A sewage treatment technology is now being used to recycle wastewater in urinals
A TECHNOLOGY to
treat domestic sewage,
in existence since the
'60s, has been put to
new use: treating and
recycling wastewater
from public urinals.
Mukesh Khare of the
Indian Institute of
Technology in Delhi claims the rotating biological contactor (RBC)
process can eliminate foul odour from the urinals, especially in the
summers when there is a
perpetual water shortage.
Wastewater from urinals contains both organic matter -
dead cells, proteins, urea and sugars
- and inorganic substances such as
phosphorus and nitrates. To make
the wastewater reusable, the urea
content, which is responsible for the
odour, had to be reduced and the
suspended and dissolved solids had
to be removed. Khare and two of his
students decided to use the RBC after
reviewing various options for treating
the wastewater.
The RBC consists of a series of
plastic discs fixed to a rotatable horizontal shaft and placed in a tank in
which the wastewater is collected.
The discs are partially submerged in
the wastewater and rotated.
Microorganisms present in the
wastewater bind to the revolving
discs, forming a layer of slime or
biofilm. The rotation of the discs
serves two purposes: it exposes the
biofilm alternately to the wastewater
and air, facilitating processes that
eliminate the odour and also enables
the thick layers of slime to be
slo'ughed off and deposited at the
bottom of the tank, from where it can be removed.
Khare and his team have fabricated a simple prototype consisting of a
tank and RBC discs made of asbestos
to keep costs low. Urinal wastewater
is collected in a tank and then fed at
a steady rate into the RBC system.
Khare says the results of this
experiment were "very encouraging".
He now plans to submit a project to
the department of science and technology for carrying out further studies. Khare intends to construct a pilot
recycling plant for IIT's academic complex.
An innovative aspect of Khare's
system is the use of solar energy to
drive the RBC discs and pump
wastewater and the treated effluents.
He is of the opinion that once the
design and other parameters of the
plant are worked out, the system
could offer an efficient and inexpensive treatment and recycling system
for urinal wastewater. He feels that
such systems would be ideal in shopping complexes, cinema halls and
other non-domestic complexes.
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