Biosorbents for hexavalent chromium elimination from industrial and municipal effluents

The presence of hexavalent chromium in wastewater is a potential hazard to aquatic animals and humans. There are various mechanisms proposed, kinetic models used and adsorption isotherms employed for the efficient removal of hexavalent chromium from industrial and municipal wastewaters using biosorbents. Biosorption of heavy metals is a most promising technology involved in the removal of toxic metals from industrial waste streams and natural waters. Metal removal treatment systems using microorganisms are cheap because of the low cost of sorbent materials used and may represent a practical replacement to conventional processes. The present review discusses hexavalent chromium biosorption properties of algae, bacteria, fungi, and agricultural products, as well as adsorption properties of non-living substances. Cell walls are responsible for biosorption of dead biomaterial; compositions of cell walls are discussed. Chemical modification of biosorbents, optimization of biosorption parameters, mixtures of different biosorbents and the study of biosorption mechanisms are the main keys to transfer the biosorption process from lab to industry.     

New procedure for the control of the treatment of industrial effluents to remove volatile organosulfur compounds

We present a new procedure for the determination of volatile organosulfur compounds in samples of industrial effluents using dispersive liquid–liquid microextraction and gas chromatography with flame photometric detection. Initially, the extraction parameters were optimized. These included: type and volume of extraction solvent, volume of disperser solvent, salting out effect, pH, time and speed of centrifugation as well as extraction time. The procedure was validated for 30 compounds. The developed procedure has low detection limits of 0.0071–0.49 μg/L and a good precision (relative standard deviation values of 1.2–5.0 and 0.6–4.1% at concentrations of 1 and 10 μg/L, respectively). The procedure was used to determine the content of volatile organosulfur compounds in samples of effluents from the production of bitumens before and after chemical treatment, in which six compounds were identified, including 2‐mercaptoethanol, thiophenol, thioanisole, dipropyl disulfide, 1‐decanethiol, and phenyl isothiocyanate at concentrations ranging from 0.47 to 8.89 μg/L. Problems in the determination of organosulfur compounds related to considerable changes in composition of the effluents, increase in concentration of individual compounds and appearance of secondary pollutants during effluent treatment processes are also discussed.     

Application of electron beam irradiation combined to conventional treatment to treat industrial effluents

A preliminary study to combine electron beam irradiation process with biological treatment was carried out. Experiments were conducted using samples from a governmental wastewater treatment plant (WTP) that receives about 20% of industrial wastewater, with the objective of destroying the refractory organic pollutants and to obtain a better performance of this plant. Samples from five different steps of WTP were collected and irradiated in the electron beam accelerator in a batch system with 5.0, 10.0 and 20.0 kGy doses. The main results showed a removal of 99% of all organic compound analysed in the industrial receiver unit (IRU) effluent and in the coarse bar screen (CBS) effluent with a 20 kGy dose, and for the medium bar screen (MBS) and primary sedimentation (PS) effluent a 10 kGy dose was sufficient. In the case of final effluent (FE), a dose of 5 kGy removed the remaining organic compounds and dyes present after biological treatment.     

Solid-phase extraction for toxicity reduction evaluations of industrial wastewater effluents

The physical, chemical and biological characteristics of industrial and municipal wastewater effluents in the United States are limited in National Pollutant Discharge Elimination System (NPDES) permits. Toxicity reduction evaluations (TREs) involving fractionation of wastewater effluents, biomonitoring for aquatic toxicity and determinations of specific chemicals are conducted when adverse effects on water quality are detected during routine biomonitoring as required by the NPDES permit. However, certain fractionation techniques are incompatible with subsequent testing for aquatic toxicity. The effect of various schemes for fractionation of wastewater effluent on biomonitoring with freshwater Cladocerans (Daphnia magna, Daphnia pulex, Ceriodaphnia dubia or Ceriodaphnia reticulata) is reviewed. Solid-phase extraction (SPE) is discussed as a chromatographic technique used for the selective fractionation of wastewater effluents during toxicity reduction evaluation.     

