2017 Progress Report: Design of Risk-reducing, Innovative-Implementable Small-System Knowledge(DeRISK) Center

EPA Grant Number: R835603
Center: Design of Risk-reducing, Innovative-Implementable Small-System Knowledge Center
Center Director: Summers, R. Scott
Title: Design of Risk-reducing, Innovative-Implementable Small-System Knowledge(DeRISK) Center
Investigators: Summers, R. Scott , Barrett, Joy , Collins, M. Robin , Cook, Sherri , Corwin, Christopher , Dotson, Aaron , Hogrewe, William , Hristovski, Kiril D , Linden, Karl G. , Malley, James P. , Seidel, Chad , Uber, Jim , Westerhoff, Paul
Institution: University of Colorado at Boulder , Arizona State University , Rural Community Assistance Partnership , University of Alaska - Anchorage , University of New Hampshire , University of Texas El Paso School of Public Health
EPA Project Officer: Hiscock, Michael
Project Period: September 1, 2014 through July 31, 2017 (Extended to July 31, 2018)
Project Period Covered by this Report: September 1, 2016 through August 31,2017
Project Amount: $4,099,973
RFA: National Centers for Innovation in Small Drinking Water Systems (2013) RFA Text |  Recipients Lists
Research Category: Drinking Water , Water

Objective:

Project 1: New Strategies for Technology Assessment and Implementation

  • Develop and test a decision support framework to evaluate the long-term sustainability of small drinking water systems.
  • Develop, refine and disseminate a risk reduction based strategy that will facilitate improvements in the effectiveness and sustainability of small drinking water systems throughout the U.S.

Project 2: Application of photochemical processes for the design and implementation of sustainable treatment for small systems

  • Explore the applications of photochemical processes, including both sunlight and engineered light sources, to advance water quality and provide effective photon-based treatment for small systems. 

Project 3: Extended Biofiltration for the Control of Microbial Contaminants and Disinfection By-Products

  • Reduce the risk associated with surges in particulate matter, an indicator of microbial contaminants, in source water and in settled water using innovative filter options that also allow for the control of disinfection by-product (DBP) precursors and preformed DBPs.

Project 4: Distribution System Innovations

  • Explore, develop, model and disseminate technologies that will offer small systems a better understanding of their distribution system so that microbial risk can be reduced and preformed DBPs controlled more efficiently at the most problematic locations.

Progress Summary:

Project 1: New Strategies for Technology Assessment and Implementation

Results:

Outputs

  • Developed a spreadsheet-based tool that utilizes source water quality and treatment specification inputs. The tool outputs relative risk reduction comparisons across alternative treatment trains based on contaminant concentrations of finished waters. Finished water qualities of alternative treatment trains are predicted using available models (e.g. USEPA Water Treatment Plant (WTP)) and those developed as a part of DeRISK Center research). The relative public health risk reductions for each technology are compared by applying the Relative Health Indicator (RHI) metric to the predicted finished water quality parameters from treatment model outputs.
  • Developed the life cycle assessment (LCA) model framework was developed using ISO 14040 methodology that uses the following steps: (1) goal and scoping (defining the functional unit and system boundary), (2) inventory assessment (quantifying all materials, energy, and chemicals used in a treatment process using Ecoinvent LCI data), (3) impact assessment (using the U.S. EPA TRACI LCIA method), and (4) interpreted (iterating as needed and conducting sensitivity and uncertainty analyses). The model framework was implemented in a spreadsheet application.
  • Developed a spreadsheet-based decision support framework, as well as guidelines for usage. The decision support tool accounts for cost, environmental impacts, health risk, and other criteria that can be described as stakeholder or community preferences. Analytic Hierarchy Process (AHP) is used to weight and rank criteria that account for social, environmental, and economic sustainability of small drinking water treatment alternatives. This framework can be used to provide a systematic, consistent, and transparent decision-making process to rank and select technologies, based on small system needs–especially to minimize environmental and health impacts without compromising water quality or affordability.
  • Developed the general structure of the Training Design Tool (TDT) that includes training design approaches as well as information that is needed by specific stakeholders to participate in the consideration of innovative drinking water technologies.
  • Created a unique framework that the ability to ingest data from State maintained Safe Drinking Water Information System (SDWIS) databases, locate them geographically, and through queries identify technology similarities between small water treatment plants. Use of this framework has the ability to improve human health and the environment by providing operators a tool to identifying nearing communities can could assist them in time of need in the case that the state-wide circuit rider or remote maintenance working program is unable to attend to their needs.
  • Installed and monitored effectiveness of UV pilot demonstration projects for a period of one year of continuous operation. Two pilots were completed and removed from the sites at HAWC-Kingston, NH using a Berson-Aquionics MP system and Bethlehem, NH using a Trojan MP.  The Star Island using a Xylem LPHO is fully operational and ran for the 2017 season. 

