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The discharge of chlorinated wastewaters may result in acute toxicity to the aquatic ecosystem. This toxicity is due to chlorine residuals and to chlorinated organics formed during chlorination. An alternative method to chlorination for effluent disinfection is ultraviolet light irradiation. Kills of more than 99% have been obtained for coliform, fecal coliform, fecal streptococci and heterotrophic bacteria by irradiating secondary effluents from conventional activated sludge sewage treatment plants with ultraviolet light (254nm). Laboratory scale treatment studies of ultraviolet sterilization as a method of reducing the toxicity of municipal effluents and producing effluents of acceptable bacterial quality is reported.

Aluminum, barium, berylliu, bismuth, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, silver, strontium, vanadium and zinc concentrations in the sewage, effluents and sludges of ten southern Ontario wastewater treatment plants are reported. The efficiency for metal removal by a conventional activated sludge plant was determined. The effect of metal concentrations in receiving waters from residual metals in sewage effluents is discussed. The environmental hazards of disposing of sewage sludges with high metal content on agricultural land is considered.

. Can. J. Chem. 55, 625 (1977). Two types of reactions occur when hexaaquoiron(II1) ion is irradiated at 254 nm in the presence of alcohols. Firstly, a charge transfer transition from a water centred orbital to an iron centred orbital produces OH' radicals which go on to abstract hydrogen from the alcohols. secondly ,!the reaction with the charge transfer excited states of iron(II1) species can lead to outer sphere oxidation of the alcohols. In this paper, these reactions have been studied in detail for the diol ethylene glycol in aqueous solutions. It has been found that the quantum yield of acetaldehyde, the major product of hydroxyl radical reactions with ethylene glycol, is 0.09 and the yield of formaldehyde, the major product of the direct charge transfer reaction, is 0.05 in 1 M ethylene glycol. The quantum yields for these major products, as well as minor products. such as glycolaldehyde and succinaldehyde, have been determined at several concentrations of ethylene glycol and iron. A detailed reaction scheme for the photolysis has been developed. JOHN H. CAREY, ERNEST G. COSGROVE et BARRY G. OLIVER. Can. J. Chem. 55, 625 (1977) I1 y a deux types de rCaction qui se produisent lorsque l'ion hexaaquofer(II1) est irradiC a 254 nm en presence d'alcools. En premier lieu, il y a une transition de transfert de charge a partir d'une orbitale centree au niveau de I'eau vers une orbitale centree sur le fer qui produit des radicaux O H qui ensuite enlevent de l'hydrogene des alcools. Deuxiemement il y a une reaction avec les Ctats excites de transfert de charge des espkces du fer(II1) qui peut conduire a des oxydations par les sphkres extCrieures de l'alcool. Dans la prCsente communication, on a Ctudit ces rkactions en detail pour le diol ethylene glycol en solution aqueuse. On a trouve que le rendement quantique d'acCtaldChyde, le produit majeur des reactions du radical hydroxyle avec l'ethylene glycol, est de 0.09 et le rendenlent de formaldehyde, qui est le produit majeur de la reaction de transfert directe de charge, est de 0.05 dans 1'6thyltne glycol 1 M. On a determine les rendements quantiques de ces produits majeurs ainsi que des produits mineurs tel que le glycolaldthyde et le succinaldthyde a plusieurs concentrations d'ethylene glycol et de fer. On a developpe un schema rtactionnel dttaillt pour la photolyse.[Traduit par le journal]