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WaterOperator.org Blog

Technology and Innovation in the Water Sector

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Innovative water treatment technologies refer to advanced and unconventional methods explored to purify and manage water resources. These solutions often leverage cutting-edge technologies and scientific advancements to address water management challenges including emerging contaminants, water scarcity, energy efficiency, resource recovery, decarbonization, etc. These technologies are often still being researched and benchmarked through laboratory or pilot-scale studies. 

We have 364 resources (and counting) on Innovative Water Technologies in our Documents Database that provide valuable information on this topic. You can search for documents about identifying water system leaks with the help of dogs, alternative water resources as we face degrading water quality and supplytreatment options for taste-and-odor problems, approaches to drinking water technology approval, and many other useful guides that will help you to deliver safe and clean water to utility customers. 

To access the wealth of knowledge on Innovative Water Technologies within our database just select "CATEGORY" in the dropdown then choose "Innovative Water Technologies." Once you make that selection, a second dropdown will appear where you can choose "HOST," “TYPE,” or “STATE” to narrow the search even further. If you have a specific search term in mind, use the “Keyword Filter” search bar on the right side of the screen.

This is part of our A-Z for Operators series.

Most Clicked Links from the Innovations Newsletter

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With growing efforts to enhance water quality and to protect public health, 2021 brought many new innovations to the water sector. From innovative PFAS treatment technologies to enhanced wastewater surveillance to track the spread of COVID-19, the following list highlights the most accessed resources featured in the Innovations for Small Systems newsletter's 2021 archive.

Small Drinking Water Systems Webinar Series
A webinar series hosted by EPA to communicate the latest information on solutions for challenges facing small drinking water systems.

EPA Cybersecurity Best Practices for the Water Sector
EPA published a webpage featuring resources to help water and wastewater utilities implement cybersecurity best practices. This new page contains various cyber resilience resources available from EPA.

Tracking SARS-CoV-2 RNA through the Wastewater Treatment Process
This paper presents data on SARS-CoV-2 RNA concentration and removal rates during the different stages of the activated sludge wastewater treatment process to better understand the fate of the virus at the different stages

EPA Drinking Water Treatability Database (TDB)
The TDB presents an overview of over 120 regulated and unregulated contaminants found in drinking water with current information on treatment processes. EPA updated the TDB on May 19 to include new references and treatment options for PFAS.

Expedited Approval of Alternative Test Procedures for the Analysis of Contaminants Under the Safe Drinking Water Act; Analysis and Sampling Procedures
On May 26, EPA approved 17 alternative testing methods for use in measuring the levels of contaminants in drinking water to determine compliance with national primary drinking water regulations.

EPA Identifies Drinking Water Contaminants for Potential Regulation
EPA announced the Draft Contaminant Candidate List 5 (CCL 5) on July 12 to include 66 individual chemicals,12 microbes, and three chemical groups – per- and polyfluoroalkyl substances (PFAS), cyanotoxins, and disinfection byproducts (DBPs).

Performance of rapid sand filter – single media to remove microplastics
This paper aims to analyze the effectiveness and mechanism of rapid sand filters (RSF) for the removal of microplastics (MPs) during drinking water treatment and analyze the effect of research variables on the performance of filter media. 

Cyanobacteria Assessment Network Application (CyAN app)
On August 3, EPA launched the CyANWeb Application, which is an easy-to-use web browser-based tool that provides access to cyanobacterial bloom satellite data for over 2,000 of the largest lakes and reservoirs in the United States.

Tap Talk: The Drinking Water in Rural America Podcast
The Private Well Class program has launched a new podcast series, Tap Talk, which highlights the unique challenges which small public water systems and many private well users experience.

18th Annual EPA Drinking Water Workshop: Small System Challenges and Solutions
This free, annual workshop, which was presented virtually in September, provided in-depth information and training on solutions and strategies for handling small drinking water system challenges. This workshop will be virtual again for 2022.

Zapping Untreated Water Gets Rid Of More Waterborne Viruses
Texas A&M University researchers published a paper in September 21, where they highlighted their research validating the effectiveness of Iron Electrocoagulation in the removal of viruses from water.

EPA Awards $6 Million in Funding to Research Human Viruses Found in Wastewater Intended for Reuse
EPA announced on October 27 that five grants have been awarded funding to research on existing and novel alternative methods to detect and monitor viruses that are excreted with feces in wastewater intended for water reuse applications. 

