Three-dimensional(3D)porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity.Given their amphiphilic surface,they have a propensity ...Three-dimensional(3D)porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity.Given their amphiphilic surface,they have a propensity to simultaneously absorb water and oil,which restricts their range of applications.In this study,a reduced graphene oxide and titanium dioxide nanocomposite(rGO/TiO_(2))was used to fabricate an ultra-hydrophobic melamine sponge(MS)through interfacial modification using a solution immersion technique.To further modify it,poly-dimethylsiloxane(PDMS)was grafted onto its surface to establish stronger covalent bonds with the composite.The water contact angle of the sponge(rGO/TiO_(2)/PDMS/MS)was 164.2°,which satisfies the condition for ultrahydrophobicity.The evidence of its water repellency was demonstrated by the Cassie-Baxter theory and the lotus leaf effect.As a result of the increased density of rGO/TiO_(2)/PDMS/MS,it recorded an initial capacity that was 2 g/g lower than the raw MS for crude oil absorption.The raw MS retained 53% of its initial absorption capacity after 20 cycles of absorption,while rGO/TiO_(2)/PDMS/MS retained 97%,suggesting good recyclability.Excellent oil and organic solvent recovery(90%-96%)was demonstrated by rGO/TiO_(2)/PDMS/MS in oil-water combinations.In a continuous separation system,it achieved a remarkable separation efficiency of 2.4×10^(6)L/(m^(3)·h),and in turbulent emulsion separation,it achieved a demulsification efficiency of 90%-91%.This study provides a practical substitute for massive oil spill cleaning.展开更多
A unique cyclonic static microbubble flotation column was developed for oily wastewater separation.The separation effciency was found to be highly dependent on gas holdup and bubble size distribution.By changing the c...A unique cyclonic static microbubble flotation column was developed for oily wastewater separation.The separation effciency was found to be highly dependent on gas holdup and bubble size distribution.By changing the circulation pressure,gas flow rate,frother concentration,the effect of operation parameters on gas holdup and oil removal effciency were attained.A mathematical modeling between the kinetic constant and the gas holdup was established for oily water separation process.The results show that higher gas holdup and smaller microbubble sizes are benefcial to improve oil removal effciency.展开更多
To deeply clean oily wastewater,molecular sieve residues(MSRs)were sufficiently recycled and utilized due to their high specific surface area,porous structure,and outstanding adsorption property.Molding MSRs(MMSRs)wer...To deeply clean oily wastewater,molecular sieve residues(MSRs)were sufficiently recycled and utilized due to their high specific surface area,porous structure,and outstanding adsorption property.Molding MSRs(MMSRs)were prepared by adding additives(starch,citric acid,and soluble glass)to MSRs and were then filled into a fixed bed for adsorbing and separating the oil in wastewater.Sodium dodecylbenzenesulfonate was used to modify the MMSRs,and their adsorption property was also investigated.In addition,the MSRs were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,Brunauer–Emmett–Teller analysis,and Fourier transform infrared spectroscopy.The results indicated that MMSRs satisfied the filling requirement of fixed bed,and their dynamic adsorption capacity could reach 0.1854 mg g^?1.Furthermore,the static adsorption capacity of MMSRs achieved 1.7346 mg g^?1 in the optimum conditions,and the oil adsorption performance of modified MMSRs was further enhanced.Therefore,this work suggests that MSRs are promising alternatives in cleaning oily wastewater.展开更多
The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitig...The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitigate the membrane fouling, coagulation for ceramic membrane microfiltration of oily wastewater was performed. The results of filtration tests show that the membrane fouling decreased and the permeate flux and quality increased with coagulation as pretreatment. At the coagulant Ca (OH)2 dosage of 900 mg/L, the removal efficiency of phosphate was increased from 46.4% without coagulation to 99.6%; the removal of COD and oils were 97.0% and 99.8%, respectively. And the permeate flux was about 70% greater than that when Ca(OH)2 was not used. The permeate obtained from coagulation and microfiltration can be reused as make-up water, and the recommended operation conditions for pilot and industrial application are transmembrane pressure of 0.10 MPa and cross-flow velocity of 5 m/s. The comparison results show that 0.2 μm ZrO2 microfilter with coagulation could be used to perform the filtration rather than conventional ultrafilter, with very substantial gain in flux and removal efficiency of phosphate.展开更多
