Distribution System Innovations
Robin Collins, UNH (Project Lead)
The overall focus of this project is to explore, develop, model and disseminate technologies that will not require the introduction of new chemicals but will offer small systems a better understanding of their distribution system so that microbial risk can be reduced and preformed DBPs, i.e. THMs and HAAs, controlled more efficiently at the most problematic locations without requiring treatment for the entire water supply.
The project will be broken into 3 separate activities. The 1st activity will evaluate the efficacy of using a more readily adaptable horizontal diffused aeration system to remove THMs from pressurized drinking water distribution system in a scalable pipe size. The variables to be evaluated and modeled include time to equilibrium, a comparison of the vertical and horizontal reactors, the use of multiple injections, different types of injection nozzles, pressure, A/W ratio, and temperature. The 2nd activity will evaluate the efficacy of using a GAC bioreactor in a distribution system environment to degrade HAAs. The variables to be evaluated in both a bench- and pilot-scale bioreactors include EBCT, temperature, TOC concentrations, bromide levels and backwash conditions. Both adsorptive and biological modes of removal will be assessed. The 3rd activity will use readily available analytics and software to develop real-time analytics and protocols to better manage distribution system resources to include residence times, chlorine residuals, non-revenue losses and pipe break detections. Such an established techniques will also be of assistance in locating the problematic sections of the distribution piping that could benefit from installation of an aeration or bioreactor system to reduce DBPs.
The completed project will provide small system stakeholders and especially consulting and regulatory engineers with pilot-tested and verified design criteria and performance models for (1) pressurized aeration systems to remove THMs and (2) GAC-based bioreactors to degrade HAAs in the most problematic reaches of small system distribution systems. Moreover, the project will also generate tested protocols and techniques using existing, readily available data to better manage distribution system residence times, hydraulics, chlorine residuals and non-revenue water losses and pipe breakage.