably an advanced oxidation process. In the present study, coagulation process using ferric chloride was employed as a pre-treatment process for landfill leachate. Design of experiment, modeling and data analysis were conducted using response surface method (RSM) considering COD, color and TSS removals as responses. In optimum conditions (pH = 7 and 1500 mg/L FeCl 3 ) the average COD, color and TSS removals were approximately 65%, 79% and 95%, respectively. Afterwards, Fenton process was applied for degradation of the leachate. Average oxidation state (AOS) and BOD 5 /COD values increased from −0.51 and 0.11 to +1.7 and 0.4 respectively. Phyto-toxicity test was also conducted based on the germination index which was dramatically increased after coagulation and Fenton processes.
99 citations
TL;DR: In this article, the Cd(II) ions adsorption equilibrium on the Fe 3 O 4 -Cit were obtained by 35min at the optimized pH 5.81, 11.45 and 12.56 at the 298,K, 303,K and 308,K respectively.
Abstract: Citric acid coated magnetite nanoparticles (Fe 3 O 4 -Cit) have been synthesized for the removal of cadmium from aqueous solutions. As-prepared Fe 3 O 4 -Cit was characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and through the determination of pH zpc . Several factors effecting the adsorption of Cd(II) ions on the surface of Fe 3 O 4 -Cit such as pH, temperature and contact time were investigated. The Cd(II) ions adsorption equilibrium on the Fe 3 O 4 -Cit were obtained by 35 min at the optimized pH 5. Kinetic study shows the Cd(II) adsorption onto Fe 3 O 4 -Cit follow the pseudo-second order kinetic model with R 2 > 0.997 at 308 K. The adsorption data was satisfactorily explained by Langmuir and Freundlich isotherm models. The experimental data found to be suitable linearity with Langmuir isotherm having maximum adsorption capacity ( q m ) values in mg g −1 10.81, 11.45 and 12.56 at the 298 K, 303 K and 308 K, respectively. The correlation coefficient R 2 = 0.997 fully supports the favorability of Langmuir isotherm in adsorption process. The negative values of Δ G °, −5.68, −6.31 and −6.95 kJ mol −l throughout the temperature at 298 K, 303 K and 308 K are indicating the feasibility of adsorption process on to Fe 3 O 4 -Cit was spontaneous in nature.
TL;DR: In this article, a novel magnetic hydroxamic acid modified polyacrylamide/Fe 3 O 4 adsorbent (M-PAM-HA) was proposed for removal of metal ions by varying test conditions.
Abstract: A novel magnetic hydroxamic acid modified polyacrylamide/Fe 3 O 4 adsorbent (M-PAM-HA) was prepared with acrylamide by microemulsion polymerization and then nucleophilic substitution of hydroxamic acid. The morphology, structure of the magnetic adsorbents before (M-PAM) and after modification (M-PAM-HA) were characterized and their adsorption properties for the removal of metal ions by varying test conditions were also investigated. The modified M-PAM exhibited lower swelling property and less magnetic leaching than M-PAM. Their adsorption kinetics followed the pseudo-second order model. The maximum adsorption capacities of metal ions ranged from 0.11 to 0.29 mmol g −1 for M-PAM and 0.88–1.93 mmol g −1 for M-PAM-HA, respectively. Sips model fitting well to experimental data revealed the surface heterogeneity of the prepared adsorbents. In multi-metal systems, M-PAM-HA showed the relative selectivity toward Pb(II), although Pb(II) was adsorbed the least in their corresponding one-metal systems. The adsorption mechanism was proposed based on the results of FTIR and density functional theory (DFT) calculation.
TL;DR: In this article, the authors investigated the possibility of the utilization of carbon residue from biomass gasification process with and without chemical activation as a low cost sorbent for iron(II), copper (II) and nickel(II) ions from an aqueous solution.
