Showing papers in "Journal of water process engineering in 2016"

A review on potential usage of industrial waste materials for binding heavy metal ions from aqueous solutions

Abstract: Presence of toxic and recalcitrant heavy metal ions in industrial effluents is a major environmental concern. These fatal metal ions are not only hazardous in exceeding concentrations but due to the property of biomagnification it is urgent to look for the plausible solutions. This review article is an attempt to gather the research findings attempted in yester years for the removal of such metals from aqueous solutions by using waste materials from industries, such as blast furnace sludge, slag and flue dust, fly ash, black liquor lignin, and red mud. Studies have been complied keeping various efficiency influencing parameters such as optimum dose, contact time, initial concentration of metal ions, and many more in consideration. This article also tries to summarize the various problems and shortcoming of the work carried so far and attempts to explore the feasible suggestions.

Pesticide degradation in water using atmospheric air cold plasma

Abstract: A high voltage dielectric barrier discharge plasma reactor using atmospheric air as the inducer gas was studied for the degradation of pesticides (dichlorvos, malathion, endosulfan) in water. The degradation kinetics of the pesticides were studied using GC–MS as a function of plasma control parameters. Electrical characterisation of the plasma revealed that the plasma discharge consisted of filamentary streamers. Excited nitrogen, reactive oxygen species and OH radicals generated in the dielectric barrier discharge (DBD) plasma reactor were identified using optical emission spectroscopy. Ozone, used as an indicator for metastable oxygen species, was quantified within the reactor at concentrations of 1600, 2200, 2800 ppm after 8 min of plasma treatment for applied voltages of 60, 70, and 80 kV respectively. The degradation efficacy of pesticides after 80 kV and 8 min of plasma treatment were found to be 78.98 ± 0.81% for dichlorvos, 69.62 ± 0.14% for malathion and 57.71 ± 0.58% for endosulfan. Degradation was found to follow first order kinetics. GC–MS analyses showed that the degraded compounds and intermediates formed were less toxic than the parent pesticide. A proposed mechanism of degradation of these pesticides is suggested.

Recent progress in development of high performance polymeric membranes and materials for metal plating wastewater treatment: A review

Abstract: Development of advanced technologies for metal plating wastewater treatment constitutes one of the major fields of research, primarily driven by the progressive environmental regulations issued to address the concerns. The emergence of various membrane-based processes and the satisfactory trial and field tests have created new avenues for minimization of the negative impacts caused by the uncontrolled discharge of metal plating waste streams. On the other hand, the progress in the polymer science and engineering provides opportunities for development of membrane materials with advanced functionalities and superior characteristics that can effectively be employed for design and fabrication of high performance membranes. The present review provides an overview on the specifications of metal plating wastewater streams and the significance of the treatment by presenting possible strategies that can be employed for heavy metal removal. Special attention is paid to nickel, chromium and zinc due to their high impacts and detrimental effects. In addition, a comprehensive review is provided on the recent advances in development of high performance polymeric materials for diverse membrane-based processes including reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), complexation–ultrafiltration (CUF), microfiltration (MF), polymer inclusion membranes (PIMs), electro-membranes (EMs), hybrid processes, liquid membranes, emulsion liquid membranes (ELMs) and membrane-based solvent extraction by highlighting the role of molecular design and architecture and other featured characteristics in the process performance and efficiency.

Degradation of 2,4,6-trichlorophenol in aqueous solutions using peroxymonosulfate/activated carbon/UV process via sulfate and hydroxyl radicals

Abstract: In this study, the activation of peroxymonosulfate (PMS) was investigated by activated carbon (AC) along with UV for 2,4,6-trichlorophenol (TCP) degradation. The effects of operating parameters including pH, PMS concentration, AC dosage, initial TCP concentration and reaction time on TCP degradation were studied and optimized at pH 5.0, 8.0 mM PMS, 0.75 g/L AC and 75 min. Single step or two step additions of PMS made no marked difference in terms of TCP removal. The results of PMS decomposition showed that, AC/UV configuration was able to significantly activate PMS to degrade TCP compared to sole application of AC or UV. The contribution of UV in activation of PMS was more than that of AC. The rate constants of TCP degradation were in range of 0.0103–0.0512 min −1 for initial TCP concentrations of 5–50 mg/L. Scavenging experiments revealed that sulfate radical was the dominant radical of its kind for degradation of TCP, although hydroxyl radical was also partly effective. The results indicated that contribution of free radicals in solution was higher than that of surface-bound radicals. Moreover, mineralization of TCP was evaluated by COD, TOC and chlorine release and related results were 50.2%, 31.2% and 55%, respectively.