In this paper, fouling mechanisms of mullite ceramic membranes for treatment of oily wastewaters in hybrid coagulation-microfiltration(MF) process presented. Hermia's models for cross flow filtration were used to ...In this paper, fouling mechanisms of mullite ceramic membranes for treatment of oily wastewaters in hybrid coagulation-microfiltration(MF) process presented. Hermia's models for cross flow filtration were used to investigate the fouling mechanisms of membranes with various coagulating chemicals concentrations. Four coagulating chemicals(FeCl2 ·4H2 O, FeSO4 ·7H2 O, AlCl3 ·6H2 O and Al2(SO4)3 ·18H2 O) plus Ca(OH)2 of the same concentration were evaluated in the coagulation-MF hybrid process with different concentrations(0, 50 mg·L 1, 100 mg·L 1and 200 mg·L 1). To determine whether the data agree with models under consideration, the coefficients of determination(R2) of all models were compared with one another. In addition, average prediction errors of models were calculated. The results showed that cake filtration model can be applied for prediction of permeation flux decline for MF and coagulation-(MF) hybrid process with the best average error equal to 0.09%. Results indicated that pore blocking behavior changes as time of filtration increases, and one model cannot predict pore blocking behavior in all filtration time with very good precision.展开更多
The removal of oil from oily wastewater in thermal power plant by coal fly ash(CFA) was investigated. It contained about 2.5 g/L of mineral oil,which had to be treated efficiently before it was discharged. The experim...The removal of oil from oily wastewater in thermal power plant by coal fly ash(CFA) was investigated. It contained about 2.5 g/L of mineral oil,which had to be treated efficiently before it was discharged. The experiments were carried out as a function of different initial concentrations of oil,mass dosage,contact time and pH value to obtain the optimum conditions for the removal of oil from oily wastewater. The experimental results show that CFA presents the most suitable conditions for the removal of oil from waste-water at a dosage of CFA 2.5 g/L,15 min of contact time and a pH value of 4.8. The adsorption process is performed with almost 96% of oil removal from wastewater. The kinetic data meet the second-order kinetic model. The Langmuir and Freundlich adsorption models were applied to describing the experimental isotherms and isotherm constants. The equilibrium data fit very well with the Freundlich model.展开更多
In this study, a novel flocculant was prepared by an inorganic polymetric flocculant (IPF) - polysilicate ferro- aluminum sulfate (PSFA) and rectorite (REC). The structure of the PSFA-REC composite was characterized b...In this study, a novel flocculant was prepared by an inorganic polymetric flocculant (IPF) - polysilicate ferro- aluminum sulfate (PSFA) and rectorite (REC). The structure of the PSFA-REC composite was characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD), in order to determine the optimal temperature. The flocculation test was made at 25℃, 45℃ and 65℃, the results indicated that when the temperature was 65℃, the removal efficiency of the oil and COD was the best, which was 87.2% and 92.6% respectively. Then by comparisons among rectorite (REC), PSFA and the composite PSFA-REC at the temperature of 65℃ and the optimal dosage of 11 mg/L, the composite PSFA-REC showed better flocculation performance than flocculant REC and PSFA alone.展开更多
Aiming at the treatment of difficult-to-handle oily wastewater, the ceramics filter mediums made from the iron and steel plant sludge were adopted to surface lipophilic modification so as to remove oil efficiently. Th...Aiming at the treatment of difficult-to-handle oily wastewater, the ceramics filter mediums made from the iron and steel plant sludge were adopted to surface lipophilic modification so as to remove oil efficiently. The hydrolysis technique by FTIR and conductivity test indicated that under acid conditions hydrogen silicon oil did not hydrolyze but release hydrogen by chemical reaction under alkaline conditions. The results of the experiments including contact angle measurement, FTIR analysis, and SEM analysis illustrate that a layer of lipophile coating indeed exists evenly on the surface of filter mediums after modification. Furthermore, the hydrogen-containing silicone oil was combined through dehydration of Si-H bond with the-OH on the surface of ceramic filter medium.展开更多