ASDWA Publishes New PFAS MCLs White Paper for States that are Considering or Developing PFAS Drinking Water Standards or Guidelines
ASDWA published a PFAS Maximum Contaminant Levels (MCLs) White Paper on November 5, to serve as a resource for states that are developing or considering developing PFAS drinking water MCL regulatory standards or guidelines.

EPA Announces Over $3 Million in Funding to Small Businesses to Develop Environmental Technologies
EPA announced on December 14 that 30 American small businesses will receive funding to develop novel technologies to address pressing environmental and public health problems such as domestic greywater, microplastics, and lead service lines.

Nutrient Smart Recognition Program
WEF and EPA launched the NutrientSmart (NSmart) program in December to help reduce nutrient loadings in waterways by encouraging the adoption of enhanced nutrient management practices by water utilities and distributing information on tools and methods for lowering nutrients.

Fifth Unregulated Contaminant Monitoring Rule
EPA published the fifth Unregulated Contaminant Monitoring Rule (UCMR 5) on December 27 to better understand the national occurrences and levels of 29 PFAS found in the nation's drinking water systems.

Check out past issues of the Innovations newsletter.

The Benefits of Drones in the Water Industry

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Unmanned aircraft systems (UAS), also known as drones, have slowly made their way into various parts of society, including the water sector. They offer a more accessible and affordable way for water utility managers to survey their systems. They also offer plant managers the ability to collect detailed information about the status of their utility through aerial photos and videos. 

The greatest benefits of drones are that they are highly efficient while still being relatively inexpensive. Drones can be used to collect data ranging from updating processes to designing additions, as well as building changes, maintenance, and demolition. 

Some water companies in France are even using drones to inspect sewer operations. They are also being used in New Zealand as part of a water quality monitoring projectDrones are being used in Ireland to survey problems before they arise and catch unlawful dumping that would eventually become issues for wastewater treatment workers to handle. Drones have proven to be especially helpful in the wastewater industry by increasing worker safety, reducing energy consumption, streamlining planning, improving insight and education, and efficiently collecting samples.

Any current or future users of drones should know that entities utilizing drones are now required to comply with new federal laws enacted as part of the FAA Reauthorization Act of 2018. Despite this hurdle, drones provide a great opportunity to help upgrade and improve an otherwise outdated water industry. Overall, drones can be a great tool to help water utilities of the past move more quickly into the future. 

Using Willow Trees to Treat Wastewater

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This article was featured in a recent edition of Innovations for Small Systems, our monthly water technology newsletter.

Researchers at University of Montreal, Canada have found a way to filter the waste from municipal wastewater through the roots of willow trees while also producing renewable bioenergy and 'green' chemicals. The study, which was published in Science of the Total Environment, details the experiment conducted in Quebec, Canada to investigate the potential for sustainable wastewater treatment through phytofiltration, an emerging method to remove contaminants from water through the use of plants, to be integrated with renewable biorefinery. 

Phytofiltration plantation is an alternative wastewater treatment method where root systems from non-food crops, such as fast-growing trees, are used to capture contaminants and nutrients from wastewater. Short rotation coppice (SRC) willow has been considered as a promising renewable bioenergy crop due to its natural tolerance to contamination and the roots ability to filter out nitrogen in sewage, which can then be harvested for renewable lignocellulosic biofuels. This concept of a biorefinery illustrate the potential of multifunctional biotechnologies to address environmental challenges caused by human activities.

Photo Credit: Katy Walters

Featured Video: Why Are 96,000,000 Black Balls on This Reservoir?

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By Jill Wallitschek

In 2015 the Los Angeles Department of Water and Power went viral when it unleashed 96 million shade balls into the Los Angeles Reservoir. The 175 acre reservoir served to store 3.3 billion gallons of treated drinking water. Shade balls were previously introduced to three other reservoirs in the LA area between 2008 and 2012. Releasing the 96 million balls marked the end of a 8 year project.

The project was first instigated when the Department of Water and Power was notified of high bromate levels in their water. Bromate (BrO3) is a disinfection byproduct regulated at 0.01 mg/L. High levels can increase risk of cancer. The chemical forms when bromide (Br ), an otherwise harmless ion, reacts with ozone (O3). For this reason treatment plants that use ozone are required to monitor for bromate monthly. Qualifying plants can reduce their monitoring to quarterly.