Outcomes

  • Project 1 provides small drinking water systems with a method of making informed decisions on infrastructure modifications that will result in more effective, efficient, and sustainable operations. The spreadsheet-based model will be provided free of cost to small systems (and will come with a user’s guide, which will include how the model can be easily modified to better meet a specific system’s needs).

Conclusions

  • The RHI model identified that as DBP regulatory compliance strategies, optimized coagulation processes and granular activated carbon (GAC) adsorption at the treatment plant were found to provide superior public health protection than GAC and aeration technologies applied within the distribution system when population-weighted RHI values were considered.  The relative efficiencies of distribution system technologies tended to be equivalent to those applied at the treatment plant as evidenced by normalizing population-weighted RHI reductions.
  • The LCA model incorporates detailed data on currently available technologies, and it can be easily modified to add new technologies as they are developed and made available. This framework provides the foundation to evaluate current and future technologies in order to minimize global public health and environmental impacts without compromising water quality. Small drinking water systems can evaluate treatment options unique to them (e.g., bag and cartridge filtration) and identify the most effective approach to reduce materials, chemicals, and energy use.
  • The spreadsheet-based decision support framework can identify and resolve conflicts of priorities and values between and in stakeholder groups. It can also provide a systematic, consistent, and transparent decision-making process to rank and select technologies, based on small system needs–particularly to minimize environmental and health impacts without compromising water quality or affordability.
  • The TDT development identified training objectives, stakeholders and their motivations, and challenges including innovative drinking water technologies when evaluating alternatives.
  • The project succeeded at creating the GIS-based tool using Alaska SDWIS data that can be used to generate the alliances; however, the project has been redirected to evaluate the potential implementation pitfalls associated with security risks associated with making data publicly available.
  • The UNW UV case studies provided key information to inform the other activities in Project 1 on small drinking water stakeholder, issues, concerns, priorities and decision-making processes.

 

Project 2: Application of photochemical processes for the design and implementation of sustainable treatment for small systems

Results:

Outputs

  • Sampling conducted at snowmelt and tropical water field sites & photochemical analyses & inactivation experiments completed for samples.
  • Demonstrated a concept reactor that employs photo-catalyst (TiO2 nanoparticles) coated optical fibers to photo-catalytically reduce nitrate to innocuous nitrogen gases.
  • Performed bench testing to understand the potential synergies of multi-wavelength UV LED combinations. UV sources included LEDs (light emitting diodes), a KrCl excimer lamp, and a conventional low pressure (LP) mercury lamp, medium pressure mercury lamps were also tested. 
  • Viral disinfection by the PearlAqua was modeled using the first application of the combined variable approach to a UV LED reactor, providing a basis for comparison of the bench validation results to pilot-scale results of quarterly virus challenge tests. 
  • The commercially available PearlAqua (Aquisense) UV LED disinfection reactor was installed in the slow sand filter effluent in the small drinking water treatment system in the mountain town of Jamestown, CO (Hull et al., 2017, in preparation). The MS2 disinfection performance of the flow-through UV LED reactor was measured at various flowrates and UV transmittances (UVTs) measured at 285 nm (the wavelength emitted by the LEDs) at the bench in dechlorinated tap water.
  • Testing completed of bench- and pilot-scale of process unit integrating ceramic membrane/ UV light.

Outcomes

    • A full patent related to this work has been received: K Doudrick, KD Hristovski, PK Westerhoff, (2017) Photocatalytic reduction of oxo-anions, US Patent 9,751,785.
    • Data and approach developed that can be used to compare, validate, and test other reactors in the rapidly developing UV LED industry.

Conclusions:

