A POTATO CHIP FACTORY IN HARIDWAR
(WHICH ALSO PRODUCED SOAP ON THE SIDE!!! )
BACKGROUND OF THE POTATO CHIP FACTORY
XYZ Limited, a highly respected Indian Multinational Company, set up a multi product manufacturing facility in Haridwar, Uttarakhand. The products manufactured at different manufacturing halls within the campus included Potato Chips, Biscuits , Soaps, Shampoo, creams, etc. XYZ recruited necessary senior and experienced manufacturing personnel for these various activities from other established competitors in the respective fields such as Frito Lays, Britannia, Nestle, Hindustan Lever etc., thereby not having to reinvent the wheel all over again.
As per customary practice in XYZ, a consultant was duly appointed for designing and engineering the utilities, plumbing system and alas, also the Wastewater Treatment Plant. The potato chip wastewater had a separate dedicated Treatment Plant, while the other production units had another common Treatment Plant in the campus.
Now, regular readers of this Adda will no doubt be keenly aware of my revulsion, bordering on disgust of Plumbing Consultants masquerading as environmental consultants without first acquiring requisite knowledge, skill or proficiency in an endeavour which is predominantly an Art : the following story will serve to illustrate my theory or point of view, if you will.
- PLUMBING CONSULTANTS CAN ONLY CUT AND PASTE
Potato chip making calls for the following stages and operations in the production process, where water is used and wastewaters are generated :
- Destoning ( Washing and cleaning the raw potatoes brought in from the fields)
- Peeling ( Peeling the outer skin of the potatoes – thick skin/ thin skin/ seasonally variable)
- Slicing ( Slice the potatoes for making the chips)
- Prewashing ( to wash away loose particles of starch and sugar on the surface of slices)
- Blanching ( a process to inactivate enzymes, gelatinize starch and reduce sugar content –otherwise, in the frying process which follows, the sugar caramelizes, and unsightly brown coloured chips are produced)
In addition to the above wastewaters, there are two other wastes from the factory, which are intermittent “dumps”
- Caustic boil out once a week : 12-16 KL per batch containing Caustic Soda ( NaOH )
- Waste oil dump once a day : 10 KL per batch
Before one embarks on designing a Wastewater treatment plant, one has to study the production/ manufacturing process in detail, understand the requirements of water at each stage of the process, both in terms of quality and quantity. One has then to characterise the wastewater from each stage again in terms of quantity, quality, pollutional potential, etc. An Environmental Engineer then investigates ways and means to conserve water, internally pretreat, recycle and reuse water, thereby achieving savings in fresh water consumption, and reduction in wastewater generation.
The water balance proposed by the “Plumbing Consultant”, cut and lifted directly from an existing Frito Lay factory, and pasted on to the XYZ unit in Haridwar, which I will call as the “Worst Case Scenario”. The Wastewater Treatment Plant was also designed accordingly for a total flow of 21 cum/Hr or approx. 500 cum/day.
When the treatment plant failed to deliver satisfactory results, I was called in to Haridwar by XYZ Ltd., to study the plant and suggest ways to improve performance. After detailed study of the various production stages, and understanding the requirements of each stage, I proposed a revised Water Balance as the “ Ideal Case”, wherein several internal recycle and reuse strategies were introduced, including a starch recovery stage from one of the waste streams. These proposals were indeed later implemented as a retrofit by XYZ Ltd.
- Fresh water consumption was reduced by over 50 %
- Wastewater generation was likewise reduced by over 50 %
- Starch was produced as a Byproduct, which was then sold for making glue for use in the paperboard/ carton making and book binding industry
MORAL OF STORY : Plumbing Consultants can never aspire to become good Env. Consultants.
