An Environmental Life Cycle Assessment Comparing Single-Use and Conventional Process Technology - The authors compare the environmental impact of monoclonal antibody production using fixed-in-place pr

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An Environmental Life Cycle Assessment Comparing Single-Use and Conventional Process Technology
The authors compare the environmental impact of monoclonal antibody production using fixed-in-place processing and single-use systems.


BioPharm International Supplements
pp. s30-s38

Key assumptions

To maintain sterility, traditional durable equipment must be cleaned and steamed in place (CIP/SIP) between each batch. This requires a large amount of process water, water for injection (WFI), acids, and bases. The energy and supporting equipment required are all considered in this analysis. Single-use components that contact media do not require rigorous cleaning and sterilization, but instead are pre-sterilized by off-site Cobalt-60 irradiation. The transport of single-use components to and from the facility is included as well as the facility's operating energy, the Co-60 source, and the concrete required for the irradiation cell. These impacts are allocated to each irradiated component as a mass fraction of irradiation facility throughput.

The traditional durable equipment is nominally assumed to have 10-year lifetimes, after which 25% of the equipment is re-used while the remainder is either recycled (90%) or landfilled (10%). The single-use process trains contain components that are designed to be used once and then discarded. The exceptions are the replacement of single-use chromatography columns, which are typically reused for several batches depending on the number of cycles per batch. In this case, a recommended usable life for a ReadyToProcess Capto S 2.5 chromatography column is 20–50 cycles. The LCA model assumed 7 cycles per batch for Protein A and 5 cycles per batch for ion exchange chromatography (at 2000-L scale). The number of cycles for traditional chromatography is assumed to be two cycles per batch for both Protein A and ion exchange chromatography.

Several assumptions were made regarding treatment at end-of-life. For single-use components such as cellbags, filters, and connectors, disposal was assumed to occur by hazardous waste incineration without waste heat recovery. Non-hazardous waste was sent to landfill or wastewater treatment. Process water was assumed to be used once without recovery.

Use-phase electricity was assumed to be from an average US grid mix. Selection of an average European electricity grid mix exhibits lower environmental impacts but does not lead to any discernable shift of relative magnitudes between single-use and traditional process technology.

The fuel mix for generation of WFI was composed of different ratios of fuel oil, natural gas and electricity. The default mixture was equally weighted for fuel oil and natural gas at 45% each while electricity was weighted at 10%.

Sensitivity and uncertainty analyses

The sensitivity of the LCA results to variations in key assumptions was extensively analyzed using a Plackett-Burman experimental design. Lifetime of durable equipment was varied from 5–25 years. Chromatography column lifetimes were varied from 10–100 cycles. Transportation distances were varied from 5–25 miles (local), 1000–5000 miles (domestic), and 1500–7500 miles (international). Different ratios of WFI fuel mixes were examined. Equipment reuse was varied from 0–25%. Equipment recycling was varied from 50–100%. Co-60 irradiation facility parameters were varied as well. None of the variations in key assumptions had a significant effect on the study conclusions. The detailed results of the sensitivity and uncertainty analyses will be reported in a subsequent publication.


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