  • Water retention ponds are a viable pre-treatment technology to initially reduce the concentrations of pathogens and natural organic matter (NOM) by sunlight enhanced mechanisms for small systems for the inactivation of pathogens E. coli and Adenovirus Type 2, but not MS2). More barriers of control must be implemented in order for water retention ponds to treat for required MS2 inactivation.
  • Flow through reactors could be designed and optimized to reduce nitrate to innocuous nitrogen gases with high quantum efficiency and low electrical energy per order of treatment (EEO) by tailoring of the photocatalyst, selectivity mechanisms, and irradiation light wavelengths.  As a result of the project, (1) an understanding of the existing reduction nitrate mechanisms has been developed and (2) feasibility has been demonstrated for a small scale reactor concept that enables low LED energy or sunlight uses to minimize the risk portfolio for nitrate.
  • The year-long resilience and effectiveness of the first drinking water treatment pilot testing of the first commercially available UV LED reactor, operated continuously for nearly one year with zero maintenance, with an electrical cost estimated to be < $25. 
  • For UV-C LEDs to match the electrical efficiency per order of log reduction of conventional LP UV sources, they must reach efficiencies of 25–39% or be improved on by smart reactor design. 
  • Data provide proof of concept as LEDs as a feasible option for disinfection, provide information to guide increased practicality of their implementation, and provide mechanistic insight necessary to optimize and possibly monitor viral inactivation by polychromatic germicidal UV irradiation.
  • Damage of MS2 proteins and HAdV2 viral proteins (as shown in Figure 1) was greatest at wavelengths < 240 nm and near 280 nm where protein absorbance is greatest.  No significant protein damage was inflicted on either virus by LP UV.  Enhanced HAdV2 and MS2 inactivation at low wavelengths correlates with protein damage at those wavelengths. 
  • Among the excimer lamp, LEDs, and the LP lamp, the excimer lamp was most effective at inactivating MS2, in concurrence with the action spectrum of this virus where low wavelengths are most effective for disinfection as shown in Figure 2. Published action spectra can be used to model optimization of wavelength-specific disinfection without prior bench testing.  Sequential exposures incorporating the excimer lamp resulted in greater inactivation at a lower total UV dose versus single exposure to the non-excimer lamp alone.
  • Using this evidence, UV disinfection systems could be designed incorporating the excimer lamp to achieve viral disinfection regulatory requirements at lower doses than are currently prescribed, as demonstrated in Figure 3.  Because the excimer lamp has similar electrical efficiency to the LP lamp, this will save electrical costs while providing equal or better public health protection. 
  • A system incorporating the KrCl excimer lamp with LED(s) would be a mercury-free way to achieve these advantages of wavelength-specific UV disinfection.
  • VUV improves the flux of silicon carbide membranes by an average 533.5% compared to NUV and decreases TMP at the same flow rate (17.1 L/min). As demonstrated below in Figure 47, VUV significantly improves flux over time (Alvey and Dotson, 2017).  Further, derivatives of these experiments are still being executed and the data is being prepared for publication early next year when fouling experiments are complete.
  • Operating at high TMPs is preferable to increase total permeate volume.  This data is ongoing in order to determine a balance between total product volume and energy used for.

 

Project 3: Extended Biofiltration for the Control of Microbial Contaminants and Disinfection By-Products

Results:

Outputs:

  • Jar test & bench scale tests completed to evaluate enhancements to course media roughing filters
  • Bench scale tests completed to evaluate the control of DBPs and DBP precursors by extending the EBCTs up to 30 minutes.
  • Biofilters in UCB pilot plant used used to evaluate DBP precursor removal and control of surges in particulate matter
  • Extended EBCT filter implemeneted in a small water system in Jamestown, CO

Conclusions:

  • Filamentous and suspended algae can enhance particle removal by GRFs and lessen the impact of water quality spikes but maintaining a monoculture or establishing uniform surface coverage of the GRF with the desired algal specie was problematic. Adding precursor material and other undesirable algae based by-products to the water supply reduced the desire to explore algae enhancements further.
  • The use of a “bio-friendly” coagulant added prior to the GRF was explored using primarily MgO/Mg(OH)2 addition. Indeed, the positive-charged MgO/Mg(OH)2 “sweep floc” showed  potential for attaching negative-charged kaolinite clay particles, E. coli and organic precursor material, but a high pH > 11.5 was required to keep the Mg in particulate form and thus amenable to capture by the GRF. Controlling such large pH changes required by small water systems was not deemed practicable to pursue further. 
  • The biofilters that were exposed to enriched nutrient solutions have continually increased active biomass over time, while the control kept the same initial active biomass concentration (see Figure 2). Over 3 weeks runtime, ATP was highest on the filter that had highest phosphorus dosage (0.5mg/L as P), indicating that phosphorus plays an important role as rate-limiting nutrient.  An E.coli challenge was performed in the end the third week of runtime. The highest E.coli removal was also observed at the filter with the highest phosphorus dosage (see Figure 3). The correlation between active biomass and E.coli removals is shown a Figure 4.
  • With each source water, DOC removal was highest at the 30 min EBCT compared to the 5 min and 15 min EBCT, which supported our hypothesis of longer EBCTs increase DOC removal. (Table 1).
  • DOC removal was highest at the warm temp (28°C) compared the colder temperatures (6 and 22 °C).
  • An increase in EBCT from 5 to 30 min improved DOC removals by 5-6% (n=14). An increase in temperature from 6°C to 28 °C improved DOC removals by 5-9% (n= 9). DOC origin, e.g., terrestrial, microbial or wastewater effluent, did not impact biodegradation, as the same DOC removal was observed for each source with the similar influent DOC. Each water had a different extent of reaction, as measured by BDOC fraction, yet Barker Reservoir had slightly higher kinetics than Wonderland Lake and Boulder Wastewater Treatment Plant Effluent. SUVA did not correlate well with biodegradation potential in the range of 1.6 – 2.9 (L/mg-C/m) nor did SUVA correlate with DBPs formed. However, SUVA did prove to be a useful indicator of DBP yields. DBP precursors were best controlled during longest EBCTs as higher biodegradation of the organic matter occurred.

