Comparison of different fluid dynamics in activated sludge system for the treatment of a stimulated milk processing wastewater: Process analysis and optimization

Ali Akbar Zinatizadeh Lorestani,Hojjatollah Bashiri,Azar Asadi,Hossein Bonakdari 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.10

Wastewater from the milk industry usually undergoes activated sludge ahead of refining treatments, final discharge or reuse. To identify the most effective bioreactor hydraulic regime for the secondary treatment of wastewater resulting from the milk industry in an activated sludge system, two lab-scale activated sludge systems characterized by a different configuration and fluid dynamics (i.e., a compartmentalized activated sludge (CAS) with plug flow regime and a complete mixed activated sludge (AS)) were operated in parallel, inoculated with the same microbial consortium and fed with identical streams of a stimulated dairy wastewater. The effect of three process and operational variables--influent chemical oxygen demand (COD) concentration, sludge recycle ratio (R) and hydraulic retention time (HRT)--on the performance of the two systems were investigated. Experiments were conducted based on a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). The region of exploration for treatment of the synthetic wastewater was taken as the area enclosed by the CODin (200, 1,000 mg/l), R (1, 5), and HRT (2, 5 h) boundaries. To evaluate the process, three parameters, COD removal efficiency (E), specific substrate utilization rate (U), and sludge volume index (SVI), were measured and calculated over the course of the experiments as the process responses. The change of the flow regime from complete-mix to plug flow resulted in considerable improvements in the COD removal efficiency of milk wastewater and sludge settling properties. SVI levels for CAS system (30-58 ml/g) were considerably smaller that for the AS system (50-145 ml/g). In addition, the biomass production yield could be reduced by about 10% compared to the AS system. The results indicated that for the wastewater, the design HRT of a CAS reactor could be shortened to 2-4 h.

Organic–inorganic Z-scheme g-C3N4-NiTi-layered double hydroxide films for photocatalytic applications in a fixed-bed reactor

Davoud Yazdani,Ali Akbar Zinatizadeh,Mohammad Joshaghani 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

A novel graphitic carbon nitride g-C3N4-NiTi-layered double hydroxide heterojunction film photo-catalyst (g-C3N4-NiTi-LDH) was prepared by facile hydrothermal synthesis. The g-C3N4 and g-C3N4-NiTi-LDH film samples were characterized by AFM, SEM, EDX, PL, XRD and DRS analysis. DRS analysis indicated a significant red shift of absorption edge due to the interfacial coupling effect between g-C3N4 and NiTi-LDH. PL analysis showed an efficient inhibition of electron-hole recombination in the blended g-C3N4-NiTi-LDH. A fixed-bed photoreactor containing conjugated g-C3N4-NiTi-LDH film-coated glass was fabricated and employed to photocatalytic degradation of methyl orange (MO). As a result, the g-C3N4-NiTi-LDH film showed greater photocatalytic activity compared with pure samples of g-C3N4 and NiTi-LDH film samples. Maximum MO degradation efficiency (100%) was achieved using g-C3N4-NiTi-LDH films within 240 min.

Milk processing wastewater treatment in a bioreactor followed by an antifouling O-carboxymethyl chitosan modified Fe3O4/PVDF ultrafiltration membrane

Z. Rahimi,A.A. Zinatizadeh,S. Zinadini 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.38 No.-

In this study, a synthetic nanocomposite ultrafiltration membrane (prepared by blending polyvinylidenefluoride (PVDF) and hydrophilic O-carboxymethyl chitosan modified Fe3O4 (OCMCS-Fe3O4) nanoparticle)was applied in a bioreactor to treat milk processing wastewater (MPW). Experiments were carriedout with two independent operating variables, mixed liquor suspended solids (MLSS) and hydraulicretention time (HRT). The region of exploration for the variables was taken as the area enclosed by MLSS(6000–14,000 mg/L) and HRT (8–44 h) boundaries. Throughout the experiments, high COD removalefficiency (92–99%) was obtained. The MLSS had an increasing impact on the removal efficiency ofnitrogen, total phosphorous (TP), and flux. HRT also showed an increasing effect on the removalefficiency of nitrogen and flux while had a reverse impact on the TP removal efficiency. The optimalmembrane performance was compared to commercial microfiltration (MF) membrane and the resultsshowed that the blended membrane with modified nanoparticles leads to a high flux ultrafiltrationmembrane comparable with microfiltration while remaining its separation properties as much as UFmembrane.

