S&P system

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The S&P system is a compact household wastewater treatment unit with a 50 to 3,000 p.e. capacity, derived from the rotating biological contactor (RBC) process.

The installation consists of a complete treatment system and the standard version comprises the following stages:

  • mechanical pre-treatment with bar-screening, grit and grease removal, multiple compartment settling pit;
  • flow rate limiting and regulation mechanism, using either an overshot wheel or a flow splitting system (when several blocks are installed in parallel);
  • rotating biological contactor treatment designed to remove carbonaceous pollution. The polypropylene discs, mounted on a horizontal rotating shaft, are fitted in polypropylene or concrete tanks. The shaft is driven direct by a reduction gear;
  • lamellar settling tank for separating sludge from treated water. As it is only the sludge that separates from the discs that goes on to the settling tank, lamella are used to reduce ground surface area covered by more than 75%.This sludge is pumped out on an intermittent basis.

Depending on the discharge standards applicable, the following treatments can be included as part of the plant:

  • nitrification (second disc stage);
  • chemical phosphorus removal (simultaneous use of FeCl3);
  • tertiary filtration and disinfection treatment (sodium or calcium hypochlorite).

There are three possible layout solutions: inside a building, semi-buried or in a container.

See photos 13.1 and 13.2 :

element readySecured image
Photo 13.1. Element ready for fitting inside a container
S&P system biodiscsSecured image
Photo 31.2. S&P system biodiscs – Semi-buried system – Carreyrat hamlet (Montauban, France – 600 p.e.)

This technology is ideal for hotels, holiday centres, housing estates or any other small community, for the following reasons:

  • ease of operation and maintenance;
  • adaptable to variations in hydraulic and organic loading;
  • quick to design and install;
  • nuisance-free (noise or odours).
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