The LA Department of Water and Power determined that while they were finding low levels at the treatment facility, levels were elevated at the reservoirs. Upon investigation the facility realized that bromate can form under chlorination as well. When chlorinated water containing bromide reacts with sunlight, it forms bromate at even higher concentrations than ozonation. This realization prompted the facility to look toward a solution.

Removing the naturally occurring bromide wasn’t an option. Chlorination residual was necessary to protect public health. Ultimately the Department determined that sunlight was the only variable left to control.

After brainstorming for affordable and effective covers that could block sunlight across 175 acres, the Department discovered a product called “bird balls”. At the time, bird balls were used to deter waterfowl from swimming in contaminated water bodies or ponds near airport runways. These balls were made from high density polyethylene, a floatable, food grade plastic. The addition of carbon black gives them a black color and increases their life expectancy to approximately 10 years without sun bleaching. After consulting the manufacture, the balls were put through a small-scale test to access their bromate reduction abilites. The shade balls passed with flying colors.

Shade balls not only reduce bromate formation in the reservoir, but they deter birds, control algae, and reduce evaporation by 80 to 90%. Having been implemented under historical drought conditions, the innovation was applauded for its water saving results. According to the Massachusetts Institute of Technology these shade balls will have to be used for roughly 2.5 years to compensate for the water required to produce them. Since less chlorine is required to control algae formation with the adoption of shade balls, the treatment facility is experiencing significant cost savings as well. Over the course of their life span the reduction in chlorine use and evaporation will have paid for roughly half the shade balls.

Shortly after their installation, one of the reservoirs was removed from service and two of the remaining reservoirs transitioned to floating covers. Federal law requires that all drinking water bodies open to the air be covered. Transitioning the final Los Angeles Reservoir would have been too cost prohibitive based on its size. So given the effectiveness of the shade balls in such a large area, they shall remain in the Los Angeles Reservoir to prevent bromate formation, evaporation, and algae for the Los Angeles people.

What's on the Drinking Water Radar for the Year Ahead: 2019

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Being a small-town water operator is not easy; it is up to you to ensure the quality of your community's water day-in and day-out, often with very limited resources. Let WaterOperator.org help you meet the challenge head-on with this list of tools and resources to put on your radar for the year ahead:

  • Have you gotten in the groove yet with the new RTCR requirements? Here are two new documents from the USEPA designed to help small public water systems: Revised Total Coliform Rule Placards and a Revised Total Coliform Rule Sample Siting Plan with Template Manual. Additional compliance help, including public notification templates, a RTCR rule guide, a corrective actions guidance and more can be found here.
  • While we know your hands are full just getting the job done, there are new and emerging issues you may have to deal with in the year ahead. For example, this past year many communities have been dealing with PFAS contamination issues. This ITRC website provides PFAS fact sheets that are regularly being updated on PFAS regulations, guidance, advisories and remediation methods. Especially of interest is this excel file that has begun to list the different state standards and guidance values for PFAS in drinking water as they are developed. Be sure to check back often for updates.
  • Your utility may also have to adjust to new compliance rules in the coming year. In Michigan, for example, a new Lead and Copper Rule arising from the water crisis in Flint has gone into effect, making it the strictest in the nation. Other states, such as Ohio, have also adopted tougher standards, or are now requiring schools to test for lead. Oregon has established temporary rules that will require drinking water systems in the state using certain surface water sources to routinely test for cyanotoxins and notify the public about the test results.
  • With a warming climate, these incidences of harmful algal blooms in surface water are on the increase, causing all sorts of challenges for water systems that now have to treat this contaminant. This cyanotoxin management template from the EPA can help assist you with a plan specific to your location.
  • Worker turnover and retirements will still be an issue in 2019. According to this article, the median age for water workers in general (42.8 years) and water treatment operators specifically (46.4 years) are both above the national average across all occupations (42.2 years). You can keep transitions as smooth as possible by using EPA's Knowledge Retention Tool Spreadsheet and/or this Electronic Preventive Maintenance Log.
  • New Tech Solutions: A UMass lab focusing on affordable water treatment technologies for small systems will be rolling out its Mobile Water Innovation Laboratory in 2019 for on-site testing. In addition, the facility is testing approaches to help communities address water-quality issues in affordable ways. "Early next year, in the maiden voyage of the mobile water treatment lab, UMass engineer David Reckhow plans to test ferrate, an ion of iron, as a replacement for several water treatments steps in the small town of Gloucester, MA.

