Tuesday, February 12, 2019
Technology Trends-2Room: Colombo A
Effect of Water Matrix on the Formation of Nitrite during the Vacuum UV Photolysis of Nitrate-contaminated Water
Mengqi Han, University of British Columbia Effect of Water Matrix on the Formation of Nitrite during the Vacuum UV Photolysis of Nitrate-contaminated WaterMengqi Han, University of British Columbia Vacuum UV (VUV), as one of the UV-based advanced oxidation processes (AOPs), has shown great promises for degradation of micropollutants in drinking water. Early research demonstrated that hydroxyl radicals generated by VUV can effectively degrade a range of micropollutants under different water matrices and operating conditions. A commonly found solute that might have significant impact on the process is nitrate. Upon irradiation with lower wavelength UV and VUV, nitrate may result in the formation of nitrite. Given that nitrate and nitrite are potentially harmful compounds, their presence and formation are important sources of concern during the VUV process, and warrant further research. This research focused on understanding the effect of water matrix including dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and chloride on the potential formation of nitrite in a nitrate-contaminated water during VUV photolysis. Experimental work involved kinetic studies using a custom-made bench top UV/VUV collimated beam set-up, equipped with a nitrogen purged chamber to avoid VUV photons being absorbed by oxygen. Water containing solutes of interests at different concentrations was irradiated and samples were collected for analysis at set intervals, corresponding to fluences of up to 1200 mJ/cm2. The results indicate increases of nitrite formation with increasing the concentration of DOC in water. The effect of DIC is only pronounced at very high concentration, where DIC resulted in lower formation of nitrite. When both DOC and DIC present in water, DOC has a dominant effect on nitrite formation. Chloride exhibits its significant impact on decreasing the formation of nitrite. In this presentation, we elaborate on these results as well as the mechanisms around the competition between inorganic radicals and OH radicals and their effects on nitrite formation. All these will provide the scientific and engineering communities with information and tools required for the implementation of VUV for drinking water treatment applications.
Peroxide Enhanced Aerosol Disinfection with Wavelength Targeted UV-LEDs
Mark Hernandez, University of Colorado Peroxide Enhanced Aerosol Disinfection with Wavelength Targeted UV-LEDsMark Hernandez, University of Colorado In urban environments, many people spend in excess of 90% of their time indoors—where air must be conditioned and exposures to airborne microbes is markedly higher than immediately outdoors. Thus, the sanitation of indoor air is gaining increased attention as a public health and infrastructure priority, particularly in high density public buildings and health care settings. In this context, using chemical biocides for aerosol disinfection or HVAC system cleaning has been discouraged by the World Health Organization because of associated environmental health risks. Filtration and ultraviolet (UV) irradiation remain among the few economically viable indoor air treatment alternatives for larger structures; however, high efficiency filtration remains prohibitively expensive for most urban building stocks. While conventional UV irradiation equipment has been adapted for the disinfection of air and surfaces in HVAC ducts, a new generation of UV-LED arrays are emerging that offer performance, wavelength controls and design flexibilities that conventional UV lamps are unable to provide. We report how UV-LEDs arrays can be engaged for potent aerosol disinfection of indoor air in model air duct systems. The bioaerosol disinfection potential of equivalent powered UV-LEDs at 260 nm and 280 nm, alone, and in combination, was demonstrated with pure cultures of airborne Bacillus subtillis cells; the effects of relatively humidity on UV-LED inactivation potential were wavelength specific. In a dose-response paradigm, bioaerosol disinfection induced by UV-LEDs was significantly enhanced by trace amounts hydrogen peroxide regardless of humidity levels. Where UV-LED exposures induced bioaerosol culturability losses on the order of 102 CFU/m3, co-exposure to H2O2 levels as low as 90 ppbv, increased inactivation response over >105 CFU/m3. At these levels, H2O2 ¬vapor alone could not induce any measureable disinfection response. These results suggest that advanced oxidation processes enabled by UV-LEDs offer new aerosol disinfection alternatives for the built environment.
Photocatalytic removal of malachite green using a novel cellulose acetate - Au/ZnO nanocomposite
Sajjad Nasiri Khalil Abad, Sahand University of Technology Photocatalytic removal of malachite green using a novel cellulose acetate - Au/ZnO nanocompositeSajjad Nasiri Khalil Abad, Sahand University of Technology The purpose of this study was to investigate the influence of compositing Au/ZnO nanoparticles with cellulose acetate on the photocatalytic removal of malachite green dye. The Au/ZnO nanoparticles were manufactured by co-precipitation method and consolidated into the cellulose acetate made by the phase inversion process. For this purpose, 0.5 wt.% nanoparticles were added to the cellulose acetate, and several characterization analysis were performed to study the properties of nanocomposites. X-ray diffraction and X-ray spectroscopy respectively employed to examine the crystal structure and oxidation state of Au/ZnO nanoparticles. Scanning electron microscopy used to study the morphology of nanocomposites. Electron microscopy showed the porous morphology of nanocomposites. The electronic properties of nanoparticles measured by UV/Vis spectroscopy. The volume fraction of pores in nanocomposites was calculated. The volume fraction of pores was 83% that is higher than pure cellulose acetate with 72% porosity. Hydrophilicity of nanocomposites evaluated using droplet contact angle test. Experiments unveiled that pure cellulose acetate with the contact angle of 51 was somewhat more hydrophilic compared to nanocomposites with the contact angle of 72. Finally, the photocatalytic activity of nanocomposites measured by malachite green removal from wastewater.
Efficient VUV Generation from Microplasma Flat Lamps for Photochemistry and Environmental Applications
Sung-Jin Park, Eden Park Illumination, Inc. Efficient VUV Generation from Microplasma Flat Lamps for Photochemistry and Environmental ApplicationsSung-Jin Park, Eden Park Illumination, Inc. Compact, flat VUV and UV lamps comprising large arrays of microcavity plasmas, and capable of efficiently generating in the wavelength from VUV to UV-C radiation, have been developed by the team of the University of Illinois and Eden Park Illumination. VUV light is desirable for a number of novel chemical processes and efficient disinfection methods which conventional UV light sources suffer from several drawbacks, including undesirable form factors and operational concerns regarding the use of mercury. Microplasmas are non-equilibrium, low-temperature plasma sources which have high power loading (several hundred kW/cm3), thereby enabling them to efficiently form UV-generating excimer molecules. This work has focused on leveraging microplasma array technology to realize low-temperature UV lamps that are flat and designed to have a scalable, slim form factor (total thickness less than ~5 mm). Each microcavity (less than a sub-millimeters in its cross-sectional dimensions) was fabricated through a series of microfabrication techniques, and the spatial variation of the electric field strength in each microcavity was tailored through the cavity cross-section and electrode geometry to efficiently generate deep UV radiation. UV light tiles capable of producing fluences up to 200 mW/cm2 at 172 nm which generates more than 25 watts of average power from a lamp of only 16 square inches in active surface area. Details concerning lamp performance of UV lamps having emitting wavelengths specifically in 146, 172, 222, and 308 nm will be discussed. The upcoming applications and case studies of the microplasma UV lighting tiles such as photochemistry, environmental and biomedical applications as well as a new source for advanced oxidation process (AOP) at air and water purification will be discussed. | WastewaterRoom: Colombo B
Degradation of THC metabolites with a photoelectrocatalytic cell equipped with a nanostructured TiO2 anode
Stephanie Gora, Dalhousie University Degradation of THC metabolites with a photoelectrocatalytic cell equipped with a nanostructured TiO2 anodeStephanie Gora, Dalhousie University The looming legalization of marijuana in many jurisdictions, including Canada, has prompted interest in research related to the environmental fate and management of its wastes, including that of THC metabolites. THC-COOH, the main urinary metabolite of THC, has been linked to adverse health effects in aquatic organisms, and its detection in and removal from water is an emerging challenge in the water field. Chlorination and UV/H2O2 have been shown to be effective for the degradation of THC-COOH in water. Other oxidation-based processes, including photoelectrocatalysis, may also prove to be appropriate for this application. Hotoelectocatalysis couples a photocatalyst with an anode in an electrochemical cell. As the electrons are formed they are pulled away from the photocatalyst surface towards the cathode, preventing recombination, increasing the availability of highly oxidative electron holes, and increasing the formation of reactive oxygen species via certain pathways. In this project, a series of anodes covered in titanium dioxide nanostructures was synthesized using a water-based anodization method and evaluated for crystalline phase structure (XRD), general morphology (SEM), and surface area. The efficacy of the anodes for the degradation of THC-COOH was also tested using a photoelectrocatalytic cell illuminated by UV light. The effect of water matrix components common to surface water and/or seawater, including various ions and humic acid, is an ongoing area of research. Preliminary results indicate that the photoelectrocatalytic treatment system is indeed able to degrade THC-COOH, and that the presence of nitrate and sulphate impacts the relative importance of different mechanisms underlying photoelectrocatalysis to the overall removal of the contaminant.
