Sewage Grid: Drifting Sensors that Monitor the Wastewater Collection System
ABSTRACT Over the past decades, the aging infrastructure of wastewater collection system (WCS) has endangered the public health by contaminating the sources of drinking water and by polluting the natural environment. The dangers caused by discharging untreated wastewater have been repeatedly proclaimed by academia, industries, and public sectors. As numerous studies have pointed out, wastewater escaped from the wastewater collection system (WCS) has been a major source of impairment of water quality. In order to identify untreated wastewater escaping from WCS, various schemes have been designed and developed. However, only a small fraction of the WCS is inspected each year due to the cost and complications associated with the current inspection techniques. In an effort to solve this environmental problem, we designed and developed a new methodology for detecting functional deficiencies in WCS. The new methodology, which is utilizing the wireless floating sensors as well as interdisciplinary researches, is not only by far simpler than any current industry methods, but also significantly more efficient. Moreover, this is the first known WCS monitoring methodology utilizing a wireless mobile sensing system.
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ABSTRACT: An explosion-proof UV/VIS sensor has been available even in sewer systems for some years for simultaneous measurement of CODeq, filtered CODeq, TSSeq and nitrateeq. This sensor allows in-situ real-time measurements with no sampling, no sample preparation and no reagents. Three case studies are presented in this paper using this UV/VIS sensor for long- term sewer monitoring issues whereby two different installation strategies are applied. The pros and cons of both different installation solutions are compared and different calibration results during dry and wet weather conditions and long-term operational sewer monitoring experiences are given in this paper.
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ABSTRACT: Many of the wastewater collection systems in the USA were developed in the early part of the last century. Maintenance, retrofits, and rehabilitations since then have resulted in patchwork systems consisting of technologies from different eras. More advanced and cost-effective methods to properly rehabilitate these systems must be considered to guarantee sustainability into the future. Achieving sustainable development presents a challenge to deliver new and innovative infrastructure and facilities needed to serve society while protecting the environment. In the context of this paper, sustainable development would provide new and improved solutions to existing and emerging problems associated with wastewater collection system infrastructure. Such solutions would, for example, include consideration of innovative approaches and practices for identifying and rehabilitating problems in existing systems and ways of preventing these problems in new construction. The paper focuses on technical issues and research needs in three major areas: (1) assessment of system integrity; (2) operation, maintenance, and rehabilitation; and (3) new construction. Many of the issues and needs discussed were identified at a USEPA sponsored experts workshop on infrastructure problems associated with wastewater collection systems.Urban Water 01/2002;
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ABSTRACT: Ultrasonic technology is evolving rapidly. It offers prospects for improving flow measurements, for serving as transfer standards, and possibly for serving as a primary flow standard. This paper describes results from several current NIST projects that have the goal of assessing travel-time ultrasonic flow measurement techniques for their potential in improving flow measurements. These projects include a meter testing program and computer simulations of travel-time techniques in ideal conditions and in measured pipe flows for a range of metering configurations. Meter test results show that the "as-received" performance of several commercially available, clamp-on, travel-time, ultrasonic flow meters have errors that range from 1% to 3% when measuring high Reynolds number water flows in nearly ideal installation conditions. These errors could be reduced if manufacturers better compensated for pipe flow profile effects using improved software or if they improved the measurement traceability of their meter calibration capabilities to NIST's flow standards. The reproducibilities of most of these units are 1% or better, thus producing conclusions that these meters could attain accuracy levels commensurate with these reproducibilities if these software or calibration improvements are made. Results also show that these manufacturers have significantly improved: (1) the awkward requirement for a "zero flow" condition to attain satisfactory performance, and (2) the "remove-replace" variations which plagued these types of meters. Additionally, test results for an in-line, 8-path, travel-time, ultrasonic meter that was set up using only length and time standards showed uncertainties of ±0.2%, or better. These results show that this kind of meter might evolve into a primary standard for flow. The computer simulations of travel-time metering arrangements provide insight into ways that this technology can improve flow measurements. If it becomes feasible to quantitativel y model all the component measurement systems that comprise the ultrasonic metering of a pipe flow using only length and time standards, this technique would be a primary standard at some specified uncertainty. This would greatly expand the capability of primary flow standards, and it would make flow measurements traceable to national standards.01/2000;