Hydraulic characteristics analysis of an anaerobic rotatory biological contactor (AnRBC) using tracer experiments and response surface methodology (RSM)

Yadollah Mansouri,Ali Akbar Zinatizadeh,Parviz Mohammadi,Mohsen Irandoust,Aazam Akhbari,Reza Davoodi 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.7

The hydraulic characteristic of an anaerobic rotating biological contactor (AnRBC) were studied by changing two important hydraulic factors effective in the treatment performance: the hydraulic retention time (τ) and rotational disk velocity (ω). The reactor hydraulic performance was analyzed by studying hydraulic residence time distributions (RTD) obtained from tracer (Rhodamine B) experiments. The experiments were conducted based on a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). The region of exploration for the process was taken as the area enclosed by τ (60, 90 and 120 min) and ω (0.8 and 16 rpm) boundaries. Four dependent parameters, deviation from ideal retention time (Δτ), dead volume percentage and dispersion indexes (Morrill dispersion index (MDI) and dispersion number (d)), were computed as response. The maximum modeled Δτand dead volume percentage was 43.03 min and 37.51% at τ and ω 120 min and 0 rpm, respectively. While, the minimum predicted responses (2.57 min and 8.08%) were obtained at τ and ω 60min and 16 rpm, respectively. The interaction showed that disk rotational velocity and hydraulic retention time played an important role in MDI in the reactor. The AnRBC hydraulic regime was classified as moderate and high dispersion (d=0.09 to 0.253). As a result, in addition to the factors studied, the reactor geometry showed significant effect on the hydraulic regime.

Preparation of high antibiofouling amino functionalized MWCNTs/PES nanocomposite ultrafiltration membrane for application in membrane bioreactor

Z. Rahimi,A.A.L. Zinatizadeh,S. Zinadini 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.29 No.-

Membrane bioreactor (MBR) is an innovative hybrid biotechnology for wastewater treatment. However,its application is constrained by its tendency to fouling. Various procedures are applied to reducemembrane fouling. In this work, nanocomposite membranes were prepared by embedding aminofunctionalized multi-walled carbon nanotubes (NH2-MWCNTs) and were used for improving membranesurface hydrophilicity and subsequently the reduction of the membrane biofouling. The NH2-MWCNTswere synthesized and used as nanofiller in preparation of polyethersulfone (PES) ultrafiltration (UF)membrane. The modified MWCNTs were blended with different weight percentage in the castingsolution, i.e. 0.05, 0.1 and 1 wt.%. In this study, the effect of the NH2-MWCNTs on membrane morphologyand antibiofouling property was investigated. The Fourier transform infrared (FT-IR) spectra analysisshowed that the –NH2 functional groups formed on the surface of MWCNTs. The nanocompositemembranes prepared with different contents of NH2-MWCNTs nanofiller were characterized usingcontact angle, scanning electron microscopy (SEM), and permeation tests. The SEM images displayeda finger-like and porous structure for all synthesized UF membranes. Contact angle measurementsindicated that NH2-MWCNTs nanofiller improved the hydrophilicity of the obtained membranes. Fouling resistances of the membranes elucidated by activated sludge suspension filtration andmeasurements of flux recovery ratio (FRR). The results of the experiments revealed that the 0.1 wt.%NH2-MWCNTs membrane had the best permeability, hydrophilicity and antibiofouling properties. It was quite a surprise to discover that inclusion of only about 0.1 wt.% of the amino functionalizedMWCNTs in the fabrication of membrane could spring up a generation of membrane with antibiofoulingcapability for MBRs.

