A biological treatment plant works automatically, but it needs regular attention. Correct maintenance ensures that the system treats the water, causes no odour and lasts a long time. In this article we sum up what you can do yourself, what a specialist should do and what the regulations require.
The short answer
- Daily — correct use: don’t pour or throw into the sewer anything the system cannot process.
- Regularly — visual check: is the compressor running, is there any smell, does the water look clear.
- As needed — removal of excess sludge according to the manufacturer’s instructions.
- Once a year — technical servicing by a specialised company, unless the manufacturer specifies otherwise.
What must not go down the drain
A biological system is run by bacteria, so most problems come from substances that kill them or clog the system:
- oils and fats in large quantities;
- wet wipes, hygiene products, cigarette butts;
- medicines, paints, solvents and construction debris;
- aggressive cleaning agents and chlorine in large quantities;
- rainwater from the roof and drainage — it must be discharged separately.
Regular checks you can do yourself
- Compressor — is it running and not making unusual noise.
- Air filter — is it clogged. Clean or replace it according to the manufacturer’s instructions.
- Smell — a strong smell indicates a problem with air supply or load.
- Treated water — it should be clear or slightly cloudy, without smell.
- Alarm signal — if the system has a control unit, check for error messages.
Sludge removal
Excess sludge gradually builds up in the system. How often it must be removed is determined by the manufacturer and depends on the system’s volume and load. Under Latvian regulations, sludge may only be removed by a sludge carrier registered with the municipality. Keep the document confirming the service — the regulations require it to be kept for at least two years.
Annual technical servicing
Latvian Cabinet Regulation No. 384 “Regulations on the management and registration of decentralised sewage systems” requires factory-made wastewater treatment plants to be serviced once a year, unless the system’s technical documentation states otherwise. The servicing is carried out by a company specialising in such work.
During servicing, the specialist usually checks the compressor and its membranes, the air distribution system, the amount of sludge, pumps and the control unit, as well as the quality of the treated water. After a breakdown and its consequences have been dealt with, an extraordinary servicing must be carried out.
Registration with the municipality
Decentralised sewage systems — including biological treatment plants — must be registered in the municipal register. The specific procedure, such as how and when to submit information about servicing carried out, is set by each municipality’s binding regulations, so check your municipality’s requirements.
Common problems and their causes
| Sign | Possible cause |
|---|---|
| Unpleasant smell | The compressor is not working, the air filter is clogged or the system is overloaded |
| Cloudy treated water | Too much sludge, overload or the biological process has not yet recovered |
| The compressor is not working | Power supply problems or worn membranes |
| Water level too high | Clogged outlet or the pump is not working |
If the problem recurs, contact a specialist — DIY repairs can worsen the system’s performance.
Maintenance requirements for a specific model
Each model’s page states what maintenance is needed.
Frequently asked questions
Do bacteria need to be added to the system?
Usually not. In a correctly used system, bacteria form by themselves from the wastewater. Use additional products only if the manufacturer recommends them.
Can I do the maintenance myself?
You can do daily checks and clean the air filter yourself. Annual technical servicing under Cabinet Regulation No. 384 is carried out by a specialised company.
How long does a biological treatment plant last?
With correct installation, the tank lasts many years. Moving parts, such as the compressor membranes, wear out faster and are replaced during servicing.