Membrane processes used for separation of effluents from wire productions

Metal wires are produced from different metals using drawing methods. The metal used influences both the technology applied and the composition of effluents generated during wires production. Ultrafiltration and nanofiltration are used for the separation of waste emulsions from cable factories. Membrane distillation was proposed for the treatment of acidic saline wastewater generated during steel wire manufacturing (etching). The possibility of the previously mentioned processes application for water reuse is presented. The application of poly(vinylidene fluoride) (PVDF) membranes (FP 100) with the molecular weight cut-off (MWCO) of 100 kDa in the ultrafiltration process resulted in the reduction of 99 % of oil and lubricants in the treated emulsions and allowed complete removal of suspended solids and colloidal substances. Such pre-treated emulsion was subsequently purified by nanofiltration (NF-90-2540) and a 98 % rejection of copper ions was achieved, resulting in a decrease of the permeate electrical conductivity from 3200 μS cm⁻¹ to 260 μS cm⁻¹. The obtained permeate was suitable for preparation of fresh oil emulsion utilized for lubrication in the wire drawing process. The spent etching baths (from steel wire production), which mainly contained FeSO₄ and about 1 mass % of sulfuric acid, were separated by membrane distillation. The obtained permeates were: clean water with electrical conductivity at a level of 3–5 μS cm⁻¹. Concentrates (190–200 g of Fe per L) from the MD process were cooled to 295 K, which enabled the FeSO₄ crystallization. Application of the above-mentioned membrane processes allows producing high quality product water, over 90 % of water was recovered from the treated wastewaters. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

Analysis of industrial effluents to determine endocrine-disrupting chemicals

Contaminated industrial effluents often contain a variety of organic pollutants that can disturb the development of the endocrine system and the organs that respond to endocrine signals in organisms. Total characterisation of the effluents to detect all these potential endocrine disruptors by standard GC-MS methods is difficult since this technique often misses the more polar or non-volatile fraction of these organic compounds. The wide spectrum of endocrine-toxic substances and their low concentrations require powerful analytical approaches like LC-MS for their identification. Furthermore, the methods for the detection of endocrine effects developed up to now do not show all the possible oestrogenic effects and results of the different tests are not comparable to one another. Therefore, further ecotoxicological research should be carried out so that new strategies can be proposed. In this article, an overview of the analytical methods for determining organic contaminants in industrial effluents and tests for the identification of endocrine disruptors and their effects is presented.     

New procedure for the examination of the degradation of volatile organonitrogen compounds during the treatment of industrial effluents

We present a new procedure for the determination of 32 volatile organonitrogen compounds in samples of industrial effluents with a complex matrix. The procedure, based on dispersive liquid–liquid microextraction followed by gas chromatography with nitrogen‐phosphorus and mass spectrometric detection, was optimized and validated. Optimization of the extraction included the type of extraction and disperser solvent, disperser solvent volume, pH, salting out effect, extraction, and centrifugation time. The procedure based on nitrogen‐phosphorus detection was found to be superior, having lower limits of detection (0.0067–2.29 μg/mL) and quantitation as well as a wider linear range. The developed procedure was applied to the determination of content of volatile organonitrogen compounds in samples of raw effluents from the production of bitumens in which 13 compounds were identified at concentrations ranging from 0.15 to 10.86 μg/mL and in samples of effluents treated by various chemical methods.     

A review on industrial wastewater treatment via electrocoagulation processes

Every year, a large amount of wastewater is discharged from various industries into the environment, and various methods are used to treat wastewater to reduce the amount of pollutants. Electrocoagulation (EC) is an electrochemically based technique that generates coagulant species in situ from the electrodissolution of sacrificial anodes, usually made of iron or aluminum destabilizes suspended, dissolved, or emulsified pollutants by using an electric current. It has a potential in removing various kinds of pollutants including organic and inorganic contaminants for various types of wastewater. The effectiveness of EC process depends on various parameters including pH, electrode, operation time, and current density. The goal of this study is to review the most relevant literatures that were published recently. The main challenges associated with the EC process are electrode passivation and energy consumption. EC compared with other common methods has advantages such as reducing energy consumption and reducing operating costs.     

