Challenges in food waste recycling in high-rise buildings and public design for sustainability: A case in Hong Kong

Solid waste management in the context of the waste hierarchy and circular economy frameworks: An international critical review

Growing populations and consumption drive the challenges of solid waste management (SWM); globalization of transport, food production, and trade, including waste trading, distributes risks worldwide. Using waste hierarchy (WH; reduce, reuse, and recycle) and circular economy (CE) concepts, we updated a conceptual waste framework used by international organizations to evaluate SWM practices. We identified the key steps and the important factors, as well as stakeholders, which are essential features for effective SWM. Within this updated conceptual framework, we qualitatively evaluated global SWM strategies and practices, identifying opportunities, barriers, and best practices. We find that, although a few exceptional countries exhibit zero-waste compliance, most fare poorly, as exhibited by the high waste generation, incineration, and disposal (open dumping, landfilling) volumes. In the Global North, SWM strategies and practices rely heavily on technologies, economic tools, regulatory frameworks, education, and social engagement to raise stakeholder awareness and enhance inclusion and participation; in the Global South, however, many governments take sole legal responsibility for SWM, seeking to eliminate waste as a public "nuisance." Separation and recycling in the Global South are implemented mainly by "informal" economies in which subsistence needs drive recyclable material retrieval. Imported, regionally inappropriate tools, economic constraints, weak policies and governance, waste trading, noninclusive stakeholder participation, data limitations, and limited public awareness continue to pose major waste and environmental management challenges across nations. In the context of the framework, we conclude that best practices from around the world can be used to guide decision-making, globally. Despite variations in drivers and needs across regions, nations in both the Global North and South need to improve WH and CE compliance, and enhance stakeholder partnership, awareness, and participation throughout the SWM process. Partnerships between the Global North and South could better manage traded wastes, reduce adverse impacts, and enhance global environmental sustainability and equity, supporting UN Sustainable Development Goals. Integr Environ Assess Manag 2024;20:9-35. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Food waste quantities and composition in Polish households

Over one-third of the produced food is wasted globally. Most food is wasted at the consumer stage. The use of waste sorting analysis is considered to deliver more precise and less biased results than self-reporting methodologies. Currently, no detailed studies on the amounts and composition of household food waste are available for Poland. In the current paper the results of a food waste generation study in the city of Opole in Poland are presented. Both the residual and biowaste from 1425 citizens living in three different city areas was analysed during five seasonal waste sorting campaigns. The food waste was sorted in 16 avoidable and four non-avoidable fractions. The results of this study showed that in the city of Opole the absolute amount of both the avoidable and non-avoidable food waste is higher in the mixed waste stream than in the biowaste (42.8 kg inh.^-1 in the residual waste and 19 kg inh.^-1 in the biowaste, yearly). Thus, the total segregation level of food waste constitutes at the moment only 31%. The four main categories of avoidable food waste in the mixed waste are: bread (23.9%), vegetables (23.3%), meat (15.1%) and potatoes (7.8%). For the biowaste, the main four categories include: fruits (35.5%), other vegetables (27.9%), meal leftovers (13.6%) and bread (8.6%). Thus the overall food waste generation is 61.7 kg inh.^-1 year^-1. When also considering alternative discarding routes (sewerage, fed to animals or home-composted), the total food wastage in Opole amounts to 79.9 kg inh.^-1 year^-1, out of which 37.1 kg inh.^-1 year^-1 is avoidable waste and 42.8 kg inh.^-1 year^-1 non-avoidable waste.

Feasibility study for estimating optimal substrate parameters for sustainable green roof in Sri Lanka

In twenty-first century buildings, green roof systems are envisioned as great solution for improving Environmental sustainability in urban ecosystems and it helps to mitigate various health hazards for humans due to climatic pollution. This study determines the feasibility of using five domestic organic wastes, including sawdust, wood bark, biochar, coir, and compost, as sustainable substrates for green roofs as compared to classical Sri Lankan base medium (fertiliser + potting mix) in terms of physicochemical and biological parameters associated with growing mediums. Comprehensive methodologies were devised to determine the thermal conductivity and electric conductivity of growing mediums. According to preliminary experimental results, the most suitable composition for green roof substrates comprised 60% organic waste and 40% base medium. Sawdust growing medium exhibited the highest moisture content and minimum density magnitudes. Biochar substrate was the best performing medium with the highest drought resistance and vegetation growth. The wood bark substrate had the highest thermal resistance. Growing mediums based on compost, sawdust, and coir produced the best results in terms of nitrate, phosphate, pH, and electric conductivity (EC) existence. This study provided a standard set of comprehensive comparison methodologies utilising physicochemical and biological properties required for substrate characterization. The findings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements.

