Proceedings

Recycling of sewage sludge on land areas is a main goal in the Norwegian sludge legislation, which is now a part of the regulation of organic fertilizers. Stringent standards have been set for heavy metal content, and there is a general requirement for stabilisation and disinfection (hygienisation) of all sewage sludge prior to land application. Bekkelaget WWTP in Oslo (280,000 p.e.) is an activated sludge plant with nitrogen and phosphorous removal. The sludge treatment consists of thermophilic anaerobic digestion and thermal drying of the sludge prior to land application.

Dust is a problem in connection with handling and spreading the dried sludge. Most of the dust is formed in the drying drum and steps will be taken to further improve the dust removal in the cyclones in connection with the dryer system. The dust content in the sludge varies and the first priority is to find spreading equipment that can perform an acceptable operation with respect to dust generation and mass of sludge spread per unit of area.

KEY WORDS: Biosolids, Dust Problems, Sewage Sludge, Regulations, Spreading Equipment, Thermal Drying.