Material Recovery Facility Research Articles

Sustainability Analysis of Anaerobic Digestion Systems for Decentralized Waste Management

Life cycle assessment (LCA) and life cycle costing (LCC) analyses were utilized to assess decentralized anaerobic digestion (AD)-based solid waste management (SWM) plans for a remote community. A hypothetical developing community of 20,000 habitants was selected with an average municipal solid waste (MSW) generation of 0.51 kg/capita/day. Sustainable SWM is needed to ensure both the environmental and economic aspects. In order to exploit the resource value of the high food fractions in developing countries, sustainable waste management alternatives have been emerged and compared to the commonly used SWM scenario (landfills). The scenario included, collection and transportation of waste, material recovery facility (MRF), AD, and landfilling processes. WRATE software databases were used to obtain data for the life cycle inventory (LCI). The functional unit has been selected as the management of 1 ton of MSW for a study period of 20 years. The scenarios were evaluated via the CML 2001 impact assessment method covering 6 categories including climate change, eutrophication potential, acidification potential, freshwater aquatic ecotoxicity, human toxicity, and resource depletion. The findings revealed that the proposed strategy improved the life cycle environmental performance in all impact categories and resulted in significant economic savings.

Life Cycle Sustainability Assessment of Single Stream and Multi-Stream Waste Recycling Systems

An increasing trend of moving towards single-stream waste management systems is occurring in many municipalities. This is because of the ability to process greater quantities of materials, minimize material management costs, and maximize recycling convenience and participation. Research on evaluating comprehensive sustainability (economic, environmental, and social) of the two streams is very limited. This study looks to gain an in-depth understanding of two waste management systems and assist in the decision-making processes of municipalities. To achieve this, the study provides a framework for evaluating economic, environmental, and social impacts as well as a sustainability assessment of single- vs. multi-stream waste management systems within the scope of a typical North American college town. A life cycle assessment framework was employed. The scope of the assessment includes production of materials, collection, sorting, and processes included in a material recovery facility (MRF). The functional unit is 1 ton of municipal solid waste. The case study was conducted on a North American college city during its transition from multi-stream recycling to single-stream recycling. The sustainability assessment result of the case study reveals that the single-stream recycling collection cost is slightly lower (USD 86.96/ton) than the multi-stream recycling collection cost (USD 89/ton). Additionally, the GHG emissions for the single-stream recycling system (10.56 kg CO2eq/ton) are slightly higher than for the multi-stream recycling system (9.67 kg CO2eq/ton). This is due to the complexity of the processes involved in the MRF. Nevertheless, recycling rate is the determining factor for life cycle GHG emissions and costs. Municipal solid waste policymakers could benefit from this study by using the framework and study results for tactical and strategic decision-making.

Economic and environmental analysis of plastics pyrolysis after secondary sortation of mixed plastic waste

Plastic usage has quickly grown in recent years as plastics have become an essential material in everyday life. Unfortunately, recycling rates have not matched the increased growth, with the majority of waste plastic currently landfilled in the United States. New chemical recycling technologies, i.e. pyrolysis, are needed to increase the recycling rates of waste plastics. However, pyrolysis is challenged with bridging of feed into the hot reactor and in the high cost of waste plastic feedstock. In this work a novel liquid-fed pyrolysis process, designed to eliminate bridging, was modeled through process simulation and assessed over a range of processing conditions. A secondary sortation of inexpensive mixed plastic waste from material recovery facilities provided a low-cost feedstock (PE, PP) for pyrolysis. A techno-economic analysis and life cycle assessment found favorable economic and environmental results for pyrolysis oil when compared to fossil naphtha ($561/t, 0.52 kg CO2 eq./kg). A sensitivity analysis found the economic results most responsive to waste plastics feedstock costs, pyrolysis gas sales, operating capacity, and waste disposal costs. Furthermore, it is recommended to recover and sell sorted PET from the mixed plastic bale and implement heat integration in pyrolysis, which in our study achieved lower minimum selling price and greenhouse gas emissions for pyrolysis oil then for fossil naphtha.

