2014 Progress Report: Improving Drinking Water Quality for Small Rural Communities in MissouriEPA Grant Number: R835173
Title: Improving Drinking Water Quality for Small Rural Communities in Missouri
Investigators: Yang, John , Hua, Bin , Inniss, Enos , Shi, Honglan
Institution: Lincoln University-MO , University of Missouri - Columbia
EPA Project Officer: Page, Angela
Project Period: December 1, 2011 through November 30, 2016
Project Period Covered by this Report: December 1, 2013 through November 30,2014
Project Amount: $499,996
RFA: Research and Demonstration of Innovative Drinking Water Treatment Technologies in Small Systems (2011) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
The overall goal of this project aims to improve drinking water quality for small rural communities in Missouri, with objectives of identifying water quality issues in three selected small drinking water systems and developing cost-effective treatment technology that addresses the identified water problems. The project has been granted a 1-year, no-cost extension, with project expiration on 11/30/2015. The major tasks focused this year are to:
- Continue to characterize the source water and drinking water in the three selected treatment systems and identify water quality issues facing the small rural communities;
- Develop novel treatment technologies to improve the water quality problems identified for each small water system based on the cause and realistic conditions of each water system; and
- Conduct pilot test studies of the developed technologies in the selected small water systems.
In an effort to address the problem of high trihalomethane (THM) formation resulting from the high ammonia source water of small water systems, three treatment technologies or strategies are being developed:
- Alternative disinfectant of peracetic acid (PAA) was tested for disinfection efficiency and reduction of disinfection byproducts (DBPs) (THMs, haloacetic acids [HAAs], and bromate) formation under various conditions of dosages, pHs, and contact times. The results indicated that PAA is an effective disinfectant that results in no significant DBPs formation under the tested conditions.
- Ammonia removal was studied using various adsorbents. Zeolite was found effective to remove ammonia from source water and lower the chlorine dosage needed for disinfection, consequently reducing the DBP formation.
- A change of water treatment processes was proposed to reduce DBPs formation. The original treatment method was to add a large amount of chlorine during the lime softening/coagulation process to reach breakpoint chlorination for ammonia removal, which resulted in high THM (TTHM > 80) due to the high chlorine usage and long contact time. Two treatment adjustments were suggested. The first change was to add chlorine at the later step of the treatment for ammonia removal (at the re-carbonation step), which could decrease the contact time. This suggested change was found to significantly lower the chlorine demand by one-third (~1/3) and resulted in a significant decrease of THMs (< 60 THM) formation in the distribution system. The second suggested change was to use chloramine as a residual disinfectant in finished drinking water. The chloraminated water must meet the EPA standard for drinking water to be in compliance with EPA's current drinking water DBP regulation.
To address the concern of elevated TOC in source water for the selected water system, several treatment approaches currently are being investigated for the TOC removal efficacy. The change of the treatment process using different types of activated carbon, such as coal-based vs. coconut-based carbons is being tested. A discussion with the facility manager also included consideration of separation of the carbon and coagulant injection locations. The carbon baffle walls also have been designed and fabricated for bench scale testing. In addition, bench-scale experiments have been conducted to investigate the efficacy of TOC removal and reduction of disinfection by-product (DBP) formation by advanced chemical oxidation using hydrogen peroxide and ferrous iron. Several operation parameters including pH, H2O2 and Fe2+ concentration and reaction time are being evaluated to achieve the maximum efficiency. Preliminary results of this study indicated that the removal of DBP precursor by the advanced chemical oxidation was fast and reached a steady state in less than 1 hour under the pH range of drinking water treatment.
Six graduate students and four undergraduate students majoring in environmental science or engineering or analytical chemistry have been fully or partially supported by this project and trained for research skills and experiential learning experience on at three university campuses. The students are working on various aspects of proposed research activities, including site sampling; chemical or instrumental analysis; literature review; experimental design/implementation; data collecting, processing, and reporting; manuscript preparation; and conference presentations. One of the graduate students completed a Master's degree thesis entitled “Sedimentation Enhancement by Fabric Inclined Settling Screen to Decrease Disinfection By-Products Formation Potential” in May 2014 as a part of the research effort on the screen technology pilot study.
Nine oral or poster presentations have been made by the PIs/Co-PIs and students at regional or national conferences during the reporting period. Five manuscripts have been drafted or submitted for publication in peer-reviewed journals. The research team attended the EPA Science to Achieve Results (STAR) Innovative Small Water Systems Progress Review Meeting in New Orleans, LA, and made an oral presentation via the National Webinar on Research and Demonstration of Innovative Drinking Water Treatment Technologies in Small Systems.
- Finish the laboratory experiments to characterize the performance of the activated carbon baffle walls for DOC removal in efforts to effectively reduce DBP formation potential.
- Construct and test pilot unit for activated carbon baffle walls at our partner facilities.
- Complete the bench-scale experiments of advanced chemical oxidation for TOC removal and reduction of DBP formation.
- Assess the water quality upon implementation of the new technology in the small water systems or pilot scale treatment.
- Conduct technology transfer and operator training.
- Prepare, submit, and publish manuscripts.
- Draft and submit the final project report.