BackgroundCurrent and upcoming regulations concerning disinfection practices for drinking water will have a significant impact on many utilities. While chlorine has been the disinfectant of choice for most systems, new regulations are resulting in a shift to alternative disinfection technologies, such as ozone, chlorine dioxide, and ultraviolet radiation.
Most of the research and application of these technologies has been directed toward medium to large systems, even though many small systems will be faced with the same disinfection requirements.
- The goal of this report is to provide comprehensive and practical information on disinfection practices for small drinking water systems (those serving populations of less than 3,300). Specific objectives are summarized below:
- Provide small-system personnel with procedures for evaluating the capability of their existing treatment facilities to meet the proposed disinfection regulations.
- Provide disinfection alternatives that small systems could use to meet the proposed disinfection regulations.
- Provide information on selection and design of alternative disinfection technologies to assist small utilities and design consultants who may have to replace chlorination with an alternative technology.
- Provide an accurate assessment of the training, routine operation, and maintenance requirements for each technology.
ContentsChapter 1: Chapter 1 includes an overview of current and pending regulations regarding drinking water disinfection. The role of these regulations in changing disinfection practices is discussed. Chapter 1 also defines the report's intended audience and the system size that is the primary focus of the report. Because implementation of most alternative technologies will require additional resources, the necessary resource commitment by small systems is discussed.
Chapter 2: The information presented in chapter 2 is intended to assist small systems with the evaluation of their current disinfection practices. Conducting an evaluation of this type will assist small systems in determining what effect the new regulations will have on their existing facilities. If changes in operational practices and minor modifications can be made to an existing system to achieve compliance with new regulations, this evaluation approach is typically recommended.
Chapter 3: Chapter 3 presents background, application, design, and operational information on the use of ozone in small systems. Of the three technologies presented in this report, ozone is the most complex alternative to design and use. Although many choices exist when selecting an ozone system, simple, reliable systems are emphasized in this chapter.
Chapter 4: The use of chlorine dioxide for small-system applications is presented in chapter 4. Chlorine dioxide equipment is similar to conventional chlorine equipment; however, operational requirements are more complex. Pending regulations may have an effect on the use of chlorine dioxide for drinking water disinfection. The uncertainty associated with these regulations is emphasized.
Chapter 5 : Ultraviolet radiation has the simplest design and operational requirements of the three alternative technologies discussed in this report. Chapter 5 presents background, application, design, and operational information on ultraviolet radiation for small drinking water systems. Ultraviolet radiation is a relatively new technology for drinking water disinfection in North America. Its use may be limited to groundwater applications because of its marginal effectiveness against protozoan cysts, such as Giardia.