Municipal Solid Waste Collection and Haulage Modeling Design for Lahore, Pakistan: Transition toward Sustainability and Circular Economy

Municipal solid waste management (MSWM) is a critical administrative, environmental and financial issue in low-income countries, such as Pakistan, where waste collection efficiency is less than 75% in all urban areas, except Lahore. Therefore, it is pertinent to develop practical decision-making tools to enhance waste collection efficiency by local municipalities and waste management companies (WMCs). A tool/calculator, holistically measure analyze forecast honestly (HMAFH), is proposed for waste collection in urban areas based on the lessons learned. The tool was developed considering local conditions, i.e., business environment, socio-economic and cultural dynamics, city infrastructure and stakeholders’ desires. It is flexible to various proposed waste collection modes, with heterogeneous fleet choices, and it presents an opportunity to integrate collection with a material recovery facility (MRF) or direct haulage to the disposal site. The HMAFH was tested successfully in the Lahore district. Based on the proposed scenarios, the result shows a material recovery of up to 33% by defining dedicated waste collection streams with a 26% saving on fuel. The proposed interventions can prove to be a defining step toward building a circular economy (CE) that allows the integration of treatment options with economic potential to account for 35% of the current operating expenditures and a reduction in greenhouse gases (GHGs) emission, i.e., 1,604,019 tons of CO2-eq./annum.

Multi-Modal Stand-Off Detection of Plastics for Sorting Application

Plastics are extremely valuable to our society and are widely used in many industries such as food, beverage, textile, healthcare, automotive, aerospace, construction, agriculture, oil, etc. Since plastics do not degrade easily with time, the discarded plastics pose a grave environmental problem. Only less than 10% of plastics is recycled in the US. Therefore, there is an urgent need to increase the recycling of plastic products. At present, sorting of plastic waste is carried out manually which is time consuming, costly and manual labor intensive. To address this problem, a novel multi-modal sensor platform capable of improving the accuracy of automated sorting of various plastics by using molecular identification has been developed. This multimodal technique of standoff photothermal-photoacoustic detection is a combination of mid-infrared (MIR) photo-thermal spectroscopy and photoacoustic spectroscopy for characterizing surfaces. Since MIR is free of overtones, this region is known as the molecular fingerprint region. In this technique, the plastic surface is illuminated with a pulsed laser beam from a tunable quantum cascade laser (QCL). The photothermal detection is accomplished by collecting the scattered light from the plastic surface which contains the molecular vibration spectrum of the sample. A silicon bi-material microcantilever, fabricated by depositing a thin metal film on one of its sides is used as a sensitive uncooled infrared detector. Monitoring the bi-material cantilever bending as a function of illumination wavelength provides the IR absorption spectrum of the plastic material. Simultaneously, the photoacoustic signal generated by the absorption of light is monitored by a sensitive microphone. A highly sensitive microfabricated acoustic resonator is used for collecting the photoacoustic signal. Monitoring the microphone response as a function of wavelength produces photoacoustic spectrum (PAS) of the sample. This non-destructive characterization technique will help in enhancing the quality of plastic sorting process at materials recovery facilities and other industries by making the process inexpensive and time efficient.

Evaluation of Improvements in the Separation of Monolayer and Multilayer Films via Measurements in Transflection and Application of Machine Learning Approaches

Small plastic packaging films make up a quarter of all packaging waste generated annually in Austria. As many plastic packaging films are multilayered to give barrier properties and strength, this fraction is considered hardly recyclable and recovered thermally. Besides, they can not be separated from recyclable monolayer films using near-infrared spectroscopy in material recovery facilities. In this paper, an experimental sensor-based sorting setup is used to demonstrate the effect of adapting a near-infrared sorting rig to enable measurement in transflection. This adaptation effectively circumvents problems caused by low material thickness and improves the sorting success when separating monolayer and multilayer film materials. Additionally, machine learning approaches are discussed to separate monolayer and multilayer materials without requiring the near-infrared sorter to explicitly learn the material fingerprint of each possible combination of layered materials. Last, a fast Fourier transform is shown to reduce destructive interference overlaying the spectral information. Through this, it is possible to automatically find the Fourier component at which to place the filter to regain the most spectral information possible.