But even without all these challenges and new ideas for the future, simply achieving compliance on a day-to-day basis can be tricky - if this sounds familiar, you may want to check out our recent video on how operators can approach the most common drinking water compliance issues.

Featured Video: The Future of Water

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Water is a scarce resource for many communities around the globe, and this scarcity is becoming more and more widespread. Our featured video this week from Quartz Media looks out how one locality half a world away has addressed this challenge, and how the rest of us can learn from systems like these where the "future of water" has already arrived.

While this video focuses on a larger metropolitan area, there are some interesting takeaways for smaller systems as well such as:

  •  Solutions to water challenges are best solved at the individual and/or community level. 
  •  Water reuse is most likely already happening in your community and efforts can be made to change public perceptions. For example, a wastewater pipe enters the Mississippi River every 8 miles - meaning almost every community using the river as a water source is already drinking someone else's wastewater!     

Cellular Metering for Small Systems

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Guest post from Brenda Koenig, Illinois State Water Survey.

Cellular-enabled water meters – also called smart meters – can make all the benefits of smart grid technology attainable for even for small systems on a budget. In this post, we’ll review the pros and cons of cellular vs. traditional metering systems.

Cellular meters offer service benefits

Due to their independence from physical infrastructure, a cellular system is better equipped to continue working through emergencies, such as floods, that might damage a large physical network. Cellular networks also make it easier to service dispersed or geographically diverse areas.

One of their greatest benefits is the speed of data. Cellular meters allow utility managers and customers to monitor their activity in real-time on the web. This improves leak detection and provides more opportunities for water conservation.

Weighing the costs

Cellular meters have potential to save utilities money on some fronts. Their use of cloud-based advanced metering analytic (AMA) software eliminates the need for expensive software installations at the plant. They also eliminate the need for a physical network of antennas, repeaters, wiring installations, and data collection units. Without the need for physical site visits to read traditional meters, utilities may also save staff time.

However, start-up costs for cellular metering can be significant, even without the expense of physical infrastructure. Buying and installing cellular meters can cost two to three times more than traditional meters. Staff and infrastructure costs will depend on what system you currently have in place. Cellular monitoring is compatible with most DEP and AWWA approved, AMR-compatible meters, but incompatible meters would need to be replaced. Staff may need to be retrained to install, maintain, and operate the new systems, as well as manage data, train customers, and set rates.

A growing trend

By 2020, it is estimated that 600,000 cellular water meters will be distributed annually, with companies such as Badger Meter, Arad Group, Neptune Technology Group, and Master Meter introducing cellular metering technologies.

So how does a small system decide if and when they too should adopt these new, game-changing cellular-based tools that are becoming more widely available and affordable? Much depends on each unique system’s needs and priorities, as well as the funding and political context in which they operate. Systems that are leak-prone or that need to step up their water conservation efforts may benefit from the daily feedback offered by cellular meters. Pilot programs or a comprehensive cost-benefit analysis can help utilities decide whether the tradeoffs in staff time, technology, and infrastructure expenses make sense. Finally, one of the best things to do is to talk to other systems about their experiences. Utilities with similar budgets, sizes, and goals can provide a lot of advice and references.

Resources:

Novato water district rolls out ‘smart’ meter pilot project news article, Marin Independent Journal 3/21/17

Big Data Flows: Water, Outsourcing, and the Flood of Data news article, EarthZine 6/30/15

Moving Towards Sustainable and Resilient Smart Water Grids journal article, Challenges 3/21/14

City looking to tap new water meters news article, Kingsville Record 3/1/15

RCAP - Water Metering Technologies presentation, RCAP Prezi 4/29/15

Advanced Metering Infrastructure, memo, City of Novi 4/24/15 

Developing and Implementing Tools for Small Systems to Evaluate and Select Appropriate Treatment Technologies

Water utilities can struggle to know which treatment technologies to consider and then which one to select and implement to solve their water quality and compliance challenges. This is particularly challenging for small water systems without resources to stay up-to-date on the range of appropriate technology options and their associated treatment and operational performance. The DeRISK Center is dedicated to addressing this challenge by developing and implementing tools for small systems to evaluate and select appropriate treatment technologies. These tools are designed to help utilities, states, consultants, and technology providers make technology selection decisions based on public health protection and sustainability beyond just regulatory compliance.

