increasing output and/or improving treatment

To optimise hydraulic conditions, if necessary, there are several different methods that can be used:

modified chemical treatment

Replacing the coagulant, adding an oxidant and/or a flocculant etc.

Including remineralisation (CO₂ + lime) for mains system protection (e.g. Pariacabo plant in Kourou, French Guyana, or Rivière Blanche plant in Martinique.

improved coagulation-flocculation

For instance, installation or modernisation of coagulation and/or flocculation tanks (e.g. Cali, Colombia; Ngith plant in Dakar, Senegal).

improved clarification

Refurbishing old static settling tanks (baffles, troughs, sludge collection etc.) if necessary with the inclusion of CFD (e.g. Telibong plant at Kota Kinabalu, Malaysia). Converting to lamellar units (e.g. Piton du Milieu, Mauritius; Rivière Blanche, Martinique).

Converting static settling tanks Pulsator (e.g. Alexandria, Egypt), or Circulators into Pulsators (e.g Montbrison, France).

Converting the Pulsator into a Pulsatube or the Superpulsator into an Ultrapulsator (see sludge blanket settling tanks): a number of such examples exist in France, Canada and the USA etc,…

modifications to the flotation system

Depending on the case, one can :

• improve the hydraulics of dissolved air flotation;
• convert a static settling tank into flotation unit;
• use pre-clarifiers to protect an existing flotation system (e.g. Nsese – Mlhatuze, South Africa);
• convert a floatation unit into a static settling tank, single or lamellar (e.g. Zenyang, China, where turbidity can rise above 3,000 NTU).

filtration

A number of different options can also be implemented :

• replacing the filtering medium (e.g. Grafham, Great Britain);
• replacing the wash system, installing nozzle floors (conventional or Azurfloor) for an air + water wash (e.g. San Martin in Buenos Aires and Suquia in Cordoba, Argentina; Ngith in Dakar, Senegal; Piton du Milieu in Mauritius; Rivière Blanche in Martinique);
• modernising control equipment (e.g. Mont Valérien and Besançon, France; Umbeluzi in Maputo, Mozambique);
• in the case of slow filtration, installation of a clarification pre-treatment system and/or polishing post-treatment using O₃ + GAC (e.g. Ivry and Joinville plants supplying Paris).