Knowledge-based system for automatic MBR control

MBR technology is currently challenging traditional wastewater treatment systems and is increasingly selected for WWTP upgrading. MBR systems typically are constructed on a smaller footprint, and provide superior treated water quality. However, the main drawback of MBR technology is that the permeability of membranes declines during filtration due to membrane fouling, which for a large part causes the high aeration requirements of an MBR to counteract this fouling phenomenon. Due to the complex and still unknown mechanisms of membrane fouling it is neither possible to describe clearly its development by means of a deterministic model, nor to control it with a purely mathematical law. Consequently the majority of MBR applications are controlled in an “open-loop” way i.e. with predefined and fixed air scour and filtration/relaxation or backwashing cycles, and scheduled inline or offline chemical cleaning as a preventive measure, without taking into account the real needs of membrane cleaning based on its filtration performance. However, existing theoretical and empirical knowledge about potential cause-effect relations between a number of factors (influent characteristics, biomass characteristics and operational conditions) and MBR operation can be used to build a knowledge-based decision support system (KB-DSS) for the automatic control of MBRs. This KB-DSS contains a knowledge-based control module, which, based on real time comparison of the current permeability trend with “reference trends”, aims at optimizing the operation and energy costs and decreasing fouling rates. In practice the automatic control system proposed regulates the set points of the key operational variables controlled in MBR systems (permeate flux, relaxation and backwash times, backwash flows and times, aeration flow rates, chemical cleaning frequency, waste sludge flow rate and recycle flow rates) and identifies its optimal value. This paper describes the concepts and the 3-level architecture of the knowledge-based DSS and details the knowledge-based control module. Preliminary results of the application of the control module to regulate the air flow rate of an MBR working with variable flux demonstrates the usefulness of this approach.

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Enhanced Removal of Organic Pollutants and Reactive Dye in Polyethersulfone Submerged Membrane Bioreactor (PES-SMBR) for Textile Wastewater

Current World Environment ◽

10.12944/cwe.16.1.33 ◽

2021 ◽

Vol 16 (1) ◽

pp. 329-341

Author(s):

Tukaram P. Chavan ◽

Ganpat B. More ◽

Sanjaykumar R. Thorat

Keyword(s):

Membrane Fouling ◽

Membrane Bioreactor ◽

Textile Wastewater ◽

Pilot Scale ◽

Reactive Dye ◽

Hollow Fibre ◽

Flow Mode ◽

Permeate Flux ◽

Chemical Cleaning ◽

Submerged Membrane Bioreactor

The present investigation was carried out to assess the operation of a pilot-scale submerged membrane bioreactor (SMBR) for the treatment of reactive dye and textile wastewater. The operation of SMBR model was conducted by using a polyethersulfone (PES) hollow fibre membrane with continuous flow mode at different HRTs at 8, 6 and 4 h, for 90 days. During the entire operation, the average permeate flux, TMP, F/M ratio and OLR was found to be 19 (L/m²/h), 2.6 (psi), 0.10 (g BOD/(g MLSS•d) and 0.89 (kg BOD/m³.d), respectively. The variations in the permeate flux, TMP, F/M ratio and OLR have not adversely effects on the operation of the SMBR model. Throughout the entire operation, despite the TP, TDS and conductivity, the high amount of COD (82%), BOD (86%), NO3-N (79%), TSS (98%), turbidity (97%) and colour (79%), removal was achieved. The permeate flux was declined by membrane fouling and it was recovered by chemical cleaning as well as regular backwashing during the entire operation. The results obtained from the study concluded that the hollow fibre ultrafiltration polyethersulfone (PES) membrane shows good performance while treating textile wastewater along with reactive dye solution.

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Membrane surface properties and their effects on real waste oil-in-water emulsion ultrafiltration

Water SA ◽

10.17159/wsa/2019.v45.i3.6733 ◽

2019 ◽

Vol 45 (3 July) ◽

Cited By ~ 1

Author(s):

Marjana Simonič

Keyword(s):