Abstract: The main goal of this research was to investigate the possibility of the utilization of carbon residue from biomass gasification process with and without chemical activation as a low cost sorbent for iron(II), copper(II) and nickel(II) ions from an aqueous solution. Commercial activated carbon was used as a reference sample. Batch experiments were done to evaluate the influence of pH, initial metal concentration and contact time. The optimum pH required for maximum adsorption was found to be 4, 5 and 8, for iron, copper and nickel, respectively. According to the results, the removal of metals by carbon residue with and without chemical activation was higher than commercial activated carbon. The highest maximum experimental sorption capacities ( q m ,exp ) for iron, copper and nickel by activated carbon residue were 21, 23 and 18 mg g −1 , respectively. The experimental equilibrium sorption data were tested for the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) equations. Depending on the system the Langmuir or Freundlich isotherms have been found to provide the best correlation. The kinetics of iron, copper and nickel sorption by different adsorbent materials followed the pseudo-second-order model. Other tested kinetic models were the pseudo-first-order and the Elovich models. Weber Morris's intraparticle diffusion model showed that there are two or three different stages for the removal of metals.
TL;DR: In this paper, the adsorption behavior of arsenic was studied in detail by synthesizing a novel adsorbent by aggregating cobalt ferrite nanoparticles during the formation of iron oxide hydroxide, i.e. schwertmannite.
Abstract: Arsenic poisoning is causing a serious threat to the environment. The application of nanoparticles in the abatement of arsenic is becoming an intense area of research nowadays. In the present study the adsorption behavior of arsenic was studied in detail by synthesizing a novel adsorbent by aggregating cobalt ferrite nanoparticles during the formation of iron oxide hydroxide, i.e. schwertmannite. Cobalt ferrite nanoparticle enhances the magnetic properties of schwertmannite and makes it a better candidate for arsenic removal. The various structural as well as morphological properties were investigated by VSM, XRD, FTIR, BET and FESEM analysis. Batch adsorption experiments were carried out by varying different process parameters such as contact time, adsorbent dose, pH, temperature and presence of other co-ions. Arsenic adsorption by cobalt ferrite nanoparticle aggregated schwertmannite (CNSh) was found to be highly pH sensitive. Maximum arsenic was adsorbed at around pH 5.3. Study of temperature effect on arsenic adsorption confirmed the endothermic nature of the process. Other thermodynamic properties were also calculated and found that physical adsorption was dominant with activation energy of 5.1 kJ/mol. Kinetic study revealed that the pseudo second order model was followed by the adsorption process having regression coefficient ( R 2 ) 0.99. The equilibrium study showed that the adsorption system followed the Langmuir isotherm model with maximum adsorption capacity of 1011 μg/g which was comparably efficient than several other adsorbents.
TL;DR: In this article, the authors explored the removal of phenol from water by peroxi-electrocoagulation method using mild steel as anode and graphite as cathode.
Abstract: The present study explores the removal of phenol from water by peroxi-electrocoagulation method using mild steel as anode and graphite as cathode. The various parameters like effect of pH, concentration of phenol, current density, temperature, and co-existing ions on the removal efficiency of phenol from the water was studied. These studies were carried out at an initial concentration of phenol of 2.5 mg/L. The results showed that the maximum removal efficiency of 92% was achieved at a current density of 0.10 A/dm2 and pH of 2.0. The results of pilot scale study show that the process was technologically feasible.
TL;DR: In this paper, a comparison between aluminum and iron plate electrodes on COD and color removal from Petrochemical wastewaters by electro-Fenton process was studied, and the experiments were conducted to evaluate the effects of reaction time, current density, pH, H 2 O 2 /Fe 2+ molar ratio, and H 2 o 2 of petrochemical wastewater (PW) (ml/l) on the performance of the process.
