BMS Package Final Effluent Media Filter

The BMS Final Effluent Media Filter is very compact ‘Plug&Play’ Multimedia Filter designed to polish the final effluent from a sewage treatment plant before discharge.  While it was compatible with any type of sewage treatment system, it is especially suited for use in conjunction with the BMS Blivet Package Sewage Treatment System.   The system is completely self contained in a steel reinforced GRP tank.  It does not require a concrete surround and is suitable for permanent/temporary use.

Background

Since its inception, BMS has been a Research & Development led organisation. Our package Final Effluent Media Filter was produced in response to customer requests for a compact package tertiary effluent treatment system.  The BMS Final Effluent Media Filter produces high-quality effluent without the need for percolation, requires very low maintenance and has a small footprint.  It is suitable for installation in conjunction with new sewage treatment plants or for retro-fitting to existing sewage treatment plants to improve effluent quality.   The Media Filter can reduce both BOD and Suspended Solids to as low as 5 mg/l before discharge.  The Media Filter is manufactured under BMS ISO 9001:2015 Quality Management System, in Longford, Ireland.  It is a perfect compliment to the BMS Blivet, the worlds most compact ‘all in one’ sewage treatment system.

Design

DESIGN PARAMETERS

Parameter	Influent	Effluent
Max Design flow	5,000 l/h	5,000 l/h
BOD	20 mg/l	10 mg/l
Suspended Solids	30 mg/l	10 mg/l

Please note: Selection of unit may vary for the final effluent quality and influent load.

Treatment

The unit is an ‘all in one’ system designed to polish final effluent before discharge, removing residual BOD and SS left over at the end of a sewage treatment system.

It consists of a steel reinforced GRP Fibreglass tank containing;

1. Distribution Pipework.
2. Filter Media.
3. Backwash tank, Backwash Pump and Backwash Channel.
4. Control Panel.

 2A. Distribution Pipework

The treated effluent flows by either gravity or pumped flow into the distribution pipework.  The pipework is specially designed to ensure even distribution over all the whole media area.   

2B. Filter Media.

The BMS Media Filter uses market leading Filtralite^® filter media, which was specially selected to provide maximum filtration and at the same time to minimise the chance of blocking.  It is combined with a first layer of a unique hard-wearing fabric, Saran, which had 0.7 micron gap and also serves a dual purpose of the securing the filter media in place.  A layer of Filtralite^® follows as per Figure 1.  Filtralite^® is made of expanded, clay granules that are crushed and sieved. The porous, sharp-edged grains have strong resistance against mechanical abrasion and low acid solubility.  Filtralite^® is an inert, ceramic material and complies with the requirements of EN 12905 (Products used for treatment of water intended for human consumption expanded aluminosilicate).  At the bottom of the chamber is collection pipework to collect the now filtered effluent.  Over time the filtration grows as the trapped solids act as an extra filtration layer.

2C. Backwash tank, Backwash Pump and Backwash Channel.

In keeping with BMS philosophy of producing added value package products that are ‘all in one’ and completely self contained, a backwash reservoir had been built in under the filtration zone.  This treated effluent collects in the chamber and then over flows via the outlet pipe to the discharge point.  The treated effluent stored in the chamber is used to backwash the media, so negating the need for an extra fresh water supply, as is the case with many similar systems.  A powerful backwash pump is fitted in the backwash chamber, which is connected to the effluent collection pipework at the bottom of the media chamber.  The pump when switched on, pumps the treated effluent through the media layer from the bottom dislodging trapped solids and cleaning the media.  The backwash then flows back to the start of the treatment plant via the backwash pipe at the top of the filter.

2D. Control Panel/Electrical

The BMS Final Effluent Sand Filter functions by gravity on a normal basis.  The only electrical part is a fully integrated backwash pump, which operates on a fully automatic basis via a timer.  The timer can be set to come on up to 12 times per day.  Normally the Sand Filter would only backwash once per day to minimise power usage.  The pump can also be operated via ‘Hand-Off-Auto’ switch.  The Sand Filter also has high level protection to prevent blockage.  If the media becomes clogged and the level rises in the filtration media chamber the backwash pump will automatically switch on to clear the blockage.  The control panel is equipped with a flashing beacon, which switches on in the case of a high level in the media chamber of the backwash pump tripping.  This can be linked to a GSM Alarm system or a Building Management System if required.

The pump is rated at 3.0 kW.  Each back wash only uses less than 100 watts of power.

Civil Works

For ease of construction the civil works consist of a flat base support slab (1.5 m wide x 0.2 m deep x 2.4 m long) in 20N reinforced concrete, the placing of the units thereon, the pipe and electrical connections and back filling with fine material if units are not free standing.  The inverts of the inlet pipe and back wash pipe are 1.54 m from the base.  The invert of the outlet pipe is 0.65 m from the base.