Comparison of suspended and fixed photocatalytic reactor systems

Photocatalysis is a promising technology for the purification of pretreated wastewaters in sun-rich countries if an economically applicable reactor system is available. Within this project the catalyst separation as an essential process step of suspended reactor systems was investigated. For the separation of suspended catalyst a sedimentation basin with and without lamella and a membrane filtration were investigated. The sedimentation was found to be very sensitive to the kind of the ion background of wastewater, the pH, the TiO2 influent concentration as well as the hydrodynamics in the clarifier. Under optimized conditions effluent concentrations of less than 5 mg SS/L and a clear water without turbidity could be reached with a specific flow rate of up to 0.7 m3/m2/h. The best performance for P25 was achieved with a TiO2 influent concentration of 5 g/L. Membrane filtration was the only method to guarantee a complete retention of the TiO2 as well as a rejection of microorganisms and high molecular compounds. With cross-flow velocities of 3 m/s and a transmembrane pressure of 100 kPa flux rates up to 1200 L/m2/h were achieved. A flow-film-reactor (FFR) was operated with the model compound DCA under identical conditions with fixed and suspended TiO2. Whereas the fixed system has the advantage that no separation step is necessary and a simple construction can be used, suspended systems offer a three times higher reaction velocity for a catalyst concentration of 10 g/L, but are also characterized by higher investment costs.

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Experimental study on filtering papermaking black liquor by dynamic blade crossflow membrane

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2020-0019 ◽

2020 ◽

Vol 35 (3) ◽

pp. 464-470 ◽

Cited By ~ 2

Author(s):

Wenjie Zhao ◽

Junfei Wu ◽

Fushan Chen

Keyword(s):

Molecular Weight ◽

Experimental Study ◽

Environmental Pollution ◽

Rotational Speed ◽

Membrane Filtration ◽

Black Liquor ◽

Cross Flow ◽

Transmembrane Pressure ◽

Filtration Equipment ◽

Fundamental Reason

AbstractThe fundamental reason for the environmental pollution caused by the papermaking industry is the inadequate treatment of the black liquor. How to dispose of the lignin macromolecules, which is the main pollutants in the black liquor, is the key to addressing the environmental pollution. At present, cross-flow membrane filtration is one of the effective ways to retain and recycle lignin macromolecules in black liquor. The paper proposes the adoption of a dynamic blade cross-flow membrane filtration equipment provided by German BOKELA company to treat papermaking black liquor. The experiment shows that when the black liquor is treated with dynamic blade rotation cross-flow, the membrane with a molecular weight cut-off of nanofiltration (NP010) delivers the best retaining effect, with 28 % more lignin in black liquor than that in untreated black liquor. Meanwhile, when the blade rotational speed reaches 300 rpm and the transmembrane pressure is 0.5 or 2 bar, the flux of black liquor through nanofiltration NP010 is relatively desirable.

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Concentration and Desalination of Protein Derived from Tuna Cooking Juice by Nanofiltration

Jurnal Teknologi ◽

10.11113/jt.v65.2318 ◽

2013 ◽

Vol 65 (4) ◽

Author(s):

Muhammadameen Hajihama ◽

Wirote Youravong

Keyword(s):

Membrane Filtration ◽

Protein Concentration ◽

Protein Hydrolysate ◽

Salt Content ◽

Cross Flow ◽

Transmembrane Pressure ◽

Permeate Flux ◽

Batch Mode ◽

Additional Process ◽

Canning Industry

Tuna cooking juice is a co-product of tuna canning industry. It riches in protein, currently used for production of feed meal as well as protein hydrolysate. The finish products are usually in the form of concentrate, produced by evaporation process. However, evaporation is energy consumable process and the salt content level of the concentrate is often over the standard, thus required additional process for lowering salt content e.g. crystallization. The use of membrane technology, therefore, is of interest, since it required less energy and footprint compared with evaporation and is also able to reduce salt content of the concentrate. The aim of this study were to employ and select the membrane filtration process, and optimize the operating condition for protein concentration and desalination of tuna cooking juice. The results indicated that nanofiltration (NF) was more suitable than the ultrafiltration (UF) process, regarding the ability in protein recovery and desalination. The NF performance was evaluated in terms of permeation flux and protein and salt retentions. The protein and salt rejections of NF were 96 % and 5 %, respectively. The permeate flux(J) increased as transmembrane pressure (TMP) or cross flow rate (CFR) increased and the highest flux was obtained at TMP of 10 bar and CFR of 800 L/h. Operating with batch mode, the permeate flux was found to decrease as protein concentration increased, and at volume concentration factor about 4, the protein concentration about 10% while salt removal was aproximately 70 % of the initial value. This work clearly showed that NF was successfully employed for concentration and desalination of protein derived from tuna cooking juice.

