Curbside Collection Research Articles

Machine learning models for estimating contamination across different curbside collection strategies

Contaminated recyclables, which are frequently discarded as waste, pose a significant challenge to the implementation of a circular economy. These contaminated recyclables impede the circulation of resources, resulting in higher processing costs at material recovery facilities (MRFs). Over the past few decades, machine learning (ML) models such as linear regression (LR), support vector machine (SVM), and random forest (RF) have evolved to provide new methods for predicting inbound contamination rates in addition to traditional statistical models. In this study, we applied ML models to predict inbound contamination rates using demographic features from 15 counties in the U.S. with different curbside collection strategies. In general, we found that ML models outperformed linear mixed models. Specifically, SVM models had the highest performance (R2 = 0.75; mean absolute error (MAE) = 0.06), which may be due to their ability to model nonlinear relationships between features and inbound contamination rates. The key predictor was population, with poverty rate being positively correlated and median age negatively correlated with inbound contamination rates. To improve the management of contamination and enhance the implementation of a circular economy, better models are needed to understand and estimate inbound contamination rates as well as identify critical factors in the present and future.

Economic and environmental feasibility of recycling flexible plastic packaging from single stream collection

As demand for plastic increases, there is an urgent need to ramp up its collection and recycling rate. This study reports results of a pilot study in the United States to recycle flexible plastic packaging (FPP) from single stream curbside collection focusing on both the economic feasibility and carbon footprint. To explore the marketability of recycled FPP, four downstream market pathways were studied, including roof coverboard, plastic pellets, pallets, and film. Results indicated that (1) the cleaning and pelletizing process at reclaimers contributed the most to the total greenhouse gas (GHG) emissions of recycled FPP products, and (2) the GHG emissions of recycled FPP products in all four pathways are lower than the comparator products. Therefore, using a higher percentage of recycled FPP substituted in a product can result in greater GHG emission reductions. All the recycled FPP products also showed favorable economics compared to their direct competitors.

Identification and characterization of sticky contaminants in multiple recycled paper grades

Organic sticky contaminants represent one of the biggest technical challenges in the paper recycling process. These contaminants reduce paper strength, cause plugging of wires and felts, and stick to or deposit on machine parts affecting the runnability of the paper machine. The removal of these sticky contaminants is difficult to achieve along the process due to the heterogeneous nature of these organic contaminants. In this study, the nature of sticky contaminants in multiple wastepaper grades was analyzed and characterized using screening, solvent extraction with subsequent analysis such as FT-IR, GC-MS, and SEM. The content of stickies in wastepaper varies among different paper grades and their recovery methods. The wastepaper from curb side collection contains nearly 4 times the amount of stickies than most of the wastepaper grades collected from a local paper recycling mill. Polyvinyl acetate polymers, styrene butadiene rubber (SBR), paraffin waxes and polyamines are the major components in the extracted sticky contaminants. In addition, these stickies deposit heavily on fibers surface leading to high negative charge in fibers suspension ranging between 2 and 4.5 µeq/L. It is expected that these findings will assist addressing the knowledge gaps in understanding the nature of stickies and their behaviors, and to eventually develop highly efficient technologies for contamination removal in the paper recycling process.

Separate collection rates for plastic packaging in Austria – A regional analysis taking collection systems and urbanization into account

