Comparing the Environmental Impact
The analysis in this section identifies distinct differences (i.e., in utility requirements, materials, consumables, labor,
space, electricity, steelwork, carbon) in the performance of the disposables-based facility when compared to the conventional
stainless-steel plant.
Utility Requirements
Figure 1
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Figure 1 illustrates the water usage (PW and WFI) per batch for the two manufacturing options. Implementing disposable bag
systems removed the use of stainless-steel bioreactors and product and solution vessels that require cleaning, thus reducing
water usage. The model indicates that the disposables-based facility consumes 87% less water than the stainless steel–equipped
facility.
Given the reduced water requirements, smaller generators and storage vessels will be needed to operate the disposables-engineered
facility. The WFI generator capacity required for the disposables-based facility is approximately 320 L/h, whereas the stainless
steel–equipped facility requires a WFI capacity of 1,200 L/h to achieve the same production rate. Using a filling time of
10 h, storage vessels of 12,000 L and 4,000 L are needed in the stainless-steel facility and the disposables-based plant,
respectively.
Steam usage results mainly from autoclave activities and the sterilization of bioreactors and vessels. For the stainless steel–equipped
facility, a substantial amount of steam (about 880 kg/batch) is needed to run sterilization operations. In the disposables
option, the vessels are substituted by single-use bags, thus eliminating the need for clean steam.
Materials
Table 3. Comparison of material usage (L/batch) in stainless-steel and disposables-based plants
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Table 3 summarizes the total amount of process materials and diluted cleaning solutions used per batch. As expected, the quantities
used for process media and buffers are the same for both facilities. The single-use setup, however, has eliminated the need
for chemicals (i.e., caustics and acids) associated with vessel cleaning operations because the bags are supplied presterilized
and ready to use. The model estimates that the quantities of cleaning materials per batch are reduced by more than 95% in
the disposables-based facility.
Consumables
The single-use nature of disposable technology has increased the volume of plastic waste. A total of about 880 kg of solid
waste per batch is generated. The solid waste is normally incinerated, which may affect air quality, causing environmental
concern, and may incur additional manufacturing cost.2 The exact cost will be linked to the disposal method used and whether pretreatment (decontamination autoclave, or kill with
a dose of chlorine dioxide or other deactivator) is required before disposal.
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