Abstract: Petrochemical manufacturing wastewaters often contain a high concentration of biodegradable compounds that possess either toxicity or activity inhibition to the biological unit. In this paper, a comparison between aluminum and iron plate electrodes on COD and color removal from Petrochemical wastewaters by electro-Fenton process was studied. The experiments were conducted to evaluate the effects of reaction time, current density, pH, H 2 O 2 /Fe 2+ molar ratio, and H 2 O 2 of petrochemical wastewater (PW) (ml/l) on the performance of the process. Response surface methodology (RSM) was employed to assess individual and interactive effects of the five main independent parameters on the COD and color removal. The results show that COD and color removal efficiencies of iron electrode (67.3% and 71.58%, respectively) were more than those of aluminum electrode (53.94% and 67.35%, respectively).
TL;DR: In this article, a column experiment with CLZMOBeads at neutral pH was successfully employed for the removal of fluoride ions from synthetic fluoride water and the regeneration ability was tested.
Abstract: Adsorbents, lanthanum (III)–zirconium (IV) mixed oxide (LZMO) and chitosan supported lanthanum (III) and zirconium (IV) mixed oxides beads (CLZMOB), were prepared. The prepared sorbents were characterized using FTIR, SEM with EDAX, XRD and TGA–DSC studies. Sorption studies were performed at different temperatures, equilibrium time, pH values and in the presence of foreign ions in batch mode. Maximum fluoride adsorption occurred at pH 7 for both LZMO and CLZMOB. The kinetic study revealed an optimum equilibrium time as 50 min with an adsorbent dose of 100 mg/L at room temperature. The sorption data were fitted well with Langmuir isotherm. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° indicated that the nature of fluoride sorption is spontaneous and endothermic. The column experiment with CLZMOB at neutral pH was successfully employed for the removal of fluoride ions from synthetic fluoride water. 0.1 M NaOH was used for desorption studies and the regeneration ability was tested. Based on the column experiment, a defluoridation model has been illustrated. The results showed that CLZMOB could be an effective sorbent for the removal of fluoride from aqueous solutions.
TL;DR: In this article, the adsorption of hexavalent chromium (Cr(VI)) ions using the Fe nanoparticle (NP)-containing carbon nanofibers (CNFs) grown on porous carbon microbeads (∼0.5mm) as adsorbents was described.
Abstract: The present study describes the adsorption of hexavalent chromium (Cr(VI)) ions using the Fe nanoparticle (NP)-containing carbon nanofibers (CNFs) grown on porous carbon microbeads (∼0.5 mm) as adsorbents. The porous carbon beads were produced by carbonization and activation of the phenolic precursor-based polymeric beads synthesized by suspension polymerization. The Fe NPs were in situ incorporated within the polymeric beads during polymerization. CNFs were grown inside the beads by chemical vapor deposition using the Fe NPs as the metal catalyst and benzene as the carbon source. Adsorption tests were performed to determine the removal efficiency of the adsorbents for Cr(VI) over the concentration range of 10–150 ppm in water under batch and dynamic (flow) conditions. The results revealed that the prepared adsorbents had significant adsorption capacity (∼41 mg g −1 ) for Cr(VI), which was comparable or larger than that of the materials discussed in the literature. Moreover, the uptake of the solute during flow was approximately the same as that obtained under batch conditions, signifying negligible mass transfer resistances. The Fe-CNF-grown porous carbon beads prepared in this study may be used as packing materials in columns for the effective removal of Cr(VI) ions from wastewater under flow conditions.
TL;DR: The kinetics data obtained from the Monod model were utilized in modeling the continuous biodegradation process and gave very good agreement with experimental results.
Abstract: In this study, the biodegradation of simulated wastewater containing p-cresol has been carried out using Pseudomonas putida immobilized in PVA gel, in batch and continuous reactors. The effects of initial concentration, temperature, pH and PVA volume fraction on the biodegradation of p-cresol were evaluated in a batch SBBR. Continuous experiments were also carried out to study the effect of other operating parameters such as air flow rate and residence time on the biodegradation efficiency. The batch experimental results indicated that the biodegradation capabilities of P. putida are highly affected by temperature, pH and PVA vol.% and optimum performance were obtained at 35 °C, 8 and 40%, respectively. The biomass did not seem to be inhabited by high concentration of p-cresol and the biodegradation data fitted well the Monod non-inhibitory Model. The kinetics data obtained from the Monod model were utilized in modeling the continuous biodegradation process and gave very good agreement with experimental results.
