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Session 02C: Wastewater 101: Secondary Treatment and Disinfection
3:00pm - 5:15pm
Session Chair: Ray Nickel, Parametrix;
3:00pm - 3:45pm
You Sure You Want A Turbo?
Aerzen USA, United States of America;
High speed turbo (HST) technology was the most quickly adopted blower design into the US wastewater market. Touted as “30% more efficient than Roots-type blowers”, it was quickly received into a market searching for energy savings. While the efficiency is undeniably high, in many cases, the technology was applied without considering its suitability in the system. As a new technology, there was still a lot to learn, and many mistakes were made by engineers and manufacturers during its early implementation.
In the years that followed, the wastewater community became cautious of the technology, based on the difficulties which occasionally resulted in completely failed installations. Some HST manufacturers gave up on the technology, raising further doubts about HST. Rumors and misinformation spread through the market. Many manufacturers seized the opportunity, offering alternative components, alternative technologies, or improved controls on otherwise less efficient technologies. The common thread remained that this electronics-intense technology was not completely understood by an engineering community with mechanical, civil, and environmental backgrounds. It’s not surprising that there was a backlash, or an avoidance of HST.
As much as the difficulties gained attention, the majority of installations for most HST manufacturers are, and continue to be, successful. The properly implemented projects are enjoying reduced electrical costs, quiet operation, and minimal maintenance.
This presentation explores the lessons learned from early installations, and provides guidance on proper selection, installation, and control. We will open the “black box” and attempt to debunk some of the myths in various areas:
Core components: Airfoil or magnetic bearings, inverter style (current or speed based), local panel (PLC or CPU)
Best processes served by turbo
Installation factors: Indoor or outdoor, proper cooling, process piping
Electrical considerations: Harmonics, ambient temperature limits
Control: Seasonal changes in turndown, operating multiple units, mixed technologies in the same system, types of control (pressure or flow based)
High Speed Turbo technology continues to evolve. When properly applied, it can deliver big benefits.
3:45pm - 4:30pm
Secondary Clarification 101
Stantec, United States of America;
Secondary clarification is a key component of Activated Sludge Systems (Activated Sludge). The performance of secondary clarifiers has direct impact on the overall performance and capacity of Activated Sludge. The primary result of poor performance of secondary clarifiers is an increase of effluent suspended solids (ESS) concentration, which in some cases may indicate a reduction of treatment capacity.
Optimal secondary clarification performance can be challenging and highly dependent on operation, design, and even construction considerations. This presentation discusses concepts of secondary clarification and summarizes tools to monitor and optimize secondary clarifier performance.
4:30pm - 5:15pm
Jay Swift1, Maria Claudia Reed2
1Gray and Osborne; 2Brown and Caldwell; ,
From the earliest examples of sanitation in 10,000 BC, to the London Cholera outbreak in 1858 that helped usher in modern sewers, disease prevention and disinfection have been at the heart of wastewater treatment. The increase in water reclamation, new research regarding pathogens of concern, and recognition of the ecological impacts of disinfection processes are driving more reliable, efficient and cost effective disinfection solutions for WRRFs that provide the maximum pathogen inactivation while producing minimal disinfection by-products and other potentially adverse effects to the environment.
This presentation will focus on the fundamental principles of wastewater disinfection. We will start by addressing the primary reasons for disinfection with a discussion of waterborne pathogens and significance for disease transmission. Various disinfection technologies (Peracetic Acid, UV, Ozone, and Chlorination through gas, bulk hypochlorite and on-site generation) and the advantages/disadvantages for each technology will then be presented; including: disinfection effectiveness for various types of pathogens, the design criteria for implementing each system, capital, operating and life cycle costs, operation and maintenance requirements and considerations for long term maintenance and efficiency of the system.