Step By Step Guide: Your Non-Collective Sewage Treatment Project in France

If you’re a French property owner and need to install a non-collective sewage treatment system at your home, there are several legal criteria you must meet, as well as various systems available. This guide will talk you through what you need to know and introduce you to Tricel’s Non-Collective sewage treatment systems.

Launched in 2011, the Tricel Novo is an approved small wastewater treatment plant. It is renowned for its purification quality, as well as for its operating mode. If it had to be summed up in just three words, they would be “simple, robust and reliable” – three adjectives that set the tone. The treatment of the wastewater takes place after it has been collected. The magic happens within the single tank in a three-step process, through three purification zones, each of which is dependent on the other. The effluent is purified by anaerobic digestion, among other things.

Operation of the Tricel Novo Microstation

These plants use a simple, proven technology, consisting of three treatment zones. In each zone a different stage of the treatment occurs.

1. Wastewater from the dwelling, toilets, sinks, shower etc.,enters the plant.
2. Effluent enters the primary settlement chamber. Settlement occurs when the heavier solids drop out of the wastewater and settle to the bottom of the tank to create sludge, and the lighter solids float to the top of the water to create a scum. The top layer acts as a sealant stops odours escaping. This chamber separates up to 70% of the solids present.
3. Next is the aeration chamber, where masses of naturally occurring bacteria inhabit specially designed plastic filter media. The bacteria feed on the waste removing it from the liquid. A continues supply of air from a low pressure, high volume compressor in the top section of the unit sustains these bacteria. Wastewater passes through the filter media over and over, ensuring a very high treatment efficiency.
4. The liquid then proceeds to the final settlement chamber. Any remaining minute bacterial particles separate from the liquid within this chamber before discharge from the plant. This process slows the liquid’s velocity, allowing for any final trace impurities to settle to the bottom of the tank section. A sludge return system then returns these impurities back to the primary settlement chamber.
5. The remaining treated liquid now meets the required standard and is safely passed out of the Tricel Novo plant system. This treated effluent is now ready for discharge to a suitably designed discharge area as required by the relevant local authority.

The Tricel Seta Simplex works for both primary and secondary residences, and both domestic and commercial uses (restaurants, hotels and premises). It is a single tank with two compartments: a septic tank, for primary treatment of wastewater; and a filter bed, for secondary treatment.

Operation of the Seta Simplex Compact Filter

1st phase: Primary treatment: Primary treatment takes place in the Primary Settlement compartment, where the wastewater from sinks, showers, toilets enters… The Primary Settlement compartment slows the effluent’s velocity, allowing solids and heavy sludge to settle at the bottom of the tank, while lighter substances (fats) float to the top of the tank to create a scum. The prefilter fixed at the end of the Primary Settlement compartment prevents solids/scum passing through to the Filter bed compartment. Anaerobic bacteria, naturally present in the effluent, develop in the Primary Compartment and liquefy sludge and solids by digesting the organic components they contain.

2nd phase: Secondary treatment: The pre-treated effluent then proceeds to the filter bed. The primary treated effluent is then evenly dispersed by a bespoke dispersion system ensuring the equal distribution of effluent over the entire filter bed, thus guaranteeing the optimum treatment of the wastewater.

Tricel Seta Simplex compact filter technology is made of coconut fibre (“coir”), which serves both as a filtering medium and bacterial support. Coconut fibre is a generic term for the natural plant fibre which, made of fibrous mesocarp, surrounds and protects the coconut. These fibres are lignin-rich, which gives them great rigidity, makes them resistant to water and gives them excellent resistance to decomposition – resulting in a long lifespan. As the effluent passes down through the coconut fibres, it undergoes two types of secondary treatment:

• physical filtration thanks to the coconut fibre, and

• biological purification, mainly thanks to the aerobic bacterial flora that develops there naturally. Anaerobic bacteria also kill nitrates.

At the outlet of the compact filter, the wastewater has been treated in accordance with current legislation in force and may discharge to the sewer network.

The Tricel Seta compact filter works in the same way as the Tricel Seta Simplex compact filter. The only real difference is that it is not a single tank. The septic tank is located outside the filter bed. It is also used for more ambitious projects, with a population equivalent of 10 to 54.