70. AN
ECONOMICAL STP FOR SMALL COMMUNITIES -
A RAY
OF HOPE
Ecotech, as you may all well know by
now, has been a staunch and unwavering advocate of the Classic, time tested,
proven Extended Aeration Activated Sludge ( EAAS ) Technology for Micro, Mini and small STPs in
Residential and Commercial complexes. SBR
-
( Sequencing Batch
Reactor ) and MBBR ( Moving Bed Biofilm Reactor) are indeed very fine technologies
appropriate only in large scale Municipal STPs of say 10 MLD and above, where sewage
flow characteristics are more uniform and favourable, where requisite and mandatory
design & engineering features may be gainfully applied as also specialised
equipments and treatment stages may be deployed such as the Mechanical Decanter
in an SBR or a Primary Sedimentation stage in an MBBR.
For long we have been hesitant and
shying away from engaging with small communities for their STP requirements : the EAAS system was not economically viable
for say 150 flats or less with sewage flow of less than 100 KLD. The cost of operation & maintenance of
such small STPs would be a killer and make the STP dysfunctional and a messy
cesspool, breeding ground for mosquitoes and other disease vectors in double quick
time. We wanted no part of this to become a blot on our escutcheon
Recently however, the Govt. of Karnataka
mandated that all apartments with 50 flats or more must perforce set up an
STP. And this got us to rethink our
policy on such micro STPs. There are several sharks, charlatans. Voodoo practitioners,
shamans and of course the usual suspects – ignorant plumbing consultants who
will swoop down upon these innocent communities like vultures of prey and suck the
lifeblood out of honest citizens.
As qualified and trained Chemical + Environmental
engineers of high technical and professional integrity and ethical business
practices we took it upon ourselves to rise to the challenge to help this
hapless lot. And thus was born the Anaerobic Baffled Reactor (ANBR) system of
STP for small communities. Not exactly
an invention, but an improvement over and adaptation for an Indian metro city urban
setting, of a seminal work in this direction by Herr Ludwig Sasse of Germany in
the 1990’s. We had to bring to bear all our Chemical Engineering knowledge and practice
in conjunction with our Environmental Engg.
qualifications to fine tune Design and Engineering of the ANBR system to
make it practically operator free with bare minimum of equipments and maintenance.
As an aside : Herr Sasse’s technical brilliance is matched by his outlandish,
peculiar sense of Teutonic humour – more on this in the footnote.
We recently commissioned our first 60
KLD ANBR STP for a residential complex in Bangalore. After initial hiccups, caused not by our design,
but by improper implementation of our instructions, the STP has settled down
well now and is yielding treated water of excellent quality, now recycled and
reused for toilet flush. Even the
lingering suspicion that long periods of stagnation of anaerobically treated
sewage may result in turbid, blackish and odorous product was proved to be ill
founded. Treated water retained its initial character even after 21 hours of
standing well into the next day. See
Images below :
From left to right :
After ANBR, before Sand filter : After Carbon Filter : After Chlorination
Crystal Clear, Colourless Odourless !!! What more can one ask for ??
FOOTNOTE : Pearls
of Wisdom from Herr Ludwig Sasse’s Handbook
“Wastewater
engineers are probably the only ones who love handling wastewater”
“It is
the duty of the technician to deliver an appropriate design which will be
realised with an
appropriate
technology” - (This is exactly what I have been preaching all
along )
“Low
maintenance does not mean NO-maintenance”
“A
wastewater treatment plant is NOT just another pair of shoes” - ( I am still trying to figure this out)
“The
first economic question is "Why", only the second question is "How
much" - ( Well Said ! )
Dr. Ananth S Kodavasal June 14, 2018
