Pilot‐scale demonstration of pre‐fermentation for enhancement of food‐processing wastewater biodegradability

A pilot‐scale anaerobic/aerobic ultrafiltration system was tested to treat high‐strength tomato‐processing wastewater, to achieve stringent dry‐ditch discharge criteria of soluble biochemical oxygen demand (SBOD) <10 mg dm^?3, total suspended solids <10 mg dm^?3, ammonia nitrogen <3 mg dm^?3 and soluble phosphorus <0.5 mg dm^?3. The anaerobic/aerobic system achieved 99.4% SBOD removal, 91.9% NH₃ N removal and 100% phosphorus removal at an overall hydraulic retention time of 1.5 days and solids retention time of 5 days during the tomato canning season. Respirometric studies confirmed that the pretreatment of tomato‐processing wastewater in the anaerobic reactor increased the readily biodegradable fraction, improved kinetics, and eliminated nutrient deficiency problem. Copyright © 2006 Society of Chemical Industry     

难降解有机污染物的生物处理

难降解有机物对环境危害巨大,生物技术是去除这类物质的重要途径。近年来国内外从不同角度研究了强化难降解有机物生物处理效率的方法。从自然环境中筛选分离有效菌和构建工程菌是强化生物处理的首要方法。针对目标污染物的结构性质,以合适的共代谢基质作为诱导物,采取共代谢的方式也可以提高难降解有机物的生物降解速率。此外,通过优化微生物的生存环境、提高微生物耐毒能力和竞争能力等工艺研究同样能够提高生物反应速率。生物技术处理难降解有机物的发展方向趋于三方面:高效菌种库和基因库的建设与丰富,新型反应器与工艺的发明以及各种交叉技术的应用。     

Treatment of air polluted with high concentrations of toluene and xylene in a pilot-scale biofilter

Air biofiltration is now under active consideration for the removal of the volatile organic compounds from air polluted streams. In order to investigate the performance of this newly developed technology, a biofiltration pilot unit was operated for a continuous period of 8 months. The biofilter column was packed with commercially conditioned peat. At start-up, the filter bed was inoculated with four species of microorganisms. The resulting biofilter was fed with air contaminated with toluene, xylene or a mixture of toluene and xylene. The maximum elimination capacities attained were 165 g m⁻³ h⁻¹ for toluene, 66 g m⁻³ h⁻¹ for xylene and 115 g m⁻³ h⁻¹ for the mixture of toluene and xylene. These specific performances exceed the values published in the technical and commercial literature for similar processes. Xylene isomers were degraded in decreasing order of reactivity, m-xylene, p-xylene, o-xylene. In the case of air polluted with a toluene and xylene mixture, it was noticed that the metabolism of toluene biodegradation was inhibited by the presence of xylene. Characterization of the biofilm microbial populations after several weeks of operation showed that the dominant strains among the isolated culturable strains from the biofilm, even if different from the initially inoculated strains, had at least one physiological property favoring degradation of aromatic organic rings. The performance of the biofilter was found to be dependent on the temperature of the filter media and the pressure drop through the bed. Finally, a steady state mathematical model was tested in order to theoretically describe the experimental results. This model is used to illustrate the operating diffusion and reaction regimes at steady state for the case of each pollutant. © 1998 Society of Chemical Industry     

Pilot plant biosorption in an integrated contact–settling system: application to Cu(II) removal by anaerobically digested sludge

Surplus biological sludge can be used as a low‐cost adsorbent in the removal of heavy metal from wastewater. A three‐zone contact–settling pilot plant was designed and operated to maintain continuous sludge–metal solution contact and subsequent separation of solid–liquid phases, all in the same vessel. Mild agitation was used to ensure good contact between Cu(II) and sludge without impairing solid–liquid separation. Heavy metal removal efficiency was largely unaffected by an increase in the Cu/sludge feed ratio as long as metal binding sites in the sludge remained unsaturated. Maximum metal uptake (75 mg Cu(II) g^?1 of total solids in the sludge) was found for Cu/sludge feed ratios ≥ 90 mg Cu(II) g^?1 of total solids. Pilot plant metal sorption uptake at different operational conditions correlated well with the calculated values from batch equilibrium adsorption isotherms. The amount of Cu(II) adsorbed on sludge influenced the degree of clarification due to the flocculating effect of Cu(II). Under operational conditions, a high degree of heavy metal removal and efficient clarification were achieved. Pilot plant operation at a Cu/sludge feed ratio around 90 mg Cu(II) g^?1 of total solids allowed efficient use of the biosorbent and high heavy metal removal efficiency in addition to a good quality metal‐free effluent in terms of low total suspended solids content. © 2001 Society of Chemical Industry     

