Sustainable solutions in single-use food containers: A comprehensive life cycle assessment comparing plastic (PP) and its green alternative (PLA coated kraft paper, PLA)

Kasidij Peantham; Viganda Varabuntoonvit

doi:10.4491/eer.2023.729

Environ Eng Res > Volume 29(5); 2024 > Article

Peantham and Varabuntoonvit: Sustainable solutions in single-use food containers: A comprehensive life cycle assessment comparing plastic (PP) and its green alternative (PLA coated kraft paper, PLA)

Research

Environmental Engineering Research 2024; 29(5): 230729.

Published online: March 8, 2024

DOI: https://doi.org/10.4491/eer.2023.729

Sustainable solutions in single-use food containers: A comprehensive life cycle assessment comparing plastic (PP) and its green alternative (PLA coated kraft paper, PLA)

Kasidij Peantham¹, Viganda Varabuntoonvit^2,^†

¹Interdisciplinary of Sustainable Energy and Resources Engineering, Faculty of Engineering, Kasetsart University, Bangkean Campus, Bangkok 10900, Thailand

²Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkean Campus, Bangkok 10900, Thailand

^†Corresponding author: E-mail: fengvgv@ku.th, Tel: +66 27970999

Received November 29, 2023 Revised February 20, 2024 Accepted March 7, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The research conducted a life cycle impact assessment (LCIA) of single-use food packaging made from PP, PLA, and Paper/PLA materials using the ReCiPe method. The assessment covered 18 environmental impacts from box processing to end-of-life treatment, with a functional unit (FU) specified as 1,000 units of single-use food container boxes. The dimensions of the boxes were standardized to reflect the average size from the Thailand market and food-delivery boxes. When focused on production stage, PP box shows the greatest impact on overall especially human non-carcinogenic toxicity (285.11 kg 1, 4-DCB). However, when focused on cradle-to-grave life cycle, the PP emerged as the optimal choice of food box due to its comparable environmental impact to biodegradable alternatives, when applying recycling processes. It recycles significantly reduces the total impact up to 73% from their waste-to-energy treatment option. To achieve environmental goals necessitates policy interventions such as extended producer responsibility laws and refund schemes to incentivize responsible disposal. In country lacking waste management infrastructure and collection system, the sensitivity analysis of this research show that biodegradable PLA material emerges as the most suitable choice, particularly over Paper/PLA, offering lower overall environmental impact due to less overall emission in landfill and composting process.

Keywords: Food container box, Life Cycle Assessment, PLA coated Kraft paper, PLA, PP, Waste management

Graphical Abstract

Keywords: Food container box, Life Cycle Assessment, PLA coated Kraft paper, PLA, PP, Waste management

1. Introduction

The market value of food delivery in Thailand, including restaurant deliveries and food delivery apps, increased significantly since 2018 to 2021, going from 7 to 105 billion Thai baht [1] They are increasingly opting for food delivery or take-home options to limit their risk of infection by avoiding crowded areas such as restaurants and shopping malls. Even though the pandemic situation has improved in 2022, the market value for food delivery services remains high due to the shift in consumer behavior toward food purchases. Its packaging can prevent product degradation, preserve processing benefits, increase shelf life, and preserve or enhance food quality and safety. As a result, packaging helps protect against three key types of external influences: chemical, biological, and physical. Chemical protection decreases compositional changes caused by external factors such as exposure to gases (usually oxygen), moisture (gain or loss), or light (visible, infrared, or ultraviolet). Physical protection includes cushioning against the shock and vibration encountered during distribution to defend against mechanical damage [2].

Plastic packaging, specifically from petroleum-based Polypropylene (PP), remains a popular choice in restaurants and the food industry due to its thermal resistance, high melting point (160°C), prevention of permeation, long shelf life, and microwave compatibility. However, the production cost of plastic has risen due to the limited and depleting petroleum-based materials. In the current year, consumers express growing concern about environmental issues, particularly the role of petroleum-based products in global warming, acidification, marine toxicity, and the microplastic problem. Consequently, the food industry is promoting various types of food packaging boxes made from different materials and techniques to meet food containment requirements, cost-efficiency, and consumer expectations. Eco-friendly alternatives, such as Kraft paper coated or laminated with plastics like Polyethylene (PE) or Polylactic Acid (PLA), provide improved tensile and impact strength, puncture resistance, thermal resistance, and water-proof capabilities. Biodegradable plastic food containers, made from microbial, animal, or marine food processing industry waste, as well as agricultural feedstock, are also gaining traction. In addition to using renewable raw materials, biodegradable materials break down to produce environmentally friendly byproducts like carbon dioxide, water, and quality compost [3]. However, improper treatment of some alternative food container boxes, such as treating waste PE coating on Kraft paper boxes with landfill techniques, may have adverse effects. The PE film does not degrade under real landfill conditions, breaking out from Kraft paper’s surface and fragmenting into microplastics, posing risks to all life forms, including humans [4]. Additionally, recycling becomes challenging due to the embedding of a significant percentage of the fiber in the PE film during the re-pulping stage [5]. Limited treatment options for this type of plastic coating on food boxes pose environmental challenges and hinder the move towards a circular economy.