According to the EU Circular Economy Package, recycling of plastic packaging waste (PPW) has to be enhanced significantly by 2025 and 2030. Although a set of measures will be required along the whole value chain of plastic packaging, the process of separate collection remains the backbone. Hence, a detailed understanding of the performance of current separate collection systems is crucial. As a case study, the separate collection of PPW was analyzed within a single country, Austria, where a variety of collection procedures are implemented. By using the method of material flow analysis, separate collection rates in terms of quantities and qualities were analyzed for separate collection systems of different settlement patterns, target fractions, and service levels provided. Results show that the highest performance was achieved in systems that cover mainly rural areas and where all plastic packaging wastes are collected through curbside collection, with separate collection rates of 74–77%. With additional collection via collection centers, these values increased to 78%-83%. In comparison, the results for urban areas showed the lowest separate collection rate of 56%. In the case that separate collection targeted plastic bottles only, maximum collection rates of around 50 % were observed, with the tendency towards higher collection rates if co-mingled with metals. To enhance separate collection, a general shift to the target fraction “all plastic packaging” instead of “plastic bottles only” is crucial. Modelling of optimized collection systems in all Austrian regions would lead to a theoretical total separation collection rate of 74%.

What predicts and prevents source separation of household food waste? An application of the theory of planned behavior

Food waste is a growing global issue with widespread environmental, economic, and social impacts. Households are both a major driver of waste generation and a key enabler of solutions such as source reduction and composting. In the U.S., household food waste is still predominantly landfilled, motivating this study to understand the beliefs, experiences, and barriers that individuals face when deciding whether to source separate household food waste as a precursor to landfill diversion. To understand these factors, the theory of planned behavior was applied using data collected via a survey of New York State residents and analyzed using structural equation modeling. Results indicate that attitude, subjective norm, and perceived behavioral control are all significantly and positively associated with the intent to separate household food waste. However, respondents also expressed significant concern that food waste separation would lead to odor, pests, and messiness in the home, ultimately resulting in a distinct “yuck factor” construct that had a significant negative association with behavioral intent. These concerns were particularly strong for individuals who had no past experience separating food waste. These findings suggest several potential interventions, including education on how to separate food waste and expansion of curbside collection systems to address consumers' unwillingness to handle waste or clean collection containers.

On the feasibility of using canals for waste collection in Amsterdam

Amsterdam, a growing city of over 800,000 people in the Netherlands, is struggling to collect waste. While residents in most districts of the city use underground bins to deposit their garbage, the historic Centrum district continues to rely on curbside collection. As such, the streets around the UNESCO-World-Heritage canals are lined with garbage bags as trash trucks rumble down roads centuries old and ill-fitted for vehicles of such size. This paper assesses the viability of moving Centrum trash collection to the canals with a fleet of tug boats and floating dumpsters. It does so by using a combination of GIS tools and integer programming to determine the quantity and optimal collection locations while ensuring that an average Centrum resident walks no farther than denizens of the other Amsterdam districts. Additionally, it proposes a schedule for emptying floating dumpsters based on one comparable to the current truck system. The results of this paper suggest that mobile trash collection using the canals is a viable solution that could reduce noise, pollution, and congestion, thus improving the quality of Amsterdam’s historic cityscape.

Expanding the collection portfolio of plastic packaging: Impact on quantity and quality of sorted plastic waste fractions

Expanding the curbside collection system for household plastic packaging could help in accomplishing the ambitious recycling targets set by the European Union. In this study, the effects of such expansion in terms of quality and quantity of sorted plastic waste fractions were investigated. By applying a validated sorting model, the flows of packages in Belgium from their use phase until the output of the sorting plant and the quantity and composition of sorted waste fractions were simulated. These data were subsequently used to calculate existing performance indicators, such as grade and recovery, as well as new indicators, such as the Simpson's Diversity Index (SDI), which is a measure for the compositional diversity of sorted waste fractions. The highest SDI was calculated for the fraction named ‘other films’, namely 82%, showing that this fraction comprised the most diverse polymer mixture. Results indicated that certain sorted fractions achieve high product grade levels, e.g. more than 99% for the PS rigid fraction, whereas others had significantly lower product grades of approximately 80% for the PE films. Material Flow Analysis showed that by expanding the collection portfolio the collection rate of plastic packaging increased from 33.6 to 64.4 m%, of which 77.3% is simulated to be separated in the targeted waste fractions. However, this will be insufficient to meet the recycling target of 50% by 2025 as in total only 49.8% of plastic packaging is sorted correctly. Hence, additional improvements in both recycling technologies and packaging design are needed to further increase plastic recycling rates.