BTEX removal from contaminated groundwater by a co‐culture of Pseudomonas putida and Pseudomonas fluorescens immobilized in a continuous fibrous‐bed bioreactor

A fibrous‐bed bioreactor with immobilized cells of Pseudomonas putida and Pseudomonas fluorescens was used to treat groundwater contaminated with benzene, toluene, ethylbenzene, and xylenes (collectively know as BTEX). The kinetics of BTEX biodegradation in the fibrous‐bed bioreactor operated under continuous well‐mixed conditions was studied at room temperature. Aeration was not used in the process fed with groundwater samples with an average total BTEX concentration of 2.75 mg dm^?3. All BTEX compounds present in the groundwater feed were concurrently and completely biodegraded even under oxygen‐limited or hypoxic conditions. Nearly 100% removal efficiency was obtained when the retention time was greater than 1 h. BTEX removal efficiency decreased with decreasing the retention time, with p‐ and o‐xylenes showed up first in the treated groundwater, followed by benzene and then other BTEX compounds. Biodegradation rates of BTEX generally increased with increasing BTEX concentration and loading rate. The maximum BTEX biodegradation rate was 5.76 mg h^?1 dm^?3 at the loading rate of 6.54 mg dm^?3 h^?1. The bioreactor had a stable performance, maintaining its ability for efficient BTEX degradation without requiring additional nutrients for more than 1 month. The good performance of the fibrous‐bed bioreactor was attributed to the high cell density (～15 g dm^?3 reactor volume) in the fibrous matrix. © 2002 Society of Chemical Industry     

Bio-electro-remediation: electrokinetic transport of nitrate in a flow-through system for enhanced toluene biodegradation

The availability of electron acceptors and nutrients is often limiting the microbiological clean-up of polluted groundwater at contaminated sites. In this study, the feasibility of electrokinetic processes to improve mass transfer was demonstrated in a model system simulating laminar groundwater flow conditions. Electrokinetic nitrate transport and enhanced biodegradation of toluene under denitrifying conditions was studied as function of voltage gradient in a new flow-through system. The study was done in a three-dimensional anaerobic model aquifer system filled with coarse sand. The influent area was divided into seven chambers thus enabling a separate addition of toluene and nitrate. Mesh electrodes were inserted laterally in order to form an electric field perpendicular to the flow direction with voltage gradients of 0, 0.125 and 0.25 V cm⁻¹, respectively. Biodegradation was studied after inoculation with a denitrifying microbial mixed culture. Application of the electric field resulted in nitrate migration into areas containing toluene. In the presence of denitrifying bacteria, the availability of nitrate in toluene polluted areas resulted in toluene biodegradation, demonstrated by nitrite formation and decreased toluene concentration.     

Bioremediation of toluene‐contaminated air using an external loop airlift bioreactor

An external loop airlift bioreactor (ELAB) has been used to capture and degrade toluene from a contaminated air stream. Using a spinning sparger, the toluene could be transferred from small, uniform bubbles into the aqueous culture media with an overall mass transfer coefficient as high as 1.1 h^?1. Due to the very volatile nature of toluene, Pseudomonas putida (ATCC 23973) was cultured and maintained on benzyl alcohol, the first intermediate compound in the metabolic degradation pathway for toluene. Consequently, before successful continuous operation of the ELAB with toluene‐contaminated air, Pseudomonas putida was acclimatized to toluene by using 30 min intermittent sparging of contaminated air into the bioreactor. Continuous sparging of toluene‐contaminated air could then be successfully carried out with 100% capture and biodegradation efficiency at a contaminated air concentration of 15 mg dm^?3 and a loading rate of 35 mg dm^?3 h^?1. Higher concentrations and loading rates were only partially degraded. Although this capture matches only the low rates reported earlier using biofilters to remediate toluene, the ELAB operates using submerged culture and requires no packing which can plug during biofilter operation. In this study, Pseudomonas putida grew on toluene at a maximum specific growth rate of only 0.05 h^?1. © 2003 Society of Chemical Industry     