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Sludge activity and cross-flow microfiltration - a non-beneficial relationship

Water Science & Technology ◽

10.2166/wst.1996.0212 ◽

1996 ◽

Vol 34 (9) ◽

pp. 205-213 ◽

Cited By ~ 13

Author(s):

M. Brockmann ◽

C. F. Seyfried

Keyword(s):

Membrane Filtration ◽

Specific Activity ◽

Potato Starch ◽

Batch Reactor ◽

Cross Flow ◽

Methanogenic Bacteria ◽

Transmembrane Pressure ◽

Anaerobic Digesters ◽

Sludge Flocs ◽

Anaerobic Reactors

For the past year a half-scale pilot plant for the anaerobic pretreatment of potato starch wastewater has been in operation. A reactor of 4 m3 was equipped with a settler and a so-called membrane thickener to reduce the amount of sludge which has to pass the membrane. According to other publications on membrane supported anaerobic digesters, organic loadings of more than 6 kg COD/m3d rarely have been achieved by this reactor. A loss of 50% of activity was observed after circulating the sludge 20 times and a 90% loss within 100 cycles. It can be shown that the symbiosis between acidogenic and methanogenic bacteria is the most sensitive part. These observations imply that a “gentle” transport of sludge through the membrane module must be developed, if membrane filtration at anaerobic reactors is to be further utilized. The results for an aerobic batch reactor implied that parallel to the destruction of sludge flocs due to the unsuitable pumps or to high transmembrane pressure, a significant decrease of the specific activity will take place.

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Impact of diffusion, transmembrane pressure and the electrical field on peptide fractionation using cross-flow electro membrane filtration

International Dairy Journal ◽

10.1016/j.idairyj.2014.07.004 ◽

2015 ◽

Vol 46 ◽

pp. 31-38 ◽

Cited By ~ 4

Author(s):

Aline Holder ◽

Christiane Merath ◽

Ulrich Kulozik ◽

Jörg Hinrichs

Keyword(s):

Membrane Filtration ◽

Cross Flow ◽

Transmembrane Pressure ◽

Electrical Field ◽

Peptide Fractionation

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Low-pressure membrane filtration with unconventional coagulation regimes

Water Science & Technology Water Supply ◽

10.2166/ws.2005.0032 ◽

2005 ◽

Vol 5 (5) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

K.Y. Choi ◽

B.A. Dempsey

Keyword(s):

Activated Carbon ◽

Membrane Filtration ◽

Membrane Surface ◽

Cross Flow ◽

Chemical Cleaning ◽

Sand Filters ◽

Charge Neutralization ◽

Floc Size ◽

Filtration System ◽

Pre Treatment

The objective of the research was to evaluate in-line coagulation to improve performance during ultrafiltration (UF). In-line coagulation means use of coagulants without removal of coagulated solids prior to UF. Performance was evaluated by removal of contaminants (water quality) and by resistance to filtration and recovery of flux after hydraulic or chemical cleaning (water production). We hypothesized that coagulation conditions inappropriate for conventional treatment, in particular under-dosing conditions that produce particles that neither settle nor are removed in rapid sand filters, would be effective for in-line coagulation prior to UF. A variety of pre-treatment processes for UF have been investigated including coagulation, powdered activated carbon (PAC) or granular activated carbon (GAC), adsorption on iron oxides or other pre-formed settleable solid phases, or ozonation. Coagulation pre-treatment is often used for removal of fouling substances prior to NF or RO. It has been reported that effective conventional coagulation conditions produced larger particles and this reduced fouling during membrane filtration by reducing adsorption in membrane pores, increasing cake porosity, and increasing transport of foulants away from the membrane surface. However, aggregates produced under sweep floc conditions were more compressible than for charge neutralization conditions, resulting in compaction when the membrane filtration system was pressurized. It was known that the coagulated suspension under either charge-neutralization or sweep floc condition showed similar steady-state flux under the cross-flow microfiltration mode. Another report on the concept of critical floc size suggested that flocs need to reach a certain critical size before MF, otherwise membranes can be irreversibly clogged by the coagulant solids. The authors were motivated to study the effect of various coagulation conditions on the performance of a membrane filtration system.

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Filtration resistance induced by ammonia oxidizers accumulating on the rotating membrane disk

Water Science & Technology ◽

10.2166/wst.1998.0690 ◽

1998 ◽

Vol 38 (4-5) ◽

pp. 443-452

Author(s):

Katsuki Kimura ◽

Yoshimasa Watanabe ◽

Naoki Ohkuma

Keyword(s):

Membrane Filtration ◽

Extracellular Polymeric Substances ◽

Drinking Water Treatment ◽

Treatment Method ◽

Operating Conditions ◽

Transmembrane Pressure ◽

Ammonia Oxidizers ◽

Filtration Resistance ◽

Rotating Membrane Disk ◽

Membrane Disk

Membrane filtration and oxidation of ammonia were simultaneously performed by using a rotating membrane disk module. Nitrification performance, composition of the accumulated cakes on the membrane and the filtration resistances were investigated under five different operating conditions. The filtration resistance due to the accumulated cake on the membrane was found to be dominant in this treatment method, compared to the resistance due to the micropore plugging or irreversible adherence. The cake consisted mainly of iron, humic substances and bacteria. The possibility that extracellular polymeric substances were related to the cake resistance was also shown. The composition of the cake depended on the length and the condition of operation. Accumulation of ammonia oxidizers caused by oxidation of low concentrations of ammonia (less than 1 mg/l) did not increase transmembrane pressure significantly. Therefore, the application of this treatment method for drinking water treatment is feasible. Filtration resistance due to the micropore plugging or irreversible adherence to the membrane was caused by organic substances.