Ready for the next decade? How wastewater sites can enhance their UV systems to be up to future tasks
Kirsten Meyer, Xylem Services GmbH Ready for the next decade? How wastewater sites can enhance their UV systems to be up to future tasksKirsten Meyer, Xylem Services GmbH When considering today’s trend of continuously growing populations in most cities, it’s easy to imagine that wastewater treatment plant operators are challenged to handle ever increasing flow streams. In parallel, regulations may have become more stringent with regards to the treatment targets and effluent standards to be met. These challenges also apply to existing UV disinfection systems that have been installed 15 to 20 years ago and now may need to be upgraded in order to comply with todays’ requirements. While new constructions in order to build an entirely new disinfection system could be fairly costly, there is a set of alternate options that UV system manufacturers may offer to operators in order to address their upgrade needs. These can either be new control algorithms that are able to better adjust the UV system to the operational requirements or take site specific wastewater characteristics into account as well as advances in UV lamp and ballast technology. When a major adjustment is required, it is even possible to use existing structures to fit new equipment in without the need for major changes to existing constructions.
The presentation will illustrate different means that operators may have when there is a need to enhance existing equipment to fit today’s requirements. Furthermore, an example how these options have been implemented at an existing site and what benefits could be leveraged will be shared with the audience.
Combined enzymatic degradation and UV-photolysis for enhanced degradation of emerging trace organic contaminants
Arbab Tufail, University of Wollongong Combined enzymatic degradation and UV-photolysis for enhanced degradation of emerging trace organic contaminantsArbab Tufail, University of Wollongong Trace organic contaminants (TrOCs) comprise groups of naturally occurring and synthetic organic compounds including pharmaceuticals and personal care products and industrial chemicals, which are ubiquitously detected in wastewater. They are resistant to conventional wastewater treatment processes. This raises concern as they have potentially detrimental effects on aquatic lives and even human. This study compares two emerging techniques, namely, enzymatic degradation and advanced oxidation process, and also investigates their combination given the available reports on the TrOC-specific effectiveness of these processes. One industrial chemical i.e., bisphenol A (BPA) and four pharmaceutical and personal care products i.e., sulfamethoxazole (SMX), carbamazepine (CBZ), oxybenzone (OXB), and diclofenac (DCF) were selected for this investigation. An enzymatic bioreactor was coupled with membrane distillation (MD) process to develop an enzymatic membrane bioreactor (EMBR) for continuous enzymatic degradation. In the EMBR, the membrane prevented wash out of the enzyme (i.e., laccase) from the bioreactor. For the combined MD—photolysis process (in absence of enzyme), MD retained TrOCs almost completely within the reactor, thus producing TrOC-free effluent. However, because most of the TrOCs (OXB, CBZ and BPA) were resistant to photo-degradation (less than 40% degradation), they accumulated in the reactor. On the other hand, in the combined process of EMBR—photolysis, 70 to 99% degradation of the TrOCs was achieved due to enzymatic- and photo-degradation. Of particular interest, 41% improvement in the degradation of the well-known resistant TrOC carbamazepine was observed in EMBR—photolysis as compared to MD—photolysis. This is the first study that compared the degradation of TrOCs by UV-photolysis when combined with the high retention membrane process MD in absence of enzyme (i.e., MD—photolysis) vs. in presence of enzyme (i.e., EMBR—photolysis). |
UV-LED-4Room: Colombo A
Enhancement to micropollutant degradation and reduction of halogenated by-product formation in the UV-LED/chlorine process by adding persulfate
Ran Yin, The Hong Kong University of Science and Technology Enhancement to micropollutant degradation and reduction of halogenated by-product formation in the UV-LED/chlorine process by adding persulfateRan Yin, The Hong Kong University of Science and Technology The UV/chlorine process has emerged as an advanced oxidation process (AOP) for micropollutant degradation in drinking water treatment and potable water reuse. It produces a diverse spectrum of reactive species including hydroxyl radicals (HO·) and reactive chlorine species (RCS), which complement each other in the micropollutant degradation. However, halogenated by-products are formed in the UV/chlorine AOP. UV light emitting diodes (UV-LEDs), which are mercury-free, compact and robust, are promising alternatives to conventional mercury-vapor UV lamp, and show potential use in the UV-based AOPs. At neutral and slightly alkaline pHs, the photolysis of chlorine and the consequential radical formation increased with increasing wavelength from 265 to 300 nm by UV-LEDs, and the radical yields were higher than that by the conventional LP-UV lamps. This study investigated the degradation of four micropollutants (i.e., nitrobenzene, benzoic acid, carbamazepine and 1,4-dimethoxybenzene) and halogenated by-product formation in the UV-LED/chlorine AOP at three wavelengths (i.e., 265, 285, and 300 nm) and neutral pH, with or without persulfate additions. The degradation of the four compounds was enhanced by adding a small amount of persulfate (e.g., 100 µM). The observed rate constants of the degradation of the four compounds in the UV-LED/chlorine/persulfate system were higher than the sum of the corresponding rate constants observed in the UV-LED/chlorine alone and UV-LED/persulfate alone systems (i.e., UV-LED/chlorine/persulfate > UV-LED/chlorine + UV-LED/persulfate), indicating that the enhancement to the micropollutant degradation was not simply due to the generation of radicals from the UV photolysis of persulfate. The enhancement was attributed to the transformation of RCS to HO· and sulfate radicals (SO4-·), which were more reactive toward the tested micropollutants, in the presence of persulfate. In addition, in the presence of persulfate, the formation of total organic chlorine (TOCl) from natural organic matter (1 mg/L as C) was reduced by 20–30% in the UV-LED/chlorine AOP. It also suggested the transformation of the halogen radicals (i.e., RCS) to the non-halogen radicals (e.g., HO· and SO4-·). The establishment a dynamic model to describe the distribution of the radicals in the UV-LED/chlorine process in the presence of persulfate is on-going and the effects of UV wavelength, solution pH and chlorine/persulfate ratios will also be evaluated and presented.
