Treatment of anthraquinone dye wastewater by hydrolytic acidification-aerobic process

Experiment on microbial degradation with two kinds of biological process, hydrolytic acidification-aerobic process and aerobic process was conducted to treat the anthraquinone dye wastewater with COD Cr concentration of 400 mg/L and chroma 800. The experimental result demonstrated that the hydrolytic-aerobic process could raise the biodegradability of anthraquinone dye wastewater effectively. The effluent COD Cr can reach 120170 mg/L and chroma 150 which is superior to that from simple aerobic process.

Treatment of Dye Wastewater by Using a Hybrid Gas/Liquid Pulsed Discharge Plasma Reactor

A hybrid gas/liquid pulsed discharge plasma reactor using a porous ceramic tube is proposed for dye wastewater treatment. High voltage pulsed discharge plasma was generated in the gas phase and simultaneously the plasma channel was permeated through the tiny holes of the ceramic tube into the water phase accompanied by gas bubbles. The porous ceramic tube not only separated the gas phase and liquid phase but also offered an effective plasma spreading channel. The effects of the peak pulse voltage, additive gas varieties, gas bubbling rate, solution conductivity and TiO2 addition were investigated. The results showed that this reactor was effective for dye wastewater treatment. The decoloration efficiency of Acid Orange II was enhanced with an increase in the power supplied. Under the studied conditions, 97% of Acid Orange II in aqueous solution was effectively decolored with additive oxygen gas, which was 51% higher than that with argon gas, and the increasing 02 bubbling rate also benefited the decoloration of dye wastewater. Water conductivity had a small effect on the level of decoloration. Catalysis of TiO2 could be induced by the pulsed discharge plasma and addition of TiO2 aided the decoloration of Acid Orange II.

Preparation and characterization of Fe_2O_3-CeO_2-TiO_2/γ-Al_2O_3 catalyst for degradation dye wastewater

In order to develop a catalyst with high activity for catalytic wet oxidation （CWO） process at room temperature and atmospheric pressure, Fe2O3-CeO2-TiO2/γ-Al2O3 catalyst was prepared by consecutive impregnation method and the prepared parameters were optimized. The structure of the catalyst was characterized by BET, XRF, SEM and XPS technologies, and the actual wastewater was used to investigate the catalytic activity of Fe2O3-CeO2-TiO2/γ-Al2O3 in CWO process. The experimental results showed that the prepared catalyst exhibited good catalytic activity when the doping amount of Ti was 1.0 wt% （the weight ratio of Ti to carriers）, and the middle product, Fe2O3-CeO2-TiO2/γ-Al2O3, was calcined in 450℃ for 2 h. The CWO experiment for treating actual dye wastewater indicated that the COD, color and TOC of actual wastewater were decreased by 62.23%, 50.12% and 41.26% in 3 h, respectively, and the ratio of BOD5/COD was increased from 0.19 to 0.30.

Heteroatom-doped porous carbon from methyl orange dye wastewater for oxygen reduction

Banana peel-derived porous carbon(BPPC) was prepared from banana peel and used as an adsorbent for methyl orange(MO) wastewater removal. BPPC-MO50 is a N,S-doped BPPC obtained via secondary carbonization. The BPPC-MO50 exhibited a high specific surface area of1774.3 m^2/g. Heteroatom-doped porous carbon(PC) was successfully synthesized from the BPPC absorbed MO at high temperature and used for oxygen reduction. The BPPC-MO50 displayed the highest ORR onset potential among all carbon-based electrocatalysts, i.e., 0.93 V vs.reversible hydrogen electrode(RHE). This is the first report to describe porous carbon-activated materials from agriculture and forestry waste that is used for adsorption of dyes from wastewater via an enhanced heteroatom(N,S) content. These results may contribute to the sustainable development of dye wastewater treatment by transforming saturated PC into an effective material and has potential applications in fuel cells or as energy sources.

Charged modified tight ceramic ultrafiltration membranes for treatment of cationic dye wastewater

Tight ceramic ultrafiltration membranes have been proven to exhibit good rejection performance for reactive dye wastewater at high temperatures because of their high thermal and chemical resistance.However,the application of ceramic membranes for the treatment of cationic dye wastewater is challenging because of their surface charge.In this study,a ceramic membrane is modified by grafting aminosilane(KH-551)to enhance the positive charge of the membrane surface.The rejection performance of the charged modified ceramic membrane toward the methylene blue solution is significantly improved.The modification substance is bonded to the ceramic membrane surface via covalent bonding,which imparts good thermal stability.The modified ceramic membrane exhibits stable separation performance toward the methylene blue solution.Overall,this study provides valuable guidance for the adjustment of the ceramic membrane surface charge for treating industrial cationic dye wastewater.