Previous packaging studies have focused on impact assessments between Polystyrene (PS), Polyethylene terephthalate (PET), and PLA trays in terms of global warming potential (GWP) [6]. The ban on PS material for food container boxes in Thailand, driven by its single-use nature and toxicity when burned with mixed waste, has led to limited research on plastic-coated packaging, with comparisons often limited to plastic film materials [7]. Some industries now promote green food container boxes using PLA as a coating film, offering slower degradation performance in blends with other polymers [8–10], but with the advantage of landfill treatment and composting to reduce microplastic environmental impact. While many studies assess the environmental impact of single-use packaging in terms of carbon footprint, resource depletion, and waste generation, comprehensive life cycle assessments considering the entire range of environmental impact categories from production to disposal are lacking. Furthermore, there is a need for a more detailed analysis of scalability and the environmental impact potential of single-use products, especially when waste management is not suitable. With Thailand grappling with a significant plastic waste problem, the national goal of reducing plastic waste from 50% to 90% by 2026 lacks clear direction and enforcement. Current policies focus predominantly on recycling techniques, with some companies proposing biodegradable products to address the plastic problem. Consequently, it is crucial to consider alternative box processing and waste management methods, as improper waste management may exacerbate environmental impacts. In single-use conditions, food delivery packaging may have a more significant impact than petroleum-based packaging in some categories due to resource requirements in the plantation process or higher impact in the disposal stage.

This study aims to provide insights into selecting the proper single-use box material, efficient implementation, and waste management to align with the plastic roadmap more directly. To summarize the environmental impact of food container box options, three major commercial food container boxes in the Thailand market and food-delivery restaurants. PP, PLA from corn, and Kraft paper with a PLA film coating - were selected. They were chosen based on having the same size, containing capacity, and thickness. The ReCiPe 2016 v1.1 impact assessment method was employed to analyze 18 environmental impacts from box processing to end-of-life treatment. All appropriate waste treatment techniques at the manufacturing scale in the country were compared to determine the best food container box. Additionally, this research experiments with sensitivity analysis, considering conditions where the food container box waste at waste collection sites cannot be separated from other mixed waste and is treated by landfill or incineration. The second sensitivity analysis explores the impact of box thickness on environmental impact, aiming to identify the type of box that highest trends to increase the environmental impact due to material usage, energy consumption, and end-life treatment. The results help determine which type of food container box provides the most negative impact when the proportion of box waste that cannot be separated and is treated like usual mixed waste increases. Furthermore, the study assesses which types of boxes yield the best outcome when the proportion of food container waste sent to the appropriate treatment increases. This information aids in choosing a suitable food container box that matches the waste collection and separation efficiency of different areas.

2. Materials and Methods

2.1. Methodology

This study aims to conduct a comprehensive impact assessment of four types of food packaging boxes, utilizing the Life Cycle Assessment (LCA) methodology as described in the ISO 14040 (2006) and 14044 (2006) standards. LCA is a robust tool employed to evaluate the environmental aspects of a product or service system throughout its entire life cycle, encompassing raw material acquisition, production, use, and waste management disposal. Specifically, we will investigate the environmental impacts of petroleum-based, bio-based, and alternative boxes. The LCA methodology enables a thorough examination of the effects on the environment and resources consumed, covering various aspects such as climate change, stratospheric ozone depletion, tropospheric creation eutrophication, acidification, toxicological impacts on human health and ecosystems, resource depletion, water use, and land use.

The LCA methodological framework comprises four integral components: goal and scope definition, life cycle inventory analysis, life cycle impact assessment, and life cycle improvement assessment and interpretation. Each of these components is interlinked and influences the entire LCA process. To provide a detailed account of our methodology, we will begin by defining the goals and scope of our assessment, delineating the boundaries and system limits. Subsequently, the life cycle inventory analysis will involve a meticulous compilation of data related to the inputs and outputs at each stage of the product life cycle.

Following the inventory analysis, the life cycle impact assessment will be conducted, employing established impact categories such as climate change, ozone depletion, eutrophication, acidification, and others. The impact assessment will involve quantitative evaluations of the identified environmental indicators based on established characterization factors. The life cycle improvement assessment will then explore potential strategies to mitigate environmental impacts and enhance sustainability. Throughout the entire process, continuous interpretation of results will be conducted to ensure a holistic understanding of the findings.

2.2. Goal and Scope Definition

The objective of this study was to compare the environmental performance of three types of commercial food container boxes: PP, PLA, and Kraft paper coated with PLA. The scope of the research focuses on the Cradle-to-Grave life cycle of these three commercial food container boxes. Fig. 1(a) – 1(c) illustrate the system boundaries for each food box, encompassing raw material acquisition, box and film manufacturing, and waste management. Various treatment processes are employed during the disposal phase, depending on the most appropriate options for each material. Specifically, PP boxes undergo treatment through incineration and mechanical recycling techniques, PLA boxes are treated through landfill, incineration, and composting techniques, and Kraft-paper boxes coated with PLA undergo treatment through landfill, incineration, and composting techniques.