Managing Solid Waste at Isabela State University Cabagan (ISUC) Campus: Current Practices and Unfolding Opportunities

Solid waste is a pressing environmental concern nowadays. Even academic institutions are not exempted on its associated problems. To this end, the practices and implementation schemes of ISUC in addressing the concerns on solid wastes were assessed. Through individual interviews, actual field observations/validations, and desk review of documents, several qualitative data were generated categorized, summarized and analyzed through content analysis. Results show that in so far as solid waste and its management is concern, the following key issues/concerns were identified: absence of an approved long-term SWM Plan; source of funding support for SWM programs; lack of manpower in implementing the SWM programs; no segregation/reduction of wastes at source; collection system needs to be revisited/changed; open burning and littering of wastes; recovery facilities need improvement; functionality of SWM equipment; and IEC campaign materials. In terms of SWM initiatives, the campus has existing institutional arrangements on dealing with solid wastes concerns. It also has various equipment and manpower to cater the needs for SWM. Source reduction and segregation-at-source are also given attention including collection system but not fully functional/operational. There are also existing recycling initiatives and marketing of recyclables/saleable materials. As to disposal, the special/hazardous wastes from laboratory and health offices are stored in the septic vault beside the campus’ Centralized Materials Recovery Facility. In addition, scientific studies were conducted vis-à-vis SWM. However, complementary activities need to be made in place which include: strengthening IEC campaigns; attendance to SWM capacity-building programs; and the adoption of a comprehensive campus-based SWM Framework

A DEMATEL Framework for Modeling Cause-and-Effect Relationships of Inbound Contamination in Single-Stream Recycling Programs

Material Recovery Facilities (MRFs) are the foundation of United States recycling programs. MRFs collect recyclable materials from end users for export to be processed abroad or to sell to mills for further refinement and reuse. The most popular type of recycling collection in the United States is Single-Stream Recycling (SSR). Numerous studies have validated the program’s popularity and consumer acceptance. In contrast to other recycling plans, SSR’s favored status rests on its minimal consumer burden, which requires only a cursory identification of potentially recyclable materials for placement in a single container separate from other waste. Researchers have also found that collecting SSR materials requires less staff and cheaper collection vehicles. While SSR generates greater end-user acceptance than other recycling collection programs, SSR differs markedly in terms of higher inbound contamination rates and quality of recovered recycling materials. Single-stream collection increases cross-contamination through mixing recyclable and non-recyclable materials in a single container. High contamination rates lower the quality of incoming recyclables and increase overall MRF operating costs due to additional sorting time and related staffing costs. This paper aims to analyze the causes of high inbound contamination in SSR using Decision-Making Trial and Evaluation Laboratory (DEMATEL) techniques to support deeper analysis of the relative importance of three factors that scholars have identified as being related to SSR inbound contamination of MRFs. Based on the results obtained, the absence of awareness campaigns is one of the crucial factors increasing inbound contamination due to the inefficiency of the SSR system in separating unrecyclable from recyclable materials; therefore, the sorting equipment at MRFs requires further improvement. Focused analysis of causal inbound contamination factors may assist in furthering efforts to reduce SSR contamination.