Bioflocculants have received increasing attention in research because they are low cost,non-toxic,biodegradable,operationally simple and useful in many water and wastewater treatment applications.In this study,we focu...Bioflocculants have received increasing attention in research because they are low cost,non-toxic,biodegradable,operationally simple and useful in many water and wastewater treatment applications.In this study,we focused mainly on the screening of the flocculant-producing strain and its application in oily wastewater treatment.Bacteria strain B-6-1 was isolated by the pyridine screening method.UPC-1 reagent produced by B-6-1 had efficient flocculating activity.It was deduced that the main component of UPC-1 reagent was polysaccharide through purification and analysis.The influence of dosage of reagent,pH value,temperature and oil concentration on the flocculation effect of UPC-1 reagent was investigated.展开更多
Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(...Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(SMS),to produce an iron-carbon composite(SMS-nZVI).The ability of the SMS-nZVI to treat wastewater containing high concentration of oil was then comprehensively evaluated.The morphology,structure,and other properties of the composite were characterized by using scanning electron microscopy,transmission electron microscopy,the Brunauer-Emmett-Teller nitrogen sorption analysis,and the Fourier transform infrared spectroscopy.The results show that the biochar prepared by using the SMS can effectively prevent the agglomeration of nZVI and increase the overall specific surface area,thereby enhancing the absorption of petroleum by the composite.Experiments reveal that compared with the SMS and nZVI,the SMS-nZVI composite removes petroleum faster and more efficiently from wastewater.Under optimized conditions involving an nZVI to biochar mass ratio of 1:5 and a pH value of 4,the efficiency for removal of petroleum from wastewater with an initial petroleum concentration of 1000 mg/L could reach 95%within 5 h.Based on a natural aging treatment involving exposure to air for 30 d,the SMS-nZVI composite retained an oil removal rate of higher than 62%,and this result could highlight its stability for practical applications.展开更多
A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and co...A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and column flotation. The dissolved air release occurred within the column separation system. As a potential application the column was investigated for its performance in separating emulsified oil droplets in oily wastewater. A high separation efficiency was obtained in a series of tests. The aeration performance of the bubble generator used in the dissolved-air flotation column was also studied in particular.展开更多
基金supported by the Universiti Brunei Darussalam Research Funding(Grant No.UBD/OAVCRI/CRGWG(022)/171001).
文摘Three-dimensional(3D)porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity.Given their amphiphilic surface,they have a propensity to simultaneously absorb water and oil,which restricts their range of applications.In this study,a reduced graphene oxide and titanium dioxide nanocomposite(rGO/TiO_(2))was used to fabricate an ultra-hydrophobic melamine sponge(MS)through interfacial modification using a solution immersion technique.To further modify it,poly-dimethylsiloxane(PDMS)was grafted onto its surface to establish stronger covalent bonds with the composite.The water contact angle of the sponge(rGO/TiO_(2)/PDMS/MS)was 164.2°,which satisfies the condition for ultrahydrophobicity.The evidence of its water repellency was demonstrated by the Cassie-Baxter theory and the lotus leaf effect.As a result of the increased density of rGO/TiO_(2)/PDMS/MS,it recorded an initial capacity that was 2 g/g lower than the raw MS for crude oil absorption.The raw MS retained 53% of its initial absorption capacity after 20 cycles of absorption,while rGO/TiO_(2)/PDMS/MS retained 97%,suggesting good recyclability.Excellent oil and organic solvent recovery(90%-96%)was demonstrated by rGO/TiO_(2)/PDMS/MS in oil-water combinations.In a continuous separation system,it achieved a remarkable separation efficiency of 2.4×10^(6)L/(m^(3)·h),and in turbulent emulsion separation,it achieved a demulsification efficiency of 90%-91%.This study provides a practical substitute for massive oil spill cleaning.
基金the National Natural Science Foundation of China(No.51104158)the Science and Technology Fund of China University of Mining & Technology (No.2011QNB08) for the financial support
文摘A unique cyclonic static microbubble flotation column was developed for oily wastewater separation.The separation effciency was found to be highly dependent on gas holdup and bubble size distribution.By changing the circulation pressure,gas flow rate,frother concentration,the effect of operation parameters on gas holdup and oil removal effciency were attained.A mathematical modeling between the kinetic constant and the gas holdup was established for oily water separation process.The results show that higher gas holdup and smaller microbubble sizes are benefcial to improve oil removal effciency.
