October 2006, Vol. 18, No.10
Around Halloween you can always catch the classic scary movies on television, often featuring an amorphous villain: “The Blob.” “The Fog.” At wastewater treatment plants, there’s “The Foam” — excessive digester foam. Not the stuff of which most horror films are made, but an ominous problem nonetheless — and one that is becoming more common throughout North America.
While some digester foaming is normal and to be expected, excessive foam is a menace, as it can overflow digester walls and keep the gas-piping system from functioning properly. This month we look at the potential sources of excessive foaming, and examine how three different plants were able to stabilize digester operations to keep foaming under control.
— Melissa Jackson, editor
Operations Forum Editor's Note
Turn Off the World
About 3 years ago I moved to a new apartment and never had a landline phone connected. I chalked it up to being busy with unpacking and finding my way around a new neighborhood. At first I worried that I would miss an important call, but voicemail handled that. Then I worried that I would lose the phone. Well, it’s 3 years later and I have found my phone any time it has gone missing (it’s usually under the seat of my car).
Along the way I also found something else: uninterrupted quiet. Any time I want, I can turn off my phone and I am unreachable. Never do telemarketers interrupt my dinner, never does a wrong number make me miss the end of the whodunit. It’s my own slice of solitude as close as the power button.
I think I’ve spoiled myself because as I read about all of the ways operators can stay informed about the status of the plant, I started to panic. Of course, it’s essential for the people who work daily to protect the nation’s water resources from pollution to be in touch. But there’s a danger in getting too many alerts.
For example, just 2 years after installing a computer control system with more than 37,000 database points, the Sacramento (Calif.) Regional Wastewater Treatment Plant had more than 700 active alarms, most of which an audit characterized as nuisance alarms. By developing a strategy dictating under what conditions an alarms should sound and eliminating nuisance alarms, they were able to reap the full benefit of their control system.
In a work setting, it’s difficult to strike a balance between being connected and being overwhelmed.
— Steve Spicer, editor