Utilizing UV-LED pulse width modulation in TiO2/UV advanced oxidation processes for the removal of emerging contaminants
Robert Liang, University of Waterloo Utilizing UV-LED pulse width modulation in TiO2/UV advanced oxidation processes for the removal of emerging contaminantsRobert Liang, University of Waterloo Advanced oxidation processes such as UV/TiO2 have been explored to mitigate the number of PPCPs that enter the environment through application in wastewater treatment plants. TiO2 has been widely accepted as a photocatalytic material with potential to break down PPCPs into smaller constituents, reducing their environmental exposure and impact. However, this process is limited by low photonic efficiency under UV systems. Controlled periodic illumination (CPI) and the use of metal-semiconductor (Schottky junctions) may overcome low photonic efficiencies by decreasing the electron-hole recombination effect. Using a CPI controlled UV-LED /TiO2 process, the degradation of a solution of eighteen PPCP compounds was analyzed with LC-MS/MS using solid-phase extract samples. The kinetic rate constants of PPCPs was analyzed using multiple regression analysis with parameters such as net charge at experimental pH, solubility, and molecular weight. Negatively charged PPCP compounds were found to have the highest removal compared to neutral and positively charged compounds due to electrostatic attraction forces with TiO2. Decreasing the duty cycle under CPI or the UV-LED illumination period did not significantly change the individual and cumulative PPCP compound removal in mass transfer limited systems (substrate systems), suggesting that the CPI controlled UV-LED/TiO2 with TiO2 substrates were effective in reducing energy requirements without sacrificing removal performance.
Advancing disinfection technologies with UVC radially emitting optical fibers
Mariana Lanzarini-Lopes, Arizona State University Advancing disinfection technologies with UVC radially emitting optical fibersMariana Lanzarini-Lopes, Arizona State University Light emitting diodes (LEDs) are becoming a competitive and lower cost alternative to mercury lamps as UVC light sources. The technology barrier of LED disinfection is their small surface area of irradiation. There is a need for better distribution of light for disinfection reactors using LEDs. Current UVC LED reactor designs use a high volume of LEDs to create a semi-leveled light distribution density leading to high cost of capital and operations. Our research seeks to use a single LED by employing radially emitting optical fiber as the distribution medium for the ultraviolet radiation. We are nano-enabling optical fibers to scatter ultraviolet radiation at controlled light fluxes. By attaching silica nanoparticles to the surface of that glass, we create opportunities for the guided photons to scatter out of the optical fiber. This scattered light flux determines the overall distribution of photons that can then be used as a source for DNA inactivation. A thin ultraviolet-C transparent polymer coating protects the fiber and stabilizes the nano-silica spheres onto the surface of the optical fiber. This presentation will focus on how modifications in nano-silica (size, loading) and polymer coating (type, thickness) affects the overall optical fiber scattering flux. We are able to scatter upwards of 3/4th of the input light through half of a meter of fiber, and can control the scattering to transmitted ratio to adjust for different required lengths. Reactor designs will be illustrated using modified optical fibers that show promise in increasing volumetric efficiency and reaction kinetics in disinfection (UV LED 260 nm) reactors. The ability to emit UV-C light from these thin and flexible optical fibers can allows us to revolutionize disinfection water treatment technologies and the knowledge can be translated for further applications such biofilm growth prevention in both membrane reactors and piping for distribution system.
The use of Ultraviolet Emitting Diode (UV LED) technology for biofilm disinfection
Carolina Ontiveros, Dalhousie University The use of Ultraviolet Emitting Diode (UV LED) technology for biofilm disinfectionCarolina Ontiveros, Dalhousie University Biofilms form on surfaces because of the attachment of planktonic cells followed by the proliferation of cell – to – cell adhesion through the excretion of extracellular polymeric substances (EPS). Biofilms on different surfaces can serve as pathogens reservoirs. The use of UV light has been emerging as a new strategy to prevent and manage biofilm formation. The exact energy required for disinfection remains dependent on the surface where the biofilm is growing and the microorganisms that are present in it. UV LEDs are a promising technology with considerable advantages over traditional UV lamps used for water treatment, such as smaller size, a variety of wavelengths and increased energy efficiency. UV LED technology could be applied to control biological load in water and for surface disinfection. The objective of this study was to explore the use of UV LED technology for biofilm disinfection and to investigate the possible synergistic effects when UV LED treatment is paired with conventional surface disinfection strategies. A set of experiments was executed to compare the efficacy of UV LEDs and wiping with commercially-available disinfectant wipes. P. aeruginosa was chosen as a target microorganism and was grown in a CDC reactor on clear polycarbonate coupons. Coupons were treated with UV light at 265 nm using a UV LED collimator beam. Manufacturer-recommended wiping techniques were compared to more realistic wiping regimes and to UV LED doses ranging from 2-20 mJ/cm2. After treatment, swabbing was used for biofilm recovery. Bacterial enumeration and ATP quantification were conducted afterwards. Preliminary results showed that the combination of UV LED and wiping was synergistic and enhanced disinfection in P. aeruginosa biofilm. A synergistic effect up to 4.5 log was observed when UV treatment was applied after the wiping procedure. This could indicate that there are advantages to incorporating UV LEDs into existing biofilm mitigation strategies.
UV-C LED Implementation Strategies for Water Disinfection Systems: The Need for Minimum Standards
Oliver Lawal, AquiSense Technologies UV-C LED Implementation Strategies for Water Disinfection Systems: The Need for Minimum StandardsOliver Lawal, AquiSense Technologies The introduction of UV-C or germicidal LEDs that emit 240 to 280 nm will have a profound impact on the water, air, and surface disinfection markets as society continues to seek more reliable, efficient, and environmentally friendly light sources for water disinfection. A review of early stage product development for UV-C LED-based systems indicates that applications can be segmented into two distinct categories: 1) Stationary lamp modules (e.g. for tank disinfection) and 2) Flow through disinfection systems. Given the early stage of market development for UV-C LEDs for water disinfection, it is important to compare the strengths and weaknesses of the two approaches to ensure the safe and effective implementation of this technology. A practical implementation approach will be taken demonstrating the importance of delivering both a homogenous and minimum UV Dose for an example water cooler disinfection application. A comparison will be made between a low and high optical output stationary UV-C LED module (e.g. tank disinfection) and a flow through reactor solution for the same operating conditions to highlight design considerations to ensure the safe implementation of the technology. An outline of current and proposed UV-C LED standards from North America, Europe, and Asia will be given. Based on analysis of the example application and with reference to existing standards, minimum regulatory or design standards will be proposed. | Regulations and ModelingRoom: Colombo B
Simulation techniques for high precision UV dose estimation in UV-LED water purification systems
Ashkan Babaie, Acuva Technologies Simulation techniques for high precision UV dose estimation in UV-LED water purification systemsAshkan Babaie, Acuva Technologies Using virtual prototyping for the design of UV-LED reactors is significantly beneficial in reducing the product development cost. Without the proper simulation tools, the reactor design may need to go through multiple design revisions and prototyping stages without delivering the required UV dose or LRV at the end. Complete simulation of a reactor’s performance requires precise modelling of reactor’s hydrodynamics, optics and the microbial kinetics, each of which are equally important for an accurate reactor simulation. Hydrodynamic simulation can be quite challenging if not all the parameters are considered or set properly. Meshing quality, flow models including turbulence, particle tracking setting can all significantly affect the flow simulation and the dose performance, respectively. In fact, through examples, it will be discussed that traditional measures of simulation convergence as having the residuals below a certain level will not necessarily verify the accuracy of simulation. In addition, optical simulation will equally be important to achieve an accurate prediction of the reactor’s performance. Precise simulation of the LED die, package, radiation pattern and wavelength, as well as modelling of optical surfaces will all influence the accuracy of the simulation tool. In this study, a step-by-step approach for both optical and flow simulation within a UV-LED based water purifier will be discussed using commercial software packages such as Ansys and Zemax. Once reliable optical and hydrodynamic data are available, it will be explained how an integrated tool can be used to determine the overall reactor’s UV dose delivery. Using the same approach, the simulation results will be compared with experimental bioassay test results, showing less than 10% variation. This level of accuracy can be achieved between experiments and simulation by paying extra attention to the detail of hydrodynamics, optics and kinetics simulation tool.