TL;DR: In this article, the applicability of electrocoagulation using aluminium electrodes for the removal of contaminants which can scale and foul reverse osmosis membranes from a coal seam (CS) water sample, predominantly comprising sodium chloride, and sodium bicarbonate, was explored.
Abstract: This work explored the applicability of electrocoagulation (EC) using aluminium electrodes for the removal of contaminants which can scale and foul reverse osmosis membranes from a coal seam (CS) water sample, predominantly comprising sodium chloride, and sodium bicarbonate. In general, the removal efficiency of species responsible for scaling and fouling was enhanced by increasing the applied current density/voltage and contact times (30–60 s) in the EC chamber. High removal efficiencies of species potentially responsible for scale formation in reverse osmosis units such as calcium (100%), magnesium (87.9%), strontium (99.3%), barium (100%) and silicates (98.3%) were achieved. Boron was more difficult to eliminate (13.3%) and this was postulated to be due to the elevated solution pH. Similarly, fluoride removal from solution (44%) was also inhibited by the presence of hydroxide ions in the pH range 9–10. Analysis of produced flocs suggested the dominant presence of relatively amorphous boehmite (AlOOH), albeit the formation of Al(OH)3 was not ruled out as the drying process employed may have converted aluminium hydroxide to aluminium oxyhydroxide species. Evidence for adsorption of contaminants on floc surface sites was determined from FTIR studies. The quantity of aluminium released during the electrocoagulation process was higher than the Faradaic amount which suggested that the high salt concentrations in the coal seam water had chemically reacted with the aluminium electrodes.
TL;DR: In this article, two commercial ultrafiltration (UF) membranes, i.e. NF-90 and NF-270, were used to treat restaurant wastewater discharged from local medium-sized restaurant which served typical Malay halal foods.
Abstract: In this work, two commercial ultrafiltration (UF) membranes, i.e. UF PES-10 kDa and UF PVDF-100 kDa and two nanofiltration (NF) membranes, i.e. NF-90 and NF-270 were used to treat restaurant wastewater discharged from local medium-sized restaurant which served typical Malay halal foods. The wastewater which was subject to membrane treatment process was collected at the point of discharge without undergoing any pre-treatment process. The separation performances of membranes were characterized with respect to BOD 5 , COD, turbidity and conductivity removal while the membrane sustainability was evaluated based on the water flux recovery. Promising results of COD and turbidity removal (between 97.8 and 99.9%) were able to achieve regardless of membrane type, indicating the size of pollutants contributing to COD and turbidity values are significantly larger than 100 kDa. Removal rates of BOD 5 and conductivity were found to be strongly dependent on the membrane pore size. As NF-90 exhibited the smallest pore structure among the membranes studied, it showed the highest BOD 5 (86.8%) and conductivity removal (82.3%). In terms of sustainability, it is found that the original water flux of NF-90 was able to be retrieved by >50% compared to between 15 and 38% reported in the UF membranes, after only a simple rinsing process. This indicated that NF-90 is less susceptible to fouling and is more suitable and reliable to be employed for restaurant wastewater treatment.
TL;DR: In this paper, the authors used an aerated heterogeneous Fenton process to remove chemical oxygen demand (COD) from anaerobically treated palm oil mill effluent (AT-POME).