Nitrate‐dependent degradation of 17α‐ethinylestradiol by acclimated activated sludge under anaerobic conditions

BACKGROUND: The synthetic estrogen 17α‐ethinylestradiol (EE2) is of great environmental concern. Batch experiments were conducted to investigate the removal of EE2 by activated sludge under anaerobic conditions with or without nitrate. The effect of temperature on EE2 removal was also estimated. RESULTS: No biodegradation of EE2 was observed in the absence of nitrate; owing to sorption onto the activated sludge, the overall removal EE2 rate was 62%; the sorption was fitted to both Freundlich and linear sorption models; the sorption rate decreased with the increase temperature. In the presence of nitrate, the overall removal rate of EE2 was greater than 97% after 72 h, mostly from biodegradation (95%); the biodegradation could be described by first‐order reaction kinetics with average rate constant of 0.0344 h^?1; increasing temperature enhanced the rate constant and the removal rate could be as high as 96–98% in the temperature range 10–30 °C. CONCLUSION: EE2 was removed by activated sludge under anaerobic conditions. In the absence of nitrate, the removal of EE2 was a result of sorption onto activated sludge. In the presence of nitrate, biodegradation was the dominant process for EE2 removal. Higher temperature improves biodegradation rate, but reduces the sorption of EE2 onto activated sludge. Copyright © 2009 Society of Chemical Industry     

Kinetic Modeling of Styrene Biodegradation by Rhodococcus erythropolis PTCC 1767: Effect of Adaptation to Styrene and Initial Biomass Concentration

Styrene is found at high concentrations in many petrochemical wastewaters and, due to its toxicity, has to be removed from these wastewaters before their discharge. Biological treatment of these wastewaters using pure or mixed microbial cultures that remove styrene through biodegradation has many advantages compared to physic-chemical processes. However, the growth of most of pure or mixed microbial cultures used previously for biodegradation of styrene is retarded at relatively low styrene concentration. In this study, the biodegradation of styrene by Rhodococcus erythropolis PTCC 1767 was considered. The effect of initial biomass concentrations (X), in the range 0.31 gL^?1 and 2.2 gL^?1, and exposure of R. erythropolis to styrene-containing media–on the kinetics of styrene biodegradation was studied.

The results of kinetic showed that, for runs at X?=?2.2 gL^?1, the kinetic data were satisfactorily fitted to the Monod model although the Haldane model gave a better fit of the kinetic data at all initial values of X. The results of kinetic modeling also showed that, with increase in X, the maximum specific removal rate (q_m) decreased whereas the threshold styrene concentration S_threshold increased. On the other hand, the exposure of the bacterial population to successive media in which styrene concentration was increased in a stepwise manner resulted in increase in the values of both q_m and S_threshold. The results of the present study showed the good potential of R. erythropolis for biodegradation of styrene in petrochemical wastewaters, although studies with real petrochemical wastewaters are needed to confirm this potential.     

Biofiltration of toluene in the absence and the presence of ethyl acetate under continuous and intermittent loading

BACKGROUND: Two peat biofilters were used for the removal of toluene from air for one year. One biofilter was fed with pure toluene and the other received 1:1 (by weight) ethyl acetate:toluene mixture. RESULTS: The biofilters were operated under continuous loading: the toluene inlet load (IL) at which 80% removal occurred was 116 g m^?3 h^?1 at 57 s gas residence time. Maximum elimination capacity of 360 g m^?3 h^?1 was obtained at an IL of 745 g m^?3 h^?1. The elimination of toluene was inhibited by the presence of ethyl acetate. Intermittent loading, with pollutants supplied for 16 h/day, 5 days/week, did not significantly affect the removal efficiency (RE). Biomass was fully activated in 2 h after night closures, but 6 h were required to recover RE after weekend closures. Live cell density remained relatively constant over the operational period, while the dead cell fraction increased. Finally, a 15 day starvation period was applied and operation then re‐started. Performance was restored with similar re‐acclimatization period to that after weekend closures, and a reduction in dead cell fraction was observed. CONCLUSION: This study demonstrates the capacity of the system to handle intermittent loading conditions that are common in industrial practices, including long‐term starvation. Copyright © 2008 Society of Chemical Industry     

