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