Abstract: Due to the extremely high content of organic pollutants, palm oil mill effluent (POME) requires multiple stages of treatment. At the primary stage, because of the high loading of organics, anaerobic treatment method was found to be the best practice nowadays. However, at the later stages, the treatment methods vary. As an option to available secondary and tertiary treatment method, we used an aerated heterogeneous Fenton process to remove chemical oxygen demand (COD) from anaerobically treated palm oil mill effluent (AT-POME). The Box–Behnken design (BBD) and response surface method (RSM) were used to design and optimize the performance of the process. Furthermore, the regression quadratic model representing the COD removal efficiency of aerated heterogeneous Fenton was developed and validated by the analysis of variances (ANOVA). The optimum parameters were determined as 3.91 g/l of nZVI dosage, 1.84 g/l of H 2 O 2 dosage, and 23.84 l/h of aeration and 240 min of reaction time. As 75% of COD was predicted to be removed at the optimum condition, the aerated heterogeneous Fenton process is a promising treatment method for AT-POME.
TL;DR: In this paper, the applicability of surfactant-modified bentonite (SMB) for removing 2,4,6-trichlorophenol (TCP) from water and petroleum refinery industry effluents has been investigated through a batch adsorption process.
Abstract: The applicability of surfactant-modified bentonite (SMB) for removing 2,4,6-trichlorophenol (TCP) from water and petroleum refinery industry effluents has been investigated through a batch adsorption process. The adsorbent was prepared from Na-bentonite by exchanging Na + ions with the cationic surfactant, hexadecyltrimethyl ammonium (HDTMA) chloride. The adsorption capacity for TCP was significantly enhanced by 2.3 times through surfactant treatment of the bentonite. The effect of pH, Initial concentration, contact time, adsorbent dose, ionic strength and temperature on adsorption of TCP was investigated. A strong dependence of the adsorption capacity on pH was observed, the capacity increasing as the pH value decreased. The long alkyl chains of intercalated HDTMA increased the hydrophobicity of the adsorbent and provided particular affinity for TCP molecules. The adsorbent showed high efficiency towards TCP and >99.0% removal was achieved from an initial concentration of 10 μmol/L at pH 3.0. The kinetics of the adsorption process was described by a pseudo-first-order model. Film diffusion was found to be the rate-limiting step. The adsorption isotherm was consistent with the Langmuir adsorption isotherm, and maximum monolayer capacity of the adsorbent was found to be 70.42 μmol/g at 30 °C, which was higher than that of commercial activated carbon (52.63 μmol/g). The adsorbed TCP can be recovered by using 0.1 M NaOH. The regeneration process was carried out in four cycles and results indicate minimum loss in adsorption capacity.
TL;DR: In this paper, a series of polyvinylidene fluoride (PVDF) hollow fiber membranes with various polymer concentrations (12-18 wt%) were prepared by dry-jet wet inversion method and were designed for direct contact membrane distillation (DCMD) application.
Abstract: The possibility of recovering water from hot dyeing solution has been investigated in this work by using membrane distillation (MD) made of polyvinylidene fluoride (PVDF). A series of PVDF hollow fibre membranes with various polymer concentrations (12–18 wt%) were prepared by dry-jet wet inversion method and were designed for direct contact membrane distillation (DCMD) application. Prior to the treatment of hot dyeing solution of 80 °C, the PVDF membranes were characterized in terms of scanning electron microscopy, atomic force microscopy, gas permeation, liquid entry pressure, contact angle and membrane porosity. It is reported that the surface roughness, contact angle and liquid entry pressure of PVDF membrane were increased while mean pore size and porosity decreased with increasing PVDF concentration in the dope from 12 to 18 wt%. Based on the DCMD results, it is found that 12 wt% PVDF membrane showed the highest permeate flux due to its smooth surface, high membrane porosity, large mean pore size as well as big macrovoids formed at the middle cross-section of the hollow fibre membrane. Although MD flux tended to decrease with increasing polymer concentration, all the resulting membranes were still able to achieve excellent dye rejection (at least 99.78%), indicating that MD is very potential to be employed in treating dyeing solution which normally discharged in hot condition from textile industry.