Polyvinylidene fluoride (PVDF) membrane for oil rejection from oily wastewater: A performance review

Abstract: The rapid rise in environmental awareness, tighter regulation, novel strategies to separate oils from industrial wastewater, polluted oceanic waters, and oil-spill mixtures, especially in the presence of surfactants have prompted the developments of novel membranes that are capable of separating oil from oily wastewater. Among numerous polymeric membranes, polyvinylidene fluoride (PVDF) membrane has been widely employed due to its outstanding properties. This review maps out the current trends and development as well as provides a perspective on potential outlook for advances in novel PVDF membrane for oil separation from oily wastewater. Despite the existing trends, there is still a challenge to produce membranes with low oil adhesive and anti-fouling properties, chemical resistance, high mechanical strength, high flux, high oil separation efficiency and long term stability during oily wastewater treatment. Fouling still remains a major dilemma restricting PVDF membranes towards their transition from laboratory to industrial scale application. To properly address this threat, there is need for researches into effective materials that can mitigate fouling phenomenon efficiently. In addition, a much stronger understanding of the basic properties of such materials will be required in order to find the relationship among the material properties, membrane morphology and the transport phenomena in the PVDF membrane. At the same time, the potential of novel non-solvent induced phase separation needs to be assessed as a comprehensive understanding between structure-surface properties and their performance for oily wastewater separation should be the backbone for future development and progress in PVDF membrane fabrication for oily wastewater treatment.

Adsorption studies for the removal of nitrate using chitosan/PEG and chitosan/PVA polymer composites

Abstract: This paper presents a study of the removal of nitrate ions using polyethylene glycol/chitosan and polyvinyl alcohol/chitosan composites were investigated. A series of batch experiments were conducted to examine the effects of contact time, adsorbent dosage and pH of the solution. Composite materials successfully adsorb nitrate from aqueous solutions at pH 3. Adsorption isotherm studies indicated that polymer composites satisfy Langmuir and Freundlich models. The rate of reaction follows pseudo-second-order kinetics. The adsorption capacities of PEG/chitosan & PVA/chitosan were found to be 50.68 and 35.03 mg g −1 respectively. The prepared adsorbents were characterized by Scanning electron microscopy (SEM), Energy dispersive analysis of X-rays (EDAX), Fourier Transform Infra-Red (FTIR), BET surface area and X-ray Diffraction (XRD). The results of the study indicated that polyethylene glycol/chitosan and polyvinyl alcohol/chitosan composites are useful materials for the removal of nitrate from aqueous solution.

Membrane fouling and modification using surface treatment and layer-by-layer assembly of polyelectrolytes: State-of-the-art review

Abstract: Membrane technology has been recognized as one of the most important technologies in water desalination. However, this technology is challenged with the fouling phenomenon which causes higher operating pressure, flux decline, frequent replacement of membranes and eventually higher operating costs. Therefore, researchers have focused on developing methods to overcome this problem and to enhance the membrane resistance to fouling. In this paper, we reviewed the membrane fouling and control through surface modification techniques. Special attention was paid to the layer-by-layer assembly of polyelectrolytes (LbL) which has been widely used as a powerful technique for surface modification and multifunctional film preparation. Furthermore, detailed effects of LbL key-parameters on the membrane performance were revealed to help understanding the working mechanism of this method.

Synthesis of nano-sized chitosan blended polyvinyl alcohol for the removal of Eosin Yellow dye from aqueous solution

Abstract: The current investigation aimed at synthesizing the nano-sized chitosan particles and blending it with the polyvinyl alcohol (PVA). This composite proved to be a good adsorbent for the removal of Eosin Yellow (EY) dye from the aqueous solution. The characterisation studies like TEM, SEM, XRD and FT-IR were carried out for the chitosan/PVA blend. The removal of EY dye by the chitosan/PVA composite was optimized by varying the certain operating parameters such as initial dye concentration, adsorbent dose, solution pH, contact time and temperature. The adsorption isotherms for the adopted system were studied in association with Langmuir, Freundlich and Temkin adsorption models. The adsorption isotherm data was best adopted with the Langmuir model. The Langmuir monolayer adsorption capacity of the chitosan/PVA blend for EY dye molecules was calculated as 52.91 mg/g. Adsorption kinetic data were applied to the pseudo-first order, pseudo-second order, Weber and Morris intraparticle diffusion and Boyd kinetic models. The adsorption kinetic was best obeyed with the pseudo-second order kinetics. The thermodynamic parameters were evaluated for the present system and it was found that the present system was spontaneous and exothermic in nature. The adsorbed EY dye molecules were desorbed from the spent chitosan/PVA using HCl solution. The desorption results indicates that the recovered adsorbent can be effectively reused for further adsorption cycles. The prepared material possesses excellent adsorption potential to treat the industrial dye wastewater.