Degradation of Dye Wastewater by Pulsed High-Voltage Discharge Combined with Spent Tea Leaves

Degradation of methylene blue （MB） was performed using the pulsed discharge process （PDP） combined with spent tea leaves （STLs）. The effects of STL dosage, concentration of initial solution, and pH were analyzed in the combined treatment. Results showed that the combined treatment was effective for dye wastewater degradation; when the dosage of STLs was 3.2 g/L, the degradation efficiency reached 90% after 15 rain treatment, and STLs showed a good repeatability. The degradation rate decreased with increasing initial MB concentration but not related to the solution pH in the combined treatment. Fourier-transform infrared spectra and N2 adsorption suggested that the number of acidic and basic groups in the STL surface increased after the treatment, but the surface area and pore volume remained unchanged.

Treating dye wastewater by TiO_2 coated on coal cinder

We investigated the photocatalytic degradation of dye wastewater by using titanium dioxide （TiO2） coated on a coal cinder. The coal cinder was used as the carrier, with a thin film of TiO2 coated on it by using the sol-gel method. Using the Congo red as the model pollutant for dye wastewater, we studied the decolorization efficiency, and effects of TiO2 film thickness and roasting temperature on the efficiency. We also evaluated the recycling and regeneration of the immobilized TiO2 （TiO2/cinder）. Results show that the decolorization rate of Congo red solution was more than 98% after 2.h treatment when we used TiO2/cinder calcined at 500 ℃ for 2 h and coated four times as the photocatalyst. At the same time, the TiO2/cinder remained high catalytic activity after being reused and regenerated for many times.

Textile dyeing wastewater negatively influences the hematological profile and reproductive health of male Swiss albino mice

Objective:To determine the effects of textile dyeing industrial wastewater on the hematological parameters and reproductive health including histoarchitecture of male gonad(testes)of mice.Methods:Twenty-four Swiss albino mice at 4-weeks old were divided into four groups(n=6 per group).Mice of group 1 supplied with normal drinking water were served as the control group.Mice of group 2,3 and 4 were supplied normal drinking water mixed with textile dyeing wastewater at 5%,10% and 20% concentration,respectively.After completing 24 weeks of treatment,different hematological profile,weight of testes,gonadosomatic index(GSI),sperm concentration and morphology were measured.Moreover,histopathological changes in testes were examined.Results:Hematocrit value and hemoglobin concentrations were decreased in all groups of wastewater-treated mice compared to the control group.Likewise,weight of testes,GSI and sperm concentration were decreased significantly in wastewater-treated mice in comparison to the control group.The percentage of morphologically healthy epididymal sperm was significantly reduced in wastewater-treated mice.Histopathological examination revealed degenerative changes in seminiferous tubules,a smaller number of spermatogenic cells,elongation of seminiferous tubules and degenerative changes of seminiferous tubules in wastewater-treated mice.Conclusions:Textile dyeing wastewater has harmful effects on hematological profile and reproductive health of male mice.

Activated carbon supported TiO_2 -photocatalysis doped with Fe ions for continuous treatment of dye wastewater in a dynamic reactor

Fe-doped TiO 2 coated on activated carbon （Fe-TiO 2 /AC, FTA） composites were prepared by an improved sol-gel method and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, inductively coupled plasma mass spectrometry and BET surface area analysis. Obtained FTA composites were applied to the continuous treatment of dye wastewater in a dynamic reactor. The effects of Fe ion content, catalyst content, UV-lamp power and flowrate of the continuous treatment of dye wastewater on degradation efficiency were analyzed to determine the optimum operating conditions of dye wastewater degradation. Continuous photocatalytic experiments provided interesting results that FTA had a high chemical oxygen demand （COD） removal rate compared with TiO 2 , Fe doped TiO 2 （FT） and TiO 2 coated on activated carbon （TA）. In particular, when using the FTA catalyst with a Fe ion content of 0.33%, the kinetic content （k = 0.0376） of COD removal was more than the sum of both TA （0.0205） and 0.33% FT （0.0166）. FTA showed a high photoactivity because of a synergistic effect between Fe ions and AC on TiO 2 , which is higher than the individual effects of AC or Fe ions on TiO 2 . Additionally, for the photocatalytic degradation of dye wastewater, the optimum Fe ion content, catalyst content, UV-lamp power and flowrate were 0.33%, 6 g/L, 60 W （two lamps） and 300 mL/hr, respectively. An investigation of catalyst reuse revealed that the 0.33% FTA showed almost no deactivation in photocatalytic degradation of naturally treated wastewater.

