Full scale validation of helminth ova (Ascaris suum) inactivation by different sludge treatment processes.

The Norwegian sewage sludge regulation requires disinfection (hygienisation) of all sludges for land application, and one of the criteria is that disinfected sludge should not contain viable helminth ova. All disinfection processes have to be designed and operated in order to comply with this criterion, and four processes employed in Norway (thermophilic aerobic pre-treatment, pre-pasteurisation, thermal vacuum drying in membrane filter presses and lime treatment) have been tested in full scale by inserting semipermeable bags of Ascaris suum eggs into the processes for certain times. For lime treatment supplementary laboratory tests have been conducted. The paper presents the results of the experiments, and it could be concluded that all processes, except lime treatment, could be operated at less stringent time-temperature regimes than commonly experienced at Norwegian plants today.

Wastewater sludge as a resource: sludge disposal strategies and corresponding treatment technologies aimed at sustainable handling of wastewater sludge.

The paper discusses different strategies for the disposal of wastewater sludge, particularly the "use on land" strategy and the "productification" strategy. In the "use on land" strategy the new regulations in Europe call for stabilization as well as disinfection of sludge to be used on land. The paper discusses the design and operation experiences with stabilization/disinfection methods in Norway where such treatment has been compulsory since 1995. In the "productification" strategy it is differentiated between the production of "bio-soils" and production of specific products (energy, nutrients, coagulants etc) and the "marketability" of these products is evaluated. An example of a sludge treatment concept aimed at recycling--the KREPRO process--is presented.