CFD modeling the impact of the channel hydraulics on the performance of UV module
Wei Yang, SUEZ CFD modeling the impact of the channel hydraulics on the performance of UV moduleWei Yang, SUEZ The performance of an open channel UV reactor is impacted by both inlet and outlet hydraulics conditions to the channel. As a UV equipment manufacturer, we have seen our share of non-ideal designs with the channel influent structure; abrupt 90o turns or wastewater gushing in from a pipe. These non-ideal hydraulics designs are also present with the channel outlet structure like a weir through being a faction of the depth of the channel for example. Depending on the proximity of these non-ideal inlet and outlet designs with respect to the UV reactors the disinfection performance of a UV system in the field can be reduced. This paper will focus on evaluating the effect of a number of non-ideal influent and effluent structures on the disinfection performance of various open channel UV reactor designs based on Computational Fluid Dynamics (CFD) modeling. CFD modeling that resolves both flow and intensity fields and generates a dose distribution via a Lagrangian particle dose tracking is a well-known tool that has been proven to accurately simulate the disinfection performance of UV reactors. The CFD modeling simulations from this study will provide detailed information about how non-ideal influent and effluent structure affects the UV dose distributions and RED dose of a UV reactor by comparison to the ideal case of the uniform inlet and outlet velocity profiles. Solutions to mitigate the negative impact of non-ideal hydraulics will be discussed with the objective to provide useful information to optimize UV system designs in the field.
A Standardized Protocol for Studying UV-LED Inactivation of Microorganisms
Fariborz Taghipour, UBC A Standardized Protocol for Studying UV-LED Inactivation of MicroorganismsFariborz Taghipour, UBC Despite rapid improvements in the performance of UV-LEDs and their enormous potential for water treatment, there is no standardized method of applying UV-LEDs for studying the inactivation kinetics of microorganisms. The lack of such protocol can result in inconsistent, inaccurate, and irreproducible results for the kinetics of microbial inactivation using UV-LEDs. This research focused on addressing the aforementioned issues by using different UV-LED setups for studying the kinetics of the inactivation of microorganisms in water. We developed a method for accurate determination of the kinetic rate constants, taking into account the characteristics of UV-LED and water as well as the optical properties of the medium. In this approach, the exact emission spectrum of UV-LED is taken into consideration by treating it as a polychromatic UV source. To study the effect of polychromatic output and radiation profile of the UV-LEDs, various UV-LEDs with different peak wavelengths radiation profiles were investigated, as the representatives of typical UV-LEDs applied to microbial inactivation studies. In addition, the definition of parameters proposed in the fluence determination of the mercury-based UV lamps were modified to measure and quantify the collimation and uniformity of the radiation for a UV-LED experimental setup. Development of these factors results in fluence determination by measuring the irradiance for studying the kinetics of microorganism inactivation. We propose a proper setup configuration for microbial inactivation studies, based on the defined correction factors. Our results demonstrate how an appropriate setup and the correctly defined parameters are critical for microbial inactivation rate studies, and the UV-LED reactor design.
Quantitative Risk Analysis - What Does it Say About UV Disinfection for Drinking Water Treatment?
Harold Wright, Carollo Engineers Quantitative Risk Analysis - What Does it Say About UV Disinfection for Drinking Water Treatment?Harold Wright, Carollo Engineers USEPA developed Cryptosporidium inactivation requirements for UV disinfection within the Long Term 2 Enhanced Surface Water Treatment Rule, published in 2006, using quantitative microbial risk analysis. The risk analysis used a Monte Carlo approach to predict infections within a human population based on source water Cryptosporidium occurrence data from the Information Collection Rule (ICR) and the Supplemental ICR, reduction of oocysts through conventional, direct, and enhanced filtration, water consumption, and human dose response for infection and death. With this work, the EPA risk model was modified to include a Monte Carlo simulation of Cryptosporidium inactivation using the original UV dose-response data used by USEPA to develop the UV dose requirements. The model was used to assess the risk to public protection and the need for UV disinfection with various water sources and upstream treatment as well as the risks associated with off spec performance by the UV system. The analysis shows that an important risk driver is the water source; the ICR data and the Supplemental ICR data show that rivers and streams have a notably higher concentration of Cryptosporidium compared to lakes and reservoirs that justify application of UV technologies with those sources. The analysis also shows the relative impact of direct, conventional, and enhanced filtration on public health risk. Last, the analysis shows the relative impact of off-spec performance on public health risk, which in turn can be used to make informed decisions on how to address off-spec performance with UV system design. This presentation will walk through the USEPA model, highlighting the important differentiators, and present data on the outcome of the microbial risk analysis.
Revision of Technical Criteria in Japan on UV Disinfection for Drinking Water
Shioko Kurihara, Japan Water Research Center Revision of Technical Criteria in Japan on UV Disinfection for Drinking WaterShioko Kurihara, Japan Water Research Center In Japan, many of the drinking water treatment plants rely on surface water for water sources. Surface water is susceptible to contamination by pathogenic microorganisms such as Cryptosporidium, which calls for careful attention in its water treatment. For this reason, the Japanese utilities using surface water have conventionally made a very strict turbidity control through the coagulation, sedimentation and sand filtration in order to protect their drinking water from pathogenic contamination. On the other hand, this turbidity control and management is becoming increasingly difficult due to related ministerial notices and guidance, mass retirement of skilled technical staff, and the effects of unusual weather patterns in recent years. For these reasons, the Japan Water Research Center (JWRC) obtained a national research funding, assembled a research team consisted of academics and other water professionals, and conducted a study on a potential application of UV disinfection to surface water sources as a way to assist and supplement the current turbidity control. Our research concluded that the combination of filtration and the UV disinfection can be regarded as a useful option against pathogenic microorganisms. In response to this research result, the Ministry of Health is planning to revise the current national guidelines on Cryptosporidium countermeasures in order to allow the utilities to use the combination of filtration and UV disinfection as a new option to treat surface water sources. To respond to the expected revision of the national guidelines, JWRC is going to revise the JWRC’s existing technical criteria for the certification of UV treatment devices, including recently developed UV-LEDs. |
Validation-1Room: Colombo A
Considerations in development of validation guidelines for ultraviolet advanced oxidation processes for water recycling
Amos Branch, UNSW Considerations in development of validation guidelines for ultraviolet advanced oxidation processes for water recyclingAmos Branch, UNSW Validation refers to the process and activities to ensure water recycling technology can, and will continuously, meet predefined pathogen log removal value (LRV) targets. In Australia, a generic framework has been developed to assist with the preparation of validation protocols for water recycling technologies. To date, validation protocols have been developed for chlorine, ozone and ultraviolet (UV) disinfection processes, membrane bioreactors and reverse osmosis filtration technologies. A successful UV advanced oxidation process (AOP) validation protocol will need to define the achievable LRV and correlate removal performance to continuously monitored operational parameters. In addition, it is critical to define appropriate target pathogens and their microbial and non-microbial surrogates. One approach would be for UVAOP processes to be validated based on UV protocols, as the UV dosages used to promote photolysis are typically much higher than those required for typical UV disinfection. While this approach may be satisfactory, it is not rigorous and cannot account for the potential benefits of UVAOP in the removal of UV resistant pathogens. One of the primary reasons for installation of UVAOP processes has been to ensure the removal of chemicals of concern (COC) that may remain after advanced treatment. Surprisingly, there has been no focus on COC removal in previous Australian validation protocols. A gap analysis is currently underway, with the aim of collecting quantitative LRV data for a range of pathogens and COC by UVAOP. As part of this analysis, metadata in the form of operational parameters is also being collected. Interrogation of the final dataset will form the basis of recommendations for appropriate UVAOP LRV expectations and also assist with the specification of monitoring technologies and appropriate performance evaluation methods. Analysis findings will provide a preliminary guideline and be relevant to water recycling stakeholders including UVAOP technology suppliers, scheme operators and health regulators.
