Membrane Bio Reactor (MBR) Vs. Fluidised Media Reactor (FMR)

Membrane Bio Reactor : (MBR)

The treatment trains for conventional treatment and MBRs are substantially different. For example, the conventional treatment train may consist of screening, grit removal, aeration basins, secondary clarifiers, and UV disinfection.

The MBR treatment train consists of screening, grit removal, fine screening, flow equalization, and membrane bioreactors. Fine screening down to 2-mm openings is required to remove fibrous material that has proved problematic to membrane operation.

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DISADVANTAGES

1) The primary disadvantages of membrane bioreactors include capital costs for the membranes and operating costs associated with routine membrane cleaning . The membrane modules will need to be replaced somewhere between five (5) and ten (10) years with the current technology. While the costs have decreased over the past several years, these modules can still be classified as expensive. (The membranes "dry out" due to the flexible polymers leaching out, the closing/plugging of the pores, and the membranes becoming somewhat hard or brittle.) These costs are often offset somewhat when life-cycle costs for comparable technologies are examined. If the costs for the membrane replacement task continue to decrease then over time, then this process is even more financially viable.

2) In most sales pitches the MBR technology is stated as an option of replacing the secondary clarifier. Usually these clarifiers are operated with a single, very low horsepower motor, usually less than 2 HP. The electrical cost for this simple motor is significantly less than the filtrate pumps, chemical feed pumps, compressors, etc., of the MBR system. While this energy cost is significantly higher, the MBR system produces a significantly higher quality effluent that most clarifiers could never achieve.

3) Fouling is troublesome, and its prevention is costly. Several papers and research endeavors have concluded that up to two-thirds of the chemical and energy costs in an MBR facility are directly attributable to reducing membrane fouling. While this is costly to be sure, future advances into this area will continue to reduce these costs.

Biofouling is a serious problem for the operation of membrane bioreactor systems because it results in decreased transmembrane fluxes. Biofouling involves the synergistic effects of biological, physical, and chemical clogging of membrane pores. Clogged pores result in: (a) reduced transmembrane fluxes, (b) a need for higher operating pressures, and (c) deterioration of the membrane

4) There may be cleaning solutions that require special handling, treatment, and disposal activities depending on the manufacturer. These cleaning solutions may be classified as hazardous waste depending on local and state regulations.

5) MBRs use more electricity than conventional systems. High biomass concentrations require more air because oxygen transfer is less efficient, additional blowers are required for membrane cleaning, and permeate pumps are required.

6) MBR sludge have been found to be more difficult to handle than conventional sludge

 

So, we rule out MBR for the time being till membrane costs come down, otherwise it is the best technology for water reuse and zero discharge conditions.

 

 

Fluidised Media Reactor (FMR) vs. submerged fixed film process (SAFF)

The FMR works on the same principle as the submerged fixed film process (SAFF) with only one exception - the media is not fixed and floats around in the aeration tank. The main advantage of this system over the submerged fixed film process is that it prevents choking of the media. Compared to conventional technologies the FMR is compact, energy efficient and user friendly. It also allows flexibility in design of the reactor tank. The advantages of the FMR are many –

• Attached growth process, with specially designed moving media.

• Compact and modular design. Requires less space
  

• Minimal pumping and chemical cost, low operating cost.
  

Fixed media in SAFF is very costly. Its called Bio Deck and sold at a rate of Rs.4000 per cu mtr at Delhi. So replacement or repair is a costly issue.

FMR is an advanced version of the SAFF which uses a floating media to avoid the practical choking problem of media in SAFF.

So, SAFF is also ruled out.

 

 

WE OPT FOR DEWATS as DEWATS is an advanced version of the FMR.

In the DEWATS, the waste water/sewage is let through a multi stage low maintenance system to treat it and recycle it for flushing, gardening and other non potable end uses.

The train of units are : Anaerobic Reactor, Anaerobic Settling tank ,FMR Aeration tank, Secondary Settling Tank, Chlorine Contact Tank and Activated Carbon Filter for odor removal

As the BOD load is reduced by installation of anaerobic system prior to FMR, the capacity of the blower to be installed in the FMR tank is reduced thereby Electrical consumption.

And if by any chance, the FMR portion is not working due to human negligence, even than the anaerobic portion is enough, which acts like a simple septic tank.

So, DEWATS is cost effective and easy to maintain.

WE OPT FOR DEWATS for smaller capacity (upto 300 KLD).