What is an Aerotor and how is it different from a normal RBC (Rotating Biological Contactor) and who came up with the idea?

Thank you for the question.  The BMS Aerotor is actually a next generation RBC, with all the advantages of traditional RBCs such as low maintenance costs and power requirements with none of the disadvantages such as one sided growth placing eccentric loads on the shaft, flow bypass in shock loading conditions and lack of aeration…

Seamus Butler, BMS Managing Director, is the inventor and original patent holder of the Aerotor, which is manufactured at BMS factory in Longford, Ireland and is in more than 50 countries worldwide.  The Aerotor is also the biological heart of the world’s most compact sewage treatment plant, the BMS Blivet.

Unlike old activated sludge and RBC systems the Aerotor is a hybrid of active aeration and fixed film reaction with an intense spiral GRP (Fibreglass) media mounted on a rotating horizontal shaft meaning that 97% of the Aerotor’s surface area is actually inside the rotor drum rather than only on the outside as is the case with traditional RBC systems. The rotational media is enclosed in an outer drum to provide active aeration, intense surface area and net hydraulic lift. The BMS Aerotor is self-cleansing and no extraneous pumping or sludge returns are required.

When settled sewage liquor flows into an Aerotor unit, it is piped to the first chamber of the BMS Aerotor which contains a lift rotor. The liquor enters the rotor through 50 mm inlet ports on the peripheral face of the rotor. The rotor is rotating at 6 rpm and the internal spiral formation lifts the liquor and cascades it through the 100 mm sandwich sections, making contact with the surface biomass (fixed film reaction) while actively aerating the liquor. The liquor emerges from the lift rotor below the centre of the rotor on the opposite face to the peripheral 50 mm inlet ports and spills into a captive tray to be conveyed into the next rotor compartment. Here it enters a float rotor below the centre and the same process occurs as in the lift rotor. This continues until the final splitter box in the BMS Aerotor which divides the elevated flow between a 110 mm recirculation pipe and a pipe into the separated final settlement zone.  The BMS Aerotor is in essence a plug flow system, which ensures full treatment up to 3 x DWF and up to 6 x DWF for up to 2 hours. The rate of recirculation, which is under gravity due to the 450 mm lift occurring in the lift rotor, can be adjusted by hand stops in the splitter box.

This unique ability to recirculate under gravity means that the flow can be adjusted depending on process requirements and without the need for extra pumping.  In low flows recirculation can be set to high to maintain growth and/or maximise treatment.  Equally recirculation can be adjusted downwards during high flows.  This is especially useful on sites that experience seasonal flows such schools, hotels and caravan parks.  The recirculation can also be readjusted upwards to achieve intensive nitrification (the reduction of ammonia) and in the case of the Blivet denitrification (the reduction of Nitrate and Total Nitrogen) in the primary settlement area, which acts as an anoxic zone.

Overall the BMS Aerotor is a world leading package low power & low maintenance solution for package sewage treatment that can achieve multiple high quality effluent parameters such as BOD & Suspended Solids (SS) of less than 10 mg/l, Ammonia of less 5 mg/l, Phosphorus of less than 1 mg/l and Total Nitrogen of less than 10 mg/l.

You can see how the Aerotor works as part of the our class leading Blivet ‘all in one’ Package Sewage Treatment System in the short video below:

Thank you for your question, if you any queries about the above answer or have questions on any areas of package waste water or surface water treatment please do not hesitate to Contact BMS.

A bit about the company

BMS is a quality manufacturer of package products for wastewater and stormwater treatment. BMS started in 1986 and has exported products to over 50 countries around the world.  It is a third generation family business with huge expertise in wastewater and stormwater.
BMS also manufacture a full range of products for surface water and wastewater treatment including our pioneering next generation RBC system the Aerotor, which forms part of our world leading Blivet package sewage treatment plant, a ‘one stop shop’ for all surface water products from design to installation including attenuation, interceptors, holding tanks (incl. chemical resistant), hydrobrakes, rainwater harvesting tanks & vortex silt/oil/debris separators, fully fitted pumping stations, our plug & play vehicle wash water recycling system; the Recyclone and much more.  Please see our enclosed Company & Product Profile for a full summary or View our full product/services catalogue at this link

BMS also can provide a Free Design Service for Sewage Treatment, Pump Stations or Surface Water and a full O&M, Repair, Advice and Testing service for existing installations.  We also can do free CPD Presentations on Sewage Treatment/Surface Water Management at any location.  Let us know when suits.

We would be delighted to discuss any requirements you might have, and we are available to meet you at your convenience.  Please do not hesitate to contact us.