Update on Method Validations for Ballast Water Testing
Brian Petri, Trojan Technologies Update on Method Validations for Ballast Water TestingBrian Petri, Trojan Technologies The adoption of UV-based ballast water treatment systems is severely handicapped by the United States Coast Guard (USCG) rejection of the culture-based MPN method for measuring treatment performance in type-approval testing. The USCG formally rejected the MPN method in December 2015, and also rejected a scientific appeal in 2016, based on a review by the US Naval Research Labs (NRL) that was finalized later in 2016. It was via the appeal rejection that the USCG and NRL criticisms of the MPN method were communicated. Despite the rejection, the scientific support for the MPN method was strong; many of the criticisms were inconsistent with the evidence. Still, the MPN method can be accepted if proposed legislative changes can be enacted. To formalize the scientific case for the MPN method, significant progress has been made to publish a body of peer-reviewed literature on various aspects. In light of stated criticisms, a number of additional studies have been executed, and their output has also been published or is in preparation for publication. This paper will give an overview of the programme of work done for the MPN method, collaboratively with numerous industry and academic experts, and the resulting portfolio of publications. MPN is now the most thoroughly validated method for use in ballast water testing.
Fundamental Measurement of Ultraviolet Radiation: Part 1 – Historical Approaches and Practical Challenges for Disinfection
Ian Mayor-Smith, University of Brighton Fundamental Measurement of Ultraviolet Radiation: Part 1 – Historical Approaches and Practical Challenges for DisinfectionIan Mayor-Smith, University of Brighton Ultraviolet (UV) systems have enabled chemical-free disinfection in many applications over numerous decades. The increasing number of applications for both water and wastewater can be attributed to several factors including; excellent disinfection performance with key chlorine resistant pathogens, improvements in efficiency and reliability of practical technology and suitable methods performance assessment through validation protocols. Validation protocols such as those in the USA, Germany and Austria vary in several specific details however they all follow the same core principle. The protocols use `type testing’ of a system design producing a validated matrix using inputs of flow, UV transmission and sensor intensity. These inputs which can be more easily measured in the field and are related to a UV Fluence during type testing. UV fluence although in theory can be assessed in several ways, practically it is achieved using microbiological surrogates. A reduction in surrogate numbers is then used to calculate a UV fluence. Depending on validation methods used and application requirements of a system, numerous limitations can be experienced with this approach. One key current limitation is a stable, high concentration, class 1 organism that can be used universally for the measurement of high fluence for disinfection applications. This first presentation will review the fundamental principles underlying organism sensitivity, variability and viability. It will then present findings on an investigation from first principles to assess the potential of a high fluence viral surrogate for use in the disinfection of water.
Fundamental Measurement of Ultraviolet Radiation: Part 2 – Investigating Next Generation Measurement Methods
Ian Mayor-Smith, University of Brighton Fundamental Measurement of Ultraviolet Radiation: Part 2 – Investigating Next Generation Measurement MethodsIan Mayor-Smith, University of Brighton Ultraviolet (UV) systems have enabled chemical-free disinfection in many applications over numerous decades. The increasing number of applications for both water and wastewater can be attributed to several factors including; excellent disinfection performance with key chlorine resistant pathogens, improvements in efficiency and reliability of practical technology and suitable methods performance assessment through validation protocols. Validation protocols such as those in the USA, Germany and Austria vary in several specific details however they all follow the same core principle. The protocols use `type testing’ of a system design producing a validated matrix using inputs of flow, UV transmission and sensor intensity. These inputs which can be more easily measured in the field and are related to a UV Fluence during type testing. UV fluence although in theory can be assessed in several ways, practically it is achieved using microbiological surrogates. A reduction in surrogate numbers is then used to calculate a UV fluence. However, there is a range of limitations imposed using a traditional surrogate which include:
In part II a novel approach to measurement will be presented and assessed in in comparison to traditional methods. The assessment will include assessing suitability for use with polychromatic sources and its impact on fundamental calculation of UV fluence. | Disinfection-2Room: Colombo B
Los Angeles Department of Water and Power: Maintaining Water Quality and Supply with UV Technologies
Michael Maxwell, Arcadis Los Angeles Department of Water and Power: Maintaining Water Quality and Supply with UV TechnologiesMichael Maxwell, Arcadis The Los Angeles Department of Water and Power (LADWP) is the largest water and power utility in the United States serving the 4 million residents of the City of Los Angeles (City). The City encompasses an area of 465 square miles. The largest source of drinking water for the City is imported surface water and the second largest is local groundwater. The use of UV technologies has become an important tool for the City to maintain both compliance with water quality regulations and the beneficial use of groundwater sources. The three projects featured in the presentation are:
The presentation will include the following:
Effect of Particles on UV Disinfection in a Recycled Water Application
Sam Costello, Melbourne Water Effect of Particles on UV Disinfection in a Recycled Water ApplicationSam Costello, Melbourne Water Western Treatment Plant (WTP) is a large lagoon-based wastewater treatment plant serving Melbourne, Australia. Class A recycled water is supplied to customers for end uses including irrigation of salad vegetables and firefighting. The recycled water treatment train includes activated sludge treatment and treatment in maturation lagoons followed by ultraviolet (UV) and chlorine disinfection, but does not include a filtration step. Melbourne Water investigated whether particle shielding affected UV disinfection of pathogens in unfiltered feed waters (indicated by turbidity >1 NTU), and questioned whether USEPA UV disinfection doses referenced in the 2006 Ultraviolet Disinfection Guidance Manual (UVDGM) were applicable to these unfiltered water recycling applications. The degree of particle shielding is highly site-specific, and some previous studies (such as Nelson, 2000, and Loge et al, 2001) suggested that lagoon effluents, and activated sludge process effluents with high sludge age and no addition of chemical coagulants (as at WTP), are less prone to particle shielding. Experimentally, particle shielding is difficult to assess directly as target pathogens are typically present in very low numbers, but the matter can be assessed using a suitable indigenous surrogate. In this case, indigenous E. coli was identified as a suitable surrogate microbe for the assessment of particle shielding. UV dose-response experiments conducted on lagoon samples demonstrated that there was no undisinfectable fraction of microbes at WTP, despite the presence of particles of sufficient size to cause shielding. In all experiments, complete inactivation of indigenous E. coli was obtained with standard UV doses, demonstrating that particle shielding was not a concern in the disinfection of the effluent from WTP, up to the maximum turbidity tested of 19 NTU. These results agree with the published literature as the operational and water quality factors that minimize the impact of particles on disinfection are characteristics of WTP lagoon effluent.