Improving Recycled Waste Management Performance in Ngaliyan District, Semarang City

The waste that enters the Jatibarang landfills does not go through the management and processing process in advance, and the people's laziness in sorting waste has resulted in an increase in waste at the Jatibarang landfills. Ngaliyan reduce, reuse, recycle (3R) waste management site is currently inactive due to a lack of implementation in aspects of waste management. Therefore, it is necessary to plan waste management as an effort to overcome urban waste by increasing performance at reduce, reuse, recycle (3R) waste management sites. Data collection methods used are sampling, interviews, and questionnaires. In this technical, operational planning of waste management, an area of reduce, reuse, recycle (3R) waste management site is required of 661 m2. Organic waste is processed through composting using the Open Windrow method, and inorganic waste is managed using the MRF (material recovery facility) method. The total cost required is IDR 11,135,856,300.00. The community is expected to be able to participate in waste processing and management through 3R-based sorting, comply with applicable regulations, and pay a retribution every month.

PortiK: A computer vision based solution for real-time automatic solid waste characterization – Application to an aluminium stream

In Material Recovery Facilities (MRFs), recyclable municipal solid waste is turned into a precious commodity. However, effective recycling relies on effective waste sorting, which is still a challenge to sustainable development of our society. To help the operations improve and optimise their process, this paper describes PortiK, a solution for automatic waste analysis. Based on image analysis and object recognition, it allows for continuous, real-time, non-intrusive measurements of mass composition of waste streams. The end-to-end solution is detailed with all the steps necessary for the system to operate, from hardware specifications and data collection to supervisory information obtained by deep learning and statistical analysis. The overall system was tested and validated in an operational environment in a material recovery facility.PortiK monitored an aluminium can stream to estimate its purity. Aluminium cans were detected with 91.2% precision and 90.3% recall, respectively, resulting in an underestimation of the number of cans by less than 1%. Regarding contaminants (i.e. other types of waste), precision and recall were 80.2% and 78.4%, respectively, giving an 2.2% underestimation. Based on five sample analyses where pieces of waste were counted and weighed per batch, the detection results were used to estimate purity and its confidence level. The estimation error was calculated to be within ±7% after 5 minutes of monitoring and ±5% after 8 hours. These results have demonstrated the feasibility and the relevance of the proposed solution for online quality control of aluminium can stream.

A REVIEW OF RECENT TRENDS TO INCREASE THE SHARE OF POST-CONSUMER PACKAGING WASTE TO RECYCLING IN EUROPE

Through the Circular Economy Package, the EU aims to reduce material imports and environmental impacts of waste management. Ambitious recycling targets should help to achieve these objectives. As a response, the waste industry developed technical and organizational solutions that can intervene at different stages of a waste management system in order to increase the recovery of recycling materials, starting with improved separate collection over the use of modern material recovery facilities up to the enhanced treatment of waste incineration ashes. The large question is how each of these options can contribute to increase recycling rates to achieve a circular economy. By reviewing case studies as presented in the most recent literature published since the year 2010 from European countries on the recycling of post-consumer packaging waste of glass, metals, paper, and plastics, this study contributes to answer this question. In the first stage, the review found 644 articles matching with the search terms and published since the year 2010. Of these, 46 remained for an in-depth analysis, since 319 did not present case studies as defined in the scope of this article. The articles reviewed provide a good overview on the state of knowledge on increasing recycling of post-consumer packaging waste by improved separate collection, material recovery facilities, and waste incineration bottom ash treatment. Additional information and case studies, however, are required, particularly large-scale experiments to test new separate collection systems, large-scale with different feedstock material at the most-modern material recovery facilities and waste incineration bottom ash treatment plants.