To analyze the environmental impacts, the ReCiPe 2016 v1.1 impact assessment method was chosen due to its cover all concerning environmental impact in nowadays. It evaluates 18 environmental impacts, including global warming, stratospheric ozone depletion, ionizing radiation, ozone formation, fine particulate matter, terrestrial ecosystems, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, human carcinogenic and non-carcinogenic toxicity, land use, mineral and fossil resource scarcity, and water consumption. These impacts are considered from the box processing stage to its end-of-life treatment. The reference flow of the FU in each box is represented in Table 1. The functional unit (FU) of the LCA is specified as 1,000 units single-use food container box. Size of box are average from Thailand market and food-delivery box: height 48 mm width 116 mm and length 169 mm. with the same capacity as 9.41× m³ per box. For calculating weight on each type of boxes required thickness value in this research, this study have chosen to use the average box thickness measured from three different commercially food container brands in Thailand market for each type of box measuring by digital vernier caliper. This approach allows us to determine the appropriate thickness of Polypropylene (PP), Polylactic Acid (PLA), and Paper/PLA box samples in the study.

2.3. Life Cycle Inventory Analysis

Validation processes are implemented to ensure the reliability of the data used in the life cycle inventory analysis. The life cycle inventory since raw material acquisition will reference from LCI database and box production until the waste treatment are references from private company data in Thailand and calculation. So, the priority is given to Thai life cycle inventory database, with thorough scrutiny to meet stringent quality standards. In cases where national data is unavailable, the secondary data sources include input-output data from the national commercial industries and relevant research articles, following a meticulous validation process to maintain the accuracy of the life cycle inventory analysis. When utilizing secondary sources for calculations in this research, a comprehensive check of mass balance in input-output usage is conducted, accompanied by a thorough comparison with multiple literature reviews to further validate the accuracy of the data employed.

2.3.1. Source of raw material acquisition data

In the assessment of raw material acquisition for PP and kraft paper with a coating layer, comprehensive life cycle inventory data were sourced from the Thailand national database by The National Metal and Materials Technology Center (MTEC). The dataset encompasses all relevant processes involved in the production of PP granules, starting from crude oil extraction to pellet creation or plantation of wood used to make kraft paper. Energy and water sources were specifically referenced from Thailand’s electricity grid mixed and municipal water, aligning with the country’s conditions. Additionally, for PLA production, input-output data, from plantation to granule production, were derived from the NatureWorks PLA industry, with energy and water sources again linked to Thailand’s infrastructure through the national life cycle inventory database.

2.3.2. Source of box production data

The box production phase involved a survey of food box manufacturing in Bangkok and Rayong province, Thailand. For petroleum-based box production, the process includes melting PP resin to a fluid state, extruding it into a sheet, and thermoforming it into the desired shape. The PLA box manufacturing process mirrors that of the PP box, as both materials have similar melting points (around 160 – 170°C). In the case of coated paper boxes, the kraft paper base undergoes a coating process using plastic film through film extrusion. Subsequently, the coated paper is cut and thermoformed to achieve the desired box shape.

The thickness of each plastic film depends on the properties of the material. For PE film used in paperboard coating products, the commercial thickness is 30.2 ± 0.5 microns. The variation in the thickness of PLA-coated paperboards, evaluated by standard deviation, is greater than that of PE-coated paperboard (ranging from 21.3 ± 2.1 to 37.8 ± 1.9 microns, depending on the PLA solution). However, the thickness of 21.3 ± 2.1 microns for PLA is the most effective in the water barrier property of paperboards [11]. For modeling this stage, the life cycle inventory from Ecoinvent database version 3 is used to represent the average material and energy used on each manufacturing process of box production.

2.3.3. Transportation

This study does not include an assessment of the environmental impact from transportation due to its broad scope, which precludes the determination of the optimal distance between box production and the market in Thailand. However, existing literature on life cycle assessments of products indicates that transportation typically has a low contribution to environmental impact compared to other stages in the life cycle.

2.3.4. End-of-life treatment

At the End-of-life (EOL) of the product after usage, there have as activities required to ensure that waste has the least practicable impact on the environment. Food container boxes have various forms of waste treatment required in EOL. Each type of food container box has its own options for treatment depending on its characteristics and properties of them. This research is scope on the 4 waste treatment techniques: Landfill, Incineration with energy recovery, Mechanical recycling, and Composting which are commercially used in Thailand.

2.3.4.1. Landfill treatment

Landfill is the most common waste disposal method. In a global warming context, the landfill is a complex unit because so many aspects must be included when counting greenhouse gases (GHG). Methane (CH₄) is a major emission from landfills caused by degradation of organic matter. The landfill gas generation under anaerobic conditions for plastics was estimated by a general equation for degradation of organic material are determined using Eq. (1) [12]. Land use change (LUC) is used 1 m³ of operation site per 1088.63 kg of plastic waste is collected by the survey from municipal landfilling in Thailand.