Surface Properties ◽

Membrane Fouling ◽

Membrane Surface ◽

Cross Flow ◽

Influential Factors ◽

Permeate Flux ◽

Chemical Cleaning ◽

Water Emulsion ◽

Oil In Water ◽

Oil In Water Emulsion

Membrane surface properties and their effect on the efficiency of ultrafiltration (UF) of real waste oily emulsions was studied. Experiments were performed in cross-flow operation at total recycle condition in a lab-scale system. The ceramic UF membrane in the tubular type module was employed. During the experiments permeate flux was measured. The most important influential factors, such as temperature, TMP, and pH, were considered during the experiments. Zeta potential was measured in order to explain the phenomena on the membrane surface. The isoelectric point of the fouled membrane was shifted to the alkaline range. COD removal efficiency reached 89%. Gas chromatography measurements were performed in order to determine the composition of waste emulsions. SEM micrographs showed the formation of calcite on the membrane, which contributed to membrane fouling. Chemical cleaning was examined using alkaline and acid solutions, and a cleaning strategy was determined.

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The substitution of sand filtration by immersed-UF for surface water treatment: pilot-scale studies

Water Science & Technology ◽

10.2166/wst.2009.684 ◽

2009 ◽

Vol 60 (9) ◽

pp. 2337-2343

Author(s):

Sun Lihua ◽

Li Xing ◽

Zhang Guoyu ◽

Chen Jie ◽

Xu Zhe ◽

...

Keyword(s):

Membrane Fouling ◽

Operating Cost ◽

Pilot Scale ◽

Permeate Flux ◽

Sand Filtration ◽

Chemical Cleaning ◽

Aeration Intensity ◽

Drinking Water Standard ◽

Average Operating ◽

Operational Processes

The newly issued National Drinking Water Standard required that turbidity should be lower than 1 NTU, and the substitution of sand filtration by immersed ultrafiltration (immersed-UF) is feasible to achieve the standard. This study aimed to optimise the operational processes (i.e. aeration, backwashing) through pilot scale studies, to control membrane fouling while treating the sedimentation effluent. Results indicated that the immersed-UF was promising to treat the sedimentation effluent. The turbidity was below 0.10 NTU, bacteria and E. coli were not detected in the permeate water. The intermittent filtration with aeration is beneficial to inhibit membrane fouling. The critical aeration intensity is observed to be 60.0 m3 m−2 h−1. At this aeration intensity, the decline rate of permeate flux in one period of backwashing was 1.94% and 7.03% for intermittent filtration and sustained filtration respectively. The different membrane backwashing methods (i.e. aeration 1.5 min, synchronous aeration and water backwashing 2 min, water backwashing 1.5 min; synchronous aeration and water backwashing 3 min, water backwashing 2 min; aeration 3 min, single water backwashing 2 min; synchronous aeration and water backwashing 5 min; single water backwashing 5 min) on the recovery of permeate flux were compared, indicating that the synchronous aeration and water backwashing exhibited best potential for permeate flux recovery. The optimal intensity of water backwashing is shown to be 90.0 L m−2 h−1. When the actual water intensity was below or exceeded the value, the recovery rate of permeate flux would be reduced. Additionally, the average operating cost for the immersed UF membrane, including the power, the chemical cleaning reagents, and membrane modules replacement, was about 0.31 RMB/m3.

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Vibratory membrane separation for wastewater treatment

Progress in Agricultural Engineering Sciences ◽

10.1556/446.14.2018.s1.3 ◽

2018 ◽

Vol 14 (s1) ◽

pp. 25-35

Author(s):

Péter Bor ◽

József Csanádi ◽

Gábor Veréb ◽

Sándor Beszédes ◽

Zita Šereš ◽

...

Keyword(s):

Wastewater Treatment ◽

Shear Rate ◽

Flow Rate ◽

Specific Energy ◽

Membrane Fouling ◽

Energy Demand ◽

Membrane Separation ◽

Permeate Flux ◽

Recirculation Flow ◽

Shear Rates

To meet the requirements defined by environmental protection regulations effective wastewater treatment is required to process effluents before discharging them into sewers or living waters. While membrane separation offers a quite advantageous method to reduce the organic load of wastewaters, membrane fouling is still limiting its application in wastewater treatment. In this study, the possibility of membrane fouling reduction by increased shear rates on the surface of the membrane was investigated. 7 and 10 kDa MWCO ultrafiltration and 240 Da nanofiltration membranes were studied, with the use of a laboratory mode Vibratory Shear Enhanced Processing. This work mostly focused on studying the effects of module vibration and recirculation feed flow rate on permeate flux, specific energy demand and membrane rejections. Using the same operation parameters, vibration and non-vibration mode experiments were carried out with high and low recirculation flow rate to have a deeper understanding of the shear rate effects. It can be concluded that higher shear rate had a positive effect on the process: increased shear rate resulted in higher flux, higher overall rejection values, as well as a significantly decreased specific energy demand. By calculating and comparing the shear rates in experiments with different operating parameters, both vibration and nonvibration mode, both low and high recirculation flow rate, we have reached the conclusion that vibration causes a significantly higher shear rate increase than setting the recirculation flow rate high.

