Virtual tour of Salher’s sewage treatment plant for a dairy industry

Oct 7, 2022

Salher has supplied a plant to treat a flow of 2500 m3 per day of wastewater generated by a dairy industry. Until the plant is commissioned, the company has developed a virtual tour of the WWTP to facilitate the installation and assembly phases, detailing the characteristics of the main equipment.

Salher is a benchmark in the industrial water treatment sector. Its latest plant of this type is designed to treat wastewater generated in the manufacture of dairy products and, thanks to a membrane technology system, to reuse the treated water for cleaning the plant.

This new WWTPI aims to reduce pollutant loads to the values required for discharge into a municipal sewer. This line of water treatment is based on the following phases:

  • After pumping and pre-treatment by rotary sieve, the incoming raw water will be conditioned.
  • The second phase corresponds to the physico-chemical treatment and consists of a dissolved air flotation (DAF), which consists of a flocculation tube, a scraper, a polyelectrolyte preparation plant, a reagent dosing system and a feed pump.
  • The water reaches its third phase by pumping to the biological treatment, where organic matter (BOD5 and COD) and nitrogenous matter (Nt) will be removed in two stages. The first stage is used to condition the water and develop the biological process and is carried out in an anoxic tank and in an aerobic tank with reactors in civil works. This stage also has a cooling system consisting of a heat exchanger and a cooling tower, the purpose of which is to maintain, if necessary, suitable temperature conditions for the good development of the bacterial population. The second corresponds to surface ultrafiltration with external cross-flow MBR membrane technology.
  • Finally, the treated water is accumulated in a tank, ready to be reused in the cleaning processes of the treatment plant.

Sludge and odour treatment for the dairy industry

The sludge generated, as a result of the elimination of the pollutant load, will be dehydrated by means of a centrifugal extractor for its subsequent treatment by an authorised manager.

Dairy industries present the singularity of needing an odour treatment. During the initial design, special attention was paid to the aerobic technology selected to avoid the formation of odour-generating compounds (methane, hydrogen sulphide, mercaptans, etc.). The treatment plant does not have anaerobic technologies, so no gases will be generated in an anaerobic environment.

However, as a safety measure and localised, air extraction points have been designed, connected to a network of air pipes. An air extractor will collect the gases from the different points and pass through a deodorisation system consisting of an active carbon tower. The clean air will exit through the ventilation duct to the outside of the installation, emitting it into the atmosphere.

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