基金supported by the National Natural Science Foundation of China (No. 21676180 and No. 21076143)the Key Technologies R&D Program of Tianjin (No. 15ZCZDSF00160)Tianjin Municipal Science and Technology Xinghai Program (No. KJXH2014-05)
文摘To deeply clean oily wastewater,molecular sieve residues(MSRs)were sufficiently recycled and utilized due to their high specific surface area,porous structure,and outstanding adsorption property.Molding MSRs(MMSRs)were prepared by adding additives(starch,citric acid,and soluble glass)to MSRs and were then filled into a fixed bed for adsorbing and separating the oil in wastewater.Sodium dodecylbenzenesulfonate was used to modify the MMSRs,and their adsorption property was also investigated.In addition,the MSRs were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,Brunauer–Emmett–Teller analysis,and Fourier transform infrared spectroscopy.The results indicated that MMSRs satisfied the filling requirement of fixed bed,and their dynamic adsorption capacity could reach 0.1854 mg g^?1.Furthermore,the static adsorption capacity of MMSRs achieved 1.7346 mg g^?1 in the optimum conditions,and the oil adsorption performance of modified MMSRs was further enhanced.Therefore,this work suggests that MSRs are promising alternatives in cleaning oily wastewater.
文摘The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitigate the membrane fouling, coagulation for ceramic membrane microfiltration of oily wastewater was performed. The results of filtration tests show that the membrane fouling decreased and the permeate flux and quality increased with coagulation as pretreatment. At the coagulant Ca (OH)2 dosage of 900 mg/L, the removal efficiency of phosphate was increased from 46.4% without coagulation to 99.6%; the removal of COD and oils were 97.0% and 99.8%, respectively. And the permeate flux was about 70% greater than that when Ca(OH)2 was not used. The permeate obtained from coagulation and microfiltration can be reused as make-up water, and the recommended operation conditions for pilot and industrial application are transmembrane pressure of 0.10 MPa and cross-flow velocity of 5 m/s. The comparison results show that 0.2 μm ZrO2 microfilter with coagulation could be used to perform the filtration rather than conventional ultrafilter, with very substantial gain in flux and removal efficiency of phosphate.
文摘In this paper, fouling mechanisms of mullite ceramic membranes for treatment of oily wastewaters in hybrid coagulation-microfiltration(MF) process presented. Hermia's models for cross flow filtration were used to investigate the fouling mechanisms of membranes with various coagulating chemicals concentrations. Four coagulating chemicals(FeCl2 ·4H2 O, FeSO4 ·7H2 O, AlCl3 ·6H2 O and Al2(SO4)3 ·18H2 O) plus Ca(OH)2 of the same concentration were evaluated in the coagulation-MF hybrid process with different concentrations(0, 50 mg·L 1, 100 mg·L 1and 200 mg·L 1). To determine whether the data agree with models under consideration, the coefficients of determination(R2) of all models were compared with one another. In addition, average prediction errors of models were calculated. The results showed that cake filtration model can be applied for prediction of permeation flux decline for MF and coagulation-(MF) hybrid process with the best average error equal to 0.09%. Results indicated that pore blocking behavior changes as time of filtration increases, and one model cannot predict pore blocking behavior in all filtration time with very good precision.
基金Project(2007BAC24B02) supported by the National Science & Technology Pillar Program during the 11th Five-Year Plan Period,ChinaProject(20070420713) supported by China Postdoctoral Science FoundationProject(CSTC2007AD7036) supported by Chongqing Key Tackle Research Project,China
文摘The removal of oil from oily wastewater in thermal power plant by coal fly ash(CFA) was investigated. It contained about 2.5 g/L of mineral oil,which had to be treated efficiently before it was discharged. The experiments were carried out as a function of different initial concentrations of oil,mass dosage,contact time and pH value to obtain the optimum conditions for the removal of oil from oily wastewater. The experimental results show that CFA presents the most suitable conditions for the removal of oil from waste-water at a dosage of CFA 2.5 g/L,15 min of contact time and a pH value of 4.8. The adsorption process is performed with almost 96% of oil removal from wastewater. The kinetic data meet the second-order kinetic model. The Langmuir and Freundlich adsorption models were applied to describing the experimental isotherms and isotherm constants. The equilibrium data fit very well with the Freundlich model.