Biological treatment of a contaminated gaseous emission from a paint and varnish plant—from laboratory studies to pilot‐scale operation

A Vapour‐Phase Bioreactor (VPB), namely a biotrickling filter, was scaled‐up and operated in‐situ for the treatment of gaseous emissions from a paint and varnish industrial plant. A microbial culture able to degrade the target compounds was enriched and a laboratory‐scale VPB was established in order to evaluate the treatment's performance. The VPB presented removal efficiencies higher than 90% when exposed to Organic Loads (OL) of ca 50 g h^?1 m^?3 of reactor. The VPB was exposed to dynamic conditions often found in‐situ (eg night and weekend shutdown periods) and showed a fast capacity to recover, with and without mineral medium recirculation. After a prolonged interruption period (10 months), the VPB was not able to cope with OL of ca 25 g h^?1 m^?3 of reactor and re‐inoculation was required in order to recover the treatment performance. The VPB also showed limited treatment when exposed to higher OL (ca 500 g h^?1 m^?3 of reactor). The VPB was then scaled‐up and a 3 m³ VPB was operated in‐situ, showing removal efficiencies higher than 50% when exposed to an OL of c 5 g h^?1 m^?3 of reactor, thus complying with current legal demands. The addition of a maintenance feed was shown to be a useful tool for VPB pilot‐scale operation when shutdown periods occurred. A factorial design of experiments was carried out, which allowed reduction to one‐tenth of the initial supply of the main mineral medium constituents, namely phosphate buffer, ammonium and magnesium salts, and also elimination of the metal supplement. Overall, the VPBs were shown to be robust equipment, being able to respond actively to dynamic treatment scenarios, particularly night and weekend shutdown periods. Copyright © 2003 Society of Chemical Industry     

Removal of TEX vapours from air in a peat biofilter: influence of inlet concentration and inlet load

This paper presents the results of the study of the removal of toluene, ethylbenzene, and o‐xylene (TEX) by biofiltration using a commercial peat as filter‐bed material. Runs with a single organic compound in air, and with the mixture of TEX in air, were carried out for at least 55 days in laboratory‐scale reactors inoculated with a conditioned culture. The influence of organic compound inlet load and of gas flow rate on the biofilter's performance was studied, including relatively high values of pollutant inlet concentration (up to 4.3 gC m^?3 for ethylbenzene, 3.2 gC m^?3 for toluene, and 2.7 gC m^?3 for o‐xylene). Results obtained show maximum elimination capacities of 65 gC m^?3 h^?1 for o‐xylene, 90 gC m^?3 h^?1 for toluene, and 100 gC m^?3 h^?1 for ethylbenzene, and high removal efficiency (>90%) even for moderately elevated concentrations: 3.0, 2.5 and 1.8 gC m^?3 for ethylbenzene, toluene and o‐xylene, respectively. The behaviour of the TEX mixture was in good agreement with the results obtained for the runs in which only one organic compound was present. Ethylbenzene and toluene are degraded easier than o‐xylene, and inhibitory effects due to the presence of multiple substrates were not observed. Copyright © 2005 Society of Chemical Industry     

Removal of lead (II) and cadmium (II) from aqueous solutions using spent Agaricus bisporus

The sorption of Pb and Cd from aqueous solutions by spent Agaricus bisporus was investigated. The effects of contact time, pH, ionic medium, initial metal concentration, other metal ions presence and ligands were studied in batch experiments at 25°C. Maximum sorption for both metals was found to occur at an initial pH of around 5.5. The equilibrium process was well described by the Langmuir isotherm model, with maximum sorption capacities of 0.2345 and 0.1273 mmol g^?1 for Pb and Cd respectively. Kinetic data followed the pseudo‐second‐order kinetic model. The presence of NaCl and NaClO₄ caused a reduction in Cd sorption, while Pb sorption was not remarkably affected. The presence of other metals did not affect Pb removal, while the Cd removal was much reduced. HCl or EDTA solutions were able to desorb Cd from the spent Agaricus bisporus (SAB) completely, while an approximately 60% and 15% desorption yield was obtained for Pb when HCl 0.01 mol L^?1 or EDTA 0.001 mol L^?1 were used, respectively. The results of FTIR, SEM and EDX analysis indicated that other mechanisms, such as surface complexation and electrostatic interactions, must be involved in the metal sorption in addition to ion exchange. © 2012 Canadian Society for Chemical Engineering     

