The Varieties of “Beneficial Use”

A certain person I know well claims that, for his psychological well-being, an occasional fine cigar is beneficial.  That determination is based on weighted values known only to him, and arguably with willful and sublime ignorance of the values held by, say, his wife.  

Spouses aside, individuals are pretty much free to deem whether something is beneficial to them or not and take it from there. But in public policy, others get to decide what is beneficial for the rest of us.  

This post is about the “beneficial reuse” of biosolids, which got me thinking about who declared their reuse to be so, and how, where, and when it’s considered a good thing. 

How biosolids come to be.  Wastewater treatment relies on both physical and biological processes to clean water. Primary clarifiers physically remove most of the organic materials simply through settling them out as primary sludge. The remaining soluble organic matter that passes on to the aeration tanks is biologically converted by bacteria. The bacteria multiply, so to keep their population in check, a portion of them is “wasted” out of the system to digesters along with primary sludge. Sludge digestion is either done aerobically or anaerobically (some sludges are incinerated), but under the EPA 503 Rule, the end product becomes “biosolids.”

So what constitutes beneficial reuse of biosolids? According to the EPA, land application of biosolids for fertilizer is one way. And from my viewpoint as a wastewater professional and environmental engineer, it’s a good thing. Biosolids not only provide nutrients like nitrogen and phosphorus, they also help condition soils by replenishing carbon and improving moisture retention. But if you are an activist, you cry foul.  “What about pharmaceuticals and personal care products?” you say.  My answer is that those are the same products you ingest or apply to your skin – but to you, what I say and what the EPA says ranks lower on your “beneficial-ness” scale.  On the other hand, my stepfather in Ft. Wayne wouldn’t care if trace cosmetics or Viagra were in the stuff he put on the lawn. He used biosolids because on the micro level, it worked for him.

U.S. Biosolids Management Practices (Adapted from the National Biosolids Partnership)

What about other uses? The Milwaukee Metropolitan Sewerage District pelletizes biosolids into Milorganite to market and distribute them as fertilizer under the 503 regulations, and has done so for 70 years. This practice is certainly beneficial reuse. Up in Canada, many large cities have big challenges managing biosolids and have few land-application choices, so the Canadian Council for the Ministry of the Environment says incineration is beneficial reuse.  The incineration process at some plants generates steam energy to run turbines or boilers, meaning the energy supplied is the most beneficial use for them. To me, the burning of sludge destroys all of the nutrients (with the exception of phosphorous-laden ash) but I don’t face the same issues some Canadian cities have to deal with.

In California, a different use of biosolids is somewhat controversial – alternative daily cover at landfills.  At the end of each day, soil is usually added between layers of garbage to reduce vectors.  Land application of biosolids is restricted in many areas of California but if biosolids are used at the landfill as cover, suddenly the use is considered beneficial.  

When it comes to public policy and biosolids, like a cigar, to some it’s a good thing and to others, a potential health nuisance. Let’s just hope that those in the position to set policy will make decisions using all of the information and experience available instead of that derived from a singular point of view.

So what do you think is the most beneficial use of biosolids and is your viewpoint influenced by personal experience, circumstances or locale?