[USCC] Vol 29, #9--Regulation by various agencies

[Alternatives, L.L.C.]

Frank,
By requiring yard waste and manure composting facilities to use biosolids,
you would be forcing the facilities to obtain permits to compost biosolids.
I think this is an unlikely alternative considering that some states do not
require the composting process to be permitted for agricultural or green
wastes.  

The temperature monitoring system currently in place is clearly not
acceptable, but, as I see it, neither is the regulatory framework.  States
can require temperatures to be taken from specific locations in the
composting materials and often do specify this in the permitting process.
Whether the actual temperatures are taken from the center of piles or not is
clearly up to the facility at this point.  As a compost producer, and having
taken many temperature readings at different locations in windrows, I can
honestly tell you from experience that the centers of windrows are often the
coolest locations.  So, the chances of achieving PFRP temperatures would be
reduced.  And, given the cross section of a typical windrow, how would I
locate the center?  

I suggest a more reasonable method would be to average the temperature taken
at stratified depths in the material, from the outer most edge of the
biosolids mix to the approximate center.  For instance, if I have a windrow
approximately six feet high and 12 ft. wide at the base, I would take a
reading at one, two, three and four ft. from the outermost biosolids layer
into the center of the windrow, at a three ft. level from the ground.
Assume the temperature stratification was as follows; 136, 141, 131, and
128 degrees F.  The average temperature would be 134 degrees F.
Redistribution by turning, coupled with longer composting periods, would
reduce the likelihood of the survival of pathogens.  We need to stop
worrying about specific temperatures.  If anything, allow lower temperatures
for extended periods.    

The problem with the theory that biosolids are free of soluble components is
not strictly true because not all biosolids undergo anaerobic digestion
processing.  Most treatment facilities aerate biosolids rather than treat
them anaerobically.  Aeration decreases the odorous components while
decreasing the pathogen concentrations as well.  Some biosolids are
anaerobically digested and treated with lime to stabilize the digest.  In
the aerobically digested material, the water is separated from the solids,
and the solids, typically Class B biosolids, can be directly land applied.
The main problem with using these biosolids in composting is that they
contain a significantly smaller fraction of organic matter, and that they
are very wet, not that the nutrient content is inadequate.  

Even though the chemicals I mentioned are organic, the half lives of many
organic chemicals, even if composted, can be greater than the period of
composting.  We recently found residuals of a herbicide in one of our
composts that had gone through six months of composting, and I seem to
remember a herbicide called cropyralid causing some problems in the past.
These are also organic chemicals, as are acrylic, latex and enamel paint
residuals, biphenyls, and a wide range of petroleum products that are not
easily degraded during the composting process. Composting greatly decreases
the residuals, usually to very low concentrations, but it some are more
recalcitrant than others.

We do test for Salmonella spp., E. Coli, Clostridium spp., and other
pathogenic forms routinely in biosolids and composts.  As I recall, there
are TMECCs for pathogen testing.  Fecal coliform analyses test for the
presence of the indicator species E. Coli because 95% or more of the fecal
coliforms present in biosolids are E. Coli.  I have no argument that we need
to reduce the pathogen levels to specified levels.  My argument is that the
current time/temperature method may have to be modified so that there is
less risk of materials in compost piles not achieving the prescribed
time/temperature objectives, yet assuring that pathogen kill is still
sufficient.  If this means composting for longer periods at lower
temperatures, so be it.  Which would be worse; removing and recomposting
none-compliant materials for 15 more days, or allowing a little more (30
days) processing time to achieve the same goal? 

Unfortunately, if we want to make changes to the biosolids composting rule
that will be applicable to all states, the rule has to be altered on a
Federal level, because every state can be more strict, but at least as
strict as required in the 503 regulations.

Dave Schellinger   
Alternatives, L.L.C.