Single-use bioproduction is advancing enormously and now offers numerous advantages over production in stainless steel drums. However, a disconcerting side effect of single-use bioproduction is the creation of a mountain of plastic waste. That is detrimental to the environment. Is it not?
Single-use has become inevitable in bioproduction. It is estimated that half the production processes for medical drugs and vaccines are now being carried out in a single-use facility; and this is on the increase. The traditional large stainless steel drums and their fixed connections have been replaced by a flexible arrangement of synthetic bags and conduits. All conduits, connections and bags are replaced after the production of each batch. The amount of discarded plastic can mount up to hundreds of kilos per batch of 1,000 litres. In hospitals, for instance, single-use material has obviously been used for a long time now: gloves and other protective materials and medical drugs packaging. But because single-use production is increasing to such an extent the question is: what is done legitimately with all that waste?
Given that these products are so specialised the volumes in bioproduction are not all that huge, both in terms of product and plastic waste, says John Boehm, manager of bioprocessing at CPC, manufacturers of single-use connections and other products, and chairman of the BPSA (Bio-Process Systems Alliance). ‘We now generate some 30,000 tonnes of plastic waste per year in single-use bioprocesses. But the total volume of discarded plastic worldwide is 300 million tonnes. In that respect, the volume of waste generated in single-use bioprocessing is insignificant.’
Boehm has been investigating what happens with that single-use waste for more than ten years now. ‘Depending on the location it is usually incinerated, the energy often being recovered (waste-to-fuel) or dumped. Waste management companies are pleased to process plastic because of its higher caloric value, therefore producing more energy in the combustion process than other solid waste.’
Recycling would also seem to be a logical option but turns out to be quite a challenge. The single-use bags used in the bioproduction process are made up of different layers of materials, each having a different function. The most often used is polyethylene and allied polymers, e.g. LDPE or EVA (ethylene vinyl acetate) on the outer sides with an interlayer of EVOH (ethylene vinyl alcohol). Others use fluorine-containing plastics. The connections are made of hard plastic and the conduits are often made of silicones. This results in a mixture of synthetic materials that cannot be recycled easily.
The second issue concerning this waste mountain is that it has been in contact with living cells, etcetera, and consequently in most cases must be sterilised on site before leaving the location. Recycling therefore calls for a large amount of energy and is expensive.
Fabienne Douven of pharmaceutical company Synthon talks about the single-use waste that the company also incinerates. ‘We use single-use in the greater part of our production at our biopharmaceutical section. The waste generated here is incinerated. It cannot be recycled because the multi-layered functional plastics inside the film cannot be separated. Also, the pharmaceutical and toxic substances used in the production of antibody drug conjugates (ADCs) prevent recycling. In that respect we must comply with the statutory regulations and directives regarding GMOs and highly potent substances and indeed do just that.’
The plastic mountain is the most visible part of the impact of single-use bioproduction technologies on the environment. Bill Whitford, Strategic Solutions Leader BioProcess at GE Healthcare, claims that a life-cycle analysis (LCA) is needed to establish a well-founded stance on this impact. He collaborated on such an LCA for bioproduction that GE Healthcare conducted in 2012 and revised in 2017. ‘There are twenty factors that have an effect on the environment, including the use of fresh water, water pollution and water acidification, the carbon footprint and the use of mineral resources. These factors are found in every step of the process, from the extraction of raw materials to what to do with plastic, the ‘end-of-life’. The latter is highly evident, but it is important that we look at all the factors, from the construction of a factory, the supply of single-use materials, right the way through to maintenance and the production process itself.’
GE Healthcare had the method and results checked by an independent agency and published in a scientific journal. The results also surprised the researchers, says Whitford. ‘In most situations it appears that for all twenty categories single use scores better in terms of environmental friendliness than traditional production in steel drums.’
The greatest impact on the environment for both production methods is the consumption of energy and water required for transport and cleaning up after production. The transport of large amounts of single-use material costs energy, but steel drums must be cleaned after use and sterilised with steam. Also, a great deal of energy is needed to produce steel for the drums. All in all, that single use is better for the environment in terms of water and energy consumption is clearly shown in the LCA.
The study also shows that the end-of-life impact, i.e. waste processing, only contributes a small amount to the total environmental impact of single-use bioproduction technology. ‘Nevertheless, we looked into the effect of incineration versus recycling. The difference is so small you can’t even see it in the graph,’ says Whitford. ‘So, if you want to do something for the environment you are better not to focus on plastic waste.’
Indeed, says Whitford, first and foremost recycling requires that the plastics are moved to a location suitable for recycling. Merck Millipore, for instance, in partnership with Triumvirate, now has a process in operation that converts hospital waste into synthetic building materials. ‘That’s fantastic,’ is Whitford’s opinion. ‘But the waste must first be transported to the recycling plant where it has to be sterilised by heat and the use of corrosive chemicals before the product can be transported to the construction site. It all depends on which factor you find important for the environment, but it’s quite possible that by recycling you are doing more harm than good,’ says Whitford. Boehm adds: ‘And if there’s no demand for the product and no market, then waste-to-energy could be the better option.’
By switching to single use, bioproduction therefore becomes more sustainable. The LCA results in the estimation that a complete switch from a steel production facility to a single-use system can reduce greenhouse gas by one fifth. But it can be better, is Whitford’s opinion. ‘The transport of single-use material costs a great deal of energy. The locations of biopharmaceutical production units and the production facilities of single-use materials will therefore need to be reasonably close to one another. Generating energy to clean stainless steel drums must be done locally and also be sustainable. Boehm adds: ‘A major problem is the actual volume of single-use material packaging. At CPC we are doing our best to reduce that volume.’
It is also important that people are kept informed, says Boehm. ‘The perception is that single-use plastic is detrimental because of the plastic soup in our oceans and seas. But in the case of bioproduction the amounts are very small. Moreover, we would be unable to make some life-saving drugs without bioproduction. I would like to make that quite clear.’
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