Knowledge, Attitude and Practices on Solid WasteManagement Among Households in the UrbanCommunities of Butuan City, Philippines

Urban agglomeration in Butuan City led to issues on solid waste management (SWM). The socioeconomic profile and effectiveness of SWM programs were assessed and evaluated through a survey questionnaire. Using a 5-point Likert scale to measure the knowledge, attitude, and practices towards SWM. Key informant interviews and focused group discussions were also conducted. On the average, respondents showed very high SWM knowledge (3.80) and attitude (4.52) which was attributed to high educational attainment and income. Majority of the respondents practice waste segregation (97.9%), reusing (83.8%), recycling (70.4%) and composting (61.3%). However, low knowledge on the location (35.6%), functionality (33.7%), and utilization (51.3%) of the materials recovery facilities was noted, an indication of non-compliance by local government units to SWM laws and policies. A significant number of respondents do not practice composting (38.7%) due to lack of facilities and available space. Clustered materials recovery and composting facilities, and adjustments on waste collection, storage, and disposal systems must be established and implemented. Incentive programs, awareness campaigns, and public participation are key elements of an efficient SWM system.

Life Cycle Assessment of Construction and Demolition Waste Management in Riyadh, Saudi Arabia

Extensive construction augmenting the infrastructure and real estate projects underpin Saudi Arabia’s Vision 2030 of sustainable cities. A part of this struggle involves the transformation of the existing infrastructure together with new construction, which generates a large amount of construction and demolition waste (CDW). In the absence of a structured life cycle assessment (LCA) framework, the waste management companies are planning future scenarios (phased expansions of material recovery facilities to improve the recycling rate) primarily on economic grounds. This study assesses the environmental impacts of the existing and planned CDW management practices of the Saudi Investment Recycling Company in Riyadh City by dint of LCA. Impact 2002+ performs life cycle impact assessment of the base case (45% recycling), four treatments (61, 76, 88, and 100% recycling), and zero waste scenarios. The study demonstrates the benefits of current CDW (mixed soil, concrete blocks, clay bricks, glazed tiles, and asphalt) recycling in terms of avoided impacts of non-renewable energy, global warming, carcinogens, non-carcinogens, and respiratory inorganics potentially generated by landfilling. For the treatment scenario of 100% recycling, CDW conversion into a wide range of aggregates (0–50 mm) can replace 10–100% virgin aggregates in backfilling, precast concrete manufacturing, encasements and beddings of water mains and sewers, manholes construction, non-load bearing walls, and farm-to-market roads. To achieve long-term economic and environmental sustainability, municipalities need to improve source segregation, handling, and storage practices to enhance the existing (45%) recycling rate to 100% in the next five years and approach the zero-waste scenario by 2030. The findings of the present study motivate the generators for source reduction as well as encourage the recycling companies and concerned organizations in the continuous performance improvement of the CDW management systems across Saudi Arabia on environmental grounds, as an addition to the perceived economic benefits.

A method for assessing the performance of sorting unit operations in a material recovery facility based on waste characterizations

AbstractThe determination of the separation efficiencies of mechanical sorting equipment is essential to improve the performance of material recovery facilities (MRFs). However, it is often a challenge to obtain these efficiencies due to the high complexity of MRFs, which often comprise several recirculation streams. In this paper, a methodology to determine the equipment separation efficiencies of a complex MRF is described and applied to an actual sorting centre located in the province of Quebec, Canada. Transfer coefficients for every unit operation and several material types, together with all material flows within the facility, have been determined for an MRF processing a stream of commingled recyclable materials. This work also provides a rare dataset of separation efficiencies for several mechanical sorting unit operations. The methodology is validated by comparing experimental data and model predictions for the recovery and purity of all main output streams. The results contribute to identify several avenues for process performance improvement, like adding a magnetic separation at the beginning of the sorting sequence or improving the separation of the 2D‐type materials collected from the second ballistic separator by changing the operation conditions or adding a quality control step. Moreover, the results also provide valuable information about material recovery and purity to help managers improve the process performance. Finally, a scenario analysis demonstrates that the performance of a second ballistic separator has an important impact on the sorting process's global efficiency and that recirculating a fraction of the rejects output stream has a negligible impact on the global performance.