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Membrane cleaning in membrane distillation of reverse osmosis concentrate generated in landfill leachate treatment

Water Science & Technology ◽

10.2166/wst.2021.614 ◽

2021 ◽

Author(s):

Xiaolin Jia ◽

Kuiling Li ◽

Baoqiang Wang ◽

ZhiChao Zhao ◽

Deyin Hou ◽

...

Keyword(s):

Reverse Osmosis ◽

Landfill Leachate ◽

Membrane Fouling ◽

Membrane Distillation ◽

Water Recovery ◽

Permeate Flux ◽

Chemical Cleaning ◽

Leachate Treatment ◽

Membrane Cleaning ◽

Cleaning Methods

Abstract As a thermally induced membrane separation process, membrane distillation (MD) has drawn more and more attention for the advantages of treating hypersaline wastewaters, especially the concentrate from reverse osmosis (RO) process. One of the major obstacles in widespread MD application is the membrane fouling. We investigated the feasibility of direct contact membrane distillation (DCMD) for landfill leachate reverse osmosis concentrate (LFLRO) brine treatment and systematically assessed the efficiency of chemical cleaning for DCMD after processing LFLRO brine. The results showed that 80% water recovery rate was achieved when processing the LFLRO brine by DCMD, but the membrane fouling occurred during the DCMD process, and manifested as the decreasing of permeate flux and the increasing of permeate conductivity. Analysis revealed that the serious flux reduction was primarily caused by the fouling layer that consist of organic matters and inorganic salts. Five cleaning methods were investigated for membrane cleaning, including hydrogen chloride (HCl)-sodium hydroxide (NaOH), ethylene diamine tetraacetic acid (EDTA)-NaOH, critic acid, sodium hypochlorite (NaClO) and sodium dodecyl sulphate (SDS) cleaning. Among the chemical cleaning methods investigated, the 3 wt.% SDS cleaning showed the best efficiency at recovering the performance of fouled membranes.

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Ultrafiltration of activated sludge with ceramic membranes in a cross-flow membrane bioreactor process

Water Science & Technology ◽

10.2166/wst.2000.0653 ◽

2000 ◽

Vol 41 (10-11) ◽

pp. 243-250 ◽

Cited By ~ 20

Author(s):

X-j. Fan ◽

V. Urbain ◽

Y. Qian ◽

J. Manem

Keyword(s):

Wastewater Treatment ◽

Membrane Fouling ◽

Membrane Bioreactor ◽

Municipal Wastewater ◽

Ceramic Membrane ◽

Treatment Plant ◽

Cross Flow ◽

Ceramic Membranes ◽

Permeate Flux ◽

Chemical Cleaning

A cross-flow membrane bioreactor (MBR) for raw municipal wastewater treatment, consisting of a suspended growth bioreactor and a ceramic membrane ultrafiltration unit, was run over a period of more than 300 days in a wastewater treatment plant (WWTP). Sludge Retention Times (SRT) of 20, 10 and 5 days, respectively, and Hydraulic Retention Times (HRT) of 15 and 7.5 hours were tested. Membrane fouling was found to be a function of SRT and permeate flux. Under an SRT of 20 days and flux of 71 l/m2\ · h at 30°C, the MBR was successfully run over 70 days without the need for chemical cleaning. However chemical cleaning had to be undertaken every 3–5 days at shorter sludge retention times (typically an SRT of five days and a flux of 143 l/m2\ · h at 30°C). In this study, fouling materials were removed efficiently through chemical cleaning, with an average permeablity recovery of 87±11%.

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Experimental and Modelling of Aqueous Radioactive Waste Treatment by Ultrafiltration

Revista de Chimie ◽

10.37358/rc.18.5.6278 ◽

2018 ◽

Vol 69 (5) ◽

pp. 1149-1151

Author(s):

Laura Ruxandra Zicman ◽

Elena Neacsu ◽

Felicia Nicoleta Dragolici ◽

Catalin Ciobanu ◽

Gheorghe Dogaru ◽

...