Steady performance of a zero valent iron packed anaerobic reactor for azo dye wastewater treatment under variable influent quality

Zero valent iron （ZVI） is expected to help create an enhanced anaerobic environment that might improve the performance of anaerobic treatment. Based on this idea, a novel ZVI packed upflow anaerobic sludge blanket （ZVI-UASB） reactor was developed to treat azo dye wastewater with variable influent quality. The results showed that the reactor was less influenced by increases of Reactive Brilliant Red X-3B concentration from 50 to 1000 mg/L and chemical oxygen demand （COD） from 1000 to 7000 mg/L in the feed than a reference UASB reactor without the ZVI. The ZVI decreased oxidation-reduction potential in the reactor by about 80 mV. Iron ion dissolution from the ZVI could buffer acidity in the reactor, the amount of which was related to the COD concentration. Fluorescence in situ hybridization test showed the abundance of methanogens in the sludge of the ZVI-UASB reactor was significantly greater than that of the reference one. Denaturing gradient gel electrophoresis showed that the ZVI increased the diversity of microbial strains responsible for high efficiency.

Efficient decolorization of dye-containing wastewater using mycelial pellets formed of marine-derived Aspergillus niger

In order to improve the efficient decolorization of dye-containing water by biosorbent and understand the biosorption mechanism, the self-immobilization mycelial pellets were prepared using a marine-derived fungus Aspergillus niger ZJUBE-1, and an azo dye, Congo red was chosen as a model dye to investigate batch decolorization efficiency by pellets. The pellets as biosorbent showed strong salt and acid tolerance in biosorption process. The results for dye adsorption showed that the biosorption process fitted well with models of pseudo-second-order kinetic and Langmuir isotherm, with a maximum adsorption capacity of 263.2 mg·g^(-1) mycelium. During 6 batches of continuous decolorization operation, the mycelial pellets could possess efficient decolorization abilities(>98.5%).The appearance of new peak in the UV–Vis spectral result indicated that the decolorization process may also contain biodegradation. The mechanism studies showed that efficient biosorption ability of pellets only relies on the active zone on the surface of the pellet, which can be enhanced by nutrition supplement or be shifted outward by a reculture process.

Experimental Study of Wastewater Treatment of Reactive Dye by Phys-Chemistry Method

Wastewater, which involves easy-soluble reactive dyes, especially non-degradable dyes, is very difficult to decolor efficiently by normal processes such as coagulation process and biological treatment. The high chromaticity se- riously hinders the reuse of reactive dye waste water. In this paper, a new method by bentonite adsorption and coagulation (PAC) is employed for removing color from synthetic dye waste water which contains reactive red K-2G, K-RN blue, K-GR blue, X-3B red, K-GN orange, KB-3G yellow, K-2BP red, K-RN yellow and K-6G yellow. Bentonite pre- treated by 4% CTMAB and milled to 160 order screen is proven to the best decoloring agent. For a 100 mL reactive red K-2G sample (CODcr 400 mg/L, 25 000 chromaticity color), 0.5 g bentonite pretreated and 2.5 mL PAC is enough to decolor wastewater up to 99.92% and the sediment time is short. Non-degradable dyes such as active red X-3B and K-GN orange are declored completely as well. Raw sewage (low chromaticity color) is decolored completely at a ben-tonite dosage of 0.001g. More researches prove the high practical value of this process.

High flux photocatalytic self-cleaning nanosheet C_(3)N_(4) membrane supported by cellulose nanofibers for dye wastewater purification

Hazardous dye substances discharged from the textile and dyestuff industries not only threaten local the surrounding ecosystems but are also hard to degraded.We report the preparation of process for a photocatalytic membrane device that can degrade dye pollution under visible light.This filtration membrane,with a well-organized multilayer structure,simultaneously achieves continuous and flow-through separation of degradation products.Cellulose nanofibers(CNFs)were used as a template for nanosheet C_(3)N_(4)(NS C_(3)N_(4))preparation;the performance for the photocatalytic degradation of dyes improved as the morphology changed from bulking to nanosheet.NS C3N4 was then attached to the surface of a prepared CNF membrane via vacuum filtration.This device exhibited high efficiency(the degradation rates of both Rhodamine B and Methylene blue both reached 96%),high flux(above 160 L·h^(-1)·m^(-2)·bar^(-1))and excellent stability(maintaining steady flux and high separation were maintained after 4 h).This easy-preparation,easy-scale-up,and low-cost process provides a new method of fabricating photocatalytic membrane devices for dye wastewater treatment.

