The treatment of sewage has advanced greatly in terms of the quality of the treated effluent and minimising the footprint of the process and the EfloMBR membrane bioreactor - or MBR - is an example of this.
The membrane is in the Ultra to Micro Filtration range meaning that it acts as a barrier to bacteria, coliforms, cryptosporidium and some viruses. And it will reject suspended solids greater in size than around 0.1 micron. It is therefore an excellent technology for clarifying biologically treated water that has a high biomass concentration.
The water sample on the right is taken directly from the permeate discharge of the MBR membrane. The quality is better than 3 mg/l BOD & 3 mg/l Suspended Solids.
Just as in the activated sludge process, the MBR plant uses an aeration tank
where the beneficial biomass consume the organic matter in the sewage.
But the clarification is performed using a membrane instead of a traditional settlement tank.
The MBR plant goes further still and performs both tertiary treatment and disinfection of the treated effluent.
This water is suitable for 'un-restricted' irrigation such as lawn sprinklers.
For clients requiring potable quality water, this can be achieved by further treating the MBR
water with reverse osmosis (RO) membranes. This water can then be used for many tasks where potable quality water is needed.
Eflo design and manufacture the EfloMBR membrane bioreator in capacities of 50 - 50,000 m3 per day. The smaller plants are
packaged type, often containerised for easy shipping and use epoxy coated steel tanks.
These are factory built and tested prior to despatch. The larger EfloMBR plants are constructed, for economy,
on site using either bolted, steel panel tanks or reinforced concrete tanks.
Packaged EfloMBR 500 m3 per day
Permeate suction pumps for a 15,000 m3 per day EfloMBR
EfloMBR 1000 m3 per day using reinforced concrete tanks
Membrane Fouling with Hair and Fibre Agglomerations - Irreversible Fouling
Hair and fibres found in the sewage pass through inlet screens, even 1 mm screens.
These hair and fibres agglomerate, in the aeration tanks, into long 'rags'.
They can grow to large sizes and they foul the submerged membranes causing loss of
process flow and ultimately damage to the membranes.
It is the single most serious problem effecting MBR plants
treating sewage and this results in downtime and excessive maintenance
input to lift and physically clean the membranes.
Without removal, the membrane can cease to work and the plant will fail.
Eflo have overcome this problem with their Eflo Biomass Screen. It very effectively removes
any agglomerated 'rags' from the process allowing the membranes to perform properly and remain submerged.
This prolongs the working life of the membranes and reduces the capital costs of replacement.
Further, the operation costs are significantly reduced.