Membrane

Bioreactor

Membrane Bioreactor

MBR stand for Membrane Bio Reactor, it is essentially a filtration process which used bio-membrane to treat wastewater. When a microfiltration or ultra filtration membrane is submerged in mixed liquor, and a positive (by gravity) or suction pressure is applied, the pores of the membrane and the resulting bio film formation on the surface of the membrane acts as a physical barrier that allow only the permeate or clean water to pass through. Pre-treated, screened influent enters the membrane bioreactor, where biodegradation takes place.

The mixed liquor from the bioreactor is withdrawn and pumped along submerged or semi cross-flow filtration membrane modules. Permeate form the membrane constitutes the treated effluent. The reject stream, consisting of concentrated bio- solids, is returned to the bioreactor. Excess bio-solids are wasted from the bioreactor or from the return line. One of the biggest advantages that MBR brings to the table is the relatively smaller foot print, making it ideal for a country like India.

membrane

Also, while expansion of capacity with a conventional treatment plant can mean installing another large clarifier, in an MBR plant you can simply add more membranes to existing basins expanding capacity without expanding footprint, this makes it even more pertinent for the growing economic like India and China, which are witnessing strong growth in population, urbanization and industrialization. Some other advantages that MBR offers over conventional

Treatment methods

  • Effluent of high quality
  • High chlorine tolerance (up to 5000ppm)
  • High mechanical strength which result in minimal defects and breaks during operation
  • A membrane bioreactor system eliminate the need for a secondary clarification tank
  • Can be operated at high MLSS concentration compared to conventional separation system(reducing reactor volume)
  • High loading rates
  • High operation flux (18-24gfd-Gallons Per Square Foot of Membrane)
  • Simple operation, low chemical consumption and simple cleaning procedure
  • Double layer membrane provides an extra barrier for pathogens and suspended solid in the event of a defect
treatment methods
features

Salient Features

  • Effluent of high quality
  • Small footprint thereby saving the prime land in the city. The process building designed on “GREEM” building concept
  • 100 % rainwater harvesting facility, 100% automation requiring minimum or NO manpower
  • The 1st STP of this capacity in India to be equipped with odourcontrol units for odour free ambience in the surrounding
  • Low sludge production and no chemical sludge
    Another aspect of MBR which it very attractive for the small industries are commercial complexes and gated colonies due to its ease of operation. This is the least appreciated aspect of this technology, but can make a great difference in the operating costs required to run the plant.

Why MBR

Some reason why MBR can be called an install and forget technology is :-

  • Eliminating phase separation (sludge settling) from the process greatly reduces the operator oversight required to keep the system running efficiently because
  • Most operators of activated sludge facilities will tell you they spend the majority of their time focused on the settling characteristics of the sludge at their plant
  • There are many factors that impact settling characteristics and these can change from one day to the next. This requires time spent in the la analyzing sludge samples, but also subsequent adjustment to the plant to maintain good settling characteristics
  • Although MBR being an advanced technology compared to its peers, it comes with a few disadvantages
  • The membrane “dry out” due to the flexible polymers leaching out, the closing/plugging of the pores, and the membranes becoming somewhat hard or brittle
  • In most cases the MBR technology is stated as an option of replacing the secondary clarifier. These clarifiers are operated with a single, very low HP motor, usually less than 2HP the electrical cist for this simple motor is significantly less than the filtrate pumps, chemical feed pumps, compressors, etc
  • Fouling is troublesome and its prevention is costly. Two thirds of the chemical and energy costs in an MBR facility are directly attributable to reducing membrane fouling
  • Operating costs for MBR systems are typically higher than those for comparable conventional systems. This is because of the higher energy costs if air scouring is used to reduce membrane fouling
  • The amount of air needed for the scouring has been reported to be twice that needed to maintain aeration in a conventional activated sludge
  • Higher operating costs are often partially offset by the lower cost for sludge disposal associated with running at longer sludge residence time and with membrane thickening / dewatering of wasted sludge

General Information

The treatment facility comprises the following:

  • Inlet works
  • Biological treatment
  • Sludge handling
  • Odour control system
  • Grit removal and screening
  • Membrane treatment
  • Electrical and control system
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