TL;DR: In this article, the perchlorate ion ion exchange capacity of five cationic resins (A532E, A520E, PWA-5, PSR-2 and A400E) was examined in batch kinetics and isotherms.
Abstract: The ion exchange capacity of five cationic resins (A532E, A520E, A400E, PWA-5, PSR-2) with regard to perchlorate ion was examined in batch kinetics and isotherms. The specificity of each resin was calculated from batch kinetic tests and results confirmed that the A532E and PSR-2 resins are more specific than the others for perchlorate removal. Furthermore, these results show PSR-2 and PWA-5 resins follow a pseudo-first order relation whereas exchanges are better described by pseudo-second order relations. The rate limiting step of ion exchange process was identified, for A400E, A520E and A532E as being the intraparticular diffusion, while PSR-2 and PWA-5 resins have an ion exchange rate limited by the external diffusion. Finally, the isotherm experiments show that the ion exchange equilibrium for perchlorate can be modelled by Langmuir relation for all resins and confirm that perchlorate ions are fixed forming a monolayer without interaction between molecules. The Langmuir model results indicate the maximal exchange capacities for perchlorates are of the same order of magnitude for all resins (from 183 mg g−1 for A400E to 115 mg g−1 for A532E). However for the removal of traces of perchlorates in drinking water, the experimental results confirm the benefit of perchlorate specific resins A532E and PSR-2.
TL;DR: It can be concluded that calcium lactate-cationic polymer has potential as a pre-treatment for AnPOME, which is unable to fully decolourise the effluent which is aesthetically important.
Abstract: The conventional palm oil mill effluent (POME) ponding system is unable to fully decolourise the effluent which is aesthetically important. Several parameters, such as low molecular mass coloured compounds (LMMCC), lignin–tannin, ammonia nitrogen (NH 3 -N) and chemical oxygen demand (COD) in the cooling pond, are much higher than for the fresh raw POME. The analysis of the POME from each pond revealed that the removal of lignin–tannin is insignificant after anaerobic ponds and hence physicochemical treatment is necessary. The POME colloid repulsion in the aerobic pond is greater than in the anaerobic pond. The coagulation/flocculation process was utilized to destabilize the anaerobically treated POME (AnPOME) colloid and calcium lactate was chosen as a coagulant. The best polymer order was identified based on an overall removal performance. The best polymer can be arranged as QF23912 (58%) > QF25610 (57%) > AN1500 (51%) > QF24807 (50%) > AN1800 (47%). All tested polymers have similarity in removing NH 3 -N. It can be concluded that calcium lactate-cationic polymer has potential as a pre-treatment for AnPOME.
TL;DR: Porous ceramic capillary membranes made of yttria-stabilised zirconia (YSZ) are presented in this paper, which are conditioned for virus filtration by varying the initial YSZ particle size.
Abstract: Porous ceramic capillary membranes made of yttria-stabilised zirconia (YSZ) are presented, which are conditioned for virus filtration by varying the initial YSZ particle size Compared to polymeric membranes, ceramic membranes offer remarkable advantages for filtration processes as they show excellent chemical, thermal and mechanical stability and can easily be cleaned by backflushing YSZ powders with different particle sizes (30 nm, 40 nm and 90 nm) are individually and mixed processed by extrusion, dried and finally sintered at 1050 °C for 2 h The sintered YSZ capillaries are characterised by microstructural analysis including Hg-porosimetry, BET analysis and 3-point bending tests By increasing the initial YSZ particle size, increased average membrane pore sizes ranging from 24 nm to 146 nm are obtained Mechanically stable membranes are provided showing high open porosities of ∼45% and ∼36% for capillaries composed of single and mixed YSZ powders, respectively By increasing the membrane pore size, reduced virus retention capacities in combination with increased water permeate fluxes are achieved Capillaries made of YSZ-40 nm ensure both, log reduction values (LRV) ≥ 4 for small model bacteriophages MS2 and PhiX174 and high water permeate fluxes (∼30 L/(m 2 hbar)), being suitable for sustainable virus filtration as requested by the World Health Organisation (WHO) and the United States Environmental Protection Agency (USEPA) Due to long-term virus filtration for two weeks, membrane pore plugging is successfully avoided by iterative backflushing and relatively high membrane fluxes in combination with requested LRV 4 level fulfilling the virus filter criterion are achieved
TL;DR: In this article, an attempt was made to prepare an activated carbon from Prosopis juliflora seeds and it was coated in a polyaniline matrix and the prepared adsorbent has a BET surface area of 1028 m 2 /g.
