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FAQs2018-07-31T15:47:06+00:00
What is a Package Sewage Treatment Plant?2018-10-23T14:25:18+00:00

Thanks for the question.  A Package sewage treatment plant is a completely self contained system for sewage treatment that is ‘plug & play’ and should incorporate the following elements in one outer tank;

  1. Include adequate primary and final settlement/clarification.
  2. Adequate biological treatment.
  3. Sludge Storage, preferably at least 3 months.
  4. Sludge return from final settlement (if required).
  5. Be delivered ‘ready to go’.
  6. Fully road transportable assembled.
  7. Fit inside a standard 40 foot container for transport.

In essence it should be a complete sewage treatment solution that does not require extra tanks to work e.g. extra settlement/sludge storage.

The diagram below shows what a package sewage treatment plant should contain;

Package Sewage Treatment

Other highly desirable traits;

  1. Fully portable when completely assembled and can be moved if required.
  2. Can be placed above/below/partially below ground without a concrete surround.
  3. Requires minimal maintenance, power and spare parts.

One such system that was designed with the above in mind is the BMS Blivet Package Sewage Treatment Plant, which meets all the above criteria.  For this reason it was the only specified package sewage treatment plant for all US Military camps in Iraq after testing against other systems.

The Blivet has been exported via truck/40 foot container to 40+ countries worldwide over 20+ years.  It is proven in every conceivable environment and climate extreme.

Figure 2: Blivet Package Sewage Treatment Plant on truck ready for delivery;

Blivet Package Sewage Treatment Plant on truck

Let us know if we can help you with your package sewage treatment plant requirement?  BMS offer a free package sewage treatment design service.

BMS design/manufacture a full range of products for surface water and wastewater treatment including the 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/filters & vortex silt separators, fully fitted prefabricated pump stations and much more.

You can find downloadable information on all our Products/Services at this link

Please contact us if we can be of any assistance.

Tommy Butler

Pictures of BMS Blivet Package Sewage Treatment Plants installed above ground

Do you have a package sewage treatment plant that can be placed free standing above ground.  Also is it portable or can it be moved?  Can it be expanded?2018-10-23T14:23:48+00:00

Thanks for the questions.

We do indeed have solution for above ground sewage treatment in the form of the BMS Blivet Package Sewage Treatment Plant.

One of the main features of our Blivet packagesewagetreatmentplant is that it can be placed above ground free standing with no extra supports.  It is also extremely compact, all units can fit in a standard 20/40 foot container.  Installation is as easy as lifting it onto hard standing and then connecting the inlet/outlet pipes & electricity.  The plant can be fully functioning in a few hours.  It also allows the easy addition of extra units if a population increases as it is a complete self contained modular system.  This type of installation is especially suited where temporary sewage treatment is required, where the inlet is via a pumped feed, where there is bad ground or a lot of rock close to the surface.  To move it to another site is only a matter of emptying it fully and disconnecting the inlet/outlet pipes & electricity.  BMS offer a free sewage treatment design service, so please contact us if you require an above ground package sewage treatment system.

BMS design/manufacture a full range of products for surface water and wastewater treatment including the 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/filters & vortex silt separators, fully fitted prefabricated pump stations and much more.

You can find downloadable information on all our Products/Services at this link

Please contact us if we can be of any assistance.

Tommy Butler

Pictures of BMS Blivet Package Sewage Treatment Plants installed above ground

We need a discharge license for our car/truck wash. Do you have a solution so that we do not have to get a discharge license or if we are not granted one?2018-09-18T11:19:12+00:00

We need a discharge license for our car/truck wash.  Do you have a solution so that we do not have to get a discharge license or if we are not granted one?

Thank you for your question.  We have a great solution in the BMS Recyclone, which can be set up to work in a closed loop with no discharge.  Basically, every time you wash a vehicle you lose some of the wash water, approximately 10% is left on the vehicle and 5-10% in evaporation depending on the temperature.  The Recyclone recycles 100% of the used wash water that falls down into the collection trap below the vehicle for immediate reuse.  However, as you are losing water all the time 15-20% the wash water will have to be topped up to continue washing.  Therefore, due to the 100% recycle these is no discharge.  At times when the wash is not functioning e.g. at night the wash water overflows from the Recyclone back to the start of the system e.g. holding tank/silt trap/interceptor etc.  The system in essence cleans itself at night without discharging.  The first tank in the Recyclone is a settlement/sludge tank, which needs to be desludged periodically.