The efficiency of municipal solid waste collection in Mexico.

Since the 1980's, some Mexican municipalities have subcontracted waste collection services to private companies, with an eye on increasing the efficiency of this service. However, the impact of private management on the Mexican waste sector performance has not been evaluated. In this study, the efficiency of waste collection in Mexico was analyzed to test the hypothesis that private companies are more efficient at waste collection than municipal governments. A two stage double bootstrap Data Envelopment Analysis (DEA) was applied to a sample of 1,626 municipalities. In the first stage, unbiased efficiency scores were calculated, and in the second stage, these scores were regressed against a set of environmental covariates which were thought to affect efficiency, including a dummy variable to identify the municipalities where waste is collected by a private company. Results suggest that private waste collection companies are more efficient than municipal governments. Other environmental variables such as population density, average household income, and tourism were also found to affect waste collection efficiency. The analysis also indicates that curbside collection is associated with a higher efficiency, while separate collection of waste is negatively correlated to efficiency.

Evaluation of sustainable e-waste collection method for urban and rural region of India.

Electronic waste is one of the most challenging waste streams to manage. It has become a significant concern in developing countries due to the ever-increasing volume of generation coupled with deficient growth in collection and processing infrastructure. For the various stakeholders, it is of paramount importance to adopt a robust and sustainable collection method for hazard mitigation. The prevalent e-waste collection methods are categorized under four major heads, namely take-back, retail store, door-to-door and curbside collection. The e-waste collection problems are analysed from various perspective, based on literature that cited developing country-specific survey and data that includes India. Economic sustainability and potential risk are included as attributes in the evaluation scheme. We attempt to establish a decision-making model. Discussion with the field experts and decision-makers (DMs) provided the weights for various attributes and sub-attributes. A fuzzy linguistic scale is used to take care of ambiguity in DMs' opinion. Fuzzy- Analytical Hierarchy Process (FAHP) is used to determine the importance of various attributes and sub-attributes, while Fuzzy-VlseKriterijumska Optimizacija I Kompromisno Resenje (FVIKOR) is used to determine the rank of the alternatives. Based on the analysis, 'take-back collection' and 'retail store based collection' are found the most suitable options for urban and rural regions respectively. The attributes, social awareness and economical sustainability are found to have the highest significance in both cases. Implementation of a collection method is an expensive activity, and the proposed Fuzzy-Multi Attribute Decision Making attempts to capture various attributes and their complex interplay to arrive at a decision on optimum e-waste collection option(s) in a specific locality.

Familiarity breeds acceptance: Predictors of residents' support for curbside food waste collection in a city with green bin and a city without.

Food waste remains a high priority greenhouse gas (GHG) emission problem and household curbside collection - green bin1 - with mass treatment is often adopted as a viable solution for GHG reduction. The aim of this study is to explore attitudinal and situational predictors of support for residential curbside green bin programs. Using responses to 517 household surveys from the mid-sized Canadian cities of London, Ontario (proposed green bin program) and Kitchener-Waterloo (KW), Ontario (operating green bin program for 10+ years) comparison of means t-tests, correlations and linear regression are used to test five hypotheses derived from the food waste and waste diversion literatures that predict green bin support: situational factors, current food wasting, theory of planned behaviour attitudes, concern that green bin encourages food wasting, and concern that food waste ends up in the garbage regardless of green bin. There is some support for all five hypotheses. Residents in Kitchener-Waterloo were significantly more supportive (83%) than those in London (65%). While residents in both communities are supportive because of the perceived convenience and environmental benefits of the green bin, the number of regression model predictors is greater in London (16 compared to 9 for Kitchener-Waterloo). The findings overall suggest sustained municipal education at the implementation stage may lead to positive resident habituation to green bin and thus, durable public buy-in.

