AN OFF CENTRE CLARIFIER

THE CASE OF THE OFF CENTER CLARIFIER

Regular readers of this Adda will have no doubt read the Story of the Potato Chip Factory : Here is the story of an STP of a Chip maker of a different kind : A true Blue American Hitech Multinational.

I have a healthy disrespect for a great majority of foreign Multinational Companies, at a level only slightly less virulent than my abhorrence of Plumbing Consultants masquerading as Environmental experts. This, from my interactions and personal experiences with MNC’s in multifarious business enterprises ranging from Soda Pop to great big IC engines.

Both of my favourite Villains foregathered in this case of a botched up Treatment Plant, succeeded in sweeping the S--T under the carpet for nearly one year, until an Auditor from H.O came calling.

It is truly mind boggling to count the number of people and agencies involved in certifying, accepting and running this absolute rubbish of a Treatment Plant !  Let me make the job a little easier for the reader.

HEAD COUNT OF PEOPLE RESPONSIBLE FOR THE STP

1. 2 Nos. (Two) EHS Managers of the MNC
2. N Nos( Enn) of civil engineers, Managers of the civil construction company ( L&T – Construction Division)
3. N Nos. ( Enn) of Consultants/ flunkeys/ monkeys from Kinetic Service Consultants ( Name changed to protect privacy)
4. N Nos. ( Enn) of Erection crew from the Equipment vendor
5. N Nos. ( Enn) of operating personnel and staff of the operating Agency at the STP
6. N Nos. ( Enn) of the External Facility Management staff employed by the Chip Maker to oversee the operations of the STP
7. N Nos. ( Enn) of KSPCB officers who come visiting to collect “statutory” dues

TOTAL : Sorry ! !   Lost count here.

AT THE CENTRE OF THE PROBLEM

For nearly one year, during the so called Defects Liability Period, the STP never got stabilized, and achieved Zero Treatment.  ( The burden of liability and sufferance apparently devolved on the User and not on the vendor or Consultant). Sewage entered the plant and exited the plant, with little difference in quality, except perhaps ageing by a day in the process. Whatever little bacteria was developed in the brief period of stay in the aeration tank, floated out of the clarifier, without any settlement.  Sand and Carbon filters got choked frequently in the process, and no healthy population of bacteria could be maintained in the aeration tank.

All this while, the above worthies consoled themselves with various specious excuses and reasons for the non performance of the plant.  Not even a cursory effort was made to investigate the cause of all grief.  Meanwhile, I presume, glowing reports were transmitted to their Overseas Head Quarters on a weekly basis of the Excellent performance of the plant.

My presumption regarding the “Glowing Reports” is not without reason.  When I was called in finally to investigate the case, the EHS manager pulled me to the side and with a worried look on his face, asked me whether I could really lick the problem.  My readers by now know of my supreme confidence in my own abilities, and absolute lack of modesty.

With a look of absolute disdain, I told the fellow “ This is Baccha ( baby) plant for me.  Don’t worry. I can set it right in no time “.  Not convinced, the EHS man persisted, and pleaded with me, almost coming to tears “ Sir ! my job is at stake if I do not show satisfactory results from this plant”.  That was the time I realized what fudging must have been going on for over a year, on paper and in reports when, on the ground things were literally falling apart.

My confidence in being able to rectify the plant was based on my inspection of the plant a little earlier in the day.  Within minutes, I had identified the cause of all grief – The core of the Problem.

THE OFF CENTER CLARIFIER

The Clarifier ( Settling tank) was a square tank 10 ft x 10 ft.  There was installed a rotating clarifier rake mechanism, meant to sweep the floor of the tank, and transport all settled solids / sludge         ( bacteria ) to a central hopper, whence, the bacteria would be recycled back to the aeration tank to maintain the desired high level of bacterial population.  Now, a clarifier’s performance is only as good as how effectively and quickly it can transport the settled solids to the central hopper.  For this to happen, it must sweep the entire floor of the tank effectively, quickly, but without too much turbulence to kick up the settled solids.

The Clarifier mechanism at this Chip Maker’s plant was, alas,  fitted off- center of the clarifier tank    ( See Sketch # 1 attached).  This resulted in a “Dead Zone”  of nearly 37 % of the floor area, which was not swept by the rake mechanism : In the Dead Zone, the bacteria stayed for hours together, and under anaerobic conditions, turned septic, generating gas ( Methane etc.) in the classic anaerobic reaction.  The bacterial mass then attached themselves  to the gas bubbles thus generated, levitating and rising up the clarifier and out of the clarifier, in an unsightly mess.

The problem found a quick solution by shifting of the mechanism to the geometrical center of the tank, extending the rake blades to the periphery, Making extreme floor slopes in the four corners of the square tank not swept by the circular motion of the rake blades, all within no time, as promised.  Since that time, I am happy to report, the EHS managers of this facility have not had to fudge their reports.

Dr. Ananth S Kodavasal                                                                          April 26, 2011

Ecotech

FOOTNOTES :

1. In my meetings with the EHS mangers of this facility, I was initially put off, when during our discussions and my technical presentations, these uncouth fellows were busily typing away on their laptops, least interested in what I was trying to convey.  I forgive them the discourtesy : After all the poor blokes were only trying to keep their jobs secure – the STP be damned. Such is the time bound, superior work culture in an MNC.

2. The concept of “Defects Liability Period” is grossly misunderstood.  This period is meant to be a “Warranty period “ only to provide relief against manufacturing defects in the equipments installed, and warrants free replacement of such defective parts OR replacement of the entire equipment, if parts replacements prove to be of no avail. ( Normal wear and tear items excluded – Oil seals, bearings, Rubber and plastic parts etc. much like in an automobile), irrespective of who runs the Treatment Plant.  And if the vendor is unable to show satisfactory results within say one or two months of commissioning of the Plant ( the normal period within which the STP can be stabilized), the User is not obliged to continue to suffer for the entire Defect Liability Period with a non functioning Treatment Plant,  the Vendor meanwhile merrily running the Plant, and sweeping all defects and lacunae under the Carpet, safely out of view.

It would be prudent, and indeed advisable to bring in a third party with sufficient expertise to run the plant and uncover various Design and Engineering deficiencies and defects during the DLP, and hold the perpetrators responsible – the Builder, the Consultant, the Vendor and the PCB.