The Recyclone also gives you the bonus of large saving on water charges and as it is completely plug&play is ideal for both new of existing sites and is compatible with all washing systems.

BMS design/manufacture a full range of products for surface water and wastewater treatment including the 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/filters & vortex silt separators, fully fitted prefabricated pump stations and much more.

You can find downloadable information on all our Products/Services at this link

Please contact us if we can be of any assistance

How do you calculate expected dry weather flow and volume of effluent to be discharged per day?2018-07-23T11:18:37+00:00

Customer Question: How do you calculate expected dry weather flow and Volume of effluent to be discharged per day?

Dry Weather Flow is in essence the sewage flow, from a premises without the addition of any surface water.

Dry Weather Flow (DWF) Full Definition: The average daily sewage flow entering a Sewage treatment plant or sewer measured following 7 days without rain (excluding local or Bank holidays etc) and during which on the preceding 7 days, rainfall did not exceed 25 mm on any day.

The volume of effluent is usually calculated using population equivalents (PE) 1 PE is the amount of sewage generated by one person living in a domestic dwelling and is generally taken as 200 L of flow and 60 g of BOD/day.  Therefore, the DWF for a 10 PE premises would be:

10 x 200 L = 2000 L.

Full worked examples of how to calculate PE in different situations can be found in our Education Blog in Sewage Parameters 3: Population Equivalent (PE) Parts 1 & Population Equivalents (PE) Part 2.  If you have any further questions please do not hesitate to contact Butler Manufacturing Services Ltd (BMS)  We will be continuing to be update our education blog with helpful straightforward information on sewage treatment and the terminology surrounding it.

Do you have any pictures of a sewage or a wastewater treatment plant that Butler Manufacturing Services worked on before and after an upgrade?2018-07-23T11:17:37+00:00

We certainly do, you can find 12 pictures of a rural 50 PE wastewater treatment plant that BMS recently upgraded below.  It includes a BMS BL500 Blivet Package Sewage Treatment Plant, control panel and flow meter.  The site contained a lot of spoilage which had to be removed along with other civil works.  Also some innovative grading of the ground avoided the need to install lifting pumps as was originally planned, saving money and maintenance in the long and short term.  This finish of the site is excellent and blends into the small rural community.  BMS can provide a full design and build excellent value fully installed package sewage treatment plant.

When designing a Treatment process for a caravan park what Population Equivalent(PE) do you assign to each caravan unit?2018-07-23T11:11:46+00:00

Customer Question: When designing a Treatment process for a caravan park what Population Equivalent(PE) do you assign to each caravan unit?

Dear Customer,

Thank you for your enquiry.  The Irish EPA assign the follow figures to Caravan Sites:

Estimating the occupancy of different caravans or mobile homes is more difficult.  Generally, it is best to plan for peak occupancy, therefore the normal size of caravan used on site of in general should be ascertained.  They have normal occupancy numbers assigned to them and these can just be multiplied by the figures above.  If it is an established site their occupancy figures should be analysed and multiplied based on the figures above to obtain the peak occupancy, especially during the July/August peak season.

If it is a new site, the best way might be to try and obtain figures from a nearby (as possible) site.  Their figures can then be analysed based on the various plots on the site and an average occupancy per caravan/mobile home/tent per day obtained at different times of the year.  This could then be applied to the new site based on their maximum number of plots available.

More answers such as the above can be found in our education blog.

If you have any further queries of if I can help you in any way, please do not hesitate to contact me.

Best regards,

Tommy

Caravan TypeFlow (L/Person/Day)   BOD (G/Person/Day)
Touring                                                                         5035
Static (Not Serviced)7535
Static (Fully Serviced)        15055
Tent Sites5025
What is an Aerotor and how is it different from a normal RBC (Rotating Biological Contactor) and who came up with the idea?2018-07-23T11:06:40+00:00

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 38 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.

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.

What is the difference between ‘Effluent Standard’ & ‘Stream Standard’?2018-07-23T11:05:46+00:00

Thank you for your question on the difference between the final effluent standard produced by a package sewage treatment plant and the stream standard.

