Objectives
The aims of this Work Package are:
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to determine the influence of main operating parameters (i.e. aeration mode and flow rate, filtration pressure and duration, backwash and relaxation conditions) on process performances in terms of filterability, energy consumption and of biodegradation kinetics. This will be based on an experimental studies to determine optimal ranges of operating parameters as a function of membrane module deign and process concept for different municipal wastewaters
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to provide information on optimal conditions for aeration (technological choice and operating parameters) related to:
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for the bioactivity (supplementary to WP4, WP5)
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for preventing fouling, aeration during filtration (supplementary to WP2)
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for removing fouling, aeration during cleaning sequences, short term (supplementary to WP6)
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to provide information on process dynamics in order to propose a dynamic modelling of the process, that could be used for process control and operation. An advanced control system will be designed in order to optimize some process performances by adapting the pertinent parameters on-line.
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to evaluate and analyze process dynamics
Membrane operation is one of the key issues for membrane bioreactors. Indeed, the way membranes are operated can affect the whole process efficiency in terms of water quality, energy consumption and filterability. Critical operating parameters are aeration and backwash and a key question to enhanced systems is how to optimise these parameters. Membrane operation also affects the sludge structure and composition and thus the biokinetics. Some studies are now available on these topics, but they are often very specific to a given bioreactor technology or to a given wastewater. More generalized and design specific data is needed to improve MBR applications and studies will therefore be conducted with a common approach and in parallel to evaluate the influence of these operating parameters for different membrane geometry (i.e. flat sheet, tubes or hollow fibres), module designs (submerged or side-streams) and different wastewater characteristics.
A better understanding of these operating modes will ultimately enable better process control for full-scale membrane system operation. Sustainable operation of the process requires design tools for automated plants in which operating parameters are adapted automatically to specific constraints or inlet water qualities with regard to optimization criteria. Such tools have been successfully developed for membrane systems in drinking water plants and similar approach will be applied to MBRs for wastewater treatment.
Methodology / work description
The tasks to be undertaken in the work package are:
WP3.1 Common methodologies
A definition of a common methodology to be applied will be set for the partners, with implementation of generic normalized parameter values as defined in WP1.
WP3.2 Laboratory-scale studies
Laboratory-scale studies experiments on the influence of operating parameters (i.e. filtration flux and duration, aeration mode and conditions, hydraulic shear, hydraulic cleaning parameters) for different wastewaters and different membrane module geometries will be conducted. Studies will investigate effects of;
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Suspension and supernatant characteristics, i.e. SS concentration, particle size distribution, floc fractal dimension and EPS concentration (supplementary to WP5)
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Module clogging and membrane fouling estimated in terms of permeate flux and flux recovery after different cleaning operations for different membrane modules (HF, FP and tubular) and process configurations (relative to WP2, WP4)
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Specific biomass behaviour (C/N/P removal kinetics, specific oxygen uptake rates, sludge production, EPS production) for domestic wastewaters and for synthetic wastewaters containing different fractions of soluble and particulate organic compounds and showing a different biodegradability (input WP5)
WP3.3 Characterization of aeration
The tasks include;
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Characterization of gas/liquid aeration for different module geometry and different processes
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Characterization of gas/liquid hydrodynamics for pure water
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Characterization of the influence of air flow on sludge properties, on permeate flux and on cake deposit (effect of air on particle adhesion and detachment).
This will be studied through global mass balances at semi-industrial and laboratory test scale using the different pilot plants. A specific visualisation cell available at INSA will also be used in order to study the different phenomena at local scale in situ.
WP3.4 Definition of optimal parameters
Definition of optimal parameters – recommendation of best technologies for aeration design (to be used in WP2, WP4 and WP6)
WP3.5 Analysis of process dynamics and modelling
Analysis of process dynamics, modelling: sensitivity of filtration and biological activity to feed quality fluctuations and to inlet parameters – this analysis will be performed on the basis of results obtained by the different project partners working with different module geometry and waste waters. Propose a dynamic modelling for process control.
Deliverables & Milestones
Month 3 definition of a common methodology completed.
Month 6 literature data
Month 12 Report - characterization of air/water flow in different modules
Month 24 experimental data on laboratory scale experimentations (WP3.2, WP3.3)
Month 36 Report - Aeration and Operation in MBRs as a function of waste water quality and module configuration
Work package nr.
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WP3
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Start date or starting event:
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0
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Activity Type
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RTD/Innovation activities
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Participant id
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NTNU
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CU
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RWTH
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INSA
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UM2
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DUT
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UNITN
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UTS
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UKZN
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Polymem
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KMS
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MILL
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WHD
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Person-months per participant:
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3
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17
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3
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25
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30
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5
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17
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16
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4
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4
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3
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4
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4
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Objectives
- to determine the influence of process configuration and of main operating parameters (aeration mode and conditions, filtration mode and conditions, backwashing or other hydraulic cleaning conditions) on process performances in terms of filterability (fouling), permeate quality, energy consumption, biokinetics, and membrane lifetime.