 

Project 4: Distribution System Innovations

Results:

Outputs:

  • Two different in-lined diffused aeration systems were designed and evaluated based on the direction of water flow.  
  • Models created for predicting THM removal using vertical in-line diffused aeration (VILDA) and horizontal in-line diffused aeration (HILDA) with consideration to the air to water (A:W) ratio, pressure and mixing intensity variables (A Henry’s Law 2nd order predictive model was developed as a function of pressure (up to 70-psig).
  • Field test completed for at least one VILDA or HILDA system where operational conditions, practical configurations and costs can be ascertained.
  • Adsorptive capacity for remote GAC characterized using RSSCT’s
  • THM and HAA removal (adsorption + biodegradation) evaluated in a pilot plant.
  • Bench scale tests conducted to investigate impacts of allowing a chlorine residual onto the GAC.
  • Preliminary real-time model built using existing utility information resources
  • Model calibrated through field investigation and data collection for pressure, flow, and water quality
  • User-friendly and open-source analytics software/data integration tool with web based analytics dashboards was developed and tested

Outcomes:

  • LINK technology platform that can usefully interpret real-time data, elevating awareness of water quality and operational efficiency issues and potential solutions, and ultimately leading to confidence that an increased investment in information infrastructure will pay dividends for the small utility.
  • Interfacing with Kentucky Division of Water regulatory support personnel, to present LINK workshops and solicit their support for including a Kentucky utility in the LINK pilot. Their ongoing support will help to support further LINK use within the State of Kentucky, with the goal of modernizing their statewide application of Partnership for Safe Water methods and goals, through automation of filter performance data collection and analytics.

Conclusions:

  • THMs are more difficult to remove by aeration at elevated pressures than at atmospheric pressures.
  • In-line diffused aeration is a fast treatment process. EBCTs required to reach THM saturation removals by in-line diffused aeration systems are typically <18 sec as noted in Figure 6. Saturation residence times appear to be slightly influenced by direction of water flow. Actual residence times required to reach saturation removals by VILDA was 3-6 sec while HILDA took 5-16 sec. 
  • Experimental results show that adsorption with bituminous GAC is an effective treatment strategy for the removal of TOC and TTHMs through at least 6,000 bed volumes (42 days at 10min EBCT) and often longer depending on influent conditions. Pore surface diffusion model (PSDM) analysis indicated that the presence of both natural organic matter (NOM) and co-solutes are important to consider when analyzing THM breakthrough, with THM adsorbability being the most important factor in determining breakthrough order (TCM< DCBM < DBCM< TBM) and influent concentration determining localized breakthrough. Experimental HAA adsorption results were nonsystematic (see Figure 8).
  • In biofiltration pilot runs, DCAA and TCAA made up >85% of HAA5. Experimental DCAA removal between 83%-97% was reported at all EBCTS (5, 10 and 20min) for the duration of the pilot runs. TCAA removal ranged between 50%-78% at 5 minute EBCT, 80%-96% at 10 minute EBCT and 93%-98% at 20 minute EBCT. No THM biodegradation was observed. HAA reduction and reformation results indicated that biofiltration is an effective treatment for the reduction in HAA5 both immediately after biofiltration as well as at the end of the distribution system, across many ranges of chlorinated influent bromide and TOC conditions (see Table 2).
  • A wide variety of useful treatment plant and distribution system operational performance measures, previously assumed to require laborious data analysis exercises, can now be fully automated using freely available open-source software tools developed with support from the DeRisk Center (see Figure 9). Such a capability is necessary, if real-time data is to be routinely and effectively leveraged for public health protection, and help move the water utility culture to a flexible and adaptive one that emphasizes optimizing performance.