Experimental investigation and artificial neural networks ANNs modeling of electrically-enhanced membrane bioreactor for wastewater treatment

Abstract: In this work, a new configuration of an electrically-enhanced membrane bioreactor has been introduced to treat medium strength wastewater at Masdar City, Abu Dhabi, United Arab Emirates (UAE). The integrated setup enhanced the reduction of wastewater contaminant concentrations. The investigated components in this study were chemical oxygen demand (COD), orthophosphates (PO 4 3− -P) and ammonium (NH 4 + -N). The percentages of COD, PO 4 3− -P, and NH 4 + -N removal obtained were 98, 99, and 98%, respectively. Variation in environmental compositions such as mixed liquor dissolved oxygen (DO), volatile suspended solids (MLVSS), pH, and electrical conductivity influenced the effluent concentration of wastewater components. Artificial neural networks (ANNs) based ensemble model was used to model the experimental findings of COD, PO 4 3− -P and NH 4 + -N removal given the initial mixed liquor compositions. Comparison between the model results and experimental data set gave high correlation coefficients for COD ( r = 0.9942), PO 4 3− -P ( r = 0.9998) and NH 4 + -N ( r = 0.9955).

Advances in biological systems for the treatment of high-strength wastewater

Abstract: The elevated organic content of high-strength wastewater makes aerobic treatment systems uneconomical. High-strength wastewaters are preferably treated anaerobically, thus providing a potential for energy generation while producing low surplus sludge. This paper provides an overview of high rate anaerobic digesters developed during the second half of the last century, focusing on anaerobic filter (AF), anaerobic fluidized-bed reactor (AFBR), and upflow anaerobic sludge blanket (UASB), along with their applications in high-strength wastewater treatment. Despite the unique compact design of these systems that combines the treatment and clarification in one reactor, they fail to provide complete stabilization of high-strength wastewater. Further downstream treatment is usually required to meet effluent regulatory limits. Therefore, advanced hybrid systems such as membrane bioreactors (MBRs), combined and integrated anaerobic–aerobic bioreactors are discussed in this review for their potential as effective treatment alternatives. The factors affecting the performance of these hybrid systems have been highlighted. MBRs provide excellent effluent quality with reduced footprint, but their major drawback is membrane fouling which increases maintenance and operating costs. Combined anaerobic and aerobic systems have been developed to provide a cost effective and efficient treatment for high-strength wastewater. Integrated anaerobic–aerobic systems employing biogranulation can provide a promising high-strength wastewater treatment technology. However, the design and operation of the integrated granular bioreactors are still in the development phase with limited data in continuous flow regime and large-scale operation. Long-term granule stability and long start-up are other obstacles. Further research is needed to overcome these shortcomings.

Dairy wastewater treatment using a novel low cost tubular ceramic membrane and membrane fouling mechanism using pore blocking models

Abstract: This study investigated the potential application of a novel low cost tubular ceramic membrane in treating wastewater generated by a local dairy industry. The low cost tubular membrane ($0.5) with 0.309 μm pore size, 53% porosity and 5.93 × 10−7 m3/m2s kPa water permeability was fabricated from natural clay materials by extrusion technique. The capability of the membrane for treating real dairy industry wastewater was tested in tangential mode of microfiltration operation at different applied pressure (207–414 kPa) and cross flow rate (5.55 × 10−7–2.22 × 10−6 m3/s). An increase in applied pressure and cross flow rate on the microfiltration process resulted in a decrease in percentage removal of chemical oxygen demand (COD). The novel membrane achieved a maximum reduction in COD up to 91% (135 mg/L) in the permeate stream with a flux of 2.59 × 10−6 m3/m2s, which is well within the permissible limit for wastewater discharge into the environment. These investigations affirmed the potential suitability of the membrane in dairy wastewater treatment to attain acceptable limit (

Enhanced adsorption of crystal violet by synthesized and characterized chitin nano whiskers from shrimp shell