Biodegradation of diesel oil in a baffled roller bioreactor

BACKGROUND: Ex situ bioremediation is a feasible and economical way to remove petroleum pollutants from contaminated soil or water. A baffled roller bioreactor was shown to be effective for biodegradation of diesel oil as a model petroleum pollutant. Microorganisms enriched from an industrially contaminated soil with heavy hydrocarbons were shown to be the best inoculum source for diesel biodegradation. RESULTS: The baffled roller bioreactor demonstrated better performance than control (roller bioreactor without baffles) or bead mill roller (control bioreactor filled partially with spherical beads) bioreactors. Biodegradation consisted of both fast and slow stages for degradation of light and heavy compounds, respectively. Among the tested temperatures ranging from 15 to 35 °C, room temperature (23 °C) was found to be the optimum temperature for biodegradation. The values of maximum specific growth rate and substrate yield (µ_max and Y_XS) for the indigenous microorganisms in the baffled roller bioreactor at room temperature were found to be 0.72 ± 0.08 h^?1 and (7.0 ± 1.0) × 10⁷ cells mg^?1 diesel, respectively. Biodegradation of diesel concentrations up to 200 g L^?1 was achieved with the highest biodegradation rate of 266 mg L^?1 h^?1 at the highest rotation rate of 45 rpm in the baffled roller bioreactor. CONCLUSION: Using indigenous bacteria enriched from industrial contaminated soil at room temperature, a baffled roller bioreactor is able to biodegrade high diesel oil concentrations at high biodegradation rates. Copyright © 2008 Society of Chemical Industry     

A Study of the Biofiltration of High‐Loads of Toluene in Air: Carbon and Water Balances,Temperature Changes and Nitrogen Effect

Biodegradable atmospheric pollutants, released at low to moderate concentrations, can be removed by biofiltration. In this work, a laboratory‐scale compost‐based biofilter has been evaluated for the removal of high levels of toluene in air (～ 4.0 g.m^?3). By applying a variable nitrogen input in the irrigation solution, it was shown that the biodegradation extent can be controlled through the nutrient supply. The maximum elimination capacity achieved was 135 g.m^?3.h^?1, for a N‐concentration of 3.0 g of N.L^?1. A quantitative analysis of the bioreaction aspects (stoichiometry, temperature) led to the determination of the water flow rates associated with the toluene oxidation. Thus, it was estimated that some 530 to 800 g of water.day^?1 were lost at the bioreactor outlet, but were balanced by the irrigation system.     

Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica

Functionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g^?1 for Cu(II), 1.16 mmol g^?1 for Pb(II) and 0.97 mmol g^?1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol^?1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g^?1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min^?1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering     

Anaerobic biodegradation of phenol in sulfide‐rich media

In the refinery industry, the washing processes of middle‐distillates using caustic solutions generate phenol‐ and sulfide‐containing waste streams. The spent caustic liquors generated contain phenols at concentrations higher than 60 g dm^?3(638.3 mmol dm^?3). For sulfur compounds, the average sulfide concentration was 48 g dm^?3(1500 mmol dm^?3) in these streams. The goal of this study was to evaluate the specific impact of phenol and sulfide concentrations towards the phenol‐biodegradation activity of a phenol‐acclimated anaerobic granular sludge. An inhibition model was used to calculate the phenol and sulfide inhibitory concentrations that completely stopped the phenol‐biodegradation activity (IC100). A maximum phenol‐biodegradation activity of 83 µmol g^?1 VSS h^?1 was assessed and the IC100 values were 21.8 mmol dm^?3 and 13.4 mmol dm^?3 for phenol and sulfide respectively. The limitation of the phenol biodegradation flow by phenol inhibition seemed to be related to the more important sensitivity of phenol‐degrading bacteria. The up‐flow anaerobic sludge bed reactor operating in a non‐phenol‐dependent inhibition condition did not present any sensitivity to sulfide concentrations below 9.6 mmol dm^?3. At this residual concentration, the pH and bisulfide ions' concentration might be responsible for the general collapsing of the reactor activity. Copyright © 2004 Society of Chemical Industry     

