April 2007, Vol. 19, No.4

From the Editors

WE&T Prelude


At this moment, at any number of wastewater treatment plants around the world, processes are running amok.

Hundred-year storms are causing collection system overflows. Urban populations are growing rapidly, pushing anaerobic digesters past their limits. Secondary clarifiers are failing, leading to permit violations. The good news? All the damage can be undone with a mouse click, because these would-be disasters are actually computer simulations designed to help utilities prevent such catastrophic failures in reality.

Modeling software enables utility personnel and engineers to run wastewater processes and systems through a variety of virtual scenarios, ranging from small changes in flow to disastrous events. Process models can arm utilities with the information needed to enhance performance, save money, or even avoid costly construction. It is no wonder that computer modeling has become an essential tool for solving wastewater treatment challenges, whether used to design a new plant or enhance an existing one.

This issue is devoted to modeling — the processes it can simulate, the benefits it can provide, and the ways in which it can help steer human decisions. This mini-tour of virtual wastewater begins here.


Operations Forum Editor's Note

Storytellers Welcome

We pride ourselves on delivering to you the best magazine content available, and our authors make this possible. We’re extremely lucky to serve a community of talented and passionate operators and engineers who want to share the problems they encounter and the solutions they find to remedy them.

It is pretty gutsy to air your laundry to 30,000 readers. To be able to demonstrate enough humility to discuss a problem openly and enough pride to present an answer confidently, takes a special type of person. Luckily, WE&T and Operations Forum attract these authors and, I hope, encourage more readers to become authors and share their successes.

The first article in this issue examines a technology that has been successful at delivering treatment plants from odors. Air-ionization units produce positively and negatively charged oxygen molecules, or ions, without creating ozone, to break down odor compounds in the air.

Another article examines how the misconception that all odors are harmful can be problematic for an odorous site and its neighbors.  A lack of distinction between public health limits, which are extremely conservative to ensure that human health is protected, and public welfare limits, which are intended to protect animal health, natural resources, and people’s quality of life, can quickly confuse matters for the public and treatment plants alike.

We also feature a utility that needs to add more wet weather treatment capacity while working around process and site constraints. The project team — an engineer, plant operations and maintenance staff, and a construction manager — worked together to decide between two alternatives.

As you can see, there is a lot of information to digest in this issue. Thank you for your continued submissions, and we look forward to seeing what’s in store for the future.

— Steve Spicer, editor sspicer@wef.org