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Data-driven Modelling of Microfiltration Process with Embedded Static Mixer for Steepwater from Corn Starch Industry

Periodica Polytechnica Chemical Engineering ◽

10.3311/ppch.10400 ◽

2017 ◽

Author(s):

Laslo Šereš ◽

Ljubica Dokić ◽

Bojana Ikonić ◽

Dragana Šoronja-Simović ◽

Miljana Djordjević ◽

...

Keyword(s):

Corn Starch ◽

Desirability Function ◽

Specific Energy Consumption ◽

Cross Flow ◽

Operating Conditions ◽

Transmembrane Pressure ◽

Static Mixer ◽

Permeate Flux ◽

Experimental Conditions ◽

Starch Industry

Cross-flow microfiltration using ceramic tubular membrane was applied for treatment of steepwater from corn starch industry. Experiments are conducted according to the faced centered central composite design at three different transmembrane pressures (1, 2 and 3 bar) and cross-flow velocities (100, 150 and 200 L/h) with and without the usage of Kenics static mixer. For examination of the influence of the selected operating conditions at which usage of the static mixer is justified, a response surface methodology and desirability function approach were used. Obtained results showed improvement in the average permeate flux by using Kenics static mixer for 211 % to 269 % depending on experimental conditions when compared to the system without the static mixer. As a result of optimization, the best results considering flux improvement as well as reduction of specific energy consumption were obtained at low transmembrane pressure and lower feed cross-flow rates.

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Membrane Fouling Controlled by Adjustment of Biological Treatment Parameters in Step-Aerating MBR

Membranes ◽

10.3390/membranes11080553 ◽

2021 ◽

Vol 11 (8) ◽

pp. 553

Author(s):

Dimitra C. Banti ◽

Manassis Mitrakas ◽

Petros Samaras

Keyword(s):

Membrane Fouling ◽

Membrane Filtration ◽

Municipal Wastewater ◽

Operating Conditions ◽

Transmembrane Pressure ◽

Aeration Tank ◽

Filamentous Bacteria ◽

Membrane Performance ◽

Low Concentrations ◽

Fouling Reduction

A promising solution for membrane fouling reduction in membrane bioreactors (MBRs) could be the adjustment of operating parameters of the MBR, such as hydraulic retention time (HRT), food/microorganisms (F/M) loading and dissolved oxygen (DO) concentration, aiming to modify the sludge morphology to the direction of improvement of the membrane filtration. In this work, these parameters were investigated in a step-aerating pilot MBR that treated municipal wastewater, in order to control the filamentous population. When F/M loading in the first aeration tank (AT1) was ≤0.65 ± 0.2 g COD/g MLSS/d at 20 ± 3 °C, DO = 2.5 ± 0.1 mg/L and HRT = 1.6 h, the filamentous bacteria were controlled effectively at a moderate filament index of 1.5–3. The moderate population of filamentous bacteria improved the membrane performance, leading to low transmembrane pressure (TMP) at values ≤2 kPa for a great period, while at the control MBR the TMP gradually increased reaching 14 kPa. Soluble microbial products (SMP), were also maintained at low concentrations, contributing additionally to the reduction of ΤΜP. Finally, the step-aerating MBR process and the selected imposed operating conditions of HRT, F/M and DO improved the MBR performance in terms of fouling control, facilitating its future wider application.

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Removal of geosmin and algae by ceramic membrane filtration with super-powdered activated carbon adsorption pretreatment

Water Science & Technology Water Supply ◽

10.2166/ws.2007.080 ◽

2007 ◽

Vol 7 (5-6) ◽

pp. 43-51 ◽

Cited By ~ 2

Author(s):

Y. Matsui ◽

T. Aizawa ◽

M. Suzuki ◽

Y. Kawase

Keyword(s):

Activated Carbon ◽

Membrane Filtration ◽

Ceramic Membrane ◽

Tap Water ◽

Powdered Activated Carbon ◽

Transmembrane Pressure ◽

Activated Carbon Adsorption ◽

Consumer Complaints ◽

Carbon Adsorption ◽

Water Treatment Plants

The musty-earthy taste and odour caused by the presence of geosmin and other compounds in tap water are major causes of consumer complaints. Although ozonation and granular activated carbon (GAC) adsorption have been practiced in water-treatment plants to remove these compounds effectively, two major problems associated with the application of these processes – formation of stringently regulated bromate ions by ozonation and unhygienic invertebrate colonisation of GAC filters – are still to be resolved. This research advanced the process of adsorption by powdered activated carbon (PAC) by reducing its particle size to the submicrometre range for microfiltration pretreatment. Adsorption pretreatment by using this super (S)-PAC removed the geosmin with vastly greater efficiency than by normal PAC. Removal was attained in a much shorter contact time and at a much lower dosage. The S-PAC was also beneficial in attenuating the transmembrane pressure rises that occurred between both physical backwashings and chemical cleanings.

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