Keyword(s):

Flow Rate ◽

Suspended Solids ◽

Waste Treatment ◽

Operating Pressure ◽

Feed Flow Rate ◽

Permeate Flux ◽

Independent Variables ◽

Opposite Trend ◽

Process Factors ◽

Volumetric Flux

Ultrafiltration of untreated and pretreated aqueous radioactive wastes was conducted using a spiral-wound polysulphonamide membrane. The influence of process factors on its performances was experimental studied and predicted. Permeate volumetric flux and permeate total suspended solids (TSS) were measured at different values of feed flow rate (7 and 10 m3/h), operating pressure (0.1-0.4 MPa), and feed TSS (15 and 60 mg/L). Permeate flux (42-200 L/(m2�h)) increased with feed flow rate and operating pressure as well as it decreased with an increase in feed TSS, whereas permeate TSS (0.1-33.2 mg/L) exhibited an opposite trend. A 23 factorial plan was used to establish correlations between dependent and independent variables of ultrafiltration process.

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Hydraulic model of a water cooling system in a chemical plant

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19880788 ◽

1988 ◽

Vol 53 (4) ◽

pp. 788-806

Author(s):

Miloslav Hošťálek ◽

Jiří Výborný ◽

František Madron

Keyword(s):

Flow Rate ◽

Cooling System ◽

Cooling Water ◽

Graph Algorithm ◽

Automatic Generation ◽

Hydraulic Calculation ◽

Return Flow ◽

Flow Rates ◽

Pressure Losses ◽

Controlled Flow

Steady state hydraulic calculation has been described of an extensive pipeline network based on a new graph algorithm for setting up and decomposition of balance equations of the model. The parameters of the model are characteristics of individual sections of the network (pumps, pipes, and heat exchangers with armatures). In case of sections with controlled flow rate (variable characteristic), or sections with measured flow rate, the flow rates are direct inputs. The interactions of the network with the surroundings are accounted for by appropriate sources and sinks of individual nodes. The result of the calculation is the knowledge of all flow rates and pressure losses in the network. Automatic generation of the model equations utilizes an efficient (vector) fixing of the network topology and predominantly logical, not numerical operations based on the graph theory. The calculation proper utilizes a modification of the model by the method of linearization of characteristics, while the properties of the modified set of equations permit further decrease of the requirements on the computer. The described approach is suitable for the solution of practical problems even on lower category personal computers. The calculations are illustrated on an example of a simple network with uncontrolled and controlled flow rates of cooling water while one of the sections of the network is also a gravitational return flow of the cooling water.

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Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽

10.3390/designs5010004 ◽

2021 ◽

Vol 5 (1) ◽

pp. 4

Author(s):

Dillon Alexander Wilson ◽

Kul Pun ◽

Poo Balan Ganesan ◽

Faik Hamad

Keyword(s):

Water Flow ◽

Flow Rate ◽

Cfd Simulation ◽

Air Flow ◽

Bubble Diameter ◽

Diameter Ratio ◽

Experimental Measurements ◽

Cfd Model ◽

Flow Rates ◽

Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

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Comparison of different models to calculate the viscosity of biogas and biomethane in order to accurately measure flow rates for conformity assessment

Scientific Reports ◽

10.1038/s41598-021-81052-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Karine Arrhenius ◽

Oliver Büker

Keyword(s):

Binary Mixtures ◽

Flow Rate ◽

Correction Method ◽

Gas Mixtures ◽

Conformity Assessment ◽

Flow Rates ◽

Unknown Composition

AbstractThe study presents an optimised method to correct flow rates measured with a LFE flowmeter pre-set on methane while used for gas mixtures of unknown composition at the time of the measurement. The method requires the correction of the flow rate using a factor based on the viscosity of the gas mixtures once the composition is accurately known. The method has several different possible applications inclusive for the sampling of biogas and biomethane onto sorbent tubes for conformity assessment for the determination of siloxanes, terpenes and VOC in general. Five models for the calculation of the viscosity of the gas mixtures were compared and the models were used for ten binary mixtures and four multi-component mixtures. The results of the evaluation of the different models showed that the correction method using the viscosity of the mixtures calculated with the model of Reichenberg and Carr showed the smallest biases for binary mixtures. For multi-component mixtures, the best results were obtained when using the models of Lucas and Carr.

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