 

 

 

Future Activities:

In the remaining implementation period through July 2018, the DeRISK center researchers will finalize research projects, analyze data, write up results, produce user manuals, complete implementation of small systems training, and submit findings as presentations and journal articles for relevant peer review publications and conferences.


Journal Articles: 8 Displayed | Download in RIS Format

Other center views: All 109 publications 8 publications in selected types All 8 journal articles
Type Citation Sub Project Document Sources
Journal Article Ling, L., Tugaoen, H., Brame, J., Sinha, S., Li, C., Schoepf, J., Hristovski, K., Kim, J., Shang, C., Westerhoff, P., (2017). Coupling Light-Emitting Diodes with Photocatalyst-Coated Optical Fibers Improves Quantum Yield of Pollutant Oxidation. Environmental Science and Technology 2017; 51 (22), 13319–13326 R835603 (2017)
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  • Journal Article Oxenford JL, Barrett JM. Understanding small water system violations and deficiencies. Journal of the American Water Works Association 2016;108(3):31-37. R835603 (2016)
    R835603 (2017)
  • Abstract: AWWA-Abstract
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  • Journal Article Stewart, J.R., Livneh, B., Kasprzyk, J.R., Rajagopalan, B., Minear, J.T. and Raseman, W.J., 2017. A multi-algorithm approach to land surface modeling of suspended sediment in the Colorado Front Range. Journal of Advances in Modeling Earth Systems 2017; 9(7):2526-2544. R835603 (2017)
    R835865 (2017)
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  • Journal Article Terry, L. G., and Summers, R. S. Biodegradable organic matter and rapid-rate biofilter performance:A review. Water Research 2018;128, 234–245. R835603 (2017)
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  • Journal Article Tugaoen, H., Garcia-Segura, S., Hristovski, K., Westerhoff, P., Challenges in photocatalytic reduction of nitrate as water treatment technology. Science of the Total Environment 2017; 599: 1524–1551. R835603 (2017)
  • Abstract: Science Direct-Abstract
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  • Journal Article Tugaoen, H., Garcia-Segura, S., Hristovski, K., Westerhoff, P., Compact light-emitting diode optical fiber immobilized TiO2 reactor for photocatalytic water treatment. Science of the Total Environment 2018;613:1331–1338. R835603 (2017)
  • Abstract: Science Direct-Abstract
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  • Journal Article Tugaoen, H., Herckes, P., Hristovski, K., Westerhoff, P., Influence of ultraviolet wavelengths on kinetics and selectivity for N-gases during TiO2 photocatalytic reduction of nitrate. Applied Catalysis B-Environmental 2018;220: 597–606 R835603 (2017)
  • Abstract: Science Direct-Abstract
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  • Journal Article Beck SE, Ryu H, Boczek L, Cashdollar J, Jeanis K, Rosenblum J, Lawal O, and Linden K (2017). Evaluating UV-C LED disinfection performance and investigating potential dual-wavelength synergy. Water Research 2017;109;207-216 R835603 (2017)
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  • Supplemental Keywords:

    gravel roughing filters, anion exchange resin, zero valent iron, algal seedings, magnesium clarification, pretreatment clarification, organic precursor removals, Biofilter; Filter Depth; Natural Organic Matter; drinking water; DOC removal, trihalomethanes, in-line diffused aeration, pressurized, distribution system, water mains, carbon dioxide, Risk reduction; Disinfection byproducts; Decision support, Lifecycle Analysis; Source Water Quality; Decision Support, Environmental Sustainability, SDWIS, GIS Model low UV wavelengths monitoring, MP UV, LPHO UV, UV-chloramines, virus inactivation, disinfection by-products, surface waters, groundwaters, rainwater disinfection, Sustainable small water systems, Photochemical Inactivation, Retention Pond, nitrate reduction, photocatalysis, electrical energy per order, quantum yield, photon fluence, hole scavenger Disinfection, UV LED, KrCl excimer lamp, water treatment, drinking water, virus, microbiome, Vacuum UV, Ceramic Membranes, Ceramic Membrane Filtration, UV-Membrane, Biofilter; Filter Depth; Natural Organic Matter; drinking water; DOC removal, Smart water systems; data analytics; data integration; SCADA historian; database; dashboard

    Relevant Websites:

    New England Water Treatment Technology Assistance Center Exit

    DeRISK Center University of Colorado Boulder Exit

    DRINKING WATER CENTERS.NET Exit

    DRINKING WATERS.NET Webinar Series Exit

    U.S. EPA Small Systems Monthly Webinar Series

    Progress and Final Reports:

    Original Abstract
  • 2015 Progress Report
  • 2016 Progress Report