Removal of suspended solids and residual oil from palm oil mill effluent

Palm oil mill effluent (POME) was pretreated to remove suspended solids and residual oil. The processes used were flocculation, solvent extraction, adsorption and membrane separation. Flocculation was used to remove suspended solids, and solvent extraction and adsorption processes were used to remove residual oil. Membrane separation was subsequently applied to remove any residual suspended solids and oil remaining after the pretreatments. The solvent extraction and adsorption processes were operated on a batch basis whereas membrane separation was performed in continuous mode. The treatment efficiency of the processes was measured as percentage removal of suspended solids and oil respectively. The optimum values of the process parameters obtained in the flocculation process were an alum dosage of 4000 mg dm^?3, mixing speed of 150 rpm for 1 h and sedimentation time of 270 min, resulting in 93% suspended solids removal. In the solvent extraction process, a 95% reduction in residual oil was obtained using n‐hexane as a solvent with 20 min of mixing at 200 rpm. The ratio of solvent to POME was 6:10 and carried out at pH 9. In the batch adsorption process, an 88% reduction in residual oil was obtained at a mixing speed of 100 rpm for 1 h, pH 9 and an adsorbent dosage of 300 g dm^?3. In membrane separation processes, GH and CE(GH) membranes gave 63% and 49% reductions in suspended solids and residual oil respectively at pH 9 and pressure of 1000 kPa. Copyright © 2003 Society of Chemical Industry     

Combination of biological and chemical processes for the treatment of textile wastewater containing reactive dyes

The treatment of a segregated textile wastewater containing reactive dyes was investigated in two continuous‐flow process trains using ozonation and biological processes. The degree of decolorization and dissolved organic carbon (DOC) removal achieved by ozonation followed by aerobic treatment (two‐stage) was compared with that found when an anaerobic and aerobic pretreatment was added (four‐stage). Although the biological pretreatment reduced color by ～70%, similar amounts of ozone were required in both trains to achieve high degrees of overall removal of color and DOC. In both trains, ozonation increased biodegradability in the following aerobic reactor, however, in order to reach ～80% overall DOC removal, a specific ozone absorption (A*) of ～6 gO₃ gDOC_o^?1 was required and >50% of the DOC was mineralized in the ozone reactor. A comparison of cost estimates based on investment and operating costs for the process alternatives showed that a four‐stage train would reduce costs only if it enabled a decrease in A* to less than 2 gO₃ gDOC_o^?1. Difficulties in comparing treatment processes for segregated vs full‐stream wastewaters are discussed. Copyright © 2003 Society of Chemical Industry     

Arsenate and Dichromate Removal Efficiency of a New Calix[4]arene Impregnated Resin

This article highlights a newly synthesized 5,11,17,23-tetra-tert.butyl-25,26,27,28-tetrakis(hydrazidecarbonylmethoxy)-calix[4]arene (3) impregnated resin 4 and it's sorption ability for the removal of selected oxoanions, i.e., (arsenate and dichromate) from aqueous environment. Resin 4 was characterized by using FT-IR spectroscopy, scanning electron microscope (SEM), elemental, and thermogravimetic (TGA) analyses techniques. Sorption study was carried out through static and dynamic methods with continuous flow operation to evaluate the potency of resin 4 under various conditions. Several parameters, such as effect of sorbent dosage, contact time, pH, and initial concentration were optimized through batch experiments. Results justify that % sorption of these oxoanions is highly dependent on pH of the solution. Equilibrium was achieved in 45 min, while sorption efficiency of resin 4 can be better explained by Langmuir and Temkin isotherm models. Furthermore, kinetically both oxoanions follow pseudo second order model. Additionally, sorption of arsenate more appropriately could be explained by Moris-Weber diffusion kinetic model. For the dynamic method, Thomas model was used to calculate the kinetic coefficient (k_TH) and maximum sorption capacity (q_o) of resin 4 which are 3.84 and 5.94 ml mg^?1 min^?1 and 0.185, 0.160 mg g^?1 for As (V) and Cr (VI) respectively. Furthermore, resin 4 has been found as potential sorbent for removal of these oxoanions from contaminated surface water samples.