Laboratory experiments and full-scale trials in Brazil and Italy are reported that show that peracetic acid is a good disinfectant (better than sodium hypochlorite) of sewage in tropical and warm temperate climates. Its demonstrated effectiveness against V. cholerae suggests it should be a significant element in cholera control efforts.

The increasing use of products containing peracetic acid for the disinfection of sewage and effluents has produced a demand for information about the activity of PAA against relevant microorganisms. Studies have therefore taken place to establish the comparative effects of peracetic acid and chlorine on both bacteria and viruses. Peracetic acid has previously been shown to be active against faecal indicator bacteria Recent laboratory studies have established that peracetic acid is also an effective agent against viruses typical of those found in sewage. This activity is maintained even in experimental systems containing high levels of organic matter such as yeast extract. In contrast, although sodium hypochlorite is an effective virucide in clean experimental systems, the presence of organic matter greatly increases the level of added available chlorine necessary to achieve a given level of viral inactivation.

E.P.R. spin trapping has been employed to study radical production during the bactericidal action of three peroxide compounds (peracetic acid, 4-percarboxy-N-isobutyltrimellitimide and magnesium monoperoxyphthalate) upon both Gram negative (Escherichia Coli) and Gram positive (Staphylococcus Aureus) bacteria. Use of the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) has allowed direct detection of both carbon-centred and hydroxyl radicals, which are produced at varying rates for the different bacteria/peracid systems studied. The inhibition of bactericidal action, by DMPO and two antioxidants, Vitamin C and Trolox C, indicates that radicals are the lethal species and evidence is presented which suggests that radical production is internal to the bacterial cell. Hydroxyl radicals are believed to be the lethal species. The effect of added iron chelators and haem protein inhibitors indicates that iron species and haem proteins in particular are involved. A marked variation is found in observed hydroxyl-radical adduct signals with both the nature and concentration of peracid. A strong inverse correlation is found between the concentration of the observed radical adduct signal and the relative strength of the peroxide as a bactericide; use of a stable nitroxide as a radical scavenger confirms that strong bactericides produce radicals at a much faster rate than weak bactericides. Plots of radical generation versus time are correlated with % bacterial kill, offering further evidence that hydroxyl radicals are the lethal species.

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.

Vines, J. R. L., Jenkins, P. D., Foyer, C. H., French, M. S., Scott, I. M. (2003). Physiological effects of peracetic acid on hydroponic tomato plants. In: Annals of Applied Biology 143 (2), pp. 153-159Peracetic acid (PAA) has potential as a disinfectant of low environmental impact for glasshouse hydroponic systems and other horticultural applications, but can have phytotoxic effects. This study examined the physiological effects of PAA when applied hydroponically to tomato plants. Plants treated with 0.5?5 ?g ml?1 PAA over several weeks exhibited a reduction in size of all vegetative organs. During the first 2 h of PAA treatment, plants also exhibited a transient wilting, with increased stomatal resistance, and reductions in transpiration and CO2 assimilation. The toxicity of PAA to roots was apparent from increased leakage of root electrolytes, reduced oxygen consumption, death of root tips, and collapse of the internal tissues. The shrivelling of PAA-treated roots resulted from loss of water to the shoot in the transpiration stream, as the effect could be eliminated by removal of the shoot and sealing of the cut stump. HgCl2, a reagent known to reduce the hydraulic conductivity of root systems, caused the same root shrivelling effects as PAA. Long-term growth of PAA-treated plants was dependent upon the replacement of taproot systems by adventitious roots, which, initially at least, displayed greater tolerance of PAA. In aqueous solution, PAA exists in equilibrium with H2O2 and acetic acid, both of which were individually toxic, but acetic acid exhibited a syndrome of effects distinct from those of PAA, while the effects of H2O2 paralleled those of PAA more closely, suggesting that oxidative rather than acidic mechanisms were primarily responsible for the phytotoxicity of PAA solutions.Peer reviewe