Pilot-scale, on-site investigation of crushed recycled glass as tertiary filter media for municipal lagoon wastewater treatment

ABSTRACT Glass recycling is a process that faces many obstacles, especially in the closed-loop context. Waste glass separation and transportation can become quite expensive, turning glass collection for remanufacture unfeasible. For this reason, it is important that alternative markets for waste glass are sought. This study evaluated crushed recycled glass as tertiary media in subsurface pilot-scale filters for on-site municipal wastewater treatment, using control sand media filters. Filters were operated over 128 days at a 24-h hydraulic retention time, treating secondary lagoon effluent from the rural municipality of Dunnottar, Manitoba, Canada. Crushed recycled glass filters removed 92%, 90% and 45% of the total suspended solids (TSS), ammonium nitrogen (NH4 +–N) and chemical oxygen demand (COD), respectively. Total suspended solids were removed equally well in sand and crushed recycled glass filters (α = 0.05), whereas NH4 +–N and COD reductions were 10% and 21% greater in sand media, respectively. Both sand and crushed recycled glass filters failed to achieve phosphorus (P) discharge guidelines. This study shows that there is potential for crushed recycled glass in wastewater filtration, especially to achieve TSS, COD and NH4 +–N removal. Small communities served by waste stabilization ponds could benefit from glass media filters, as waste glass could be diverted from curbside collection and utilized locally to polish municipal lagoon effluent.

Single stream or dual stream? A game-theoretic approach to the sustainable evolution in waste recycling systems

The rapid development of information and communication technologies has created more opportunities for the channel innovation in residential curbside collection and the technical revolution of material recovery facilities. In waste management, single stream allows the households to bundle the recyclable waste, and dual stream requires the households to separate the recyclable waste individually. However, the sustainable development of the environment has led the government to focus on the transition between two waste recycling systems. In this study, we establish an analytical framework of the sequential game to study the sustainable evolution from single stream to dual stream and from dual stream to single stream. When the households are heterogeneous about the recyclable waste, there is a duopoly price competition in waste management, and two waste recycling systems can sequentially adopt the neutral pricing, penetration pricing and skim pricing strategy. Numerical experiments discuss the impacts of collecting costs and bundling discounts on the sustainable evolution. No matter what the evolution sequence is, two waste recycling systems can set a full or partial bundling discount policy to maximize the profit.

Economic rationalism or administrative rationalism? Curbside collection systems in Sweden and Japan

Abstract Sweden and Japan are environmental leaders in their regions; however, Sweden has shown much better performance in the development of a circular economy. This paper suggests that different environmental discourses between the two countries help explain this gap. An actor-discourse analysis was conducted, taking the case of curbside collection systems. Results show that in Sweden, producers have physical and financial responsibility for collection and recycling while municipalities are responsible for planning and providing information. Economic incentives are well considered, and easy waste sorting at home is a shared norm, fostering systematic improvement of curbside collection systems and drastically increasing recycling rates. In Japan, in contrast, producers address recycling, municipalities do collection, and consumers cover sorting. The necessity of promoting consumer awareness of recycling is broadly accepted, but systematic thinking has not been introduced; as a result, primitive curbside collection systems remain mainstream in Japan, and it is not easy to sort waste at home. Thus, Sweden has favored economic rationalism while Japan administrative rationalism and, the former has been more effective.