Adsorption behavior of rice husk for the decontamination of chromium from industrial effluents

Rice husk, an agricultural waste product, was studied as a potential decontaminant for chromium in the effluents of leather tanning industries. Physico-chemical parameters such as selection of appropriate electrolyte, shaking time, concentration of adsorbent and adsorbate were studied to optimize the best conditions in which this material can be utilized on commercial scale for the decontamination of effluents. The radiotracer technique was used to determine the distribution of chromium. In certain cases atomic absorption spectrophotometry was also employed. Maximum adsorption was observed at 0.01 mol·dm⁻³ acid solutions (HNO₃, HCl, H₂SO₄ and HClO₄) using 3.0 g of adsorbent for 2.73·10⁻³ mol·dm⁻³ chromium concentration in five minutes equilibration time. Studies show that the adsorption decreases with the increase in the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 2.73·10⁻³ to 2.73·10⁻² mol·dm⁻³ chromium concentration. The characteristic Freundlich constants, i.e., 1/n=0.86±0.06 andA=2.35±0.06 mmol·g⁻¹ have been computed for the sorption system. Thermodynamic parameters, i.e., ΔG ⁰, ΔS ⁰ and ΔH ⁰ have also been calculated for the system. Application of the method to a test case of a medium size industry showed that 21 kg of rice husk was sufficient to maintain the NEQS limits of chromium for industrial effluents.     

Tracing polar benzene- and naphthalenesulfonates in untreated industrial effluents and water treatment works by ion-pair chromatography-fluorescence and electrospray-mass spectrometry

This paper presents a protocol for the determination of a class of polar, ionic and highly water-soluble organic pollutants: benzene- and naphthalenesulfonic acids, compounds widely used in chemical, pharmaceutical, tannery, paper and textile industries. This protocol involves the use of a solid-phase extraction (SPE) followed by ion-pair chromatography-electrospray-mass spectrometry (IPC-ESI-MS). In this work two polymeric solid-phase extraction cartridges (Isolute ENV+ and Lichrolut EN) were compared, with the more effective being Isolute ENV+ sorbent. Recoveries and breakthrough volumes were calculated by loading volumes of 150, 200 and 300 ml of spiked ground water through the SPE columns. To enhance the effectiveness of the methodology, 1 ml of water containing 5 mM TEA was added before eluting with methanol. Average recoveries ranging from 70 to 100% were obtained for a variety of 13 analytes (only two naphthalenesulfonate compounds had recoveries below 50%.). Determination of benzene- and naphthalenesulfonates was accomplished by ion-pair chromatography-fluorescence detection (IPC-FLD).

The ESI-MS parameters were optimized to achieve maximum sensitivity. [M–H]⁻ ion was the base peak using low energies (fragmentor voltage: 80 V). Significant fragmentation of the quasi-molecular [M–H]⁻ ion occurs at higher fragmentor voltages, leading to [M–SO₂H]⁻, [M–SO₃H]⁻ and [SO₃]⁻ as diagnostic ions, but with some sensitivity losses (more than two orders of magnitude when 150 V are applied as fragmentor voltage). Collision-induced dissociation (CID) of the parent ions for the benzene- and naphthalenesulfonates studied gave the [SO₃]⁻ fragment ion common to sulfonated compounds, it has been shown to be characteristic of aromatic sulfonated compounds and could be used as a diagnostic tool to indicate the presence of these compounds.

Limits of detection (signal-to-noise ratio = 3) ranging from 0.03 pg to 0.05 ng, were achieved when 150 ml of ground water were processed and quantified by IPC-FLD. In IPC-ESI-MS, time-scheduled SIM mode with post-column addition of 0.2 m min⁻¹ of methanol was used. LODs range from 0.6 pg to 0.13 ng. In summary, with the development of a methodology based on SPE followed by IPC-ESI-MS, good sensitivity, structural information and unequivocal identification can be achieved.

This protocol was applied to the analysis of surface waters, untreated industrial waste waters and wastewater treatment works effluents and influents. In the case of tannery effluent samples, isomers of naphthalenesulfonic acid were found as major pollutants in concentrations up to 0.8 and 1.0 mg l⁻¹, for 1-naphthalenesulfonate and 2-naphthalenesulfonate, respectively. The main contaminants in wastewater treatment work samples were 2,6-naphthalenedisulfonate, 1-hydroxy-3,6-naphthalenedisulfonate, 3-nitrobenzenesulfonate, 1-naphthalenesulfonate and 2-naphthalenesulfonate, with levels of ug/l.     