A conventional analysis of technology alternatives is typically performed when water systems need to upgrade or replace major treatment facilities. This analysis consists of identifying the feasible alternatives that will accomplish the treatment goals, comparing the alternatives based on some criteria, and selecting the “best” alternative. The criterion most used is cost—capital cost, operation and maintenance cost, or an engineering life-cycle cost analysis that includes the anticipated life-span of major equipment.
 
The DeRISK Center tools employ a decision support methodology that improves on this conventional approach. The major steps in the methodology are deciding what criteria are most important to stakeholders and providing and easy way to compare technology alternatives to each other with respect to each criterion. Our approach strives to go beyond just a comparison of costs. As shown in Figure 1, the decision support methodology expands on the conventional analysis of alternatives process by including:
  • Facilitated methodology that incorporates stakeholder input
  • Data on innovative treatment technologies
  • Relative health risk protection of treatment approaches
  • Sustainability measures of treatment approaches
  • Stakeholder preferences

Performance information such as treated water quality and performance data along with other characteristics, including source water quality constraints, are used to identify feasible technology alternatives. The characteristics for feasible alternatives are then fed into the analyses of health risk, sustainability, and stakeholder preferences in order to provide data to the decision support methodology.  
 
Microbial and chemical agents in drinking water can pose significant human health risks. Evaluating the combined impacts from multiple contaminants can provide new insights into how best to manage that risk and protect public health to meet regulatory compliance and achieve the greatest risk protection possible given feasible alternatives. The DeRISK Center tools utilize the Relative Health Indicator (RHI)—a semi-quantitative metric developed to harmonize the cancer and non-cancer impacts from a wide range of drinking water contaminants—to compare the relative health risks posed by multiple waterborne constituents.
 
The DeRISK Center is also focused on analyzing and improving the environmental and economic sustainability of small drinking water treatment systems. To achieve this, life cycle analysis (LCA) methodology is being used to quantify and characterize environmental impacts associated with various drinking water technologies. These impacts (using EPA’s TRACI assessment method) include ozone depletion (kg CFC-11 eq), global warming (kg CO2 eq), smog (kg O3 eq.), acidification (kg SO2 eq.), eutrophication (kg N eq.), carcinogenics (CTUh), non carcinogenics (CTUh), respiratory effects (kg PM 2.5 eq.), ecotoxicity (CTUe), and fossil fuel depletion (MJ surplus). A comprehensive LCA model framework was developed utilizing water treatment data, experience, and commercial information.
 
Last, the DeRISK Center is putting these tools to the test evaluating treatment technology decisions through cases studies with actual small water systems needing to address water quality and compliance challenges. The first case studies are assessing disinfection alternatives for small water systems in New Hampshire. 

If you are interested in testing these tools and collaborating with DeRISK Center researchers to assess treatment technology alternatives for your water system, please contact Chad Seidel at chad.seidel@colorado.edu

In-Line Diffused Aeration to Reduce THMs in Distribution Piping

This post from University of New Hampshire's M.R. Collins is a continuation of a project update originally shared in our Technology News newsletter. 

Several methods exist for controlling THM formation, including reducing natural organic matter (NOM) prior to chlorine disinfection, and using an alternate disinfectant such as ozone, chloramines, or UV. Using these disinfectants will prevent or reduce the formation of THMs, but could facilitate the production of other potentially harmful byproducts.  Also, using ozone or UV as a disinfectant will not provide a residual in the distribution system (USEPA, 1981 & USEPA, 1999).  While effective at reducing THM formation, changing or upgrading the water treatment plant to include these control techniques could be costly and negatively affect other plant processes.

Posttreatment aeration is another strategy to control THMs, and involves removing the THMs after formation.  Countercurrent packed towers, diffused aeration in open reactors, and spray aeration in storage tanks are all viable aeration methods to remove THMs (USEPA, 1981 and Brooke & Collins, 2011).  While the above methods are viable and have been applied in the field, all require depressurization of the water, and are limited in terms of placement in the water distribution system.  Placement in the distribution system is important since THMs continue to form in the system, and often exceed regulations when at the far end of the system.  This research explores both vertical in-line diffused aeration (VILDA) and horizontal in-line diffused aeration (HILDA) to reduce THMs, which has the potential to be cost effective and conveniently placed where needed in the distribution system.