- PLUMBING CONSULTANTS ARE BLISSFULLY IGNORANT OF SIDE EFFECTS AND OTHER ENVIRONMENTAL IMPACTS OF THEIR ACTIONS
In the same potato chip unit of XYZ Ltd., there are two intermittent waste dumps as described above :
a. Caustic boil out once a week : 12-16 KL per batch containing Caustic Soda, NaOH
- Waste oil dump once a day : 10 KL per batch
The accursed Plumbing Consultant had proposed a conveyance system for all the wastewaters from the process, as also these intermittent dumps, from the production hall to the Treatment plant located at a considerable distance. A single common drain line was installed, with two intermediate pumping stages, each stage consisting of a collection tank and pumps for further carriage of the wastes.
Imagine the surprise and also the great consternation of XYZ Ltd., when they discovered that in addition to producing potato chips, they were also producing soap on the side, in the pipelines and pits long the way to the Treatment Plant !!!
Over a period of time, the waste and tramp oil collected in the intermediate tanks were reacting with the caustic dumps also carried along the same line, getting converted into soap - the classic chemistry of “Saponification”
Caustic + Fat = Soap + Water
My recommendation for the above wastes which was later implemented consisted of storing the weekly caustic dump in a tank and gradually dripping it into the sewer line over the week, thereby not affecting pH adversely.
The oil was proposed to be disposed off as slop oil to refiners to manufacture low grade lubricants.
MORAL OF STORY : Plumbing Consultants do not have knowledge of Chemistry/ Chemical Engg. to become good Env. Consultants.
- PLUMBING CONSULTANTS WILL HIT ROCK, MISS THE POINT !
Not entirely satisfied by the great harm caused to XYZ Ltd., on account of their ignorance compounded by their casual, cavalier attitude in their above acts of omission and commission, the Plumbing Consultant went on to heap further misery on the hapless Client.
Any Good biological Treatment plant is only as good as the synergistic working of the Aeration tank, the Settling tank and the sludge ( Bacteria / Microbes) recycle system. The very many intricacies and nuances of design and engineering of the settling tank are well beyond the limited comprehension of the common Plumbing Consultant.
In the same Treatment plant at Haridwar of XYZ Ltd., the original design called for a water level difference between the Aeration and the settling tank of only 0.3 M. All is well in this design. The water gets conveyed to the settling tank, and because of the very marginal difference in levels ( just sufficient to make the water flow from the Aeration tank to the Settling tank), not much turbulence is caused in the Settling tank, thereby also not disturbing the settled solids/ settling solids in the tank.
At the time of construction however, the Contractor encountered hard rock just beneath ground level at the exact spot earmarked for the Aeration tank. Presuming to be doing a great favour to XYZ Ltd., by saving on construction time and excavation costs in hard rock, the untutored Plumbing Consultant blithely altered the design, raising the Aeration tank by 2.5m, meaning to avoid thereby tedious blasting and excavation in hard rock.
Now, Water gushing into the settling tank from the aeration tank from a height of nearly 2.8 m ( the altered level difference) is virtually a torrent, in the nature of a smallish waterfall, and the kinetic energy of this mass of water can only be dissipated when it traverses an equal distance down into the settling tank. By which time of course, all the settled solids and settling solids are well and truly stirred and kicked up. Solids settlement under a calm and quiescent condition can never occur in the settling tank under these turbulent circumstances.
If solids do not settle in the settling tank, there can be no solids capture and recycle back to the aeration tank : if there are not enough solids ( bacteria) in the aeration tank, no treatment can take place : the wastewater enters the Treatment Plant, dutifully passes from one unit to the next and finally exits the Treatment Plant in the same condition that it entered the Treatment Plant.
Surely, XYZ Ltd., needed no Treatment plant to achieve “Zero Treatment”. Adding insult to Injury, the Plumbing Consultant laid the blame for non performance of the Treatment plant to an overload of waste ! I call it an overload of B--l S--t from the Plumbing Consultant.
MORAL OF STORY : Shun Plumbing Consultants like the Plague, if it is a Treatment Plant you want
Dr. Ananth S Kodavasal April 24, 2011
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