Trace Element Distribution in Gassified Sewage Sludge residues.

[NNadir]

Again, from this month's coming "Energy and Fuels" we have this article on the Gassification of sewage sludge which is a source of methane, syn gas (CO + H2), carbon dioxide, and hydrogen sulfide.

"The production of sewage sludge in the European
Union (EU) has been forecasted to grow as the population
increases and becomes increasingly urbanized. In
the past, the main disposal routes for sewage sludge
have been marine disposal, application to agricultural
land, landfill, and incineration. Sewage sludge disposal
has been the focus of much attention within the water
industry in recent years, as some of these disposal
routes have been banned or become subjected to greater
constraints. Disposal at sea was banned in 1998,1
because of concern about the marine environment...

...Incineration has met with increasing local resistance,
in regard to planning applications, and is affected by
government measures that are intended to reduce CO2
emissions by extending the use of wastes as fuel for
energy production. Consequently, gasification has attracted
considerable interest from water utilities as an
alternative technology with the same advantages of
destruction of pathogenic bacteria and volume reduction,
and the additional benefits of energy recovery and
lower-cost atmospheric emissions control.
Trace elements (defined as elements with a fuel
concentration level of <1000 ppm wt), including heavy
metals such as copper, mercury, lead, and zinc, are
present in sewage sludges at levels significant to their
disposal..."

The good news in this article is that lead in sewage sludge are immobilized in three insoluble forms, the metal, Pb(II)Cl2, and PbS. (Some lead is apparently volatilized however, but presumably can be recovered.) The bad news is that they have no idea where the mercury went.

(We can guess where the mercury went: The reaction conditions are at high temperatures >900C and mercury is volatile.) Unfortunately the Barium is also in soluble forms, the chloride, sulfide although Barium doesn't typically get very far in the environment because of it's extremely insoluble carbonates and sulfates.

[Spinzonner]

1. That's a real page-turner

[NNadir]

4. I left out the part where the syn gas gets hot (wink, wink).

Syn sounds like "sin" in those parts, baby. Don't read them unless the kids are in bed and if your lover likes talking dirty.

[Maple]

2. Lemme know

when you have a linkable source. Interesting info.

[Ian David]

3. Duplicate thread

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x18073