Removal of some dyes from industrial effluents by polymeric materials and gamma-irradiation

The radiolysis of two basic dyes (Astrazon Red 6B and Astrazon Blue BG-200%), was investigated as a function of dye concentration, pH, irradiation dose and dose rate. It was found that the Astrazon Red 6B dye showed more radiation degradation than the Astrazon Blue BG-200% dye. Combining irradiation with the conventional treatment enhanced the degree of degradation. Addition of oxygen or hydrogen peroxide showed this enhancement, while nitrogen showed no change. A pH drop was observed and may be attributed to the degradation of the dye molecules to lower molecular weight compounds such as organic acids. Experiments on the adsorption or exchange the dyes onto GAC, some polymeric ion exchange resins and polymeric membranes were carried out showing that GAC had the highest adsorption capacity. By combined treatment of irradiation and adsorption, the total removal of these toxic dyes was achieved.     

Sterculia foetida fruit shell based activated carbon for the effective removal of industrial effluents

In this work, Sterculia foetida fruit shells were used for the preparation of activated carbon and utilized for the removal of industrial effluent methylene blue is described. The carbon materials were prepared by washing the shells with water, dried in sunlight and subjected to heating at 700 ​°C in a muffle furnace to get the carbon material. This is divided into three portions, one is used as pristine and two portions were subjected to physical activation using steam and chemical activation using K₂CO₃. The impurities were removed by treatment with NaOH (0.1 ​M) and subsequently with HCl (0.1 M). Turbostatic structure was determined by XRD and the specific surface area was determined using BET showed 4, 1017 and 596 ​m²/g as the surface areas. Using these activated carbon materials, we have achieved 93% removal of methylene blue, found in industrial effluents.     

Advanced oxidation process by electron-beam-irradiation-induced decomposition of pollutants in industrial effluents

Electron-beam irradiation considered on advanced oxidation process induces the decomposition of pollutants in industrial effluent. Experiments were conducted using a radiation dynamics electron beam accelerator with 1.5 MeV energy and 37 kW power. The effluent samples from an industrial complex were irradiated using the IPEN's liquid effluent irradiation pilot plant. The experiments were conducted using one sample from each of eight separate industrial units and five samples of a mixture of these units. The physical–chemical characterization of these samples is presented. The electron beam irradiation was efficient in destroying the organic compounds delivered in these effluents, mainly, chloroform, dichloroethane, methyl isobutyl ketone, toluene, xylene and phenol. The necessary dose to remove 90% of the most organic compounds from industry effluent was 20 kGy. The removal of organic compounds from this complex mixture was explained by the destruction G value (Gd) that was obtained for those compounds with different initial concentrations and was compared with literature.     

Calorimetric monitoring of industrial chemical processes

Enthalpimetric methods used in chemical production and in process development are reviewed.On-line methods are applied to concentration analysis, to safety monitoring and to the control of reaction progress.The most promising applications of thermal methods are found in process development: enthalpimetric process investigation on the bench scale. Design principles for “process calorimeters” are outlined and applications to a pressure reaction, to a highly unstable radical reaction and to fermentations are shown.     

Remotion of organic compounds of actual industrial effluents by electron beam irradiation

Organic compounds has been a great problem of environmental pollution, the traditional methods are not effecient on removing these compounds and most of them are deposited to ambient and stay there for long time causing problems to the environment. Ionizing radiation has been used with success to destroy organic molecules. Actual industrial effluents were irradiated using IPEN's electron beam wastewater pilot plant to study organic compounds degradation. The samples were irradiated with and without air mixture by different doses. Irradiation treatment efficiency was evaluated by the Cromatography Gas Analyses of the samples before and after irradiation. The studied organic compounds were: phenol, chloroform, tetrachloroethylene (PCE), carbon tetrachloride, trichloroethylene (TCE), 1,1-dichloroethane, dichloromethane, benzene, toluene and xilene. A degradation superior to 80% was achieved for the majority of the compounds with air addition and 2kGy delivered dose condition. For the samples that were irradiated without air addition the degradation was higher.     

Advanced separation of harmful metals from industrial waste effluents by ion exchange

Advanced separation methods of harmful metals from industrial waste effluents, i.e., radionuclides from nuclear waste solutions, transition metals from metallurgical waste effluents, developed at the Laboratory of Radiochemistry, are discussed.     