Retrofitting the largest UV disinfection drinking water plant in Australia at Melbourne Water’s 600 MLD Winneke WTP
Jon Bates, Jacobs Retrofitting the largest UV disinfection drinking water plant in Australia at Melbourne Water’s 600 MLD Winneke WTPJon Bates, Jacobs Approximately 40% of Melbourne’s water can be supplied from Sugarloaf Reservoir, which sources water from the Mid Yarra ‘open’ catchment and the Maroondah Reservoir. This supply is treated by Winneke Water Treatment Plant (WTP), a 600 MLD conventional treatment plant. Flows are pumped to the WTP, with gravity flow within the WTP. Opportunities were identified to optimize UV system sizing and plant hydraulics through modification of plant controls to reduce the peak design flow and variability. The Australian water industry is preparing for the introduction of Health Based Targets (HBTs) in the Australian Drinking Water Guidelines. Melbourne Water has completed sanitary surveys and source water assessments for its drinking water supplies, following the Water Services Association of Australia Draft HBT Manual (WSAA 2015). In addition, for the Mid Yarra source water, a point-estimate Quantitative Microbial Risk Assessment (QMRA) was conducted. Results confirmed the recommended Log Reduction Values (LRVs) achievable by Winneke WTP. A best practice approach applies multiple treatment barriers to achieve the recommended LRVs. This is particularly advisable when treating ‘unprotected’ source waters such as the Mid Yarra. Winneke WTP’s multiple barriers include coagulation / sedimentation / filtration and chlorination. However, a further consideration is planning for future uncertainty, with regards to climate change and drought, which may present particular water quality challenges. Under this context, Winneke WTP’s treatment train is being augmented with UV disinfection, to manage water quality risks into the future. The UV system will be capable of 3.0 log protozoa reduction. This paper discusses these issues and presents the concepts developed to enable retrofitting of UV disinfection at Winneke WTP, which will be the largest drinking water UV disinfection system in Australia.
Confessions from a UV Performance Assessment
Graham Smith, Fluidquip Australia Pty Ltd Confessions from a UV Performance AssessmentGraham Smith, Fluidquip Australia Pty Ltd Confessions from a UV Performance Assessment In March 2018, South Gippsland Water (SGW) engaged Fluidquip Australia (FQA) to undertake a review of the performance of two UV disinfection systems installed at its Meeniyan and Dumbalk WTPs, some 150 kms south east of Melbourne. The brief of the assessment was as follows:
While the UV systems were found to be performing adequately, it was determined that the relative UV intensity monitors were constantly fixed at 100% intensity regardless of lamp age. This led to a detailed investigation into why this was the case as it was highly unlikely the lamps would remain at 100% intensity until they were replaced at the routine 12 month intervals. The investigation involved the somewhat forensic examination of SCADA traces, FQA servicing and maintenance procedures and operator diary entries. This led to the determination that it was highly likely that the inappropriate resetting of the intensity monitors was responsible for the spurious monitor readings. This presentation examines the methodology employed in conducting this UV assessment and the subsequent investigation, as an example of how to conduct such an assessment. It also covers the sometimes unexpected findings that may result and the operational and procedural benefits that can be derived and implemented.
Application of a novel, continuous-feeding ultraviolet light-emitting diode (UV-LED) system to disinfect domestic wastewater for discharge or agricultural reuse
Thi Minh Hong Nguyen, Asian Institute of Technology Application of a novel, continuous-feeding ultraviolet light-emitting diode (UV-LED) system to disinfect domestic wastewater for discharge or agricultural reuseThi Minh Hong Nguyen, Asian Institute of Technology This research investigated the application of ultraviolet-C light emitting diodes (UV-C LEDs) for wastewater reuse for agriculture in low- to middle-income countries. Research conducted at the Asian Institute of Technology (AIT) north of Bangkok, Thailand evaluated an inexpensive option for pretreating domestic wastewater to an appropriate quality for disinfection by UV-C LED irradiation. Domestic wastewater collected from a manhole at the Asian Institute of Technology was continuously flowed through a low-cost pretreatment system with an inclined settler and a sand filter before exposure to a novel UV-C LED flow-through reactor emitting at 280 nm. At an inlet flow rate of 30 L/h, the COD, TSS, and turbidity of the effluent were 17.7 mg/L, 3.0 mg/L, and 3.9 NTU, respectively. UV transmittance at 285 nm was enhanced from 29% to 70%, improving the influent quality for UV LED disinfection. In the flow-through UV LED process, 3.7-log MS2 inactivation was achieved at a flow rate of 10 mL/min, corresponding to an applied UV dose of 69.4 mJ/cm2. The increase of the inlet flow rate to 20, 30, 40, and 50 mL/min reduced disinfection performance to 3.4, 3.1, 2.8, and 2.6-log MS2 inactivation, respectively. The corresponding UV doses reached are sufficient for disinfecting water for agricultural use, which would meet the USEPA guideline for water reuse. It has been claimed that fouling in mercury lamp UV disinfection reactors is due primarily to inorganic constituents, taking place mostly on the quartz sleeve and resulting from the effects of temperature. In contrast, the fouling in this UV LED system was primarily organic, taking place both on the quartz and on the reactor’s interior surface; it was also attributed in part to hydrodynamic conditions and the reactor’s configuration. In this study, volatile solids content accounted for 67% of the total fouling constituents. Fouling of the flow-through reactor occurred within 2 days of operation with an average reduction of 0.12 ± 0.03 log MS2 inactivation per day. After 25 days of continuous operation, the UV LED system fouling coefficient reduced from 1.0 to 0.27. Fouling reversal was possible with 4 hours of citric acid soaking, restoring the UV LED flow-through reactor to its original disinfection efficacy. The required frequency of offline chemical cleaning, which depends on the water quality, the degree of fouling, and the applied dose, depends on the reactor configuration and UV emission source as well. This study can act as a starting point from which to base future research and future guidelines. Given additional advancements and cost reduction and scaling up to meet capacity, UV-C LED technology has great potential for application for wastewater reuse for agriculture. | UV for Food & Beverage SafetyRoom: Colombo C
Opportunities for UV Solutions in Food and Beverage Safety and IUVA’s role
Peter Gordon, Bolb Corporation Opportunities for UV Solutions in Food and Beverage Safety and IUVA’s rolePeter Gordon, Bolb Corporation Coming Soon.
Sterilisation of skim milk and whey protein using UV in combination with heat
Mohammed Farid, The University of Auckland Sterilisation of skim milk and whey protein using UV in combination with heatMohammed Farid, The University of Auckland Ultraviolet (UV) treatment has been used for the treatment of clear liquids including some juices and water providing the benefit of microbial inactivation at lower temperatures with minimum energy. UV can inactivate microorganisms by targeting their DNA and thereby, affects replication and leads to cell death. It is usually used as a non-thermal processing, which retain most nutrients and physicochemical properties. In this presentation, the effect of using a combination of thermal and UV treatments to inactivate spores in a range of liquid food products will be discussed. This is an attempt to replace conventional UHT processing, which requires treatment at elevated temperature that causes negative impact on quality.