(1)

\begin{matrix} C_{a} H_{b} O_{c} N_{d} S_{e} + (\frac{4 a - b - 2 c + 3 d + 2 e}{4}) H_{2} O \to (\frac{4 a + b - 2 c - 3 d - 2 e}{8}) {CH}_{4} \\ + (\frac{4 a - b + 2 c + 3 d + 2 e}{8}) {CO}_{2} + {dNH}_{3} + {eH}_{2} S \end{matrix}

(2)

Kraft-Paper: C_{6} H_{10} O_{5} + H_{2} O \to 3 {CH}_{4} + 3 {CO}_{2}

(3)

PLA: C_{3} H_{4} O_{2} + H_{2} O \to 1.5 {CH}_{4} + 1.5 {CO}_{2}

Polypropylene was the predominant polymer type. The microplastics were derived from the fragmentation of plastic waste buried in landfill. So, taking plastic with petroleum based to the landfilling management will cause the plastics to undergo fragmentation and present hazardous risks in all life forms including humans. According to this reason, only food container box which not including the plastic petroleum-based: PLA box and Kraft-paper box with coating it surfaces by PLA are suitable for landfilling condition.

2.3.4.2. Incineration with energy recovery

As a result of the development of conventional incineration, technology has the potential to be a source of energy in addition to a waste management solution. The controlled combustion of waste products to generate power and/or heat. The system generates energy and heat and minimizes municipal solid waste volume (MSW). Due to the biogenic composition of trash, such as food and other organic waste, cardboard, and wood, a portion of the energy created is renewable. The waste components derived from fossil fuels (e.g., plastics) are nonrenewable. The gas combustion emission from this incineration process was calculated using Eq. (4).

(4)

C_{a} H_{b} O_{c} N_{d} S_{e} + (a + \frac{b}{4} - \frac{c}{2} - \frac{d}{2} - \frac{e}{2} + \frac{f}{2}) O_{2} \to {CO}_{2} + (\frac{b}{4} - \frac{d}{2} - \frac{e}{2}) H_{2} O

(5)

PP: C_{3} H_{6} + 4.5 O_{2} \to 3 {CO}_{2} + 3 H_{2} O

(6)

Kraft-Paper: C_{6} H_{10} O_{5} + 6 O_{2} \to 6 {CO}_{2} + 5 H_{2} O

(7)

PLA: C_{3} H_{4} O_{2} + 3 O_{2} \to 3 {CO}_{2} + 2 H_{2} O

Recovery heat efficiency of incineration was 88% which resulted in energy product for electricity and heat of 19.5% and 65.4%, respectively. Sodium Hydroxide (NaOH), Calcium Carbonate (CaCO₃) and Ammonia (NH₃) were used as flue gas cleaning [13]. The amount of electricity and heat produced from waste plastics incineration was estimated based on the generating efficiency of MSW incineration and the low calorific values (LCV) of MSW and waste plastics calculated using Eq. (8, 9) [14]. Then calculate amount of electricity and heat recovery (MW) in Eq. (10) [15] by using the lower heating value (LHV), mass flowrate, and the efficiency of the power plant. The emission of Carbon Dioxide (CO₂), Methane (CH₄), Nitrogen Dioxide (NO₂) from fuel gas combustion is reference from the default emission factor for stationary combustion in the energy industries [16].

For calculating the high heating value (HHV), percent component of each box material is required. The elementary composition of C; H; N; O; and S, of box materials are average from secondary data report in Table 2.

(8)

HHV = 0.339 (C, %) + 1.440 (H, %) - 0.139 (O, %) + 105 (S, %) (\frac{MJ}{kg})

(9)

LHV = HHV (\frac{MJ}{kg}) - 0.0244 (moisture, %) + (9 x (H, %)) (\frac{MJ}{kg})

(10)

MW = Mass Flowrate \times LHV \times η

The incineration process is usually used with mixing of waste material. It can destroy a wide range of highly contaminated wastes, so petroleum plastic allows in these techniques as well as the others material like bioplastic and paper.

2.3.4.3. Composting

Composting is used as an alternative recycling technology for organic waste and compostable products. It was acknowledged as a beneficial method for reducing methane emissions, global warming potential (GWP) impact, and garbage volume to landfill, hence extending landfill life. Most PLA plastics are promoted as compostable, and their decomposition involves a “time and temperature” reaction. PLA has numerous advantageous features; it is simple to manufacture, non-toxic and carcinogenic, biocompatible, bio-durable, and compostable. It decomposes into biodegradable polymer fragments in approximately one week at 140°F in a moist atmosphere. The material can then be composted like other organic stuff. To check the biodegradability of PLA, the plastic box will be composted with organic waste for 180 days in accordance to ISO 14855–1 the amount of organic waste must be used during compost. The fertilizer are gained from the study of [6] after the composting is finish. The organic matter and box waste will turn to fertilizer: Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), and Magnesium (Mg). CO₂ is also the emission during the process. To calculate the theoretical amount of composting gas generation using Eq. (11).

(11)

{ThCO}_{2} = M_{TOT} \times C_{TOT} \times \frac{44}{12}

where M_TOT is the total dry solids (plastics sample), in grams; C_TOT is the proportion of total organic carbon in the plastics sample, in grams per gram; 44 is the molecular mass of carbon dioxide and 12 is the atomic mass of carbon.