The difference between the 2 is as follows:

1. Effluent Standard or Final Effluent Standard is the standard of effluent that a given wastewater treatment plant (WWTP) needs to produce based on a set maximum inlet load in terms of Flow, BODSS (Suspended Solids) & Ammonia (NH4)Nitrate (NO3), Nitrite (NO2), Total Nitrogen (TN)Orthophosphate (OP) and Total Phosphate (TP) if specified.  The outlet effluent parameters are set relative to the influent parameters.  N.B. Industrial effluent may have other parameters listed.  Package sewage treatment is concerned with the treatment of normal domestic sewage or equivalent.

2. The Stream standard is the standard of the water in a particular water course to which a sewage treatment plant is discharging into.  If a stream standard exists the Effluent standard for a particular WWTP is set by working back from the Stream standard.  For example if a water course is used for drinking water, bathing or as a fishery, the stream standard and thus the effluent standard discharging into that stream will be set relatively high and will probably include low BOD/SS and NH4/TN/TP concentrations.

However, if a watercourse can provide significant dilution/biodegradation then the stream standard can be set lower, thus resulting in a lower effluent standard.

The stream standard is often set relative to the ‘assimilative capacity’ of a watercourse.  This means how much dilution/biodegradation it can provide before pollution such as Oxygen stripping or eutrophication results.

What is the difference between COD and BOD?2018-07-23T11:05:05+00:00

I have received a laboratory analysis report for effluent from my sewage treatment system and am wondering what the difference between BOD and COD is?  Do I need to get both BOD and COD tested?

Thank you for your question. COD stands for ‘Chemical Oxygen Demand’ where BOD stands for Biochemical Oxygen Demand.

It is a test of the amount of oxygen required to oxidise organic matter in a sewage sample by chemical oxidation with a powerful oxidising agent such Potassium Dichromate.  COD is closely related to BOD or Biochemical Oxygen Demand, the difference being that BOD is a test of the level of organic matter that can be biologically oxidised while COD is a test of the amount of organic matter that can be chemically oxidised.  (A full explanation of any of the parameters can be found by clicking on the blue links).

The higher the BOD/COD the more oxygen stripping capacity the discharged effluent has when discharged into receiving waters (oxygen is used biologically/chemically to break down the organic matter) and the more potential for damage to biological life in those waters.

COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised.  This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.

In regards to normal domestic effluent e.g. BOD & Suspended Solids (SS) 300 mg/l, which is usual for package sewage treatment systems, COD is not always stated as part of the discharge license.  If it is not part of your license you do not need to get it tested. However, COD does have a big advantage over BOD in that the test only takes approximately three hours, as opposed to the five days required for BOD testing and it is usually possible over a period of time to establish a ratio of BOD:COD, which allows extrapolation of the BOD.

More information can be found by clicking on the Chemical Oxygen Demand Link.

What is the difference between a Class 1 & Class 2 Separator?2018-07-23T10:58:18+00:00

We still have a few more questions to answer as regards Petrol/Oil Interceptors (Separators), next up; What is the difference between a Class 1 and Class 2 Separator?

A Class 1 Interceptor is designed to achieve a concentration of 5 mg/l of petrol/oil at discharge under normal conditions, includes a coalescer and a closure mechanism.  A Class 1 Interceptor is usually required for discharge to any surface water.

A Class 2 Interceptor is designed to achieve a concentration of 100 mg/l of petrol/oil at discharge under normal conditions and is normally used when discharge is to a foul sewer.

BMS have introduced a full set of Petrol Interceptor/Holding Tank Sizing & Selection Charts to help you easily size and select an Interceptor/Holding Tank suitable for your requirements. They can be downloaded at this link.

BMS manufacture produce a full range of ‘plug & play’ interceptors/separators from 1,000 – 100,000 litres manufactured in corrosion and rot proof GRP under ISO 9001:2008 to European Standards and are Irelands leading producer.

What are the different types of Petrol/Oil Interceptor (Separator) and what is the difference between them?2018-07-23T11:00:09+00:00

Following on from last week’s question on the difference between a Petrol/Oil Interceptor & a Separator, another customer asked; What are the different types of Petrol/Oil Interceptor (Separator) and what is the difference between them?

There are 2 main types of Petrol/Oil Interceptor;

Full Retention Interceptors, which are designed to treat the full flow delivered by a drainage system up to 50 mm/hr.

Bypass Interceptors which, are designed to treat flows of up to 5 mm/hr.  This covers 99% of rainfall.

A Full Retention Interceptor is normally used when there is a risk of regular contamination of surface water run off with petrol/oil and/or the risk of larger spills e.g. vehicle maintenance areas, heavy goods parking areas or where frequent vehicle manoeuvring takes place.