A standardized inspection methodology to evaluate municipal solid waste collection performance

The success of separate collection of municipal solid waste, the efficiency of the other connected services and the justification of a large cost assumed by an authority, depends on the level of service provided to customers as well as the citizens’ attitude towards waste management. In this paper, a semi-qualitative inspection method to evaluate both the door-to-door collection system and the conventional curbside system is proposed. The method is based on the combined evaluation of waste collection using a set of indicators and the assessment of the perception of the citizens towards collection and street cleaning services using behavioural questionnaires. The ultimate goal was to assess potential differences between door-to-door and curbside collection systems. The standardized inspection evaluation method was applied to the city of Reggio, Calabria (Italy), since both collection systems are used there. The standardized inspection evaluation proved to be simple to implement and was effective to accurately evaluate the quality of the service delivered to the citizens. The results of the behavioural survey revealed that citizens that practised door-to-door separation had a higher recycling conscience and were more satisfied with the city waste management system than the ones that practised curbside separation. According to the results of the study, there was a qualitative agreement between the results of the standardized inspection evaluation and the behavioural survey. The door to door collection system is suggested to replace the curbside collection system.

LCA of a Consortium-Based MSW Management System to Quantify the Decrease in Environmental Impacts Achieved for Increasing Separate Collection Rates and Other Modifications

In this study, the collection, transport, and treatment phases (including the management of products and processing residues) of six fractions of municipal solid waste (MSW) generated in the Sinistra Piave Basin (Veneto, Italy), a consortium of 44 municipalities, were analyzed by life-cycle assessment (LCA). Specifically, two different scenarios were assessed for paper and cardboard, glass, multi-material (plastics and metals), food waste, garden waste, and dry residual fraction management, one referring to the year 2015 and the other to 2004. The primary aim was to investigate what consequences the increase in separate collection rates progressively achieved by the consortium (65% in 2004 versus to 80% in 2015) exerted on the management system and its potential environmental impacts. For each scenario, the type of separate collection method employed (door-to-door in 2015, and mixed door-to-door and curbside collection in 2004), the collected amounts, the geographic location of the main sorting/treatment plants, and the type of treatments applied to manage the products and processing residues were considered. The results of the study indicate that, among the variations that occurred in the management system for the two considered years, the increase in separate collection rate achieved was the factor that most affected all of the potential environmental impacts taken into account. In particular, for the 2015 scenario, differently from the 2004 one, all of the categories considered (apart from ecotoxicity) were negative, indicating savings instead of impacts. Treatment was the stage that by far mostly affected potential environmental savings, with regard to paper and cardboard recycling in particular.

Recycling and Waste Generation: An Estimate of the Source Reduction Effect of Recycling Programs

Recent analyses maintain that recycling in developed countries, being mostly the result of costly policies, may be already above its socially optimal level. These analyses in fact underestimate such level if increasing recycling not only reduces residual waste, but also total waste. We find that this is the case: a 10% increase in recycling rate is associated with a 1.5–2% decrease of total urban waste. This effect is largely attributable to curbside collection programs, whose adoption increases recycling rates by 8–14% and reduces waste generation by about 4%. This paper contributes to the literature on the relations between waste and recycling by providing estimates of the source reduction effect of recycling policies and pointing out the important role played in it by curbside collection programs.

A comparison of the transport requirements of different curbside waste collection systems in Denmark

With an increased focus on recycling, local authorities need to adapt their systems for curbside collection of household waste to accommodate an increased degree of sorting of waste types. Therefore, it is essential to study the transport aspects of waste collection. In this paper, we analyze the driving requirements for curbside collection of household waste for different systems in the context of Denmark. We consider a Collect, then sort system, as opposed to two Sort, then collect systems using single and multi-compartment vehicles, and compare the systems among themselves, and to the collection for incineration system. Our approach consists of solving the underlying capacitated arc routing problems of each system, and comparing the transport requirements in terms of driven distance and number of routes across systems. Our findings show that an increased degree of sorting is synonymous with a significant increase in the driven distance and the number of routes. Moreover, we find that the sort, then collect by multi-compartment vehicles system outperforms the others in terms of driven distance, and that the sort, then collect by single compartment vehicles system outperforms the others in terms of number of routes. We found that three cost drivers affect the overall results: the change in the size of the vehicle, the compression factor inside the vehicles’ compartments, and the packing of the vehicles’ compartments.

