Pre-treatment of industrial effluents: a tailor-made solution for the Breton agri-food industry

Opened two years ago in Trégueux, the new Marie Morin production site is dedicated to making chocolate creams. The result of a true family adventure with strong roots in Brittany, the company wanted to take its environmental approach to the next level by calling on Séché Traitement des Eaux Industrielles to design and build a pre-treatment plant tailored to its business.

"There were three challenges: complying with our discharge agreement, designing a compact facility suited to our site, and having a simple and reliable tool for everyday use," explains Bruno Morin, manager of the Breton company. For Marie Morin, it was also an opportunity to precisely control the quality of its discharges and affirm its environmental commitment. The challenge: treating water loaded with organic matter and fats

At the end of the manufacturing process for the famous chocolate creams, the wastewater is particularly rich in organic matter and fats. That is why the STEI teams opted for a solution that has proven itself in numerous industrial installations: a physico-chemical pretreatment process involving coagulation/flocculation and flotation. This technology guarantees optimal performance while offering safety and reliability in terms of the process.

A very precise characterization phase of the effluents made it possible to size the equipment as accurately as possible:

• A main lifting station of 5 m³/h
• A fine mesh (1.5 mm) rotary screen
• A 25 m³ agitated and covered buffer tank
• A dedicated deodorization system
• A coagulation/flocculation/neutralization unit with mixing lyre
• A 5 m³/h pressurized water flotation unit (Dumontech technology)
• A 5 m³ grease storage tank
• A complete self-monitoring system

The process selected follows a rigorous sequence: all of the plant's wastewater is first collected and then pumped to the buffer tank to homogenize the flow. After screening to remove the largest particles, the effluent is treated by injecting a coagulant and then a flocculant, which agglomerate the pollutants. The mixing coil (a serpentine-shaped piece of piping) ensures that the reagents are distributed evenly. The fats and suspended solids are then separated in the pressurized water flotation unit: the equipment generates microbubbles of air which rise to the surface, carrying the pollutants with them. All that remains is to "skim" the grease and organic matter by scraping the surface. They are then stored for disposal by a specialized company.

Daily operation, maintenance, and support

Beyond design and construction, Séché ensures the operation and maintenance of the facility with weekly technical monitoring on site. "We spend two to three hours each week checking that the facility is operating correctly, adjusting the settings if necessary, and supporting Marie Morin's teams," explains Freddy Got.

Regular samples are taken to continuously analyze the system's performance and ensure compliance with regulatory thresholds.

Convincing results

The first few months of operation confirm the effectiveness of the system. The purification efficiency has achieved a 70% reduction in pollution, with particularly significant results for several key parameters: COD (Chemical Oxygen Demand, an indicator of organic matter), fats, TSS (Total Suspended Solids), nitrogen, phosphorus and pH.

For example, COD has fallen from 2,500-3,000 mg/l to less than 1,000 mg/l, a reduction of more than 70%.

This performance enables Marie Morin to strictly comply with its discharge agreement and significantly reduces the pollutant load arriving at the Saint-Brieuc Armor Agglomération wastewater treatment plant. The facility has been designed to be ready to adapt to future regulatory changes.

Local expertise at the service of industry

Today, the Trégueux unit is operating at full capacity and the discharged water strictly complies with environmental requirements. Marie Morin knows it can count on a reliable, high-performance treatment plant that will keep pace with its production rate and regulatory changes over the long term. This compact, tailor-made solution is the result of a successful project, from design and implementation to daily operation. It also bears the mark of a strong relationship of trust between the teams of two family-owned companies committed to preserving the environment in all the regions where they operate.