Grantee Research Project Results
2021 Progress Report: Distributed Fiber-optic Turbidity Sensor Network
EPA Grant Number: SU840152Title: Distributed Fiber-optic Turbidity Sensor Network
Investigators: Wu, Tingting , Duan, Lingze
Current Investigators: Wu, Tingting , Duan, Lingze , Savoir, Gabrielle , Rakinul, Nabil Md , Sheppard, Sarah
Institution: The University of Alabama in Huntsville
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2020 through November 30, 2021 (Extended to November 30, 2022)
Project Period Covered by this Report: December 1, 2020 through November 30,2021
Project Amount: $25,000
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2020) RFA Text | Recipients Lists
Research Category: P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards
Objective:
This project aims to develop a low-cost, distributed turbidity sensor network that utilizes glass optical fibers as both the light-transmission medium and the sensor probes for real-time water quality monitoring in Drinking Water Distribution Systems (DWDS). The innovative technological approaches undertaken in this project will enable a true distributed sensor network with low cost, contributing to safe drinking water supply to the public. Water is critical to sustainability in the 21st century. While much research effort has been devoted to improve the treatment efficiency and to develop novel purification technologies, maintaining high-quality water supply goes beyond treatment. Water distribution network is an important component of the municipal water system. However, water quality deterioration may occur in DWDS due to reactions within the bulk water or interactions between the pipe wall and the water, which can only be exacerbated by the aging infrastructures in the U.S. Moreover, intended or unintended contamination in DWDS also poses threats to public health. Therefore, real-time information of the water quality in DWDS is a necessary prerequisite for operational response or critical decisions to safeguard our drinking water supply. In this project, the research team utilizes the compactness and low optical loss of glass fibers and develops a novel sensor network with distributed fiber probes and a centralized interrogation-detection-data processing system for real-time water quality monitoring in DWDS. During phase I of this project, we focus on two objectives (1) development of a glass fiber based optical system with high sensitivity and low detection limit for drinking water turbidity measurement; and (2) performance evaluation of the glass fiber based optical system under drinking water relevant conditions.
Progress Summary:
So far the outputs/outcomes of the Phase I study include design and assembly of a glass-fiber turbidity measurement unit in the lab, correlation between the sensor output voltage and the water sample turbidity, and demonstration of a measurement resolution down to ~1 NTU. Our ongoing research include further improvement the sensitivity of the sensor by exploring fibers with larger core sizes and the addition of lock-in amplification as well as comprehensive performance evaluation of the glass-fiber turbidity sensor including tests in real environmental matrices.
Future Activities:
The results obtained so far have demonstrated proof-of-concept that glass-fiber sensors can be effective tools for drinking-water turbidity monitoring. With further improvements to be made in the 2nd half of Phase I, such as the use of 400-μm core size glass fiber and the addition of lock-in amplification, we firmly believe that a sensor resolution as low as 0.1 NTU is attainable. Such sensitivity has not been reported in the literature for glass-fiber sensors, which warrants further investigation. The Phase-I research progress has laid solid groundwork for the development of a glass-fiber-based real-time turbidity-sensing network in Phase II. There are several research questions that need to be answered in Phase II in order for us to achieve the overarching goal of this project:
1) What are the potential challenges of building a multi-node, glass-fiber sensor network outside of the research lab?
2) How do environmental conditions such as temperature and water flow affect the reliability and consistency of remote turbidity measurement?
3) Are there any long-term impacts the fiber sensor assemblies may cause to the water quality, i.e., potential pollution?
4) Are there any performance degradations the fiber sensors may suffer from due to immersing in the water for extended periods?
5) To what extent fouling can occur and how to mitigate its impact?
6) What other water qualities may be monitored by such a sensor network?
Supplemental Keywords:
drinking water; monitoring; remote sensing; turbidityProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.