Abstract: Chitin nanowhiskers (ChNW) were extracted from shrimp shell and subjected to alkali, bleaching and acid hydrolysis treatment. The Fourier transform infrared (FTIR) spectra confirmed the functional group moieties present at each stage of the purification process. The X-ray diffraction (XRD) analysis determined the crystallinity of the ChNW. The scanning electron microscopic (SEM), transmission electron microscopic (TEM) and atomic force microscopic (AFM) studies were carried out to examine and compare the morphology of the products at each stage of purification. The synthesized ChNW were used for the crystal violet adsorption studies. Along with ChNW, a series of adsorbent materials like chitin-Fe 3 O 4 , cellulose, and cellulose − Fe 3 O 4 were used for comparing the results and for the better understanding of adsorption phenomena. The absorbance of the solution during a time interval was investigated using UV–vis spectrophotometry. The prepared ChNW showed higher removal efficiency (79.13%) and adsorption capacity (39.56 mg g −1 ) compared to other adsorbents. The results proved that ChNW can be a potential candidate for the removal of crystal violet from contaminated water.

Solar photocatalytic mineralization of antibiotics using magnetically separable NiFe2O4 supported onto graphene sand composite and bentonite

Abstract: Adsorbent supported photocatalysis is developing as a potential waste water treatment technology. In this work, NiFe 2 O 4 was supported onto graphene sand composite (GSC) and bentonite (BT) supported to prepare magnetic NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT nanocomposties. Graphene sand composite (GSC) was prepared by graphitization of sugar over river sand. The size of NiFe 2 O 4 /BT and NiFe 2 O 4 /GSC was found to be 50 and 60 nm respectively. Mesoporous nature of prepared photocatalysts was confirmed by BET adsorption/desorption experiments. NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT exhibited ferromagnetic behaviour and could be separated from treated water using external magnetic field. The band gaps of NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT were found to be 2.41 and 2.42 eV, respectively. The adsorption and photocatalytic activity of NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT was tested for the mineralization of ampicillin (AMP) and oxytetracycline (OTC) antibiotics under solar light. The adsorption process had significant effect on the mineralization of AMP and OTC. Simultaneous adsorption and degradation (A + P) process were the most efficient for antibiotic degradation. The complete mineralization of antibiotics was obtained using NiFe 2 O 4 /GSC/A + P and NiFe 2 O 4 /BT/A + P catalytic processes. The kinetics of mineralization were explored using power law model. Magnetically recoverable NiFe 2 O 4 /GSC and NiFe 2 O 4 /BT are recyclable and displayed significant recycle efficiency and quick recovery for 10 consecutive catalytic cycles.

Fouling and cleaning of high permeability forward osmosis membranes

Abstract: This study critically assesses the fouling behavior in forward osmosis (FO) when operating with new generation of high permeability commercial thin film composite (TFC) FO membranes. Low fouling behavior, commonly accepted in FO with the membrane active layer facing the fouling feed solution (AL-FS), is demonstrated to be mainly the consequence of operating at a low permeation flux (typically lower than 10 L m −2 h −1 ). A higher water flux is observed to lead to severe fouling when using high permeability novel TFC membranes. Advanced membrane surface characterisation and FO fouling experiments over a range of initial fluxes (5–17 L m −2 h −1 ) demonstrate that the intense fouling behavior of high permeability TFC membranes is mainly connected to the initial flux, whereas membrane surface properties only play a minor role. Like for any membrane processes, it is demonstrated that a (so-called critical) flux can be defined in FO systems operated in AL-FS, above which stable operation cannot be maintained over an extended period of time. At higher flux, the fouling cake deposed on the active layer creates additional hydraulic resistance to filtration and consequently significant flux decline is observed over time. A typical anti-fouling strategy, such as high cross flow velocity cleaning, is not efficient to sustain high flux, but fouled membranes can be successfully cleaned using extended osmotic backwashing.

Mesoporous activated carbon from date stones (Phoenix dactylifera L.) by one-step microwave assisted K2CO3 pyrolysis

Abstract: Preparation of activated carbon (KAC) from date stones (DS) by microwave K 2 CO 3 activation has been studied. Methylene blue (MB) dye was sufficiently adsorbed on KAC compared to raw DS. The effects of radiation time (4–12 min), radiation power (540–700 W) and impregnation ratio (0.5–2.5 g/g) on the yield and MB uptake of KAC were studied. MB uptake of 460.12 mg/g and 19.99% yield were reported at 8 min radiation time, 660 W radiation power and 1.5 g/g impregnation ratio. The characteristics of KAC were examined by pore structure analysis, scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR). The BET surface area and total pore volume were 1144.25 m 2 /g and 0.656 m 3 /g, respectively. The equilibrium data were well correlated by Langmuir isotherm compared to Freundlich and Temkin isotherms with maximum Langmuir capacities of 256.15 and 485.44 mg/g on DS and KAC, respectively. Pseudo- second order model showed well representation for adsorption kinetics data.