Statistical analysis and optimization of simultaneous biological nutrients removal process in an intermittently aerated SBR

Amir Mohammad Mansouri,Ali Akbar Zinatizadeh,Mohsen Irandoust,Aazam Akhbari 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.1

Simultaneous removal of carbon and nutrients from a synthetic wastewater in aerobic/anoxic sequence batch reactor (SBR) was investigated. The experiments were conducted based on a central composite design (CCD)and analyzed using response surface methodology (RSM). Two significant independent variables, cycle time and aeration time, were studied to analyze the process. Five dependent parameters--total COD (TCOD) removal, total nitrogen removal,total phosphorus removal, total Kjeldahl nitrogen removal and effluent nitrate concentration--were monitored as the process responses. The region of exploration for the process was taken as the area enclosed by cycle times (2,4.25 and 6.5 h) and aeration times (30, 40 and 50 min/h) boundaries. The maximum COD (87.18%) and TKN (78.94%)removal efficiencies were obtained at the cycle time and aeration time of 6.5 h and 50 min/h, respectively. While the maximum TN (71.15%) and phosphorus (68.91%) removal efficiencies were obtained at cycle time of 6.5 h and aeration time of 40min/h. As a result, high cycle time (6.5 h) and moderate aeration time (40min/h) were found to be the optimal region for maximum carbon and nitrogen removal efficiencies.

Photocatalytic oxidation of organic dyes and pollutants in wastewater using different modified titanium dioxides: A comparative review

H. Zangeneh,A.A.L. Zinatizadeh,M. Habibi,M. Akia,M. Hasnain Isa 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.26 No.-

This article compares the effectiveness of pure and modified TiO2 for photocatalytic degradation of different organic matters and clarifies the advantages of the modified TiO2 with photoactivity under visible light. Photocatalytic degradation technique with titanium dioxide is generally applied for treating wastewater containing refractory organic contaminants with the purpose of reuse due to its ability to achieve complete mineralization of the compounds under mild conditions such as ambient temperature and pressure. Performance of different types of photocatalytic reactors, effects of important parameters on the reactors performance, effect of various methods used to enhance the photocatalytic activity of TiO2 including doping, sensitization of TiO2 and surface modification are discussed in details. So far, a few review papers have been published and extensive information have been reported on the structure and electronic properties of TiO2, difference between TiO2 with other common semiconductors used for photocatalytic applications, various methods used to enhance the photocatalytic characteristics of TiO2 including dye sensitization, doping, coupling, the effects of various operating parameters on the photocatalytic degradation of phenols and dyes and types of reactors, comparison between effective modes of TiO2 application as immobilized on surface or as suspension, and photocatalytic hybrid membrane system are presented. However, in the published review papers, performance of the different modified photocatalysts is rarely compared quantitatively. Therefore, in order to provide an inclusive and effective comparison among the studies, specific removal rate (SRR) (mg compoundremoved/g cat. h) was calculated as a response.

A comparative study on the performance of different advanced oxidation processes (UV/O3/H2O2) treating linear alkyl benzene (LAB) production plant's wastewater