2.3.4.4. Mechanical recycling

Mechanical recycling refers to the recovery of plastic waste by mechanical processes such as sorting, washing, drying, grinding, re-granulating, and compounding. Mechanical recycling does not alter the chemical structure of the material, allowing for the reuse and recycling of polymeric materials several times. This process is only suitable to petroleum-based boxes since their return value is greater than that of the PLA recycling product. For the coating box, it is difficult to detach the film layer from the Kraft paper foundation, the operation is expensive, and the technique is not yet commercial. The life cycle inventory of PP mechanical recycling is based on the study of [22]. For the natural gas used for being fuel in melting and extrusion process is assumed to be compensated by the electricity to produce heat instead, 1 ft³ of natural gas in the energy industries can be convert to 1,039 BTU. NaOH is therefore needed for the plastic cleaning procedure as well. In this study, NaOH was also added to the inventory for resource consumption using the typical amount from previous studies [23].

3. Results and Discussion

3.1. Life Cycle Inventory

The database for the production of raw materials and energy sources used in cradle-to-gate production are extracted from Thailand national database and private company. At the waste treatment section, several research work and equation as mentioned in previous chapter were used to calculate the material balance between each waste treatment technique to evaluate and compare the life cycle environmental impact per 1 functional unit of PP, PLA, and Paper/PLA single-use packaging box as shown on Table S1–S4 in the supplementary materials.

3.2. Life Cycle Impact Assessment Result

The life cycle impact assessment is an important step to evaluating the impact in each category based on the inventory acquired. The impact assessment results are separated into 3 sections. Firstly, the results focus on mid-point analysis with cradle-to-box production, and it waste treatment technique to compare their emission in each stage of life cycle. Secondly, doing normalization analysis to compare the overall impact score with using the same baseline unit to find the best box decision and its treatment used to reduce the overall environmental impact. However, the environmental impact from transportation still avoids being calculated in this analysis due to unable to decide the precise distance and route for transporting box product and its waste at EOL. The calculation will be based on ReCiPe 2016 v1.1 with hierarchist perspective method on the Simapro 9.2.0.2 program. These 18 impact categories will correspond with the emissions from LCI results of PP PLA and Paper/PLA food container boxes. The result of impact categories is interpreted and reported as follows.

3.2.1. Midpoint analysis: cradle-to-gate

The three types of food packaging boxes are being analyzed for the emissions at each stage of their life cycle using ReCiPe 2016 v1.1 methods. Table 3 illustrates the midpoint impacts of PP, PLA, and Paper/PLA during manufacturing stage (since raw material acquisition to box production).

Regarding the global warming impact caused by CO₂ equivalent emissions, the PP box yielded the highest results due to the greater energy and fuel consumption required in making virgin plastic material acquisition when compared to other box materials. When comparing the two biodegradable boxes during the raw material acquisition until box production, the Paper/PLA box surpassed the global warming impact results because PLA material consumes more electricity in processing and absorbs carbon dioxide during photosynthesis. Therefore, the proportion of PLA required is lower in a paper-coated box, resulting in decreased GWP. The stratospheric ozone depletion and marine eutrophication from PLA box are the highest due to the use of ammonium nitrate fertilizer during corn plantation, leading to increased CFC11 equivalent and nitrogen equivalent emissions. The higher consumption of chemical substances and electricity in PP box manufacturing causes impacts on terrestrial, freshwater, and marine ecotoxicity, as evidenced by the kg 1,4-DCB equivalent and fossil resource scarcity from oil, resulting in 2.3–6.5 times greater impact than biodegradable boxes. Moreover, the land use of PLA boxes requires more crop area (for plantation and drying of maize straw) than Paper/PLA boxes during the manufacturing stage, resulting in a higher impact on water consumption and human-carcinogenic toxicity. When comparing the midpoint environmental impacts at manufacturing stage among different types of food container boxes, overall, the manufacturing of PP boxes yields the highest environmental impact, followed by PLA and Paper/PLA boxes, respectively. Thus, the findings underscore the importance of transitioning away from virgin petroleum-based materials and towards environmentally friendly alternatives to mitigate these impacts.

When comparing the midpoint environmental impact from whole life cycle among their suitable EOL waste treatment options as shown on the Fig. 2 The global warming impact from landfill Paper/PLA the highest impact 399.73 due to methane emission during waste degradation, while PP box from recycle treatment provide least emission (61.80 kg CO₂ eq) result from regaining of material and compensate the virgin PP. Global warming impact from incineration with energy recovery of biodegradable box having impact close to its compost option because incineration process can return heat also generate the electricity. The Ionizing radiation impact, the recycle process of PP is the highest impact from using NaOH as plastic cleaning substance in recycle process. Ozone formation impact shows that incineration process with energy recovery of PP boxes perform the highest impact pollute followed by landfill process on both degradable boxes. For the terrestrial ecotoxicity impact, found that PP with incineration energy recovery having 62.35 kg 1,4-DCB however biodegradable box with composting options returns higher negative impact on this category which are −92.08 kg in Paper/PLA and −71.82 kg in PLA.

