Wastewater Treatment Plant - How to choose

Questions the wastewater treatment Unit manufacturers DON'T want you to ask are:-

Does it require electricity?

All plants apart from Biorock sewage treatment plants require electricity to operate.  Some require much more than others!  Make sure you ask what the average KW hours/year the plant uses BEFORE you buy it!  This is particularly important for the larger wastewater treatment plants as the cost for a 100 person plant can be £12,000/year.

How often should the wastewater treatment plant be emptied?

 

Emptying is often the most expensive part of system running costs. All of the 3 stage package plants require emptying every 1 to 12 months as they don't digest the solids, but store them as sludge in the primary tank.  The extended aeration sewage treatment plants digest the solids as well and have a 1 to 5 yearly emptying interval, depending on the model. The BIOROCK has a 4 year emptying interval.

 

Can I have a copy of the full EN12566-3 2005 test RESULTS?

 

BEWARE as many sewage treatment plants for sale in the UK have NEVER been tested by anyone! 

Others, even some made by the leading names, which have passed the EN12566-3 2005 would NOT pass the UK Environment Agency     standards which YOU have to adhere to!!  This is because the EN12566-3 2005 only tests the percentage reduction of pollutants in the final effluent, NOT the final effluent quality produced by the sewage equipment!  Yes, it IS stupid as many sewage treatment plants which failed, during the test, to achieve the UK Royal Commission Standard of 20BOD:30S.S.:20NH3 on a 95 percentile basis have been given the EN Certification!   This is why many manufacturers will only offer the Test Conformity Certificate and not the test results! 

 If they WON'T give you the test RESULTS, DON'T buy the unit!! 

 It is YOU that the Environment Agencyprosecutes ( see Latest News) not the sewage equipment manufacturer! 

 

Does it have a Primary Settlement Tank?

 

If it does, then it is a 3 stage wastewater treatment plant as described above. Unvented UK Primary Settlement Tanks do not tend to be odourless as gases can escape through the sewage treatment unit lid, particulary when the bath, etc. is emptied, displacing air through the lid of the plant.  It is called Primary Settlement Tank Odour.  Ask if the PST is vented! 

 

Does it rely on internal moving parts?

 

Moving parts wear out and sewage is very corrosive.  Replacement parts and labour can be very expensive for some plants. 

 

How thick is the fibreglass/polyethylene?

 

This can vary between plants from about 3mm to 8mm, depending on the make of unit. Obviously, the thicker the better as thin walled tanks can distort or crack under the pressure of groundwater. 

 

What do you see when the sewage treatment unit is installed?

 

Some plants are an eyesore, either because the lids are enormous and protrude well above ground level, or because there are multiple large lids on view.  Some sewage treatment units have unsightly Kiosks containing compressors and timers etc.

 

How much is the annual servicing cost?

 

Servicing costs for sewage equipment also varies enormously, from £75.00 to over £300.00, depending the complexity of the unit. A general rule is, the simpler the treatment system, the cheaper the service.

How long is the tank warranty?

This varies from 1 year to 25 years, depending on the plant manufacturer.

All sewage treatment plants, except for the Klargester Sigma, should be suitable for direct discharge to a ditch or watercourse, subject to Environment Agency     Consent to discharge.  However, not all sewage equipment is designed for this type of disposal system.  Septic Tanks are NOT, and expensive soakaways, with a limited lifespan, must be constructed to dispose of all septic tank effluent.

 

 You will need a CONSENT TO DISCHARGE from the Environment Agency     to discharge to a watercourse.  It is not difficult to obtain and we will help you with the forms free of charge.

Waste Tech gives INDEPENDENT advice on all the above wastewater treatment plant and equipment