Novel products based on peracetic acid (PAA) have recently been developed for the disinfection of sewage and sewage effluents. The efficacy of such products has been assessed under both laboratory and operational conditions.
Comparative laboratory studies of the effects of peracetic acid, chlorine dioxide and chlorine on indicator bacteria in secondary sewage effluent have shown peracetic acid to be a viable alternative to these halogen biocides.
In a trial carried out at two small rural works, PAA was dosed into secondary effluent from either an activated sludge plant or a percolating filter bed prior to tertiary lagoon treatment. LOW levels of PAA greatly enhanced the natural decline in coliform levels across the lagoon, enabling much lower concentrations of bacteria to be discharged into the receiving streams.
In another trial, secondary effluent from an activated sludge plant was treated before discharge into a stream leading to the sea. Coliform concentrations were greatly reduced along the watercourse downstream from the plant.