Mixed modeling approach for mechanical sorting processes based on physical properties of municipal solid waste

Material recovery facilities (MFRs) play an important role in today’s waste management systems to maximize recycling efficiency for several waste materials. These facilities face multiple challenges, often due to a poor understanding of the mechanisms occurring within the sorting equipment. Improving modeling techniques of these unit operations appear to be a promising opportunity to mitigates these challenges. Mechanical sorting efficiency of municipal solid waste is often predicted from simple transfer coefficients, which are obtained for a specific set of operating conditions of the sorting equipment and sorting sequence configuration. When these transfer coefficients are used in situations that are different to those in which they were obtained, poor predictions can be expected. To overcome these limitations, a new predictive tool, based on the integration of mechanistic models and transfer coefficients, is presented. Mechanistic models are developed only for the most influential unit operations in a MRF, in order to predict their sorting efficiency based on the physical phenomena occurring. Integration of these models with the use of transfer coefficients for the other unit operations allows the entire predictive tool to remain as simple as possible while providing high prediction accuracy and flexibility. The use of the tool is validated with a real case study of a material recovery facility. Results indicate a good prediction of the mass flows of the facility. Moreover, a new modeling technique is proposed for the representation of a ballistic separator based on the shape factor of the waste items.

Challenges to reducing post-consumer plastic rejects from the MSW selective collection at two MRFs in São Paulo city, Brazil.

​The present study is concerned with an overview of the main aspects of the selective collection from the municipal solid waste in São Paulo City and the limitations of its two automated Material Recovery Facilities (MRFs) to tackle the problem of reducing recyclable plastic waste sent to landfills as rejects. The research aimed to characterize the composition of screened mass flows of as-received mixes from the selective collection at the two MRFs through in situ random collection campaigns. The results of the gravimetric analysis have shown that both MRFs provided higher recovery yields (> 40%) for paper, cardboard, Tetrapack®, ferrous and non-ferrous metals (aluminium), akin to some post-consumer plastics (PET, HDPE/LDPE and PP) that ranged from 38% for PP up to 89% for HDPE, Losses in recovery yields of recyclable plastics after the screening process resulted from lack of clear resin label identification, inefficient materials sortation by households and poor recognition capabilities of the MRFs screening devices to target and segregate specific types of plastics such as PS and vinylic. Packaging design complexity, multi-layered material diversity, and food contaminated post-consumer packaging pose further challenges to improve the plastics recovery capabilities of the two MRFs.

Assessment of Performance and Challenges in Use of Commercial Automated Sorting Technology for Plastic Waste

Recycling plastic is an important step towards a circular economy. Attaining high-quality recycled plastics requires the separation of plastic waste by type, color, and size prior to reprocessing. Automated technology is key for sorting plastic objects in medium- to high-volume plants. The current state of the art of commercial equipment for sorting plastic as well as challenges faced by Material Recovery Facilities (MRFs) to sort post-consumer plastics are analyzed here. Equipment for sorting plastic recyclables were identified using publicly available information obtained from manufacturers’ websites, press releases, and journal articles. Currently available automated sorting equipment and artificial intelligence (AI)-based sorters are evaluated regarding their functionality, efficiency, types of plastics they can sort, throughput, and accuracy. The information compiled captures the progress made during the ten years since similar reports were published. A survey of MRFs, reclaimers, and brokers in the United States identified methods of sorting used for plastic, sorting efficiency, and current practices and challenges encountered at MRFs in sorting plastic recyclables. The commercial sorting equipment can address some of the challenges that MRFs face. However, sorting of film, multilayered, blended, or mixed-material plastics is problematic, as the equipment is typically designed to sort single-component materials. Accordingly, improvements and/or new solutions are considered necessary.