H. Zangeneh,A.A.L. Zinatizadeh,M. Feizy 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

A detailed investigation on photooxidation of linear alkyl benzene (LAB) industrial wastewater is presented in this study. The process analysis was performed by varying four significant independent variables including two numerical factors (initial pH (3–11) and initial H2O2 concentration (0–20 mM)) and two categorical factors (UV irradiation and ozonation). The experiments were conducted based on a central composite design (CCD) and analyzed using response surface methodology (RSM). To assess the process performance, two parameters viz. TCOD removal efficiency and BOD5/COD were measured throughout the experiments. A maximum reduction in TCOD was 58, 53, 51, and 49%, respectively for UV/H2O2/O3, H2O2/O3, UV/O3 and UV/H2O2 processes at the optimum conditions (initial pH of 7, initial H2O2 concentration of 100 mM, and reaction time of 180 min). A considerable increase in BOD5/COD ratio was obtained in the combined processes (0.46, 0.51, 0.53, and 0.55 for UV/H2O2, UV/O3, H2O2/O3 and UV/H2O2/O3, respectively) compared to the single oxidant process (0.35). The results showed that mineralization of the LAB industrial wastewater in neutral pH is more favored than in acidic and basic pH. Gas chromatography–mass spectrometry (GC–MS) was applied to show the fate of organic compounds. In conclusion, the photooxidation process (UV/H2O2/O3, H2O2/O3, UV/O3 and UV/H2O2) could be an appropriate pretreatment method prior to a biological treatment process.

Magnetic field-augmented coagulation bath during phase inversion for preparation of ZnFe2O4/SiO2/PES nanofiltration membrane: A novel method for flux enhancement and fouling resistance

S. Zinadini,A.A.L. Zinatizadeh,M. Rahimi,V. Vatanpour 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.46 No.-

Nanocomposite polyethersulfone (PES) nanofiltrationmembranes were prepared using self-synthesizedmagnetic ZnFe2O4/SiO2 nanofiller by the phase inversion method. The main aim of this paper was toinvestigate effect of magnetic field in coagulation step on characteristics of the prepared membranes. The performance of the fabricated mixed matrixmembranes was studied by measuring pure water flux,salt retention and fouling parameters. As a result, coagulation bath under magnetic field significantlyenhanced pure water flux of the membranes from about 12 kg/m2 h (without magnetic field) to 38 kg/m2 h in the presence of 1 wt.% ZnFe2O4/SiO2 nanoparticles. This described by amount of magneticnanofillers on the membrane morphology coagulated under the magnetic field of 0.1 T, which changedthe skin-layer structure. EDX mapping showed that the magnetic nanoparticles migrated to themembrane surface, when the membrane coagulated under magnetic field. The water contact anglemeasurement showed the excellent hydrophilicity of 0.5 wt.% ZnFe2O4/SiO2 embedded membranesunder magnetic field, which resulted in the superior antifouling properties against powdermilk solution. The salt retention sequence for 0.5 wt.% nanoparticle under magnetic field was in sequence of R(Na2SO4) > R (MgSO4) > R (NaCl).

A new antifouling metal-organic framework based UF membrane for oil-water separation: A comparative study on the effect of MOF (UiO-66-NH2) ligand modification

Mahya Samari,Sirus Zinadini,Ali Akbar Zinatizadeh,Mohammad Jafarzadeh,Foad Gholami 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11

Surface-modified metal-organic frameworks (MOFs) were used for the fabrication of polyethersulfone (PES)- based polymeric composite membranes by phase inversion method. Initially, zirconium-based MOF, UiO-66-NH2, was modified with melamine (denoted as UiO-66-NH-Mlm) and ethylenediamine (UiO-66-NH-EtNH2) via a solvothermal post-modification technique. The fabricated polymeric membranes were then employed for oil-water separation and showed satisfactory hydrophilicity and antifouling performance (PWF: 55.38 kg/m2·h, FRR: 90.67 %, Rr: 46.94%, Rir: 9.33% and >99% rejection to the oil). It was due to the formation of the hydration layer, arising from the available -NH2 groups (providing hydrogen-bonding) on the surface of the modified MOFs (WCA: 51.66o), and the lower surface roughness. Higher hydrophilicity and better antifouling efficiency were obtained for the membranes using UiO-66- NH-Mlm, compared to UiO-66-NH-EtNH2, due to the higher number of -NH2 groups. The membranes also exhibited good thermal stability owing to the fine dispersion of the modified MOFs in the polymeric texture and the presence of metallic cores in the MOFs. The membranes were also applied for frequent filtrations with great performance.