Seminar Project on Membrane Bioreactors

7/31/2019 Seminar Project on Membrane Bioreactors

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Seminar Project on Membrane Bioreactors

Made by: - Naman M. Modi

(CM2008026)

Project Guide: - Prof. Arvind Prasad


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Introduction


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History

Introduced by Dorr-Olivier Inc in the late1960s

In 1989,Yamamoto and co-workers were

the 1st

to submerge the membranes inthe bioreactor

Acceptance of modest fluxes and the ideato use two-phase bubbly flow to controlfouling were key development steps

Earlier SRT was 100 days and now it is10-20 days


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CAS v/s MBR - 1


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CAS v/s MBR - 2


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Major Considerations in MBR

Fouling and foulingcontrol:-

Filtration performanceinevitably decreaseswith filtration time.

It remains one of themost challenging issuesfacing further MBRdevelopment.

The energy required toachieve filtration

increases. More frequentmembrane replacementis also expected.


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Fouling and Fouling Control


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Factors influencing Fouling


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Cleaning of Membrane


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COD Removal and Sludge Yield

Due to the high number of microorganismin MBRs, the pollutants uptake rate canbe increased.

Conventional activated sludge process(CAS) which typically achieves 95%, CODremoval can be increased to 96-99% inMBRs

In CAS, flocs may reach several 100 min size whereas it goes upto 3.5 m insidestream MBRs.

Little or no sludge is produced at sludgeloading rates of 0.01 kgCOD/(kgMLSS d).


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Nutrient Removal & Anaerobic MBRs

Nutrient removal is one of the main concerns inareas that are sensitive to eutrophication.

N-removal from municipal wastewater,phosphorus precipitation, enhanced biologicalphosphorus removal (EBPR) can be implementedwhich requires an additional anaerobic processstep.

Anaerobic processes are normally used when alow cost treatment is required that enablesenergy recovery but does not achieve advancedtreatment.

If maximum energy recovery is desired, a singleanaerobic process will be always superior to acombination with a membrane process.


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Mixing/Hydrodynamics

The removal of pollutants is greatly influenced by thelength of time fluid elements spend in the MBR.

An example of the effect of mixing is that a continuousstirred-tank reactor will not have as high pollutantconversion per unit volume of reactor as a plug flow

reactor. The control of fouling is primarily undertaken using

coarse bubble aeration. The mixing within the system can also influence the

production of possible foulants. Physical properties (e.g. mixture rheology and

gas/liquid/solid density etc.) to the fluid boundaryconditions (e.g. inlet/outlet/recycle flowrates,baffle/mixer position etc.) affect the hydrodynamics ofwastewater processes and hence MBRs.


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Internal (Submerged) v/s External (Sidestream)


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Operating Parameters of Membrane Configurations


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Membrane Materials


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Membrane Specifications of Various Companies


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Design Criteria of MBR


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Capital and Operating Costs


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Advantages of MBR

Almost complete solids and bacteria (Giardia andCrypto) removal;

High effluent quality; modular design with goodexpandability;

Robustness in recovery resistant to upsets due toshock loadings or peak and fluctuating flows;

Sludge age or SRT (solids retention time) andhydraulic residence time (HRT) are controlledseparately;

Less odor; Sophisticated but yet simple controls.


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Disadvantages of MBR

Membrane fouling

Higher energy consumption to

overcome trans-membraneresistance and to prevent foulingusing aeration etc

High cost of membranes


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Conclusion

Documents

Seminar Project on Membrane Bioreactors