Intercalation modification of FeOCl and its application in dye wastewater treatment

The textile industry spreads globally with the challenges of its wastewater treatment,especially dyes,which are difficult to degrade.To improve coagulation-flocculation process in dye wastewater treatment,an intercalation process was employed to prepare a new efficient coagulant of lithium borohydride-iron oxychloride(LiBH_(4)_FeOCl) in this study.The layered crystal pristine iron oxychloride(FeOCl) material was prepared by chemical gas phase migration.LiBH4 was introduced into the layers of two dimensional(2 D) FeOCl nanosheets by a simple method of liquid phase insertion.The samples were characterized by a field emitting scanning electron microscopy(SEM),a rotating anode X-ray powder diffractometer(XRD),etc.The cationic dye was employed as the simulated pollutant.A coagulation and decolorization experimental device was built to study the coagulation performance of the new coagulant LiBH_(4)_FeOCl.It is found that the intercalation modified LiBH_(4)_FeOCl exhibits the characteristics of crystal structure,and the layered structure of FeOCl is preserved.LiBH_(4)_FeOCl,as an insoluble inorganic solid coagulant,performs well for dye pollutants of methyl red,basic yellow 1,methylene blue,rhodamine B,ethyl violet and Janus green B.The reaction rate is significantly 68% higher than the current commercial coagulants of Al_(2)(SO_(4))_(3).The mechanism analysis reveals that LiBH_(4)_FeOCl breaks and disperses rapidly in the water environment.Its negatively charged material particles can be electrostatically adsorbed with dye pollutant molecules through electrostatic action.The above collaborative actions of breaking,dispersion and electrostatic adsorption are the main coagulation mechanisms of LiBH_(4)_FeOCl.The solid inorganic coagulant of LiBH4FeOCl provides a competitive alternative for traditional inorganic salts and organic coagulants.

Application of electrode materials and catalysts in electrocatalytic treatment of dye wastewater

The dye industry produces a large amount of hazardous wastewater every day worldwide,which brings potential threaten to the global environment.As an excellent method for removal of water chroma and chemical oxygen demand,electrocatalytic methods are currently widely used in the treatment of dye wastewater.The selection and preparation of electrode materials and electrocatalysts play an important role on the electrocatalytic treatment.The aim of this paper is to introduce the most excellent high-efficiency electrode materials and electrocatalysts in the field of dye wastewater treatment.Many electrode materials such as metal electrode materials,boron-doped diamond anode materials and three-dimensional electrode are introduced in detail.Besides,the mechanism of electrocatalytic oxidation is summarized.The composite treatment of active electrode and electrocatalyst are extensively examined.Finally,the progress of photo-assisted electrocatalytic methods of dye wastewater and the catalysts are described.

Novel-structured Mo-Cu-Fe-O composite for catalytic air oxidation of dye-containing wastewater under ambient temperature and pressure

A novel‐structured Mo‐Cu‐Fe‐O composite was successfully prepared by co‐precipitation and impregnation method.The properties of the as‐prepared samples were determined using X‐ray diffraction,temperature‐programmed reduction by H2,cyclic voltammetry,and temperature‐programmed desorption by O2.The results showed that Mo6+diffused into the Cu‐Fe‐O crystal lattice and then formed a new crystalline phase of CuMoO4.The Mo‐Cu‐Fe‐O catalyst had redox properties,and its surface contained active sites for oxygen adsorption.In addition,the catalytic activity of the Mo‐Cu‐Fe‐O composite was evaluated by the degradation of Cationic Red GTL,Crystal Violet,and Acid Red in catalytic wet air oxidation(CWAO)at ambient temperature and pressure.The Mo‐Cu‐Fe‐O catalyst showed excellent activity at basic conditions for the degradation of Cationic Red GTL.High removal efficiencies of91.5%and92.8%were achieved for Cationic Red GTL and Crystal Violet,respectively,in wastewater,and the efficiency remained high after seven cycles.However,almost no degradation of Acid Red occurred in the CWAO process.Furthermore,hydroxyl radicals were formed in the CWAO process,which induced the decomposition of the two cationic dyes in wastewater,and the toxicity of their effluents was decreased after degradation.The results indicate that the Mo‐Cu‐Fe‐O composite shows excellent catalytic activity for the treatment of wastewater contaminated with cationic dyes.