How to improve recycling rate in developing big cities: An integrated approach for assessing municipal solid waste collection and treatment scenarios

This paper investigates municipal solid waste management future scenarios of La Paz, developing big city of Bolivia, for improving the selective collection of recyclable materials. The objective of the paper is to suggest a multidimensional approach, both quantitative and qualitative, for planning sustainable waste management systems in areas with no data availability. The research assessed six different long-term management plans, considering all recycling settings feasible for La Paz. For that purpose, a multi-criteria decision analysis has been introduced, supported by environmental and financial impact assessment concerning transportation, final disposal, and material recovery. Results suggest that the inclusion of the informal sector could be the most feasible option from an economic and technological point of view. Moreover, the curbside collection of organic waste could be considered the best solution for reducing the global warming potential and for improving the useful life of the sanitary landfill. The approach introduced, as well as the combination of solutions evaluated, could be of interest for stakeholders of Latin America for reducing environmental impacts and introducing a new business. Though the multi-criteria decision analysis and the impact-assessment do not provide a dynamic view of future scenarios, their combination could offer a first integrated insight into the possible challenges and opportunities for developing a new municipal solid waste management system in developing cities, encouraging the circular economy and sustainable development.

Applying the Theory of Planned Behavior to Recycling Behavior in South Africa

This paper reports on an application of the Theory of Planned Behavior to understand the relationships between the determinants (latent variables) comprising the Theory of Planned Behavior and, based on these findings, to guide decision-making related to household recycling in South Africa. Data from a representative sample of respondents in large urban areas (n = 2004) was analyzed using Structural Equation Modeling (SEM). The results of the SEM analysis showed a good fit of the survey data to the Theory of Planned Behavior theoretical model. The Theory of Planned Behavior explains 26.4% of the variance in recycling behavior and 46.4% of the variance in intention to recycle. Only 3.3% of South Africans in large urban areas show dedicated recycling behavior, considering the recycling of five materials: paper, plastic, glass, metal, and compostable organic waste. The recycling frequency item in the recycling behavior construct is the most likely to be over-reported. South Africans lack sufficient knowledge, positive attitudes, social pressure, and perceived control that would encourage recycling behavior. Awareness drives containing moral values (injunctive norms) and information about available recycling schemes, combined with the provision of a curbside collection service for recyclables, have the greatest chance to positively influence recycling behavior amongst South Africa’s city dwellers.

Barriers to Household Waste Recycling: Empirical Evidence from South Africa

A small percentage of South Africans regularly recycle most of their recyclables, which was only 4% and 7.2% in 2010 and 2015, respectively. This empirical quantitative study, the first study on this scale in South Africa, aimed to ascertain the reasons why people do not recycle. This paper reports the results from a survey conducted among a representative sample of 2004 respondents in eleven of South Africa’s large urban areas. Each respondent selected three main reasons why people do not recycle from ten possible options as well as the one main reason. The results show that (i) insufficient space, (ii) no time, (iii) dirty and untidiness associated with recycling, (iv) lack of recycling knowledge, and (v) inconvenient recycling facilities are perceived as the main reasons why people do not recycle. Non-recycling households (74% of the respondents) give high priority to time and knowledge. Low recyclers—those that sporadically recycle few items—and young South Africans give high priority to services (inconvenient facilities and no curbside collection). Lack of knowledge is an important factor for people from dense settlements as well as the unemployed looking for work. Improved recycling services such as regular curbside collections have the potential to overcome time and space barriers. Recycling services as well as recycling knowledge will have to improve to encourage the youth, the unemployed, and those living in informal areas to recycle and realize the opportunities locked in the waste sector. The perceptions of respondents from non-recycling households differ from those from recycling households. The larger representation of non-recyclers in developing countries emphasize the importance of understanding local evidence when comparing and implementing results from developed countries. The learning from this study could also assist other developing countries to encourage household participation in recycling initiatives.