[OKC] From NY Times: ... And Sewage, Too

[Miles, Karen]

... And Sewage, Too 


By ROSE GEORGE

Leeds, England

ON several quiet streets in Sheffield, a northern English city an hour
from here, are street lamps that look like ordinary gas lamps, but do
not burn ordinary gas. Instead, their light comes from gas released from
the sewers that run beneath them. Thus, they are both relics of the
past, when gas lamps lighted our streets, and of the future, when
excrement and wastewater will again be seen as a resource, not a waste. 

"Wastewater" has always been recognized to have some value. In 1860, as
waterborne sewer systems were becoming the norm, an alderman named Mechi
told Farmer's Magazine that "if the money value of our sewers could be
shown to the British farmer in bright and glittering heaps of
sovereigns, he would gasp at the enormous wealth, and make great efforts
to obtain the treasure." Mechi was talking about the fertilizing
nutrients in human "waste," which he thought were needlessly ruined by
mixing excrement with water, but he might also have been talking about
its wasted energy potential. 

Sludge, the solids that remain after sewage has been cleaned into
effluent, has a high B.T.U. content (a measurement of fuel's energy); it
burns efficiently and well. Other aspects of wastewater treatment can
also reap energy: anaerobic digestion (whereby bacteria munch on the
organic contents) produces methane, which with turbines can become
combined heat or power. Microbial fuel cells can use bacteria to get
electricity from sewage, while gasification, a high-temperature process,
can reap fuel-ready gas from sludge. 

 

Article continues at: 
http://www.nytimes.com/2010/04/28/opinion/28george.html?th=&emc=th&pagew
anted=print

 

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