By-product formation during ultraviolet disinfection of a pretreated surface water

Abstract

A low-pressure (LP-UV) and medium-pressure UV lamp (MP-UV) were compared for the formation of nitrite, assimilable organic carbon (AOC), and genotoxicity using pretreated surface water in a bench UV unit. The results have been compared with the by-products formed in pretreated surface water using a pilot unit equipped with four mediumpressure lamps identical to the one used in the bench unit. It was found that although significant nitrite formation occurred in the MP-UV bench tests, it remained well below the European standard (0.1 mg/L NO − 2 ) in the pilot unit. The LP-UV gave no or very low amounts of nitrite (bench unit). The AOC and genotoxicity increase with LP-UV was negligible. The AOC content and genotoxicity after MP-UV irradiation in the bench unit was significant as well, whereas AOC was formed limitedly in the pilot unit. Genotoxicity was elevated but not significant. Résumé :Une lampe UV à basse pression (LP-UV) et une lampe UV à pression moyenne (MP-UV) ont été comparées quant à la formation de nitrite, de COA (carbone organique assimilable) et pour la génotoxicité en utilisant de l'eau de surface prétraitée dans une unité UV de laboratoire. Les résultats ont été comparés aux sous-produits formés dans l'eau de surface prétraitée en utilisant une unité pilote équipée de 4 lampes à pression moyenne, identiques à celle utilisée dans l'unité de laboratoire. Bien que des quantités importantes de nitrite aient été formées dans les essais MP-UV en laboratoire, il a été trouvé que le niveau demeurait bien en deçà de la norme européenne (0,1 mg/L NO − 2 ) dans l'unité pilote. La lampe LP-UV ne donnait pas de nitrite ou seulement en très faibles quantités (unité de laboratoire). L'augmentation de la teneur en COA et de la génotoxicité avec la lampe LP-UV était négligeable. Après une irradiation MP-UV dans l'unité de laboratoire, la teneur en COA et la génotoxicité étaient aussi significatives, alors que la formation de COA était limitée dans l'unité pilote. La génotoxicité était élevée mais pas significative.

Field investigation of advanced oxidation of secondary effluent from municipal wastewater treatment plant

“…However, it was reported that nitrite formation rarely exceeded 100 µg L −1 , showing that nitrite levels were in compliance with regulations when low UV fluences were employed. [19,21] Hydrogen peroxide was shown to increase nitrite formation during polychromatic UV irradiation of drinking water. [22] There is a lack of information on the AOT treatment of secondary effluent in two aspects.…”

“…[2,5,6,8,14,19,22] There is insufficient information on the impacts observed from practical field application of the AOT to water and wastewater treatment. The objectives of this study were to test the field applicability of AOT at a pilot scale to a secondary effluent from an activated sludge process without nutrient removal, and to investigate the effect of AOT on inactivation and on changes in nitrate-nitrite concentrations in the product water under field conditions.…”

Biofouling of Polyamide Membranes: Fouling Mechanisms, Current Mitigation and Cleaning Strategies, and Future Prospects

“…Studies by Choi, et.al. [230] and IJepaar, et al [231] found that the use of MP mercury lamps did increase AOC in bench- and pilot-scale studies, and in actual drinking water facilities; LP mercury lamps did not appreciably increase AOC concentration. The increase in AOC and possible regrowth of microorganisms downstream of the UV system are critical considerations for membrane systems using MP-lamp, UV radiation for pretreatment disinfection.…”

Assimilable organic carbon (AOC) variation in reclaimed water: Insight on biological stability evaluation and control for sustainable water reuse

“…Some articles discovered increased AOC after UV irradiation and showed that the bioavailability of organic matter could be enhanced by UV as the generation of oxygen-rich compounds as well as the increase of low molecular weight compounds such as amino acids and carbohydrates (Shaw et al, 2000;Thayanukul et al, 2013). Higher UV irradiation doses could lead to elevated AOC concentrations (Ijpelaar et al, 2005). Nevertheless, others detected no obvious impact (Polanska et al, 2005) or even declined AOC levels (Lehtola et al, 2003).…”