Names Do Matter

The solid end product of a clean-water plant is a beneficial thing. We shouldn’t persist in calling it by an ugly and offensive name.

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Back in the 1980s while working on a public participation project for a clean-water agency involving land application of what we now call biosolids, I invited a state regulatory official to speak at a meeting of our citizens' advisory committee.

During the phone call, I told him various alternate names this agency was trying out as replacements for "sludge," which was then the only term available. His response: "Call a spade a spade, or I won't come and speak."

In a way, I still respect his position: As a writer I have never liked euphemisms, if defined as nice-sounding words used to make something awful sound better. But in "sludge," we had an awful-sounding word making something good seem bad.

Resisting change

So now we call it "biosolids." In all candor, I have never liked that handle either, but try as I might I can't think of anything better. So, "biosolids" it is — except that a surprising number of people in the clean-water industry still call
it "sludge."

Ironically, those ranks include some manufacturers of biosolids-handling equipment. They send press releases that talk about "sludge" processing and, maybe even worse, about "disposal" (and here, of course, the preferred terms are "beneficial use" and "recycling," unless the material is being burned or landfilled).

Some operators still use that old word, too. We run across it now and then in interviews for our stories about exemplary biosolids programs. Why do some of us in the industry persist in using words that make one of the end products of wastewater treatment sound ugly? Is it vestige of the "call a spade a spade" mentality? Does it even matter what we call the stuff?

Gray areas

Well, as a matter of fact, yes, it does. I'll admit it gets a little confusing when you're an insider looking at the treatment process as a whole. Because on the way to clean water, we have primary sludge, waste activated sludge and return activated sludge — terms of art for which substitutes don't exist and aren't really necessary.

But at some point a line gets crossed at which these materials have been changed enough so that we really should not call them simply "sludge." Where is that point? We've argued a little about that here at TPO magazine. While I don't claim to be the final authority, for my money it becomes "biosolids" the moment it enters an aerobic or anaerobic digester or some other treatment or stabilization process.

What comes out of a digester is very different from what went in. It is transformed in a fundamental way, even before it enters further steps that dewater it and, in some cases, turn it into Class A material, essentially free of odor and pathogens. If "sludge" goes in, and something very different from "sludge" comes out, why should we still call that end product "sludge"? Doing so does a disservice to the product and the profession.

Outmoded tradition

So, what we apply to cropland, or turn into compost, or spray on forest land, or plow into the soil on reclaimed mine sites, is biosolids. We really should banish the term "sludge" from the clean-water process vocabulary (with the exceptions mentioned above).

The industry should look for unanimity on this. The solids side of the clean-water process is quickly becoming a part of the green-energy movement — digester gas (biogas) is quickly gaining favor as a renewable fuel. As treatment plants look to produce more biogas, they are going to digest more material and make more biosolids. That end product is valuable, too, and we shouldn't devalue it by calling it an ugly name.


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