Freshwater ecotoxicity and Marine ecotoxicity, when PP box send to incineration energy recovery it will return the highest impact result. But however, if adjusting it treatment option to recycle route, it will reduce the amount of impact almost as close as the impact biodegradable product at waste treatment stage. The human toxicity, especially non-carcinogenic toxicity, the petroleum-based emission the 1,4-DCB up to 269.05 kg from the incineration process which is far greater than the impact from biodegradable boxes which around 10.36 – 24.94 kg. But when regaining the PP granule from choosing the recycle option it can reduce 5 times decrease from incinerate option.

The land use of PLA still performs the highest impact in every waste treatment option starting from composting, incineration, and landfill respectively, the major area required for the PLA granule production stage, followed by the Paper/PLA and PP. For the fossil resource scarcity, the PLA box with landfill option resulted in the highest impact followed by the Paper/PLA with the same treatment technique and PP with recycle option. When applies incineration energy recovery at EOL, the PP incineration returning the benefit which is regaining 13.68 kg oil eq reason from having a high amount of heating value so have more efficiency to return heat and electricity from this process than other box materials. Water consumption impact is highest on PP box with recycling process that about 14.87 m³ water required the least water required is PP with incineration options because of two reasons. Firstly, regaining PP can reduce water use to produce the virgin pellet. Secondly, the other two biodegradable boxes require much water during plantation stage.

3.2.2. Normalization results

Fig. 3(a) and Fig. 3(b) show the comparison of the total environmental impact score of food packaging boxes with different waste treatment options. The result shows that the PP food container box with incineration energy recovery option has returned the highest cumulative point (Pt) from of 18 impact categories, especially in marine and freshwater ecotoxicity impact. The Marine Ecotoxicity impact scores from PP box with incineration route is 53.5% out of the total score, followed by the Freshwater Ecotoxicity and Human Non-carcinogen which are 32.2% and 8.9% respectively resulting from the manufacturing stage. When choosing the alternative waste treatment option for PP, mechanical recycling can reduce the total impact score by 73.48% because it can return 90% of PP waste into recycle pellets. So, it saves a high amount of virgin pellets used in producing PP box. When comparing two biodegradable boxes, the Paper/PLA box is slightly higher impact scores in landfill, composting, and incineration with energy recovery than the PLA box which are 1.52, 1.80, and 1.49 times respectively, due to the highly number of human and marine ecotoxicity categories.

At the box production, the impact from this stage has similar values between each box due to the same process of box forming process and their material having close melting point for extrusion. When focusing on treatment options among green alternative box, the landfill options resulting a highest environmental impact score followed by incineration with energy recovery and composting respectively. Moreover, from normalization analysis results show that choosing PLA as food container box will meet the goal the reduce overall environmental impact whatever waste treatment options are chosen. However, if we need to reduce the specific impact such as global warming the Paper/PLA better option due to less GHG emission at production stage. In addition, the result shows the using PP box material returns the overall impact result as close as biodegradable box when it manages by mechanical recycling treatment at EOL.

3.3. Sensitivity Analysis

From the impact assessment and normalization, if PP box material is managed by mechanical recycling treatment at EOL, it yields an overall impact outcome that will be comparable to that of a biodegradable box. So, it can be concluded that waste collection & separation system has major role to reduce environmental impact. However, waste cannot be collected and separated by 100%, it depends on the waste management system and potential implications use in country. According to this reason, the first sensitivity purpose to identify the variation of environmental impact from each box material when its proper treatment cannot cover all of waste due to different waste management efficiency and show the result that which types of food container materials are most likely to cause significant environmental harm when improperly manage.

Moreover, when scope on the production stage, food box industries always have different machine and specific desire packaging. The environmental impact result may variant from different scaling of thickness between product. Reason to the second sensitivity analyses will focus on the variation of box thickness, to identify the increasing of environmental impact when box thickness is expanded.

3.3.1. Difference waste treatment proportion

In the current situation in Thailand, the management of food container boxes at the end of their lifecycle is inadequate. Only 33% of plastic waste is properly managed through appropriate treatment solutions. This deficiency stems from several factors: Firstly, the collection and separation systems do not cover every community. Secondly, the government’s enforcement of laws and penalties to encourage waste separation behaviors remains insufficient. Consequently, at waste disposal plants, food containers often end up mixed with other types of waste. The separation of PLA food containers from mixed waste is uncommon due to high costs, as the return profit from recycling PLA is not competitive compared to petroleum-based materials like PP. Moreover, not all PP waste is recycled at the end of its lifecycle due to flaws in the collection and separation systems, as well as the poor quality of some plastic waste.

