Flush-mounted instruments with no dead legs. Photo: The Words Workshop Ltd.
Biotech applications are particularly susceptible to contamination. Some of the cells used in biotech processing are very sensitive to contamination from the outside; carrying cells from one batch to another too can be disastrous. So, designing a plant in the right way to minimize the opportunity for contamination is a primary requirement that can help prevent expensive mistakes. Here, Thorsten Vammen, director of GEA Liquid Processing in Skanderborg Denmark, looks at what can be done to avoid contamination from your white biotech plant at the design stage.
White biotech is the name given to that particular branch of biotechnology that is concerned with industrial processes. It uses living cells – from yeast, moulds, bacteria and plants – and enzymes to synthesize products that are easily degradable, require less energy and create less waste during their production.
The equipment used for white biotech processing includes fermenters, separators, evaporators, freeze- and spray-dryers, valves, pipework, etc. All of this equipment is designed for efficiency, efficacy and to minimize the opportunities for contamination. So when designing a complete plant, it’s not the equipment itself that causes the problem when designing out opportunities for contamination. It’s the way the whole system is put together and integrated that makes the difference.
Biotechnology is a relatively new science. Although it has been an accepted practice for decades it has only been relatively recently that the shortage of oil worldwide, and the environmental concerns relating to fossil fuel emissions, has seen the rise of biotechnology as an alternative to oil. It is this driver that has, largely, been at the root of the recent rise in investment. However the meteoric rise in popularity has also meant that only the newest sites have been designed specifically to handle biotech products. Many existing plants were originally designed as chemical plants where Clean in Place (CIP) technology was not generally employed. Therefore, some of these plants that today are used for producing biotech products are not made for CIP, either because they used to be chemical plants or because people are not used to designing CIP’able systems.
One of the problems of not having proper cleaning is that ‘left overs’ from the product stay in the system. When sterilizing, the product that is left over will build up over time and be burned onto the equipment. This makes it difficult for the sterilizing steam to reach all the crevices and corners. Even if the left over material is sterile in itself, it creates a perfect environment for bacteria to grow. In addition, burnt-on product remains will, over time, produce particles which can easily clog and cause a malfunction in steam traps and small drain valves, etc.
Dead legs too are another challenge. These are areas, usually within pipework, that cause air pockets making it difficult for the steam to reach to the bottom of the dead leg area. These dead leg areas typically have seals at the bottom which can be notoriously difficult to clean.
Multi-purpose plants
In today’s competitive world plants have to work harder. Many biotech plants are now multi-purpose, producing different products based on different types/strains of bacteria. In these cases it is very important that there is no cross contamination from the previous batch especially if the previous batch was based on a bacteria type that is ‘stronger’ than the one being produced. If so the stronger bacteria will take over the environment and decrease the yield or worst case ‘kill’ the one being produced.
Effective cleaning
The part of the industrial biotech segment that are producing living bacteria, frequently require their cleaning and sterilization systems to achieve a very high efficacy level during product treatment at F0= log10 9 to log10 16. To obtain this high level it is necessary to have a well-functioning CIP system combined with a well-designed steam sterilization system (SIP).
To achieve this level of efficacy many factors come into play. The physical system design, selection of best suited components, care in mechanical manufacturing and a well-designed control system will be of outmost importance. Even very small design flaws can lead to product losses. More importantly, perhaps, if there are faults, finding them can be very complicated, difficult and time consuming leading to lost production.
Frequently it is not the production systems that are the main culprits: utility systems such as water supply, steam generation, ventilation systems and gas and chemical supply systems can harbour bacteria if the cleanliness of these systems does not fall within design parameters. It is often these utilities that do not always receive the attention they require and, therefore, can be the starting point for serious problems.
Designing out contamination
Effective cleaning is important, however designing systems that are not bacteria friendly is a vital part of a system. For example, all instruments should be flush mounted to avoid creating dead legs or crevices where bacteria can collect. Every piece of pipework must be designed in such a way as to ensure that the CIP fluid hits all surfaces at the correct velocity and temperature. Utility systems too should be designed to be cleaned and sterilized or if this is not required, a sterile barrier should be created at the point where the utility product meets the sterile process.
Air pockets can be a problem and should be designed out as far as possible. If this is impracticable, the air should be capable of being vented. Air creates an isolation layer between the steam and the metal preventing the metal surface from reaching the correct temperature for effective sterilization to take place.
It is also necessary to design out human intervention as much as possible to avoid contamination. Instruments too need to be placed correctly to ensure that they provide accurate readings of temperature and pressure to validate sterility and, therefore, verify that sterilization has been performed to the correct level.
The environmental gain
Designing a plant to limit contamination and to make sterilization easy limits the amount of chemicals, water, and power necessary during the sterilization process. In turn, this saves money and limits the effect of the process on the environment. The initial investment might be a little higher but the total cost of ownership will be lower, more than compensating for the additional up-front expenditure. Less use of power reduces fuel bills, avoids penalties for unacceptable emissions and saves resources. Efficient use of chemicals and the clever use of water – including closed circuit systems – minimizes disposal costs. Good cleaning means less down time and can reduce the need to use preservatives.
Saving money and avoiding contamination with heat recovery
Heat recovery systems save money and help the environment too so they make good commercial sense and can save up to 20 per cent on heating bills for chemical plants. Modern systems can also contribute significantly to reducing contamination in sanitary operations. Heat recovery systems re-use heat that has already been generated in the plant. One of the main opportunities for heat recovery is after CIP and SIP operations that inherently require high temperatures to be effective. By recovering this energy and using it for pre-heating of the next batch, it’s possible for plants to make a significant power saving.