A schematic of an in-line diffused aeration system is depicted in Figure 1. The basic components consist of an air compressor, air-water reactor, air injector, air release system and associated air and water flow meters. The basic difference between VILDA and HILDA systems is the configuration of the air-water reactor. The VILDA system will utilize a countercurrent arrangement where air is injected in the bottom of the vertical reactor while the water enters at the top of the reactor. The HILDA will have air and water flowing concurrently through the horizontal reactor.

Figure 1. Schematic of basic in-line diffused aeration system. 

The most efficient air-water reactor is one where equilibrium or saturation THM removals can be achieved. The work of Matter-Müller et al. (1981) provides a mass balance method which allows equilibrium or saturation THM removal values to be predicted as depicted in Equation 1:

Equation 1:                             

where QG = the gas flow in (m3/s), Hcc = the dimensionless Henry’s law constant of compound, and QL= the liquid flow rate (m3/s). Hence, the higher the air/water ratio, the greater the removals of THMs.

For Equation 1 to be applicable to distribution piping conditions, the Henry’s Law Constant will have to be adjusted for both temperature and pressure. The former has been well documented in the literature but the latter had to be determined during this research. Basically, a second order relationship as shown in Equation 2 was used to correct for pressure (Zwerneman, 2012).

Equation 2:                                

where Hcc  = the dimensionless Henry’s law constant at system pressure, Hcc,o   = the dimensionless Henry’s law constant at atmospheric pressure, P = the system pressure (psi), and k= the experimentally determined rate constant (psi-1).

HILDA REACTOR DESIGN. The most problematic concern with a HILDA system was to configure an air-water reactor where equilibrium or saturation conditions will be achieved since injected air in a horizontal pipeline will have a strong tendency to raise to the top of the pipe and not be mixed with the water sufficiently to reach saturation. Through trial and error, Komax static mixers were determined to provide adequate air-water mixing to approach saturation removal conditions provided fluid turbulence or mixing intensity was high enough. A modified Reynolds Number (Re’) was developed to capture the magnitude of fluid momentum and mixing intensity and can be seen in Equation 3 (McCowan, 2015).

Equation 3:                                           

where, v= velocity of water (ft/s), d=pipe diameter (ft), Lm=length of reactor (ft), and v=kinematic viscosity (ft2/s). Figure 2 shows a graphical representation of % removal vs. Re’ at 10:1 and 20:1 A:W ratios.  Re’ appears to be a good indicator of when saturation values are achieved and could be used to design of the HILDA reactor.

Figure 2. HILDA model predictions of THM removals for various A:W ratios as a function of modified Reynolds Number.

VILDA REACTOR DESIGN. Equilibrium or saturation removal conditions in a VILDA system is easier to achieve than with a HILDA system although a HILDA system could be easier to install in the field. The countercurrent flows in a VILDA reactor encourages adequate contact time between the air bubbles and bulk water to achieve saturation conditions quickly as depicted in Figure 3. Basically, in-line diffused aeration is a fast treatment process.

Figure 3. Influence of A:W ratios on VILDA EBCTs required to reach saturation THM removals.

SUMMARY. Both HILDA and VILDA have shown potential to achieve significant reductions in THMs in distribution pipelines especially if the most dominant species is chloroform. Research on bench and pilot scale versions of these posttreatment aeration systems have resulted in prediction models that could be used to design HILDA and VILDA reactors in the field. Field assessment and treatment verification of this innovative technology are currently being explored and developed. Opportunities to participate in these assessment studies are still available. Please inquire within.

REFERENCES

Brooke, E. & Collins M.R., 2011. Posttreatment Aeration to Reduce THMs. Journal AWWA, 103:10.

Komax Systems, Inc. Triple Action Static Mixer. http://www.komax.com/triple-action-static-mixer/ (accessed 3/31/15).

Matter-Müller, C.; Gujer, G.; Giger, G., 1981. Transfer of Volatile Substances from Water to the Atmosphere. Water Research, 15:1271.

McCowan, M.L.,2015. Developing a Horizontal In-Line Diffused Aeration System for Removing Trihalomethanes from Water Distribution Mains. Master’s Thesis, University of New Hampshire, Durham, N.H.

USEPA (United States Environmental Protection Agency), 1999.Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.

USEPA (United States Environmental Protection Agency), 1981. Treatment Techniques for Controlling Trihalomethanes in Drinking Water. EPA/600/2-81/156, Washington, DC.

Zwerneman, J., 2012. Investigating the Effect of System Pressure on Trihalomethane Post-Treatment Diffused Aeration. Master’s Thesis, University of New Hampshire, Durham, N.H.