A Bypass Interceptor is normally used when there is a risk of infrequent light contamination of surface water run off with petrol/oil and/or the risk of only small spills e.g. car parks, airports, industrial estates, roads and other

low risk

areas.

Under normal flow conditions the BMS Full Retention Interceptor is designed to retain the full contents of an oil spill or contamination up to flows of 50 mm/hr.  For flows under 5 mm/hr a bypass interceptor functions in the same way.  In the case of storm water flows above 5 mm/hr an internal vortex a   rrangement allows the stormflows to bypass the retention chamber, this has the benefit of considerably reducing the size of the interceptor required while still treating 99% of rainfall.  The majority of pollutants in any storm water event will be trapped before the bypass takes place.

BMS manufacture produce a full range of ‘plug & play’ interceptors/separators from 1,000 – 100,000 litres manufactured in corrosion and rot proof GRP under ISO 9001:2008 to European Standards and are Irelands leading producer.

BMS have introduced a full set of Petrol Interceptor/Holding Tank Sizing & Selection Charts to help you easily size and select an Interceptor/Holding Tank suitable for your requirements. They can be downloaded at this link.

How do you calculate the size of a Petrol/Oil Separator needed for a site?2018-07-23T10:55:23+00:00

The last in our customer questions regarding Petrol/Oil Interceptors/Separators is; How do you calculate the size of a Petrol/Oil Separator needed for a site?

Firstly you need to determine if you require a Bypass Interceptor or a Full Retention Interceptor; this is answered in a previous Customer Question answer; What are the different types of Petrol/Oil Interceptor (Separator) and what is the difference between them?  Secondly you need to determine if you require a Class 1 or Class 2 Interceptor; this is also answered in our last customer question answer; What is the difference between a Class 1 & Class 2 Separator?

After selecting the interceptor size and type, the correct size of interceptor is based on the flow into it based on rainfall onto a given surface area, this is known as nominal size or NS.

Each interceptor is allocated a nominal size based on EN858; the European Standard for Interceptor Design and Sizing.  This will indicate the nominal flow that the interceptor is sized for e.g. 4 l/s.  A full retention interceptor with a capacity of 4 l/s would be designated NS04 while a By-Pass interceptor with the same capacity would be designated NSB04.

(Please note Petrol/Oil Separator and interceptor mean the same thing)

Example 1

An interceptor required for a 25,000 m2 car park discharging into a local authority surface water sewer.

As there is a low chance of oil spillage a Bypass Interceptor would be most appropriate.

As discharge is to a surface water sewer a Class 1 Interceptor, which is designed to achieve a concentration of 5 mg/l of petrol/oil at discharge under normal conditions and includes a coalescer and a closure mechanism is most appropriate. A Class 1 Interceptor is usually required for discharge to any surface water.

Based on EN858 a drainage are of 25,000 m2 gives a nominal size (NS) of 45 l/s.

So in this case BMS would select a BMS PB5 Class NSB 47 l/s Bypass Interceptor, which is the closest available in our range.

Example 2

An interceptor required for a 1,700 m2 fuelling area discharging direct to surface water.

Due to the high risk or fuel spillage a Full Retention Interceptor designed to contain the full contents of a full spill is required.

As discharge is to a surface water a Class 1 Interceptor, which is designed to achieve a concentration of 5 mg/l of petrol/oil at discharge under normal conditions and includes a coalescer and a closure mechanism is most appropriate. A Class 1 Interceptor is usually required for discharge to any surface water.

Based on EN858 a drainage area of 2,600 m2 gives a nominal size (NS) of 47 l/s.

So in this case BMS would select a BMS PB9 Class 2 NS 47 l/s Full Retention Interceptor, which is the closest available in our range.  Please note that the Nominal Size of a Full Retention Interceptor can also be denoted as NSF e.g. NSF; 47 l/s.

BMS manufacture produce a full range of ‘plug & play’ interceptors/separators from 1,000 – 100,000 litres manufactured in corrosion and rot proof GRP under ISO 9001:2008 to European Standards and are Irelands leading producer.

BMS have introduced a full set of Petrol Interceptor/Holding Tank Sizing & Selection Charts to help you easily size and select an Interceptor/Holding Tank suitable for your requirements. They can be downloaded at this link.

Creating Lasting Solutions

BMS have always operated on the principle of providing innovative products of superior design and quality that are built to last and are very easy/cost effective to install and operate.

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