Continuous fixed-bed column study for the removal of nitrate from water using chitosan/alumina composite

Abstract: A continuous adsorption study in a fixed-bed column was conducted for the removal of nitrate from water by using chitosan/alumina composite as an adsorbent. The effects of influent nitrate concentration, flow rate, and bed depth on the adsorption characteristics of adsorbent and column performances were evaluated at room temperature and original pH of the solution. The results revealed that the breakthrough curves are significantly affected by the variation of flow rate, initial concentration and bed depth. The nitrate removal efficiency increased with increase in bed height and decreased with increase in influent nitrate concentration and flow rate. The breakthrough time increased with increase in bed height. Thomas and Yoon-Nelson kinetic models were applied for the analysis of adsorption kinetics. The model data confirmed that both models are fitted well with the experimental results of continues fixed-bed column adsorption study. Bed-depth service time (BDST) model was used to study the effect of bed depth on breakthrough curves and to predict the time required for breakthrough. The model data revealed the applicability of the BDST model for the present system. The result show that chitosan/alumina composite can be used in fixed bed column for the removal of nitrate from water.

One-step facile synthesis of mesoporous graphene/Fe3O4/chitosan nanocomposite and its adsorption capacity for a textile dye

Abstract: Hierarchical mesoporous graphene@Fe 3 O 4 @chitosan hybrids were prepared by a one-step facile solvothermal method. SEM and TEM pictures showed that the Fe 3 O 4 @chitosan nanoparticles were well dispersed on the graphene matrix. The incorporation of Fe 3 O 4 in the nanocomposite was confirmed by FT-IR and XRD. The adsorption behavior of the as-prepared composite to methylene blue was conducted, where the effect of the adsorbent dosage, pH, contact time, dye concentration, and recyclability were studied. The composite exhibited rapid adsorption, high capacity, and easy separation and reuse owing to the mesoporous nature of graphene sheets and Fe 3 O 4 @chitosan nanoparticles, as well as to the magnetic property of Fe 3 O 4 nanoparticles. The adsorption capacity could reach 98% within a contact time of 5 min at pH 9 and an initial dye concentration of 25 mg L −1 .

Fly ash based ceramic microfiltration membranes for oil-water emulsion treatment: Parametric optimization using response surface methodology

Abstract: This article addresses the fabrication of ceramic microfiltration membranes (M1-M3) with uni-axial dry compaction method and fly ash, quartz and calcium carbonate as inorganic precursors. Raw material and membrane characterizations were conducted using particle size (PSD), thermo gravimetric (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), mechanical stability, chemical stability, porosity, pore size and pure water permeability analyses. Dead-end flow microfiltration (MF) experiments were conducted to evaluate the membrane performances with 50–200 mg/L synthetic oil-water emulsions. The MF experiments enabled to evaluate (M1-M3) membrane performance in terms of flux and rejection for variant combinations of feed concentrations and applied pressures. Among all membranes, M2 membrane demonstrated superior rejection (80.82–99.99%) and membrane flux (0.337–4.42 × 10 −4 m 3 /m 2 s). Response surface methodology (RSM) via central composite design (CCD) was employed to optimize and understand the interaction of possible influencing process variables on the treatment efficiency in terms of flux and rejection. The optimum parametric conditions are found to be at an applied pressure of 345 kPa and feed concentration of 176.07 mg/L at which M2 membrane exhibits a maximum oil rejection of 97% with permeate flux of 2.6 × 10 −4 m 3 /m 2 s.