Optimization of UVC LED emitters for safety, shelf-Life extension and spoilage avoidance of fresh produce
Tatiana Koutchma, Agriculture and Agri-Food Canada (AAFC) Optimization of UVC LED emitters for safety, shelf-Life extension and spoilage avoidance of fresh produceTatiana Koutchma, Agriculture and Agri-Food Canada (AAFC) Coming Soon.
UV-C tolerance of microorganisms from food processing water stream
Eirini Vitzilaiou, University of Copenhagen UV-C tolerance of microorganisms from food processing water streamEirini Vitzilaiou, University of Copenhagen Coming Soon.
Ultraviolet light inactivation of microorganisms in fruit juices
Roman Buckow, CSIRO Agriculture & Food Ultraviolet light inactivation of microorganisms in fruit juicesRoman Buckow, CSIRO Agriculture & Food Coming Soon. |
Validation-2Room: Colombo A
Comparison of UV Reactor Validations using Combined Variable and Bracketing Approaches
Brian Petri, Trojan Technologies Comparison of UV Reactor Validations using Combined Variable and Bracketing ApproachesBrian Petri, Trojan Technologies UV reactors are validated for disinfection performance through challenges using non-pathogenic microorganisms. However, UV reactor performance varies with microorganism UV sensitivity (DL). In order to obtain disinfection credit for a target pathogen with a different DL , the USEPA Ultraviolet Disinfection Guidance Manual (UVDGM) introduces a necessary correction factor called the RED Bias. Tables of RED Bias values based on model calculations are given in Appendix G of the UVDGM. An alternative to testing a UV reactor with one microbe and using generic RED Bias values to adjust the results to different DL values of target pathogens, is to test with multiple microbes with a range of DL values. This approach includes the variable DL as part of the test matrix, and produces an operating equation for the UV reactor as a function of flow, UVT, sensor intensity, and also DL. This operating equation can be used to determine sizing for any target pathogen with a DL within the range of DL values tested through interpolation. Recently the USEPA produced a UV Compendium to the UVDGM, that describes another alternative approach that builds upon the bracketing approach. In this new approach, testing is done with two specific challenge microbes (MS2 and T1), and an operating equation as a function of UVT and a combined variable (CV: sensor intensity/flow/DL) is determined. This operating equation can be used to determine sizing for any target pathogen with higher or lower DL than those tested, where the CV is within the range of tested CV values (as long as the CV is constrained to remain within the tested flow range). We completed a multiple microbe challenge of a family of UV reactors, using 4 different test microbes including MS2 and T1. We developed UV reactor operating equations using both the bracketing approach (using all 4 microbes) and the combined variable approach (using MS2 and T1 and the combined variable). In this paper we will show how the operating envelopes and credited performance differ by processing the same datasets by these two accepted methods.
Innovative Approaches for UV Validation - Critiques and Response
Harold Wright, Carollo Engineers Innovative Approaches for UV Validation - Critiques and ResponseHarold Wright, Carollo Engineers USEPA is currently finalizing the document entitled ‘Innovative Approaches for Validation of Ultraviolet Disinfection Reactors for Drinking Water Systems.’ This document is the result of a four year project, funded by USEPA, to develop new approaches for UV dose monitoring and validation that incorporates advances in UV dose monitoring developed since the publication of the 2006 UV Disinfection Guidance Manual. The draft final document has completed a one-year review by stakeholders that include regulators, academia, consultants, and UV system manufactures. An important aspect of the review was provided theoretical and experimental evidence that supported the approaches provided in the document, and providing validation protocols that robustly demonstrated these approaches. The EPA document states that log inactivation by a UV reactor at a given UVT can be modeled as a function of a combined variable defined as S/S0/Q/DL where S/S0 is the relative lamp output indicated by UV sensor readings, Q is the flow through the reactor, and DL is the UV sensitivity of the microbe. Furthermore, analysis of these relations can be used to define an equation that predicts log inactivation as a function of UVT and the combined variable. The equation can be used to provide direct predictions of pathogen inactivation by setting DL to the value specific to that pathogen, hence eliminating RED bias and considerably simplifying the application and reducing the costs of UV technologies. With the use of low and high wavelength UV sensors, the approach can also take advantage of low wavelength UV dose delivery by UV systems using MP lamps, eliminating the need to apply action spectra correction and polychromatic bias factors. This presentation provides an overview of these approaches, feedback from the one year stakeholder review, and presents theoretical and experimental data that prove the approaches
The Significance and Quantification of UV dose for Potable Water Reuse Applications
Mark Heath, Carollo Engineers, Inc. The Significance and Quantification of UV dose for Potable Water Reuse ApplicationsMark Heath, Carollo Engineers, Inc. The increasing demand for water, due to drought, population increase or climate change, has placed an increased focus on the need for potable reuse in the water treatment industry. Treatment goals for potable reuse include extensive pathogen removal (e.g., 12-log virus), comprehensive chemical removal (e.g., meeting all MCLs), and layers of redundancy for both pathogens and trace level chemical pollutant destruction. UV is the most critical of all the potable water reuse treatment processes, providing three critical values:
UV dose requirements to achieve these goal range from 250 mJ/cm2 to greater than 1500mJ/cm2, and are significantly greater than those required for drinking water treatment, specified in the USEPA UVDGM, or for non-potable reuse applications outlined in the NWRI guidelines. A primary challenge to the industry is how to validate, monitor and control UV treatment processes for potable reuse applications. Validation testing is widely used and accepted for drinking water and non-potable reuse applications. However significant challenges exist for high UV dose validation in potable reuse applications. Demonstrating pathogen removal requires the use of large amounts of MS2 phage or the use of highly resistant surrogates such as Bacillus or Aspergillus spores. Often UV treatment in potable reuse applications follows RO treatment, which produces a water in which biological surrogates are highly unstable, further complicating the validation process.
This presentation will discuss UV validation testing that Carollo has performed for three pilot scale and one full-scale potable reuse project in the US, focusing on validation of UV dose delivery using biological surrogates, procedures developed to overcome biological instability in RO permeates, and evaluation of NDMA removal by photolysis and removal of 1-4 dioxane removal via UV advanced oxidation processes.
UV Dose Monitoring Simplified for Small Systems
Traci Brooks, Carollo Engineers UV Dose Monitoring Simplified for Small SystemsTraci Brooks, Carollo Engineers The UV Disinfection Guidance Manual (UVDGM) provides 2 approaches for UV dose monitoring, the UV intensity setpoint approach and the calculated dose approach. The setpoint approach relies on the UV intensity and flow rate to determine if the reactor is providing an adequate dose without the need for a UVT monitor. The calculated dose approach monitors the UV dose using the measured flow rate, lamp output, and UVT values. A new approach has been developed that uses the calculated dose approach to predict log inactivation and RED as a function of the flow rate, UV sensor readings, and the UV sensitivity of the predicted microbe without requiring an on-line UVT monitor. CFD-based UV dose models and validation data show that log inactivation by a UV reactor operating with a given number of lamps at a fixed UVT lies along a single relationship defined as a function of the combined variable, S/(QxDL). If the UV sensor is optimally positioned, the relationships between the log inactivation and the combined variable at different UVTs tend to align on top of each other. When this occurs, a single relationship between log inactivation and the combined variable can be defined for efficient UV dose monitoring that does not require an online UVT monitor. This approach is ideal for small systems that require simple effective monitoring for pathogen inactivation credit.