The purpose of this study is to discern which types of food container boxes are prone to causing the most significant environmental impact when subjected to improper waste management practices due to their inability to be separated from mixed waste. This evaluation is achieved through a comparison of the percentage of waste treated by the most effective waste management option (B) against that treated by the least effective option (W), delineated across three scenarios: 100% (B) versus 0% (W), 50% (B) versus 50% (W), and 0% (B) versus 100% (W). Upon normalization of the results, the analysis reveals that for petroleum PP food container boxes, mechanical recycling emerges as the least environmentally impactful option. Conversely, for biodegradable Paper/PLA and PLA boxes, composting stands out as the most eco-friendly alternative. Consequently, these waste management strategies are identified as the optimal EOL treatments for their respective containers. Further examination of the normalization impact highlights that PP boxes subjected to incineration with energy recovery exhibit the most adverse environmental effects, whereas recycling options yield the most favorable outcomes. Similarly, both biodegradable boxes exhibit consistent trends, with composting offering the least detrimental impact and landfill disposal resulting in the highest environmental burden.

The graphical representation in Fig. 4 provides a comprehensive overview of the overall environmental impact associated with each type of box as the proportion of their worst waste treatment increases. This visualization aids in elucidating the escalating environmental ramifications linked to inadequate waste management practices.

In Fig. 4(a), when PP is only recycled (100% recycle options), the overall impact score is −14.49 Pt. But when the proportion of incineration with energy recovery increases from 100(B):0(W) to 50(B):50(W) and 0(B):100(W), the total impact scores rise to 44.31% up to 88.62%, respectively. This happens because improper treatment has a bigger impact, and recycling turns out to be more effective in reducing overall environmental impact than incineration with energy recovery. However, the analysis finds that if landfill treatment is the major proportion for managing PLA box waste, the overall impact scores will turn upside as shown on Fig. 4(b). This change means that when biodegradable boxes are solely disposed of in landfills, they will return to the environmental impact. In Fig. 4(c), when transitioning from 100% composting to a half compost-half landfill condition, the normalization score a change of 58.79%. Moreover, it will cause higher impact because Paper/PLA emits more CH4 from degradable reactions compared to PLA alone. The best solution involves enhancing collection and separation systems, implementing stricter enforcement of waste management regulations, and promoting cost-effective recycling and composting programs tailored to the specific characteristics of different types of containers.

3.3.2. Expansion of box thickness

The thickness of food boxes is often determined by the type of materials used. Their materials thickness tends to offer more protection and strength to the contents. The specific thickness of a commercial food box in Thailand would depend on the manufacturer and the intended use. It’s essential to choose the appropriate thickness and material based on the type of food being stored or transported to ensure that it maintains its integrity and keeps the food safe. So, these specifications can change over time and may vary between manufacturers. The change of box thickness will require more resources for production and generate different emissions in the manufacturing process. Several factors related to thickness influence emissions during production stage, the food boxes typically require more raw materials such as paper pulp or plastic resin. The extraction and processing of these materials can lead to increased emissions, including energy consumption and greenhouse gas emissions or even demand for more water during the production process. Fig. 5 shows the sensitivity analysis when the average thickness on food packaging box increases by 20%. It seemed not much significantly different between each box material. The highest impact from thickness variation is PLA box which is 20.02% impact increased when thickness expanded due to higher required of land use and fertilizer during plantation stage, followed by PP and Paper PLA which is 19.98% and 19.87% respectively.

4. Conclusions

In the research, single-use food packaging made from PP, PLA, and Paper/PLA material was evaluated the life cycle impact assessment (LCIA) by using the ReCiPe method which employed to analyze 18 environmental impacts from box processing to end-of-life treatment. The functional unit (FU) of the LCA is specified as 1,000 units single-use food container box. The size of box is average from Thailand market and food-delivery box: height 48 mm width 116 mm and length 169 mm. with the same capacity as 9.41× 10-4 m³ per box. The environment at cradle-to-gate (cradle-to-box production) Overall, the manufacturing of PP boxes yields the highest environmental impact, followed by PLA and Paper/PLA boxes, respectively. In terms of global warming impact, the PP box exhibits the highest emissions due to its reliance on energy-intensive virgin plastic material acquisition. However, the Paper/PLA box outperforms the PLA box in this regard, thanks to its lower proportion of PLA material and the carbon dioxide absorption during photosynthesis. Nevertheless, the PLA box shows elevated levels of stratospheric ozone depletion and marine eutrophication due to the use of ammonium nitrate fertilizer during corn plantation. Additionally, the PP box’s manufacturing process incurs substantial impacts on terrestrial, freshwater, and marine ecotoxicity, along with fossil resource scarcity.

After analysis whole life cycle of food packaging from cradle-to-grave, it was returned the unexpected result that petroleum-based packaging boxes such as PP, emerged as the optimal choice for food packaging due to its overall environmental impact, which is comparable to that of biodegradable alternatives when considering the recycling process at the EOL. Recycling PP boxes appears to offer several environmental benefits compared to other waste treatment options. It results in lower global warming impact, ionizing radiation impact, and freshwater ecotoxicity compared to incineration or composting options. Additionally, it reduces water consumption and fossil resource scarcity, and it helps mitigate human toxicity. This finding negates the need for additional infrastructure for manufacturing biodegradable products. Conversely, in countries with inadequate waste management infrastructure or limited resources for constructing a recycling facility. the biodegradable food packaging, PLA emerges as the most suitable material choice for food packaging. The first sensitivity analysis in this research supports that biodegradable PLA material emerges as the most suitable choice, particularly over Paper/PLA, offering lower overall environmental impact when focus among whole life cycle.

