THE MBBR, THE SBR AND THE UF : THE CATCH -22

The heading here reminds me of the classic spaghetti western starring three outstanding actors but only here slightly paraphrased to suit the setting : The Bad, the Worse and the Worsted. A catchall phrase, many use Catch-22 loosely and out of context – like the aspiring Writer in the picture above. Rest assured my usage of the phrase is apposite and based on years of observing scores of these malfunctioning STPs

During my IIT days, books like Catch-22, Atlas Shrugged, Fountainhead, Catcher in the Rye etc., caught the fancy of not only the ubercool chic gang, but also the hoi polloi like yours truly brought up on a steady and staid diet consisting of Biggles, Gimlet, Enid Blyton and the like during my growing up days borrowed from our School Library to more adult fare in late teenage years. Perry Mason, Agatha Christie, James Hadley Chase, Right Ho, Jeeves ! etc.,

BIGGLES IN AFRICA, BIGGLES IN ITALY, BIGGLES GOES WEST, BIGGLES IN FRANCE, BIGGLES, BIGGLES, BIGGLES EVERYWHERE

All of these books Courtesy my dear departed father who on his frequent train travels out of Bombay on business trips was a loyal client of A H Wheeler & Co. And every one of his trips added a book or two to his Library of these breezy novels meant for light reading and never to test your mental prowess or exercise the grey cells in the least.

 I am digressing here. Pardon me if I get carried away when recounting tales of yore.

MBBR - THE BAD

 In simple Chemical Engineering Parlance this is a Fluidised Bed Reactor, which I fully understand given my Chemical Engg. Background. Excellent Technology, when applied judiciously, with the right flowsheet and in the appropriate scale and size of plant. Can't plonk a Bullet train in the Bombay suburban train service, Can we ?

 1. As we all know, no MBBR STP can work without a primary sedimentation stage. 

 2. No MBBR will work with a Tube or Plate settler. 

TYPICAL MBBR FLOWSHEETS. OBSERVE PRIMARY SEDIMENTATION IN EVERY CASE, WITHOUT EXCEPTION. AND LOOK MA - NO TUBE SETTLER !

3. No MBBR will work without the right amount of Plastic carrier media of the right specifications ( Useful Surface area, Density when coated with 1 mm thick attached growth of bacteria, roughness coefficient etc),

4. No MBBR will work if the D.O level is not maintained at around 4 PPM.

5. All MBBRs will produce excess sludge which is light, in thin slurry form, difficult to settle, difficult to dewater Etc., Etc. 

All these aspects and considerations are not diligently addressed in the Mini and small STPs by the Environmental Pundits with a common plumber’s background. Therefore these MBBR Gurus try to make up for these deficiencies by adding an Ultrafiltration Stage as a crutch, which also helps to pad up their commissions.

THE SBR - THE WORSE

 Again in simple Chemical Engineering Parlance, this is a batch processing of a first order Biological reaction, which I would fully recommend provided all other aspects and considerations are favourable. Alas, they are not in the case of a small STP

Unfortunately, in a mini or a small STP Upto 5000 KLD, all the stars in the firmament are aligned against this process :this for the benefit of such of those plumbing consultants taking inspiration from Astrology when designing an STP

Since the SBR treats the daily flow of sewage in three equal batches, This system is inherently unsuitable where there are distinct peak flows like in an Residential complex, a commercial establishment, a mall, a hotel etc.  Case Closed even before a Preliminary hearing.

But, being a man of infinite patience, fairness being in my DNA , let me take you through irrefutable and unimpeachable scientific and technical evidence that will trash the claim that SBR occupies less Footprint, consumes less energy in comparison to the EAAS (Extended Aeration Activated Sludge- My all time favourite). These are the two main pillars on which the SBR edifice is built by ignorant plumbing consultants

1. The Equalisation tank in an SBR STP must have a minimum 8 hour holding capacity (one batch) as compared to 4-5 hours in a comparable EAAS STP. Therefore in SBR, the Equalisation tank is at least 60 % larger

2. In an SBR, by Universally accepted norms only one third of the tank depth may beused to treat and decant one batch. Therefore the SBR tank must have 24 hour holding capacity. In EAAS we need only 14-16 hours. Therefore in SBR, the aeration tank is at least 50 % larger

3. Excess sludge generated in the biological reaction can be extracted in thick slurry from the Secondary settling tank in the EAAS. In the SBR, since it is a flat bottomed tank, excess sludge is very thin compared to EAAS. Therefore in SBR, the Sludge Holding tank is at least 50 % larger.

4. When you have so many tanks in the SBR so much larger than in the EAAS, energy consumption to mix and aerate these tanks is also equally and proportionally much higher.

CASE HEARD, EVIDENCE WEIGHED, ADMITTED AND SBR BANISHED TO PERDITION.

Of course there are other incontrovertible reasons why SBR as designed and engineered by imbecilic consultants will fail.

5. A Rudimentary Pipe decanter used in SBRs cannot hold a candle to a sophisticated motorised Decanter which ensures that no sludge is pulled up from the bottom in the decant stage

SCIENTIFICALLY ENGINEERED, UNIVERSALLY RECOMMENDED MOTORISED, MECHANICAL, LONG WEIR DECANT SYSTEM TO PREVENT SLUDGE CARRYOVER FROM THE SBR TANK DURING DECANT STAGE

6. In SBR STPs even battle hardened veterans like the PSF and ACF pack up in the face of high level of solids from the decant stage. Typically these units are bypassed in a vast majority of SBR STPs.

What chance then does a freshly minted Virgin UF membrane have with such tight median pore size of 0.20 Micron to withstand constant and determined onslaught by solids bent upon penetrating at any cost, damaging and tearing the fragile and sensitive membrane ?

Exactly. The chance of a snowflake in hell.

NOW THE CATCH-22  - WORSTED

The Paradox should be clear for all to see. In order to take up the slack of the MBBR and the SBR and their inability to produce good clean water, the imbecilic plumbing Gang seek refuge in the UF System. And this very defect in the MBBR and the SBR will also kill the UF system.

To put it in a few simple phrases everybody can understand, the real Catch -22 :

 - You are damned if you do and damned if you don’t

 - MBBR or SBR with UF – What is the point ? You are going to get Ducked anyway

 But then again if you think such ignominy is inevitable, you do not have to lie back and enjoy it as Confucius say.

Or you could follow Bob Marley's excellent advice : "Get up, Stand up, Don't give up the fight". Convert the delinquent SBR, MBBR to the EAAS System through scientific precision surgery by Ecotech.

That's all folks !

Dr. Ananth S Kodavasal                                                                    June 20, 2020

FOOTNOTE : On several occasions in the past one year or so I have invited these imbecile consultants promoting SBR, MBBR,, EADOx etc., to attend my presentations on Appropriate STP technologies. But then I realised even with all my experience and expertise in such surgical procedures, it is well- nigh impossible to convert imbeciles and idiots to ordinary thinking human beings. They prefer to remain forever the commission agents - The ugly.