Abstract: An attempt was made to prepare an activated carbon from Prosopis juliflora seeds and it was coated in a polyaniline matrix. The prepared adsorbent has a BET surface area of 1028 m 2 /g. The adsorbent was analyzed for its ability to remove Direct Red 23 in its aqueous solution. Effect of pH proves that maximum uptake of DR23 by PPAC was obtained at pH 3.0. The adsorption of DR23 by PPAC follows pseudo second-order kinetics with a very high correlation coefficient of 0.9968 r 2 Q 0 ) increases from 90.91 to 109.89 mg/g while increasing the temperature from 30 to 45 °C. Column model analysis was also carried out to evaluate the adsorbent performance for continuous operation. Thomas, Yoon–Nelson and Bohart–Adams mathematical models were applied to evaluate the column performance. YN model provides excellent fit with very high r 2 (0.9844–0.9953) and low Sd (0.09–0.37).
TL;DR: In this paper, the effect of system variables such as pH, contact time, initial concentration and adsorbent dose were investigated in a batch process, and the adsorption equilibria of the system at constant temperature were modeled by Langmuir, Freundlich and Temkin isotherms.
Abstract: Massive use of an insecticide such as malathion has caused a setback to the environment and also has increased potential risk to human health as it is an endocrine disruptor chemical. This work was carried out to study the removal of malathion from aqueous solution using adsorbents, such as rice husk (RH) activated rice husk (ARH) and commercially available powdered activated carbon (PAC). The effect of system variables such as pH, contact time, initial concentration and adsorbent dose were investigated in a batch process. The adsorption equilibria of the system at constant temperature were modeled by Langmuir, Freundlich and Temkin isotherms. Langmuir model showed excellent correlation with experimental data. For kinetic study, the adsorption process fitted the pseudo-second order model. Maximum malathion removal efficiency of 53, 87 and 94% were obtained with RH, ARH and PAC, respectively, under optimum conditions.
TL;DR: In this article, a combination of physical and biological process was employed for the treatment of dyeing wastewater in a sequencing batch reactor (SBR), where tamarind seed was found to be the most efficient sorbent and hence it was used in the SBR along with the microorganisms.
Abstract: In this work, a combination of physical and biological process was employed for the treatment of dyeing wastewater in a sequencing batch reactor (SBR). Mixed culture comprising of white rot fungus (WRFs), Pleurotus floridanus , Ganoderma lucidum and Trametes pubescens , was used as microorganisms in the reactor. Various sorbents were screened for their ability to decolourize the dyeing wastewater. From the results, tamarind seed was found to be the most efficient sorbent and hence it was used in the SBR along with the microorganisms. Statistical design was employed for the optimization of process variables like air flow rate, sludge retention time (SRT) and sorbent dosage. The effects of these variables on decolourization, chemical oxygen demand (COD) reduction and sludge volume index (SVI) were studied. The optimum conditions were: air flow rate – 13 LPH, SRT – 17 d and sorbent dosage – 11 g/L. At the optimized conditions, the performance of SBR was studied at various organic loading rates by changing the initial substrate concentration and HRT. At an organic loading rate of 0.165 kgCOD/m 3 d, a maximum decolourization and COD reduction of 86.6% and 96% respectively was achieved. SEM analysis confirms the sorption of dye molecules onto the sorbent.