This presentation describes the validation and application of this new approach on the Hanovia UVEO UV reactor series.
| Disinfection-3Room: Colombo B
Comparison of two UV disinfection systems performances, operation and maintenance, after the complete substitution of one parallel by one staggered
Alvaro Irigoyen, estudio irigoyen Comparison of two UV disinfection systems performances, operation and maintenance, after the complete substitution of one parallel by one staggeredAlvaro Irigoyen, estudio irigoyen This study examines in depth the complete substitution of one parallel disinfection system by one staggered after an initial failure. The maximum capacity of the system is 4,960 cubic meters per hour (m3/h) The ultraviolet transmittance (UVT) of the influent to the systems is less than 50 per cent (sometimes 40) and the total level of suspended solids is typically less than 30 mg/l. This low value was the design objective for treatment. To reach better values of UVT, we need to use higher doses than designed of flocculants with the risk of inhibition of the anaerobic sludge digestion. After an initial failure, the operation and maintenance group working in close collaboration with provider engineers ,studied in depth the design and performance of the system, concluding the equipment installed in this plant had a design with some parameters that limited it, making more difficult the access to the desired performance. After more than two years of working with each equipment (parallel first and inclined now) we are ready to compare in depth the design and the efficiency of each one. The author made studies and comparison of: costs of installation, time and costs for startup and commissioning, costs and time of maintenance, and costs of disinfection including energy and spare parts. All of these are relative to the performance of disinfection and are expressed in absolute values. The cost of the substitution was lower than the expected and the performance in order of disinfection higher. During the past year, the first important scheduled maintenance for the transversal system was performed, including changing lamps and ballasts. All those cost were compared with the same works made to the parallel one. Finally we can made recommendations for future works similar as this one we made.
Big Sky County Water & Sewer District Installs UV Disinfection System for 4-Log Virus Credit
Phyllis Butler Posy, Atlantium Technologies Big Sky County Water & Sewer District Installs UV Disinfection System for 4-Log Virus CreditPhyllis Butler Posy, Atlantium Technologies For more than 40 years the Big Sky County Water & Sewer District in Montana has maintained great tasting, award-winning, safe water. In 2015 the district drilled two new groundwater wells to help meet growing demands, and these new wells were for 4-log virus treatment. In 2015, the District had won state and national AWWA taste awards and they were reluctant to add chemicals that could spoil the quality and taste of their water. As a result, ultraviolet (UV) was evaluated and selected as the disinfection technology of choice. UV provided a non-chemical treatment approach that would help preserve their clean tasting water while achieving full disinfection credit and compliance. A medium pressure UV system, validated for 4-log virus removal using live adenovirus, was selected and implemented at Big Sky. This paper will profile the UV disinfection installation for 4-log virus credit as an example of how small systems can comply now and assure future compliance even as conditions change.
UK’s largest Nereda Plant followed by UV
Ludwig Dinkloh, Xylem Services GmbH UK’s largest Nereda Plant followed by UVLudwig Dinkloh, Xylem Services GmbH A sewage treatment plant in the North West of England has a domestic population equivalent of 31,000 and a total population equivalent of 83,000 when taking into consideration trade load. The overall population equivalent is set to increase to 92,897 PE by 2036. The final effluent is discharged to a river in a designated Special Area of Conservation (SAC). Prior to a major upgrade, the works consisted of a COAST (Combined Oxygen Activated Sludge Tank), four secondary settlement tanks, ten nitrifying trickling filters with four humus tanks, and three disc filters. Iron was dosed downstream of the nitrifying filters / into the humus tanks for chemical phosphorus removal, when required, and the disc filters were primarily to limit the iron concentration in the final effluent. The majority of the main existing process stream is now replaced with a new proprietary “Nereda” activated sludge system. The system continues to use the disc filters to ensure the limit on final effluent iron and phosphorus concentration is achieved. In addition, a UV disinfection system is installed to achieve a reduction in faecal indicator organism (FIO) load to the Shellfish designated area. At a maximum flow rate of 533 l/s, the UV system has to deliver a validated UV dose of 20 mJ/cm² at a UV transmittance of 20.2% / 1 cm. The utility’s construction partner selected a Xylem Wedeco Duron UV system with a total of 9 UV banks with inclined high intensity low pressure UV lamps of which one is a dedicated stand-by bank. The Nereda system and the down-stream UV system will become operational October 2018. The paper will describe the background of the project, the UV-specific challenges (e.g. low UV transmittance), the on-site installation and commissioning of the selected UV system.
First large-scale UV Crypto Barrier in Florida
Ludwig Dinkloh, Xylem Services GmbH First large-scale UV Crypto Barrier in FloridaLudwig Dinkloh, Xylem Services GmbH Cryptosporidium is the leading cause of waterborne disease outbreaks in the US, impacting almost 750,000 people each year with potentially severe symptoms. As the chlorine-resistant cryptosporidium parasite is easily inactivated with a low ultraviolet (UV) dose, many drinking water plant operators are turning to UV disinfection to provide safe drinking water for their communities. The West Palm Beach Water Treatment Plant treats water from East Clear Lake for potable use by the city and surrounding communities, including a number of critical medical facilities. Upon completion of the major upgrade project, the plant will serve over 110,000 people, with a maximum treatment capacity of 47 MGD. Besides the flow rate, the UV disinfection design is specified as follows:
Xylem’s Wedeco LBX 1500e UV disinfection systems were selected by West Palm Beach because they deliver the lowest life-cycle cost. This is primarily due to the energy efficiency of the low-pressure high-output (LPHO) Wedeco Ecoray lamps and the relative low head loss of the UV reactors. Construction at the West Beach Water Treatment Plant began in 2016, and the facility is expected to enter operation in 2018.
The paper will describe the background of the project, the UV-specific challenges (e.g. low UV transmittance), the pre-selection process with its outcome and the on-site installation and commissioning of the selected UV systems.
Proliferation potential of UV-254 nm irradiated drinking water
Regina Sommer, Medical University Vienna, Institute for Hygiene Proliferation potential of UV-254 nm irradiated drinking waterRegina Sommer, Medical University Vienna, Institute for Hygiene In recent years, UV irradiation has gained great international importance as an essential treatment step in primary disinfection of drinking water. Primary disinfection targets fecal orally transmissible pathogens, as there are pathogenic viruses (e.g. Norovirus), bacteria (e.g. Campylobacter) and protozoa (e.g. Cryptosporidia). Even disinfected and safe drinking water contains a large number of indigenous microorganisms, the so-called microbiota. Some representatives of this group are opportunistic pathogens that can endanger human health, if proliferation takes place and the concentration of the microorganisms reaches the infective dose. These pathogens include for instance Legionella species and Pseudomonas aeruginosa. In our study, we were interested in the extent to which water bacteria can proliferate after UV irradiation of drinking water under regular conditions in the water work by applying a UV fluence (254 nm) of at least 400 J/m2. For this purpose, we established a standardized method for the measurement of the proliferation potential. It is based on the controlled storage of water samples in carbon-free vessels over a period of one to three weeks. The analysis of the concentration of heterotrophic water bacteria was performed with a culture-based method. Water samples have been taken under regular waterworks operation immediately before and after irradiation in UV systems validated according to Austrian Standard ÖNORM M 5873-1.
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