(354g) Techno-Economic Analysis of Non-Thermal Plasma-Assisted of Single-Use Plastics Film Wastes to Polyhydroxyalkanoates

The demand for plastics increases every year because of its wide application. Worldwide, plastics production reached over 390 million metric tons in 2021 and is estimated to increase by more than 50 percent in 2050 [1,2]. However, less than 9% of plastics produced get recycled or incinerated, and the remaining waste is dumped into landfills [3]. Single-use plastics film (SUPF), mainly composed of polyethylene (PE), represent the highest percentage of plastic waste sent to landfill because of the lack of technical and economical recycling processes [4]. Poor plastic waste management causes serious environmental problems, such as air, soil, and marine pollution.

Recent studies have investigated biopolymers, such as Polyhydroxyalkanoates (PHA) or Polylactic acid (PLA), as possible alternatives to mitigate the use of petroleum-based plastics because of their sustainability, ease biodegradability, compatibility, and climate-friendly production [5]. This study evaluates the techno-economic and feasibility of a non-thermal CO₂ plasma to upcycle mixed SUPF wastes into PHAs via pyrolysis oil fermentation.

A process model of the plasma degradation of SUPF waste was developed using BioSTEAM. A simulation was performed to estimate the plant’s mass and energy balance, and it was assumed that 200 MT/day of plastics is processed in a day. The process takes place in four steps: Plasma reaction, PHA fermentation, PHA recovery, and oil recovery. The process outputs includes PHA and pyrolysis oil-derived chemicals. The mass balance showed conversion yields of 11.52 MT PHA, 51.51 MT alcohols, 16.1 MT paraffin, 11.56 MT olefins, 12.21 MT carboxylic acid, 7.61 MT day carbonyls, and 28.71 MT heavy oil (C29-44) per day, from 200 MT of plastics. For the economic analysis, we assumed three scenarios for the pyrolysis oil product value: 1) No-value, 2) Energy content-value, and 3) Market-value.

We estimated capital costs and the PHA minimum selling-price (MSP) based on three scenarios. The fixed capital investment is estimated at about $64 million. The PHA MSP ranges from $0.82 to $3.00/kg for the three scenarios. Sensitivity analysis indicates that PHA fermentation yield, SUPF plasma conversion, and plant size are the most important cost factors. Power consumption and electricity price have a small impact on the MSP. These findings suggest that plasma pyrolysis is a viable alternative for the upcycling of SUPF. Future work will investigate the lifecycle impacts of the technology.

References:

[1] Statista, "Global plastic production 1950-2020," Statista, https://www.statista.com/statistics/282732/global-production-of-plastics-since-1950/, Accessed on: Mar. 29, 2023.

[2] Statista, "Global thermoplastic production forecast 2025-2050," Statista, https://www.statista.com/statistics/1220981/thermoplastic-production-worldwide-forecast/, Accessed on: Mar. 29, 2023.

[3] H. Ritchie and M. Roser, "Plastic Pollution," OurWorldInData.org, 2018. [Online]. Available: https://ourworldindata.org/plastic-pollution.

[4] Y. Chen, A. K. Awasthi, F. Wei, Q. Tan, and J. Li, “Single-use plastics: Production, usage, disposal and adverse impacts,” Sci. Total Environ., vol. 752, p. 141772, Jan. 2021, doi:10.1016/j.scitotenv.2020.141772.

[5] R. Sirohi, J. Prakash Pandey, V. Kumar Gaur, E. Gnansounou, and R. Sindhu, "Critical overview of biomass feedstocks as sustainable substrates for the production of polyhydroxybutyrate (PHB)," Bioresour Technol, vol. 311, p. 123536, Sep. 2020. doi: 10.1016/j.biortech.2020.123536.