Simultaneous removal of phenol and cyanide from aqueous solution by adsorption onto surface modified activated carbon prepared from coconut shell

Abstract: The present study is devoted to the elimination of phenol and cyanide from binary component aqueous solution by adsorption onto copper impregnated coconut shell activated carbon (Cu-CSAC). Effects of initial concentration, adsorbent dose, pH, temperature and contact time on phenol and cyanide elimination have been examined. At an optimum temperature 30 °C, pH 8, and the adsorbent dose of 40 g/L, 71.43% phenol and 86.8% cyanide were removed from binary aqueous solution comprising 300 mg/L of phenol and 30 mg/L of cyanide. The isotherm modeling study is carried out by accompanying batch experiments at range of initial concentration 100–1000 mg/L of phenol and 10–100 mg/L of cyanide. Three mono component isotherm model and six binary component isotherm models were considered. The model parameters were predicted by using non-linear regression analysis technique. It was observed that the experimental data indicate a better fit with an Extended Freundlich isotherm model for adsorption of phenol and cyanide in the binary component system. The adsorption efficiency of Cu-CSAC was observed to be 239.85 mg/g of phenol and 5.30 mg/g of cyanide. The mechanism of adsorption process was found chemisorption followed by Pseudo second order kinetics. Thermodynamic studies indicated the adsorption process onto Cu-CSAC as endothermic nature and reversible.

Domestic greywater treatment by electrocoagulation using hybrid electrode combinations

Abstract: Greywater (GW) treatment by the electrocoagulation (EC) process was investigated in this study. Eight different electrode combinations were evaluated. The effect of such important parameters as current density, initial pH (pH i ) and supporting electrolyte concentration (SEC) on the GW treatment by EC were researched. The highest COD removal was obtained with the Al–Fe–Fe–Al hybrid combination. Current density of 1 mA/cm 2 provided the highest efficiency. Further increase of current density did not show better performance. The original pH value (7.62) was found to be the most suitable condition. SEC did not affect the removal efficiencies. The EC process showed good performance to treat GW and provided allowable limits to reuse. The energy consumption was 9.46 kWh/m 3 for optimum conditions.

Heterogeneous photo-Fenton degradation of methyl orange by Fe2O3/TiO2 nanoparticles under visible light

Abstract: A novel heterogeneous photo-Fenton catalyst Fe2O3/TiO2 nanoparticle was successfully prepared by sol-gel method and characterized by X-ray diffraction (XRD), UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), Photoluminescence spectra (PL) and porosimetry analysis. The characterization results showed that the nano-sized Fe2O3 particles appeared on the TiO2 support and the Fe2O3/TiO2 nanoparticle exhibited enhanced absorption in the broad visible-light region together with an apparent red shift in the optical absorption edge. The XPS results revealed that the presence of Ti4+ and Fe3+ in Fe2O3/TiO2 materials. The activity of heterogeneous photo-Fenton catalyst Fe2O3/TiO2 combined with the photocatalytic and photo-Fenton was assayed in the degradation of methyl orange (MO) in the presence of visible light and H2O2. The results showed that the heterogeneous photo-Fenton was much faster and higher removal of methyl orange than the photocatalytic degradation alone. The mineralization of the organic pollutant was investigated by total organic carbon (TOC) measurements. The Fe2O3/TiO2 + H2O2 showed the highest TOC mineralization of MO. All these results indicate the possibility of the practical application of this photocatalyst for water treatment.

Dynamic adsorption of ciprofloxacin on carbon nanofibers: Quantitative measurement by in situ fluorescence

Abstract: Antibiotics have been considered to be a potential risk to human and ecological health. In an effort to develop convenient and effective treatment technology for the removal of fluoroquinoline antibiotics ciprofloxacin (CIP) from aqueous solution, a dynamic adsorption experimental apparatus based on carbon nanofibers (CNFs) was built and the adsorption of CIP was quantitatively measured by in situ fluorescence (FL) for the first time. The experimental results show that the adsorption kinetics and isotherms match well with the pseudo-second-order model and the Langmuir model, respectively. The adsorption equilibrium accomplished within 4 h, which is much shorter than the adsorption of CIP on the other carbon materials reported before. The maximum adsorption capacity ( q m ) is 10.36 mg/g, which is similar to the q m of CIP adsorption on biocomposite fibers. The strong adsorption affinity exhibited by CNFs was ascribed to the contributions of π–π electron–donor–acceptor (EDA) interaction, hydrophobic interaction and electrostatic interaction. The dynamic adsorption of CIP on CNFs provides a novel and effective approach for CIP removal, implying the potential practical application of CNFs in the field of water treatment.

