WHAT IS THE RPM?

This is one of the most common and most abused terms used in fermenter when dealing with the speed of rotation of stirrer in fermentation studies. The speed of rotation of the stirrer is commonly expressed as rounds per min (RPM). The power of stirring is often associated directly with the speed of RPM. Higher RPM means more power to stir

There is a simple correlation generally accepted that the higher the RPM, the higher will be the agitation or mixing of the fermentation broth and hopefully a better mass transfer is achieved between the microorganisms and the environment.
One of the common beliefs is that with higher mixing or RPM we should be able to achieve higher mass transfer of oxygen leading to more efficient fermentation process.

This belief has its limitation as there are many factors that affect the mass transfers of oxygen besides RPM other than just obtaining the optimum RPM
What is most surprising is that the use of RPM seems to be carried out with out the proper understanding of the various processes that occur during the fermentation in the bioreactor.

In most textbooks there seems to be a complete trust in one particular set value of RPM without thinking the use of various other options to enhanced the fermentation process and minimizing the negative impact of excessive or under use of RPM
I have seen almost majority of books suggesting the range of RPM around 200 to 250 RPM. Simple visual observations can show how fast or how damaging such high speed of stirring can be on the fermentation process.

We all know that in the case of mass transfer of oxygen to the fermentation broth will be influenced by the volume of air introduced into the fermentor and stirring among other factors. A choice of high RPM may be even more damaging to filamentous microorganisms. Thus great care must be taken in choosing the proper RPM and not to trust blindly by the 200 to 250 RPM often recommended

Mixing of the fermentation broth is not a simple process. Each researcher must find their very own optimum values in terms of both economic and technical success of their fermentation. After all no two fermentors carrying out the fermentation process are the same! This situation will be most critical when the fermentation is carried out on a large scale. In considering stirring and RPM. the impeller or the paddles influence must be considered. Adding an additional impeller will increase the efficiency of the agitation of the fermentation broth but at the additional expense on the load of the stirrer which will increase the strain on the stirrer system


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OUR FIRST “MADE IN MALAYSIA” PILOT PLANT FERMENTORS

I have mentioned earlier that fermentation can be carried out in any vessel or container. The difference is that if fermentation are carried out in such vessels we might not end up with a proper and efficient fermentation process. Inefficiency could arise out of poor mass transfers, monitoring and lack of stringent aseptic control.
The design and building of good fermentors depends on inputs of engineers and microbiologists. It is just risky to just depend on one set of people to design and build a good fermentor.
Yes, while it is true we can build a vessel or structure that seems to be identical with well known fermentors on the market, however, that is where the similarity just ends. Functionally the fabricated fermentor could just be a failure
A few days ago I was surprised by the news that we have successfully designed and built our pilot plant fermentors. The project is the involvement of a few universities and research institutes. Large amount of money was invested in the project and the opening ceremony was even officiated by the respective Minister of the relevant department.
As I said earlier that I am not surprised we can build fermentors but more worried about the fact as to whether in depth studies have ben carried out to ensure the functionality of the fermentor built. It will be a tragic day to find out later that that there might be serious problems ‘overlooked’ in the design and construction of such fermentor.
Building fermentors require the in depth knowledge and experience of experts and specialists in the field of building fermentors. The only data that I can gleam from the article is more towards the capacity of the pilot plant fermentors. Not much or any other important technical detail were provided.
Building a fermentor is a project in science and technology. Hearsays are just not enough to convince people who wish to rent or even buy the fermentors. Don’t be surprised if such multi million dollar projects will just be underused or just become white elephants! If it happens it will be a waste of the taxpayers money.
As mentioned in this blog earlier there are a number of universities and companies which all ready have existing pilot plant facilities,,,,, almost unused and dying to look for clients to use their pilot plants.
It is most surprising the pilot plant built seems to be equipped with standard components as judged by the type of stirrers used. As we know it has always been the case of the type and rheology of the fermentation of the broth and the type of fermentation that dictates the type of fermentors used in the pilot plants. Having similar geometry in the scale up is idealistic but need not always be obligatory.
I have always wondered if the building of the pilot plants were tested and validated by standard methods? If such preliminary studies were not carried out, it will be a disaster awaiting to happen and reputation at stake.