Impact of China’s National Sword Policy on the U.S. Landfill and Plastics Recycling Industry

This paper analyzes the impacts of China’s Green Fence and National Sword Programs, under which strict contamination limits were imposed on recyclable materials, besides prohibiting imports of low quality recyclables. Specifically, this study investigates the impacts of this policy on landfills, and the risks to the U.S. plastics secondary materials market and material recovery facilities (MRFs). A hierarchical regression analysis reveals the significant impacts of China’s Green Fence and National Sword polices on the amount landfilled plastic. Controlling for oil prices, producer price index (PPI), and amount of plastic scrap exported, our findings show that the Green Fence had no statistically significant impact on the amount of plastic landfilled in the U.S. However, the quantity of plastic landfilled in the U.S. increased by 23.2% following the implementation of National Sword. Furthermore, analysis of the annual reports submitted by registered MRFs in New York (NY) state reveals that the total amount of plastic recovered by them has decreased. We suggest that demand creation and investments that improve the quality of bales are needed to help solve this economic dilemma.

Decontamination of Mixed Paper and Plastic Municipal Solid Waste Increases Low and High Temperature Conversion Yields

With the implementation of China’s Green Fence Policy and the following National Sword Policy, there is a need to divert previously accepted waste materials away from the landfill. Mixed plastic and paper wastes that are too contaminated to be economically recycled can be used for conversion into fuels and products. The effect of common contaminants present in waste streams must be determined to make municipal solid waste (MSW) a viable alternative to agricultural feedstocks for conversion. In this study, MSW was sourced from a dual stream materials recovery facility (MRF) in Emmet County, Michigan and characterized via mass balance. The most common contaminants in mixed paper and plastic were quantified and targeted for decontamination when mixed paper was explored for low temperature conversion pathways and plastics for high temperature conversion pathways. Ink, stickies, and plastic contamination were sorted out of the mixed paper stream and did not have an impact on sugar yields during enzymatic hydrolysis (EH). Although no improvement in yield was found, it was noted that copy paper within the mixed paper stream had an elevated pH and higher concentration of fermentation inhibitors, suggesting that intrinsic properties of some paper types may not be ideal for EH and fermentation conversion. Dilute alkaline pretreatment and mechanical refining of mixed paper increased the EH yield of mixed paper, suggesting this previously established process could be used as a decontamination method. “Dirt” and particulates were washed from mixed plastic using either an aqueous detergent or a non-aqueous chemical washing method. Liquid oil yields were increased during microwave assisted fast pyrolysis. All decontamination techniques met the cost target of less than $30/dry ton with plastic decontamination ranging from $18.16 to $24.81/dry ton. Because dilute alkaline pre-treatment and mechanical refining is considered part of the conversion process, the decontamination cost during feedstock preprocessing was considered $0/dry ton.

Recycling of Plastics in the United States: Plastic Material Flows and Polyethylene Terephthalate (PET) Recycling Processes.

As efforts are made toward establishing a circular economy that engages in activities that maintain resources at their highest values for as long as possible, an important aspect is understanding the systems which allow recycling to occur. In this article a common plastic, polyethylene terephthalate, i.e., PET or plastic #1, has been studied because it is recycled at relatively high rates in the U.S. as compared to other plastics. A material flow analysis is described for PET resin showing materials collected, reclaimed for flake, and converted into items with recycled content. Imports/exports, reclaimer residue, and disposal with mismanaged waste are all shown for U.S. flows of PET. Barriers to recycling PET exist in the collecting, sorting, reclaiming, and converting steps, and this article describes them, offers some solutions, and suggests some research that chemists and engineers could focus on to improve the systems. This effort also models sorting at material recovery facilities (MRF) and reclaimers, with detailed descriptions of the material streams involved, to characterize the resource use and emissions from these operations that are key processes in the recycling system. Example results include greenhouse gas intensities of 8.58 kg CO2 equiv per ton of MRF feed and 103.7 kg CO2 equiv per ton of reclaimer PET bale feed. The results can be used in system analyses for various scenarios and as inputs in economic input-output and life cycle assessments.