To achieve environmental objectives, the government should clearly specify type of food box material and the proper waste management used in the country, so that there isn’t much variety of materials making it efficient in separating waste types for disposal. For managing food packaging waste requires consideration of potential policy implications. Implementing extended producer responsibility (EPR) laws becomes imperative to hold producers accountable for managing their product’s end-of-life, including plastic packaging. Introducing refund schemes, where consumers pay a deposit on plastic packaging and reclaim it upon recycling, could further incentivize responsible disposal. Government support is essential in aiding manufacturers and retailers in developing take-back programs for PP packaging and streamlining the collection and recycling of used plastics. Additionally, consumer behavior plays a crucial role; promoting a shift towards products with minimal or sustainable packaging and ensuring proper waste sorting for recycling is imperative. However, if countries with inadequate waste management infrastructure or limited resources for construct a recycling facility, the EPR laws need to support producers accountable for the end-of-life management of their biodegradable packaging, incentivizing them to design for composability and invest in composting infrastructure as well as encourage businesses and consumers to choose biodegradable packaging options and support companies that prioritize sustainability and composability in their products. However, this research only focusses on single-use situation food box, there still be more investigation of assessment in the assumption when the reuseable condition play a role in the study.

Supplementary Information

eer-2023-729-supplementary.pdf

Acknowledgments

This research is funded by Kasetsart University through the Graduate School Fellowship Program.

Notes

Author Contributions

K.P. (MS student): Investigation, Data collection, Analyzation, Writing – the original draft and revised manuscript. V.V. (Assistant Professor): Conceptualization, Resources, Supervision, Review & Editing.

Conflict-of-Interests

The authors declare that they have no conflict of interest.

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Fig. 1

System boundary of (a) PP food box, (b) PLA food box, and (c) Paper/PLA food box.

Fig. 2

Life cycle assessment results at midpoint level of food packaging box per 1 FU since cradle-to-grave

Fig. 3

Normalization results of food container box since cradle-to-grave (a) with 18 impact categories, and (b) with each stage of life cycle.

Fig. 4

Normalization score with difference proportion between best(B) and worst(W) treatment option of three types of food container box. (a) PP box with recycle and incineration treatment ratio, (b) PLA box with compost and landfill treatment ratio, and (c) Paper/PLA box with compost and landfill treatment ratio.

Fig. 5

Endpoint environmental impact result from box manufacturing when 20 percent thickness expansion on food container boxes.

Table 1

Characteristics of PP PLA and Paper/PLA food container boxes per 1 FU.

Characteristic	Average thickness (mm)	Weights of boxes (kg / FU)	Density (kg / m³)
PP	0.55	34.64	946
PLA	0.26	22.38	1,310
Kraft Paper with PLA coating	0.36	28.69	1,201 for Kraft Paper / 1,310 for PLA

Table 2

Elemental composition of each material included in food boxes.

Sample	C	H	N	O	S	Moisture	References
PP	84.62	15.23	0.14	-	0.01	0.065	[17] [18, 19]
PLA	50	5.61	43.81	0.56	-	0.28	[6] [20]
Kraft paper	43.5	6.0	44.0	0.2	0.3	10.2	[21]

Table 3

LCA results at midpoint level of PP PLA and Paper/PLA per 1 FU since cradle-to-box production.

Impact category	Unit	PP	PLA	Paper/PLA
Global warming	kg CO₂ eq	101.83	85.27	66.20
Stratospheric ozone depletion	kg CFC11 eq	5.21E-05	2.13E-04	4.70E-05
Ionizing radiation	kBq Co-60 eq	6.66	3.69	2.48
Ozone formation, Human health	kg NO_x eq	0.18	0.13	0.12
Fine particulate matter formation	kg PM_2.5 eq	0.16	0.10	0.08
Ozone formation, Terrestrial ecosystems	kg NO_x eq	0.19	0.14	0.12
Terrestrial acidification	kg SO₂ eq	0.33	0.26	0.21
Freshwater eutrophication	kg P eq	0.07	0.03	0.01
Marine eutrophication	kg N eq	0.003	0.04	0.01
Terrestrial ecotoxicity	kg 1,4-DCB	75.57	39.62	31.98
Freshwater ecotoxicity	kg 1,4-DCB	8.55	1.19	1.38
Marine ecotoxicity	kg 1,4-DCB	11.94	1.49	1.82
Human carcinogenic toxicity	kg 1,4-DCB	3.34	1.68	5.34
Human non-carcinogenic toxicity	kg 1,4-DCB	285.11	22.80	24.94
Land use	m²a crop eq	0.68	23.90	10.96
Mineral resource scarcity	kg Cu eq	0.62	0.03	0.05
Fossil resource scarcity	kg oil eq	64.45	23.65	21.18
Water consumption	m³	0.83	5.90	8.29