Comparing Polyethersulfone and Polyurethane-immobilized Cells of Comamonas testosteroni QYY in Treatment of an Accidental Dye Wastewater

Well-channeled porous polyethersulfone（PES） beads were synthesized and used for the immobilization of Comamonas testosteroni QYY cells for an aerobic reactor to remove quinoline, phenol, and other refractory com- pounds in accidentally-released dye wastewater supplemented with domestic wastewater. The pore size in PES beads mainly depended on the dripping time through the Water vapor cylinder. When the cylinder was 2.5 m in length, the pore size in the obtained beads was enlarged to 3 ~m, which provided an ideal surface for cells to pass through and grow inside. The reactor with the immobilized C. testosteroni QYY on PES beads resisted organic loading shock and enhanced total organic carbon（TOC） removal, which had 100% removal efficiencies of both quinoline and phenol when the volume ratio of the accidental wastewater to domestic wastewater was increased from 1：2 to 1：1, as compared with the 100% and 34.7% removal efficiencies by the reactor with immobilized C. testosteroni QYY on polyttrethane（PU） cube or the 82% and 2.4% removal efficiencies by the reactor with only the suspended C. testosteroni QYY cells, respectively. The PES beads had a specific surface area of 1843 cm2/cm3, which had immobilized （0.0244-0.003） g of C, testosteroni QYY cell dry mass/cm3, compared with the specific surface area of 564 cm2/cm3 of the PU cube with （0.0184-0.002） g of cell dry mass/cm3. The kinetic study revealed that the quinoline and phenol degradation followed zero-order reactions for all the three reactors. The PES reactor demonstrated the highest quinoline and phenol removal efficiencies. The immobilized C. testosteroni QYY on the low-cost inert PES beads demonstrated good shock resistance and was able to completely remove the toxic compounds, including phenyl carbamate, 2-nitrotoluene, and dioctyl phthalate. Therefore, the beads were ideal for large-scale accidental wastewater treatment.

A pilot scale anoxic/oxic membrane bioreactor(A/O MBR) for woolen mill dyeing wastewater treatment

A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, BOD 5 under 5 mg/L, turbidity lower than 0 65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, BOD 5, colour, and turbidity were 92 4%, 98 4%, 74% and 98 9%, respectively. Constant flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.

Biodegradability of terephthalic acid in terylene artificial silk printing and dyeing wastewater

As the characteristic pollutant, terephthalic acid(TA)was in charge of 40%—78% of the total COD of terylene artificial silk printing and dyeing wastewater(TPW-water). The studies on biodegradability of TA were conducted in a serial of activated sludge reactors with TPW-water. TA appeared to be readily biodegradable with removal efficiency over 96.5% under aerobic conditions, hardly biodegradable with removal efficiency below 10% under anoxic conditions and slowly biodegradable with a turnover between 31.4% and 56.0% under anaerobic conditions. TA also accounted for the majority of BOD in TPW-water. The process combined by anoxic, anaerobic and aerobic activated sludge reactor was suitable for TA degradation and TPW-water treatment. Further, the aerobic process was essentially much more effective than the anaerobic or anoxic one to degrade TA in TPW-water.

Dyeing and printing wastewater treatment using fly-ash coated with chitosan

Printing and dyeing industry is a considerable source of environmental contamination. In this study treatment of printing and dyeing wastewater with a new type of sewage treatment agent, fly-ash coated with chitosan particles （FCCP）, was examined. The effects ofpH, stirring time, sedimentation time and temperature on color, COD, turbidity and NH3-N removal were determined. The optimum dosage of FCCP and the influence of individual factors on removal efficiency were tested. The optimum parameters determined using the L16 （45） orthogonal experiment were as follows： FCCP （weight ratio of chitosan to fly-ash 1：6） dosage, 4 g.L^-1; temperature, 35℃; pH, 4. The stirring time and sedimentation time were 20 min and 5 h, respectively. Under these optimum conditions, the color, COD and NH3-N removal ratios were 97%, 80% and 75%, respectively.