文摘In this study, a novel flocculant was prepared by an inorganic polymetric flocculant (IPF) - polysilicate ferro- aluminum sulfate (PSFA) and rectorite (REC). The structure of the PSFA-REC composite was characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD), in order to determine the optimal temperature. The flocculation test was made at 25℃, 45℃ and 65℃, the results indicated that when the temperature was 65℃, the removal efficiency of the oil and COD was the best, which was 87.2% and 92.6% respectively. Then by comparisons among rectorite (REC), PSFA and the composite PSFA-REC at the temperature of 65℃ and the optimal dosage of 11 mg/L, the composite PSFA-REC showed better flocculation performance than flocculant REC and PSFA alone.
基金Funded by the National Natural Science Foundation of China(No.20876122)Self-determined and Innovative Research Funds of WUT
文摘Aiming at the treatment of difficult-to-handle oily wastewater, the ceramics filter mediums made from the iron and steel plant sludge were adopted to surface lipophilic modification so as to remove oil efficiently. The hydrolysis technique by FTIR and conductivity test indicated that under acid conditions hydrogen silicon oil did not hydrolyze but release hydrogen by chemical reaction under alkaline conditions. The results of the experiments including contact angle measurement, FTIR analysis, and SEM analysis illustrate that a layer of lipophile coating indeed exists evenly on the surface of filter mediums after modification. Furthermore, the hydrogen-containing silicone oil was combined through dehydration of Si-H bond with the-OH on the surface of ceramic filter medium.
基金Funded by the scientific research and technological development project of China national petroleum corporation(No. 2006A50302)
文摘Bioflocculants have received increasing attention in research because they are low cost,non-toxic,biodegradable,operationally simple and useful in many water and wastewater treatment applications.In this study,we focused mainly on the screening of the flocculant-producing strain and its application in oily wastewater treatment.Bacteria strain B-6-1 was isolated by the pyridine screening method.UPC-1 reagent produced by B-6-1 had efficient flocculating activity.It was deduced that the main component of UPC-1 reagent was polysaccharide through purification and analysis.The influence of dosage of reagent,pH value,temperature and oil concentration on the flocculation effect of UPC-1 reagent was investigated.
基金This study was supported by the State Key Laboratory of Petroleum and Petrochemical Contaminant Control and Treatment,the Open Project(Authorization:PPC2019021)the Research and Promotion Project of Key Technologies for Safety and Environmental Protection of CNPC(2017D-4013)the PetroChina Technology Innovation Fund Research Project(Authorization:2017D-5007-0601,2018D-5007-0605).
文摘Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(SMS),to produce an iron-carbon composite(SMS-nZVI).The ability of the SMS-nZVI to treat wastewater containing high concentration of oil was then comprehensively evaluated.The morphology,structure,and other properties of the composite were characterized by using scanning electron microscopy,transmission electron microscopy,the Brunauer-Emmett-Teller nitrogen sorption analysis,and the Fourier transform infrared spectroscopy.The results show that the biochar prepared by using the SMS can effectively prevent the agglomeration of nZVI and increase the overall specific surface area,thereby enhancing the absorption of petroleum by the composite.Experiments reveal that compared with the SMS and nZVI,the SMS-nZVI composite removes petroleum faster and more efficiently from wastewater.Under optimized conditions involving an nZVI to biochar mass ratio of 1:5 and a pH value of 4,the efficiency for removal of petroleum from wastewater with an initial petroleum concentration of 1000 mg/L could reach 95%within 5 h.Based on a natural aging treatment involving exposure to air for 30 d,the SMS-nZVI composite retained an oil removal rate of higher than 62%,and this result could highlight its stability for practical applications.
基金Projects 50425414 supported by thte National Fund for Distinguished Young Scholars2006A019 by the Science and Technology Fund of China University of Mining &Technology
文摘A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and column flotation. The dissolved air release occurred within the column separation system. As a potential application the column was investigated for its performance in separating emulsified oil droplets in oily wastewater. A high separation efficiency was obtained in a series of tests. The aeration performance of the bubble generator used in the dissolved-air flotation column was also studied in particular.