- to provide information on the required conditions for aeration (technical choice and operating conditions) in order to . (i) enhance or maintain bioactivity, (ii) prevent fouling, (iii) remove fouling
- to provide information on process dynamics in order to develop a dynamic model for process control and operation
- to analyse process dynamics
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Description of work
This work package has been divided into sub-tasks. The nature of this activity requires high a degree of collaboration and interaction between the respective partners. The following gives a description of the proposed tasks;
3.1 Common methodologies
(NTNU, CU, RWTH, INSA, UM2, DUT, UNITN, UTS, UKZN, Polymem, KMS, MILL, WHD)
Definition of a common methodology for the different partners, implementation of generic normalized parameter values as defined in WP1.
3.2 Lab-scale studies
(NTNU, CU, RWTH, INSA, DUT, UNITN, UTS, UKZN, Polymem, UM2, WHD)
Lab-scale study experiments on the influence of ;
(i) operating parameters,
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filtration conditions: flux/pressure and duration,
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relaxation conditions: duration, frequency
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aeration mode and conditions (injector technology, air flow rate/pressure, continuous/sequential pulsed/intermittent)
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hydraulic shear due to sludge recirculation or to air-lift in side-stream systems,
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backwashing and other hydraulic cleaning parameters
and (ii) MBR configuration,
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direct wastewater treatment by MBR (will concern the main part of the WP)
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hybrid MBR or MBR in parallel or in series with a conventional lane
on the following process performances: filterability/fouling, permeate quality (pathogens removal), flux recovery (short term and long term), energy consumption, biokinetics and membrane lifetime.
Experiments will be conducted for different waste waters (domestic/industrial/synthetic wastewater, some enriched in toxic compounds), different module configurations (i.e. submerged/side stream, liquid flow/air-lift mode, flat sheet/ hollow fibre/tubular membrane) and different kinds of biological processes (aerobic/anaerobic, suspended/fixed)
Investigations will include : direct or indirect characterisation of
(i) floc properties (size distribution, deformability, concentration),
(ii) supernatant and suspension characteristics (contents in colloids, SMP and EPS, filterability),
(iii) membrane fouling and ability to remove fouling hydraulic resistance, measurement and observation of deposit accumulation and removal, flux recovery after different cleaning operations),
(iv) specific biomass behaviour (C/N/P removal kinetics, specific oxygen uptake rates, sludge production, SMP production) - in relation with WP5,
(v) membrane ageing tests on small and large hollow fibre modules (stress-stain tests, burst pressure, SEM.) – in relation with WP6
3.3 Characterization of aeration
(INSA, UM2)
Characterization of gas/liquid aeration for different module geometry, different processes (side-stream and submerged systems, airlift side-stream) and different ways of aeration (continuous, or pulsed/intermittent); Characterization of gas/liquid hydrodynamics for pure water and for synthetic suspensions in relation with membrane packing density, air injection mode and gas and liquid flow rates; Characterization of the influence of air flow on sludge properties, on permeate flux and on cake deposit (effect of air on particle adhesion and detachment). This will be studied through global mass balances at semi-industrial and laboratory test scale using the different pilot plants and by in-situ determination of deposit kinetics.
3.4 Definition of optimal parameters
(NTNU, CU, INSA, UM2, UNITN, UTS, Polymem, KMS, WHD)
Definition of optimal parameters – recommendation of best technologies for aeration design (to be used by WP2, WP4) Results coming from WP3.2 and WP3.3 will be synthesised in order to provide information on the control of membrane fouling according to the choice of hydrodynamics conditions generated by air flow-rates, module configuration and suspension characteristics.
3.5 Analysis of process dynamics and modelling
(RWTH, INSA, UNITN, UKZN, Polymem)
Analysis of process dynamics, modelling: sensitivity of filtration and biological activity to feed quality fluctuations and to inlet parameters – this analysis will be performed on the basis of results obtained by the different project partners working with different module geometry and waste waters. Propose and validate a dynamic modelling for process control.
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Deliverables
D2 – Definition of (a) normalized parameters, and (b) common analytical methodology
D5 – Literature review / data on aeration and main operating conditions in MBRs
D11 – Report - characterization of air/water flow in different module configurations
D20 – Report - Experimental data on laboratory scale experiments, aeration trials
D35 – Report - Aeration and operation of MBRs as a function of wastewater quality and module configuration
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Milestones and expected result
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M3.1 +3 definition of normalized parameters and common analytical methodology completed
- M3.2 +6 literature review on aeration and main operating conditions in MBRs
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M3.3 +12 characterization of air/water flow in different modules
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M3.4 +24 laboratory-scale experiments completed (3.2 & 3.3)
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M3.5 +36 report on aeration and operation of MBRs
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