Start up performance of biochar packed bed anaerobic digesters

Abstract: The development of microbial biofilm community in biochar packed anaerobic digesters was explored during start up at demonstration scale on high strength grease trap waste wastewater. Total and soluble chemical oxygen demand reduction reached 68% and 69%, respectively, after just fifty nine days at an HRT of 1.8 days. Methane head space gas compositions averaged across all reactors exceeded 60% and total methane production rates approached the theoretical maximum per kilogram of chemical oxygen demand reduced. Aggressive consumption of volatile organic acids correlated linearly with an increase in pH from 5.86 in the mixing reactor to a value of 7.61 in the final effluent. Both soluble and total phosphorous and total nitrogen were relatively unaffected by the treatment. Active methanogenic microbial biofilm communities possessing high proportions of methanogens were established despite the presence of feed wastewater streams possessing significantly different populations of planktonic bacteria. In sum, these results indicate that biochar alone can support the rapid development of robust well balanced methanogenic microbial biofilms that effectively minimize the impact of influent microbial communities on the reactor microbial biofilm communities.

Facile and green rout to prepare magnetic and chitosan-crosslinked κ-carrageenan bionanocomposites for removal of methylene blue

Abstract: The objective of this investigation was to prepare magnetic bionanocomposite adsorbents based on κ-carrageenan using a simple and efficient method. The magnetic κ-carrageenan was prepared through in situ method and was crosslinked by chitosan polysaccharide through electrostatic attractions. The magnetic bionanocomposites were assessed as adsorbents to remove methylene blue (MB) from its aqueous solution. The effects of preparation conditions and operational terms including contact time, dye concentration, ion strength, pH, and temperature on removal of MB were investigated. The experimental adsorption isotherms of bionanocomposites for MB were described well by Langmuir model. According to the Langmuir constant ( q m ), the maximum adsorption capacities of non-magnetic and magnetic adsorbents for MB were obtained 130.4 and 123.1 mg g −1 , respectively. Desorption experiments indicated that regeneration of the adsorbents can be made by using KCl solution in water/ethanol mixture. According to the data of the present work, it can be concluded that the magnetic κ-carrageenan bionanocomposites can be considered as an eco-friendly adsorbent for removal of cationic dye from aqueous solutions.

Electrocoagulation treatment of rice grain based distillery effluent using copper electrode

Abstract: This article reports the electro coagulation treatment (ECT) of rice grain based distillery effluent in a batch reactor using copper electrodes. ECT with copper electrode is a better alternative as compared to aluminum/iron electrode to treat rice grain based biodigester effluent (BDE), due to less power consumption at acidic pH which is the main attraction of the present work. The ECT in batch mode is conducted in a 1.5 L cubical shape electrocoagulation reactor using four-plate configurations. A current density of 89.3 A / m 2 and pH 3.5 is found to be optimal, providing a maximum chemical oxygen demand (COD) and colour removal of 80% and 65%, respectively. At pH 3.5 electrode loss was 3.667 mg/L and power consumption was 11.42 WH/L. It is noted that treated slurry at pH 8 has shown best settling characteristic, which decreases with decrease in pH. Thermogravimetric analysis indicates that the residues obtained from the EC treated BDE may be used as fuel.

Surface modified spinel cobalt ferrite nanoparticles for cationic dye removal: Kinetics and thermodynamics studies

Abstract: Present study is an endeavour to explore adsorption potential cobalt ferrite nanoparticles which were synthesised by combustion method and its surface modification was done by a SDS surfactant to make it suitable for the removal of cationic dye. Characterization was carried through FTIR, SEM and XRD analysis. Batch adsorption studies were carried out for removal of crystal violet cationic dye by SDS coated cobalt ferrite. Various parameters like initial concentration (50–300 mg/L), effect of contact time, adsorbent dose (0.1–0.5 gm/50 mL), and pH (2–9) were studied at constant temperature. Equilibrium time for the adsorption process was found to be 2 h. Adsorption percentage of dye increased with an increase in the adsorbent dose and amount of adsorption increased with an increase in initial dye concentration. Initial pH in the basic region exhibited better results as compared to acidic pH. Langmuir adsorption isotherm fitted better than Temkin followed by Freundlich and Dubinin-Raduskevich adsorption isotherms. Monolayer adsorption capacity was found to be 105 mg/g which is comparable to other reported adsorbents. Adsorption followed Lagergren pseudo second order kinetics model better than Lagergren pseudo first order and Elovich models. Adsorption studies conducted at different temperatures (301–313 K) indicated rise in adsorption with the increase in temperature. This implied that sorption phenomenon was endothermic in this case. Data was fitted to Van’t Hoff equation to study thermodynamics. Value of ΔH° was in the range of 23–88 kJ/mol for different concentration which indicated that mechanism of adsorption was complex comprising of both physical and chemical adsorption.

