Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).
Key Factors that Affect Chemical Mixing in Water and Wastewater Treatment Facilities
Jie Zhang, Edward Wicklein
Carollo Engineers, United States of America;
Many chemicals are commonly used in water and wastewater treatment, including chlorine, caustic, ammonia, ferric chloride, hydrogen peroxide, and many others. Monitoring needs to occur after chemical addition to ensure chemicals are completely mixed for proper dose pacing. Rapid mixing is essential to maximize chemicals usage efficiency and reaction time while minimizing facility sizes. Computational fluid dynamics (CFD) modeling has been shown as an ideal tool for providing comprehensive information on chemical mixing systems, as well as useful in optimizing designs.
This presentation will review the important factors that affect chemical mixing through several project case studies. Key findings include:
1) Injection devices (such as nozzles) and diffuser size can significantly affect mixing efficiency, and the design should be selected based on the required complete mixing distance and available pumping head;
2) Injection location is critical. Mixing may be quite different depending on where chemicals are injected with respect to flow streams and fittings;
3) Additional mixers increase mixing efficiency. With installing mechanical or static mixer, mixing can be improved dramatically. However additional mixer should be used with caution since mechanical mixer consumes energy and static mixer increases head loss, and;
4) The ratio of injection flow rate to main stream flow rate affects mixing. An optimum ratio may exist to maximize mixing efficiency.
The case studies and findings from this presentation will provide insights into chemical feeding system for designers.
2:00pm - 2:45pm
Inertia, Incentives, & Indifference: Stories from the Frontlines of Energy Efficiency
Layne McWilliams, Wendy Waudby
Cascade Energy; ,
Let’s face it: addressing energy efficiency in capital projects is kind of like the diet we all think we should start in January but often don’t get around to until September – just in time to give up during the holidays! It’s difficult; it’s not fun; it’s hard to see the impact. It’s often not asked for or appreciated.
We know that municipal infrastructure is built to meet the needs of our communities for decades into the future. We rely on conservative projections of flows and loads, coupled with safety factors and provisions for load peaks, storm flows, maintenance and outages. All this while staying within the budget provided by our funders who ultimately seem most concerned with the price included in the lowest, responsive bid. These factors often lead to systems which can meet the needs of the worst-case scenarios yet can’t operate efficiently at the lowest flows or loadings.
For the past decade, we’ve worked on behalf of regional electric utilities to help bridge the gap between energy conservation programs and our industry. We’ve learned a few things along the way, and we’d like to share them with you. Our presentation will show how to incorporate efficiency into every decision and while taking advantage of the funding and assistance that utility programs provide. We’ll share some project examples from our region to illustrate how relatively small changes can create big savings. And, we’ll share some of the things we look for when we perform efficiency reviews at various stages of design.
As we progress, we will present an overview of energy conservation programs in the Pacific Northwest including how capital project incentive programs typically work, who to talk to about a project, the application process, cost effectiveness, and measurement and verification of savings.