Skip to main content

Fouling Mechanisms in a Laboratory-Scale UV Disinfection System

Buy Article:

$22.00 plus tax (Refund Policy)

The fouling of quartz sleeves surrounding UV disinfection lamps is a perennial problem affecting both drinking water and wastewater applications. The mechanisms of fouling are not fully understood, but factors promoting fouling are believed to include heat, high hardness and/or high iron concentrations, and hydrodynamic forces. The role of UV radiation itself is unclear. The goal of this paper is to attempt to isolate the fouling mechanisms and to provide key information about those induced by UV radiation, using a unique laboratory-scale continuous-flow UV reactor. Its design allowed for irradiated and nonirradiated zones and control of both temperature and UV intensity at the fouling surface. Synthetic wastewater samples were tested with two levels of calcium, iron, phosphorus, and biochemical oxygen demand (as beef broth), and constant levels of magnesium and nitrogen to assess the effects of the four key variables. Average UV fluence before fouling exceeded 35 mJ/cm2, based on collimated beam tests. Foulant accumulation was monitored by UV intensity measurements and by mass and composition of foulant collected after an average of 56 hours of continuous operation. Tests showed that relative UV intensity dropped by as much as 100% when iron was present. Detailed results were assessed and yielded support for the following three UV-induced fouling mechanisms: (a) precipitation of ferric hydroxide [Fe(OH)3], (b) release of calcium from calcium-organics complexes followed by precipitation of iron-organics complexes, and (c) calcium carbonate precipitation. Other fouling mechanisms, such as sedimentation of preformed particles and sorption of calcium onto preformed colloids of Fe(OH)3, occurred outside the zone of UV radiation. Hence, these could be confused with concurrent UV-induced mechanisms in full-scale reactors. Iron and/or calcium undoubtedly created the most favorable conditions for fouling to occur; in the absence of both, fouling would be unlikely. The rates of fouling were enhanced when organics were also present; however, when phosphorus was present, fouling in the UV section was reduced. Indeed, UV may be viewed as inhibiting the fouling caused by phosphate complexes.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Data/Media
No Metrics

Keywords: UV disinfection; calcium; fouling; hardness; iron; phosphate complexes

Document Type: Research Article

Publication date: 2006-11-01

More about this publication?
  • Water Environment Research (WER) is published monthly, including an annual Literature Review. A subscription to WER includes access to the latest content back to 1992, as well as access to fast track articles. An individual subscription is valid for 12 months from month of purchase.

    Water Environment Research (WER) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year.

    Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
  • Editorial Board
  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Membership Information
  • Information for Advertisers
  • WEF Bookstore
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more