Sludge conditioning is a topic of considerable interest around the world, with increasingly strict requirements for sludge application to land and the high costs of landfill providing a timely focus. In this vein, Swedish, company Kemira has brought out a sludge conditioning technology called Kemicond that is intended to reduce volumes, disinfect and control odours. Kemicond is a three-step technology, beginning with acidification, moving to oxidation and then finally to flocculation. Sulphuric acid is added to the wastewater sludge to acidify it to a pH of below five - the pH of digested sludge is normally around seven. Carbon dioxide is released during acidification, ferrous phosphates, hydroxides and other salts are dissolved and water-retaining gel-like inorganic structures broken down.Acid consumption is lower for undigested sludge because of its lower alkalinity.
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