Variations in Wastewater Quality Parameters Influencing UV Disinfection Performance: Relative Impact of Filtration

Loge, Frank J.; Bourgeous, Keith; Emerick, Robert W.; Darby, Jeannie L.

doi:10.1061/(asce)0733-9372(2001)127:9(832)

Cited by 28 publications

(19 citation statements)

References 19 publications

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“…After a 3 log 10 value of inactivation of E. coli was achieved, a pronounced deviation from the first-order kinetics occurred at a relatively high concentration of goethite particles. This is similar to previous studies with large particles from wastewater solids (9,18). It suggests that small-sized goethite particles protect bacteria from UV disinfection even at very low levels of turbidity (1 to 5 NTU).…”

supporting

confidence: 79%

“…The inactivation of E. coli (Fig. 1) seemed to follow first-order kinetics as reported previously (9,18), and no significant difference in inactivation was observed under different concentrations of goethite particles in the range of UV doses of 2.5 to 10 mJ/cm 2 . After a 3 log 10 value of inactivation of E. coli was achieved, a pronounced deviation from the first-order kinetics occurred at a relatively high concentration of goethite particles.…”

mentioning

confidence: 60%

“…SEM analysis showed that the freshly synthesized goethite particles were mostly 0.2 by 2 m in size, smaller than bacterial cells. Such small particles were ignored or excluded in the previous studies on the protective effects of particles against UV disinfection (18,25). However, our results showed that bacteria were protected by these particles from a UV dose of 10 to 30 mJ/cm 2 , which is comparable to the range of 21 to 36 mJ/cm 2 recommended by the U.S. Environmental Protection Agency for drinking water treatment (20).…”

mentioning

confidence: 99%

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Impacts of Goethite Particles on UV Disinfection of Drinking Water

Clevenger

Deng

2005

Appl Environ Microbiol

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A unique association between bacterial cells and small goethite particles (ϳ0.2 by 2 m) protected Escherichia coli and Pseudomonas putida from UV inactivation. The protection increased with the particle concentration in the turbidity range of 1 to 50 nephelometric turbidity units and with the bacterium-particle attachment time prior to UV irradiation. The lower degree of bacterial inactivation at longer attachment time was mostly attributed to the particle aggregation surrounding bacteria that provided shielding from UV radiation.Particles may inhibit chemical disinfection of water and wastewater and enhance the regrowth of pathogens in drinking water distribution systems (14,26,27), thus causing outbreaks of waterborne diseases (10,29). Mechanisms for the reduced chemical disinfection efficiency, analogous to the biofilm system (3,4,8), could be through colonization of particle surfaces by bacteria, where the disinfectant is present at a lower concentration due to (i) the high reactivity of particle surfaces for disinfectant degradation and (ii) limitation of mass transfer to the interface. Particle-attached bacteria are known to be more resistant to chemical disinfection than suspended bacteria (23,30).UV radiation has been increasingly used in the United States as an alternative approach for drinking water disinfection, promoted by the need of reducing potentially carcinogenic disinfection by-products (11,21,22,31). Similar to chemical processes, UV disinfection is also negatively affected by the presence of suspended particles (6,15,19). However, particles can protect bacterial cells from UV radiation via shielding, absorbing, scattering, and blocking (25, 31), not necessarily through bacterial attachment to particles as in chemical disinfection. Microorganisms can be present in the "shadow" cast by attaching to particles, thus allowing escape from full exposure to the UV radiation (6, 9, 15). The protective effects against UV inactivation of attached bacteria depend on particle sizes (9, 15) and turbidity levels (6, 7). Past research on particle-associated bacteria and UV shielding mostly used particles greater than 10 m (12, 28).Little information is available on the effects of small-sized particles on bacterial inactivation in drinking water. Predominant mechanisms of UV attenuation in such systems are unknown. Although research conducted using wastewater provides useful information on UV attenuation in drinking water, particles in drinking water and wastewater are different in nature, likely affecting UV transmission differently (6). For example, suspended particles in water supplies can be smaller and have more mineral components, including clays and metal oxides. Studies have shown that Na-montmorillonite clay can neither prevent viruses from being inactivated by chlorine (26) nor protect bacteriophage (MS2) from UV disinfection at low concentrations (24). Very little information is available on the effect of other clays and mineral oxides such as goethite (␣-FeOOH), which is one of the most common met...

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confidence: 79%

mentioning

confidence: 60%

mentioning

confidence: 99%

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Impacts of Goethite Particles on UV Disinfection of Drinking Water

Clevenger

Deng

2005

Appl Environ Microbiol

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“…One of the possible explanations for the tailing phenomenon is the presence of aggregates. Aggregation of cells with other cells may be induced by the UV treatment [4,1,16] or microbes may be associated with particulate matter [19,9,[12][13][14]6,7,11,15,18].…”

Section: Introductionmentioning

confidence: 99%

UV-induced self-aggregation of E . coli after low and medium pressure ultraviolet irradiation

Kollu

Örmeci

2015

Journal of Photochemistry and Photobiology B: Biology

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“…The primary reason UV treatment has not been employed for stormwater treatment is the orders of magnitude of larger amounts of suspended solids, in addition to dramatically different solution chemistry, observed in stormwater when compared to drinking water sources [2]. Additionally, unlike typical sources of drinking water, the composition of stormwater is extremely dynamic, particularly during combined sewer overflow (CSO) events.…”

Section: Introductionmentioning

confidence: 99%

UV treatment efficiency for E. coli in storm water containing different size fractions of suspended solids

McElmurry

Ingram²,

Khalaf³

et al. 2016

WIT Transactions on Ecology and the Environment

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Ultraviolet (UV) treatment of water is known to be an effective means for reducing bacterial concentrations. While previous research has typically focused on UV treatment efficiency for disinfection of drinking water, the utility of this technology in treating more turbid samples is less clear. This study investigates the use of UV treatment for the disinfection of stormwater from combined sewer overflow (CSO) events and specifically focuses on how suspended solids influence treatment efficiency for Escherichia coli. Stormwater containing different size fractions of suspended solids was exposed to UV treatments and the rate of disinfection was determined. After approximately 3-orders of magnitude reductions in E. coli survival, significant tailing in the rate of disinfection was observed for unfiltered stormwater and stormwater containing particles less than 20μm. A particle-associated bacteria (PAB) model which directly utilizes the concentration of suspended solids to estimate the effect of shielding is proposed and evaluated as well as a biphasic model, with two first-order rate constants. Experimental results confirm that suspended particles are important and need to be accounted for when determining UV treatment efficiency of CSO stormwater. However, tailing observed may not be accurately described by current models and particle size suggests a mechanism other than shielding is responsible for tailing.

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Variations in Wastewater Quality Parameters Influencing UV Disinfection Performance: Relative Impact of Filtration

Cited by 28 publications

References 19 publications

Impacts of Goethite Particles on UV Disinfection of Drinking Water

Impacts of Goethite Particles on UV Disinfection of Drinking Water

UV-induced self-aggregation of E . coli after low and medium pressure ultraviolet irradiation

UV treatment efficiency for E. coli in storm water containing different size fractions of suspended solids

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