Study of the Nature of the By-Products Formed and the Risks of Toxicity when Disinfecting a Secondary Effluent with Ozone

Abstract

Among the disinfection processes of urban waste water, ozonation and UV irradiation are fast gathering interest. To avoid what happened with chlorine it is necessary to have a look at the formation of by-products and the risks of toxicity when such processes are used. We were already working on this type of problem in 1984, although we did not make a point of communicating in extenso the results obtained during a 2-year period of pilot plant and laboratory studies at La Roche sur Yon (Vendée, France). The present paper reminds of the changes in chemical nature of the effluent after an ozonation from 6 to 12 g O3/m3 resulting in an abatement of fecal coliforms and fecal streptococci to the extent of 3 to 4 logarithmic units. No evidence of compounds known for their toxicity was brought to light. The toxicity tests performed on fish (Brachydanio rerio) and crustacean (Artemia nauplii) showed that the secondary effluent upstream or dowstream of the ozonation did not have toxic effects on the used biological material except for the fish when strong ammonia nitrogen concentrations occur. The toxicity tests performed on green algae (Scenedesmus subspicatus) showed that ozonated effluent seemed less conductive to algal growth than non ozonated effluent.

Population response to ozone application in wastewater: an on-site microcosm study with Gammarus fossarum (Crustacea: Amphipoda)

“…These beneficial effects of ozone application in WW on chlorophyll-a are in accordance with Escher et al (2009), who reported increased growth rates of Pseudokirchneriella subcapitata when exposed to ozone treated WW samples. The study by Escher et al (2009) and the present study differ from that by Langlais et al (1992), who observed a growth inhibition of the green algae Scenedesmus subspicatus following exposure to ozone treated WW. Langlais et al (1992) hypothesised that biologically available dissolved organic substances were partially destroyed, which limited nutrient availability and, ultimately, reduced algal growth.…”

“…The study by Escher et al (2009) and the present study differ from that by Langlais et al (1992), who observed a growth inhibition of the green algae Scenedesmus subspicatus following exposure to ozone treated WW. Langlais et al (1992) hypothesised that biologically available dissolved organic substances were partially destroyed, which limited nutrient availability and, ultimately, reduced algal growth. But transformation products also might have adversely affected algal growth, as they can be more toxic than their parent compounds (e.g., Li et al 2008;Zouboulis et al 2008).…”

Use of Ozone in Wastewater Treatment to Produce Water Suitable for Irrigation

“…Studies show that ozone treatments are able to reduce COD, BOD, pH, colour, turbidity, SS and TOC (Total Organic Carbon) (Gardiner and Montgomery 1968;Nebel et al 1973;Paraskeva et al 1998;Alfafara et al 2000) as well as aromatic compounds, unsaturated fatty acids, anionic detergents, amino acids and polysaccharides (Langlais et al 1992), trihalomethanes and organic halides (Amirsardari et al 2001). Then, it is more advantageous the use of ozone than chlorine, since studies (Fatta-Kassinos et al 2010) show their presence in treated wastewaters after chlorine treatment.…”

Novas tendências no tratamento de efluentes têxteis

“…OH) que é gerado pela decomposição do ozônio. No entanto, um inconveniente muitas vezes encontrado nos estudos de degradação com ozônio refere-se ao aumento da toxicidade de alguns intermediários de reação 58,61 , o que torna necessário o acompanhamento do processo através de testes de toxicidade.…”