Next time you flush a toilet in Whangarei, you could be helping
to save ratepayer money and enlighten local farmers to a better way of
dealing with effluent.
A new unit at the city's wastewater
treatment plant will use methane - a byproduct of the sewage treatment
process - to generate electricity. This power would be used to run other
processes at the plant, said Whangarei District Council waste and
drainage operations engineer Adam Twose.
The unit would also
serve as a demonstration project for Northland farmers wanting to put
similar technology to use with animal effluent.
"The electricity
produced won't be enough to export to the grid because this site [the
treatment plant] uses about 250 to 300 kilowatts all the time," Mr Twose
said. "This process is only going to generate about 70 kilowatts, but
that will save the council about $60,000 worth of electricity a year."
The WDC's Kioreroa Rd plant would soon see the
installation of a General Motors 8-litre V8 en
gine next to its sewage
digestors. The engine is similar to what can be found inside many
American muscle cars and would form the basis of a co-generation unit,
which produces useful electricity as well as the heat needed to "cook"
sewage sludge as part of the treatment process.
"We cook the
sludge at 37C for about 30 days, allowing the solids to break down," Mr
Twose said. After this, the sewage sludge was dried and taken to
landfill.
Mr Twose said sludge was now cooked using boilers, which ran off the methane this process produced - a self-contained process.
http://www.nzherald.co.nz/environment/news/article.cfm?c_id=39&objectid=11651940
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