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SMOOTH FINISHING OF FERMENTOR SURFACES

Of course in the context of our discussions we are talking mostly of the internal or inside surfaces of fermentors and even of stainless steel pipings to and from the fermentors.
In the fermentation industries involved in the production of biopharmaceuticals and innobiologics such stringent sanitary and sterilized conditions could be the make and break of the fermentation process. It could be a successful and profitable fermentation process or it could be a financial disaster.
The provision of smooth surfaces will not only eliminate microbial contaminants or fermentation residues but also will help improve the cleaning and washing of the surfaces. Not only is the cleaning process becomes more efficient but it is even proven that substantial cost savings made in water and cleansing solutions
Smooth finishing of internal surfaces as provided by stainless steel material and structure have always been regarded as the solution to providing the smooth surfaces of fermentors and the ancillary piping to and from the fermentors
However, most of these statements are often not tested. Different fermentation processes show different fluid properties and thus also different washing and cleaning regimes. Smooth or mirror polishing could itself result in smooth surfaces but also provide hidden niches where microbial contaminants and organic deposits could be hidden in the smoothened crevices. Visually we may see the stainless steel as being very smooth but under the magnification of the microscope, it is not as smooth as we expected.
One of the solutions to producing smooth surfaces is of course by electro polishing, in which passing current help to smoothen the rough surfaces
Whatever the outcome any stringent fermentation industries have to carry out their own cleaning validation process to ensure that they are on the right track.


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tasmanian holiday

A Tasmanian holiday to remember


'There's nothing like a sunset experience with good friends, each personality as different as the sea, sun and sand but together, a lasting memory to be cherished.'

Fun, friends and sunrise over a white beach – it was all a world away from Raja’s “boring and downright insane” study schedule in Malaysia. Raja and three of her friends had just finished another demanding semester in their architecture degree and were desperate for a holiday. They all agreed that Tasmania, with its pristine nature and tranquil pace, was the best place for a study escape.

“The holiday was memorable because both the company and destination complemented each other. What began as a simple road trip brought us closer as friends, despite our different nationalities and differences in opinions. Together, we were united and awed by the breathtaking sights of Tasmania’s nature,” Raja said.

Raja and her friends spent most of their holiday in and around Hobart, where as photography enthusiasts, they had a special appreciation for the historic architecture. They captured lots of great shots of Salamanca Place, with its cobblestone streets and rows of Georgian warehouses. They also climbed craggy, windswept Mount Wellington, photographing the panoramic vistas over Hobart and the Derwent River. After their descent, the group enjoyed what Raja described as “one of the best fish and chips” of her life, from a little shop near the Hobart waterfront.

Bruny Island wasn’t originally on the itinerary, but Raja and her friends decided to visit after discovering it was only a short drive and ferry ride from Hobart. They also liked the sound of its scenery - emerald countryside, plunging sea cliffs, fern-fringed forests, pristine beaches and coastal heathland. It was here that Raja took the photo which she entered in the Nothing Like Australia competition, and which came to symbolise the essence of her holiday.

“We spent the night there to witness the sunrise and to take more pictures of us frolicking by the beach. It was in three words, a pleasant surprise,” said Raja, who also remembers sharing jokes with locals while waiting for the return ferry.

Later the group ventured along Tasmania’s east coast to Wineglass Bay on the Freycinet Peninsula. Despite missing out on seeing the famous sunset from the lookout, Raja and her friends treasured this time to commune with nature and bond with each other.

It certainly made a welcome change from Raja’s daily student life, which she describes as being “glued to my computer screen and leading a topsy-turvy schedule of eating and sleep.”

For her “next great Australian escapade”, Raja is determined “to set foot in Sydney’s famed Opera House and view the Sydney Harbour Bridge.” After that, she wants to discover Australia “by the chapters….like a great love story.”
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VENTILATION AND HEATING PROBLEMS IN THE ARCHITECTURAL DESIGN OF MALAY HOUSES