On-line dilution with sequential injection analysis: a system for monitoring sulphate in industrial effluents

 On-line dilution with sequential injection analysis has been evaluated for sulphate monitoring in industrial effluents using a dilution coil in the conduits of the manifold system and a dilution step as part of the timing sequence. The manifold of the SIA system with the dilution coil is more complex than the system including the dilution step. The former method needs more complicated programming as well. Shorter analysis time favoured the dilution with the dilution step, but the limited linear range of this method is a large drawback. The large linear range of the SIA system with dilution coil makes it very suitable to be used as a process analyser. The proposed SIA system is suitable to monitor sulphate in industrial effluents in the range 50–5000 mg/L with a dilution coil, in the range 50–1000 mg/L with a timing sequence of 6.5 s and in the range 750–5000 mg/L with a timing sequence of 15 s using a dilution step; all three ranges with a RSD <4.5%. Received: 11 March 1996/Revised: 1 July 1996/Accepted: 4 July 1996     

On-line dilution with sequential injection analysis: a system for monitoring sulphate in industrial effluents

 On-line dilution with sequential injection analysis has been evaluated for sulphate monitoring in industrial effluents using a dilution coil in the conduits of the manifold system and a dilution step as part of the timing sequence. The manifold of the SIA system with the dilution coil is more complex than the system including the dilution step. The former method needs more complicated programming as well. Shorter analysis time favoured the dilution with the dilution step, but the limited linear range of this method is a large drawback. The large linear range of the SIA system with dilution coil makes it very suitable to be used as a process analyser. The proposed SIA system is suitable to monitor sulphate in industrial effluents in the range 50–5000 mg/L with a dilution coil, in the range 50–1000 mg/L with a timing sequence of 6.5 s and in the range 750–5000 mg/L with a timing sequence of 15 s using a dilution step; all three ranges with a RSD <4.5%. Received: 11 March 1996/Revised: 1 July 1996/Accepted: 4 July 1996     

Identification of estrogenic activity change in sewage,industrial and livestock effluents by gamma-irradiation

In this study, reduction of estrogenic activity in three different types of effluents from sewage, industrial and livestock wastewater treatment plants by gamma-irradiation was investigated using the yeast two-hybrid assay. After gamma-ray treatment at a dose of 10 kGy, estrogenic activities of sewage, industrial and livestock effluents decreased from 4.4 to 3.0, 1.5 to 1.0 and 16 to 9.9 ng-EEQ L^?1, respectively. The substantial reduction of estrogenic activity in livestock effluent was attributable to the degradation of 17β-estradiol (E2), estrone (E1) and 17α-ethynylestradiol (EE2). Although bisphenol A (BPA) was found at the highest concentration in all effluents, its contribution to the estrogenic activity was not significant due to its low relative estrogenic potency. Meanwhile, the calculated estrogenic activity based on concentrations of E2, E1, EE2 and BPA in the effluents significantly differed from the measured ones. Overestimation may have resulted by dissolved organic matters in effluents inhibiting the estrogenic activity of E2, E1, EE2 and BPA, whereas underestimation was likely due to estrogenic by-products generated by gamma-irradiation.     

Evaluation of toxic metals in the industrial effluents and their segregation through peanut husk fence for pollution abatement

The industrial pollution is exponentially growing in the developing countries due to the discharge of untreated effluents from the industries in the open atmosphere. This may cause severe health hazards in the general public. To reduce this effect, it is essential to remove the toxic and heavy metals from the effluents before their disposal into the biosphere. In this context, samples of the effluents were collected from the textile/yarn, ceramics and pulp/paper industries and the concentrations of the toxic metal ions were determined using neutron activation analysis (NAA) technique. The observed concentration values of the As, Cr and Fe ions, in the unprocessed industrial effluents, were 4.91 ± 0.8, 9.67 ± 0.7 and 9.71 ± 0.8 mg/L, respectively which was well above the standard recommended limits (i.e. 1.0, 1.0 and 2.0 mg/L, respectively). In order to remove the toxic metal ions from the effluents, the samples were treated with pea nut husk fence. After this treatment, 91.5% arsenic, 81.9% chromium and 66.5% iron metal ions were successfully removed from the effluents. Then the treated effluents contained concerned toxic metal ions concentrations within the permissible limits as recommended by the national environmental quality standards (NEQS).