Ultraviolet and Chlorine Disinfection of Mycobacterium in Wastewater: Effect of Aggregation

Authors: Bohrerova, Zuzana; Linden, Karl G

Source: Water Environment Research, Volume 78, Number 6, June 2006 , pp. 565-571(7)

Publisher: Water Environment Federation

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Abstract:

Mycobacteria naturally aggregate in water, a characteristic that may serve to protect them against disinfection in wastewater. Secondary effluent was spiked with Mycobacterium terrae (M. terrae), sequentially filtered through 100-, 41-, and 20-μm nylon filters to partition aggregate sizes, confirmed using particle-size analysis and microscopy. Each sample was exposed to doses of UV light (10 to 60 mJ/cm² at 254 nm) and free chlorine (27 to 150 mg-min/L at 4°C). Inactivation of M. terrae in wastewater was initially rapid, with 2.5 log reduction at 14 mJ/cm² and 56 mg-min/L for UV and free chlorine, respectively. However, in effluent and 100-μm filtered wastewater, spiked M. terrae was present to the highest doses evaluated. Interestingly, M. terrae passed through 41- and 20-μm filters were inactivated rapidly, with no survivors after moderate disinfection doses. Inactivation of Mycobacteria in wastewater may be compromised by aggregates larger than 41 microns.

Keywords: UV; chlorine; inactivation; particle association; Contaminant Candidate List

Document Type: Research article

DOI: 10.2175/106143006X99795

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