In the first place, I am not an architect and not trained in anyway in architecture. I have never attended any formal courses in architecture be it at colleges or universities. But I am interested in architecture in terms of appreciating its design and function.
There is one strong point that I have in trying to appreciate and understand ( a bit) about architecture. I am trained in the science and the logics and principles of science. Throughout my life I was brought up in a Malay kampong or village environment where most if not all the houses built are the traditional Malay houses with strong input of Minangkabau influence.
Despite of what is being said and heaps of praises thrown out towards the traditional design of the Minangkabau and Malacca houses, I got a very uneasy feeling that the writers of these articles have never really stayed that long in the traditional houses. In terms of architectural design the traditional houses may be rich in culture or beautiful in its presentation but in terms of its functionality and comfort it shows a mediocre performance.
Any one staying in such houses should know how poor the ventilation of the houses and how hot the interior environment of such houses. Most of these houses are often located within the proximity of trees or even forests resulting in such a high humidity content of the air around the area. Not only it is hot but humid which are indeed very uncomfortable to the house dwellers.
The situation was not bad when the original roofs are made of thatched roofs which are cooler compared to the use of zinc layers which makes the house a wonderful oven.
The argument that there is sufficient ventilation to cool the indoor environment is not good enough/ Most of the writers would easily try to explain in terms of “theory” how hot air will rise from the floor to the roof by thermal convection. What they forgot to explain is that the hot air that rises to the ceiling or roofs are not easily dissipated to the external environment. This may be attributed to their poor understanding of the physics of ventilation in their courses or in the universities
Very few or little scientific studies are really carried out to understand the movement of heat or formation of heat sinks in such houses .It doesn’t take much to use tracers or heat sensors to study the heat, humidity and data could easily be analysed by computers
It is time that the local architecture schools carry out proper scientific studies and modellings to understand the ventilation and heat circulations of the traditional houses that can contribute to better designs of such houses. Gone are the days when architecture is likened more to just designing without understanding the physic principles behind it.

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MAN HOLE DEATHS- THE DARK SIDE OF FERMENTATION GASES

Again we are awakened by the news of the death of workers working in the man hole.
SUBANG JAYA: A Bangladeshi kitchen hand and a Nepalese security guard died while two other foreigners were hospitalised after inhaling dangerous fumes in a manhole behind the Subang Parade shopping complex. ( The Star 11 Feb 2011)
The most likely cause of the death is probably difficulty in breathing due to low oxygen content and the high concentration of methane gas in the man hole.
It is not surprising that there is a connection between the low oxygen gas and the production of methane. Methane as an anaerobic gas are only produced by the very strict and obligate anaerobes such as the methanogen bacteria. The very low dissolved oxygen promotes the anaerobic digestion process to produce methane bacteria and methane gas.
Despite what is being said above even though the conditions are anaerobic, methane would still not be produced if there is no decaying or rotting organic matter. There is the need for water, as well as the organic substrate to produce the methane.
It is easy to imagine where the organic matter comes from or even the source of water.
The often high temperature in the manholes and conduits help in the acceleration of the organic decay resulting in the higher production rate of methane.
Methane as a gas need the escape route. This is one reason why septic tanks, landfills are often equipped with these pipes to prevent the buildup of methane gas in enclosed spaces. Adding insult to injury most of these manholes are often not serviced and air tight which prevent the methane gas from escaping
It is easy to detect ammonia or hydrogen sulphide due to their foul odour, but in the case of carbon dioxide and methane you cannot smell it, and it might be too late to realize that they are there…
It is essential that most involved in the design and servicing of these sewers, man holes to be educated, aware and properly trained and equipped in the face of these silent killers….

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JUST WHY IS THE RUSH TO USE THE FERMENTOR?

We must remember it took perhaps thousands of years for the human civilizations in various countries to discover the secret arts of fermentation until they have perfected the art of producing wine. The science and technological input into the field of fermentation technology have to await the discovery of Pasteur, Fleming and even the World Wars to push it forward to what it is almost today. In fact the structure of fermentor hardware has really remained unchanged even though the use of sensors, computers and engineering has influenced it. The increase in fermentation productivity is more from improvements in strain development
However, nowadays with the prolific offering of degrees in biotechnology and subjects like fermentation technology, the understanding and transfer of this technology seems to be very fast or take a very short learning curve. Having a degree in this field does not always automatically a fermentation technology expert. Especially in the field of fermentation technology more is learnt through trial and errors or through experience with the operation of the fermentor.
The true understanding of fermentation technology is not merely by reading books or lectures. Such approach will nly gives you the superficial scraping on the surface of the subject. This is often reflected by the students in only operating a standard lab model fermentor by following the attached manual or instructions. The manual does not teach you the way one should carry out any fermentation work or even in the design of experiments in fermentation.
It is at this point where the teacher or lecturer of the course must be able to teach the students the proper way to use and carry out the fermentation experiment
I have observed that most courses offered in fermentation technology stressed mainly in the operation of the fermentor according to the manual but failed badly in teaching the students how to exploit the fermentor as a powerful tool in research or teaching
Various upstream, downstream procedures, standard operating methods and validation are not executed. Practical fermentation technology by McNeil and Harvey should be a good starting point in understanding some aspects of the fermentor

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