Photocatalytic degradation of Acid Red dye stuff in the presence of activated carbon-TiO2 composite and its kinetic enumeration

Abstract: The present paper deals with photocatalytic degradation of effluents from dye industries which have known toxic impacts on flora and fauna. Nano composite of titanium dioxide having activated carbon (TiO 2 /AC) base was synthesized using sol-gel method. The synthesized catalyst was then characterized by Fourier Transform-Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD) and Brunauer Emmet Teller (BET) surface area analyzer. A synthetic solution of AR-131 dye was subjected to photocatalytic degradation using TiO 2 /AC nano composite as catalyst. The degradation mechanisms of dye (AR-131) via photo-catalysis were found to follow a first order kinetics mechanism (vis. Langmuir- Hinshelwood Model). Toxicity of spent catalysts was further investigated in seed germination of Vigna radiata . Enhanced seed germination along with elongation of root and shoot was noticed up to the concentration of 500 ppm confirming its non toxicity.

Equilibrium studies of ammonium exchange with Australian natural zeolites

Abstract: This paper is concerned with the study of the equilibrium exchange of ammonium ions with two natural zeolite samples sourced in Australia from Castle Mountain Zeolites and Zeolite Australia. A range of sorption models including Langmuir Vageler, Competitive Langmuir, Freundlich, Temkin, Dubinin Astakhov and Brouers–Sotolongo were applied in order to gain an insight as to the exchange process. In contrast to most previous studies, non-linear regression was used in all instances to determine the best fit of the experimental data. Castle Mountain natural zeolite was found to exhibit higher ammonium capacity than Zeolite Australia material when in the freshly received state, and this behavior was related to the greater amount of sodium ions present relative to calcium ions on the zeolite exchange sites. The zeolite capacity for ammonium ions was also found to be dependent on the solution normality, with 35–60% increase inuptake noted when increasing the ammonium concentration from 250 to 1000 mg/L. The optimal fit ofthe equilibrium data was achieved by the Freundlich expression as confirmed by use of Akaikes Information Criteria. It was emphasized that the bottle-point method chosen influenced the isotherm profile in several ways, and could lead to misleading interpretation of experiments, especially if the constant zeolite mass approach was followed. Pre-treatment of natural zeolite with acid and subsequently sodium hydroxide promoted the uptake of ammonium species by at least 90%. This paper highlighted the factors which should be taken into account when investigating ammonium ion exchange with natural zeolites.

Reuse of Treated Sewage Effluent (TSE) in Qatar

Abstract: Qatar has one of the fastest growing and funded water sectors in the GCC region, with significant government funds being focused into water supply and sanitation. However, it is anticipated that there will be an increase in the demand on desalinated water supply due to increase in urban population and expansion of industrial and agriculture activities. This is expected to cause water shortages and a serious need for new water sources. There is a critical need to evaluate the efficacy of applying certain advanced technologies to improve the quality of Treated Sewage Effluent (TSE) for reuse in more applications in the industrial and agriculture sectors to reduce the demand on desalinated water. Treated sewage effluent (TSE) and wastewater have tremendous potential in supplementing the ever-growing water demand. It can be effectively recycled for both potable and non-potable purposes, provided it meets specific water quality requirement and type of application. Generation of treated wastewater is also cheaper and consumes lower energy when compared to desalinated water. Nevertheless, wastewater effluent contains a wide range of pathogens and other pollutants including chemicals of emerging concerns and heavy metals. Many studies have confirmed the abundance presence of pharmaceuticals, personal care products (PPCPs) and endocrine disrupting chemicals (EDCs) in wastewater that could pose a severe threat to public health. Therefore, it is essential that wastewater effluents are adequately treated and monitored to ensure a safe supply and reuse of treated effluents.

Petroleum refinery wastewater treatment: A pilot scale study

Abstract: A three-step pilot plant was designed, fabricated and tested for the treatment of highly contaminated petroleum refinery wastewater. The three-step process consisted of an electrocoagulation (EC) unit, a biological treatment in a spouted bed bioreactor (SBBR) using immobilized Pseudomonas putida in PVA particles, and an adsorption process using granular activated carbon in a packed column. The pilot plant was operated for a period of ten months at a flow rate of 1 m3/h, with continuous runs lasting up to 12 h. Different arrangements of the three units were tested to determine the most effective sequence. Placing the EC unit as the pretreatment step resulted in the best performance, since it reduced the COD and suspended solids, and consequently enhanced the performance of the succeeding biodegradation and adsorption units. At the optimum conditions and unit arrangement, the pilot plant was able to reduce the COD by 96% and the concentrations of phenol and cresols by nearly 100%.