Barriers and Enablers to Food Waste Recycling: A Mixed Methods Study amongst UK Citizens

We aim to identify influences on UK citizens' household food waste recycling as a basis for designing strategies to increase household food waste collection rates via local services. Using a UK dataset (n = 1801) and the COM-B (Capability-Opportunity-Motivation-Behaviour) model as a theoretical framework, we conduct quantitative regression and supporting thematic analyses to investigate influences on citizens' recycling of food waste. Results show that automatic motivation (e.g., emotions and habit) and psychological capability (e.g., knowledge) predict household food waste recycling. Physical opportunity (i.e., dealing with food waste in other ways such as home-composting or feeding pets/strays, time and financial costs) was the main barrier to recycling food waste identified in thematic analyses. Participants also reported automatic motivation-related barriers such as concerns over pests, odour, hygiene and local authorities' food waste collection capabilities. Based on findings we recommend the development of clear, consistent communications aimed at creating positive social norms relating to recycling and increasing knowledge of what can and cannot be put in food waste bins. Improved functional design and free distribution of bins and compostable caddy liners developed according to user-centred needs for cleanliness, convenience and hygiene are also needed. These will not be sufficient without a nationally uniform, efficient and reliable system of household food waste collection.

Energy Recovery from Waste—Closing the Municipal Loop

Municipal waste management in the EU has been challenged to a thorough transformation towards a Circular Economy. It is addressed by a number of quantitative policy targets, including a restriction on municipal waste landfilling to 10% in 2035. This paper presents the data on municipal waste composition in a large Polish city, based on thorough waste sorting analyses. On average, 374 kg of municipal waste is collected per capita in Wroclaw, of which 41% are separately collected fractions. The approach to implement the EU recycling targets until 2035 is presented, including an increase of sorting and recycling efficiency and a significant share of recyclables being retrieved from the residual waste fraction. Notwithstanding the recycling targets, an important stream of residual waste remains, amounting to 200 k ton in 2020 and approx. 130 k ton in 2035, which is available for energy recovery. The respective LHV values range from 8.5 to 7.6 MJ/kg. The results indicate that the residual waste stream, after satisfying the recycling targets, is still suitable for energy recovery through the whole period until 2035. Moreover, it is a necessary step towards closing the materials cycling in the municipal sector and the only option so far to reduce landfilling sufficiently.

Food waste generation in a university and the handling efficiency of a university catering facility-scale automatic collection system

Purpose

This study aims to evaluate the generation of food waste in a university and the handling efficiency of an automatic waste collection system.

Design/methodology/approach

The quantity of food waste generated and collected from a university canteen was surveyed. The food waste handling efficiencies using manual collection strategy and automated food waste collection system were determined by the density of food waste. Life-cycle costing analysis was done to evaluate the economic impacts of various food waste collection methods.

Findings

As compared with the manual collection approach, the automatic system can improve the food waste handling efficiency by 30% (from 0.01 to 0.007 bin kg−1) and reduce the water use by 20% (from 0.512 to 0.406 L kg−1); however, it also consumes 4.4 times more energy (from 0.005 to 0.027 kWh kg−1). Under ideal system operation, the 10-year cost of food waste collection was significantly reduced from $3.45 kg−1 in the manual collection to $1.79 kg−1, and the payback period of the system collection was 1.9 years without discount.

Practical implications

The outcomes of this study show that an automatic food waste collection system is feasible, and it is recommended for small- and medium-sized catering facilities (e.g. canteens and food courts) to improve food waste handling efficiency. This study also provides useful reference data of automatic food waste collection systems for planning food waste management programs for catering facilities.

Originality/value

To the best of the authors’ knowledge, this is the first study to evaluate the waste handling efficiency, operational expenditure and life-cycle cost of a small-scale automatic food waste collection system.

Evaluation of models for household recycling behaviour in high-rise buildings: A Chinese case study in urban Guangzhou

Recycling strategies and waste management for the source separation of recyclables are still in their infancy in China and many other developing countries. Unlike formal recycling systems with strictly regulated management in high-income countries, waste management and recycling activities in low-income and middle-income countries are predominantly informal. Formal recycling systems often have very small amounts of recyclables in comparison to informal recycling systems. Considering the Chinese case of urban Guangzhou, where formal and informal recycling systems coexist, this study investigated household recycling behaviour and explored the sociodemographic and contextual factors that affect this behaviour. Based on data collected through questionnaire surveys and interviews, a model of the use of public recycling facilities (UPRF) and a model of the use of informal recycling sectors (UIRS) were evaluated using correlations and multiple regression analyses. The findings indicated that the use of public recycling facilities can be significantly predicted by the launch of a source separation scheme, the physical setting and satisfaction with public recycling facilities. The sociodemographic variables did not significantly predict the use of public recycling facilities but did significantly predict the use of informal recycling sectors. This study's findings have implications for researchers and policymakers and shed light on public designs for sustainability.

Effects of improved information and volunteer support on segregation of solid waste at the household level in urban settings in Madhya Pradesh, India (I-MISS): protocol of a cluster randomized controlled trial

BACKGROUND

Segregation of household waste at the source is an effective and sustainable strategy for management of municipal waste. However, household segregation levels remain insufficient as waste management approaches are mostly top down and lack local support. The realisation and recognition of effective, improved and adequate waste management may be one of the vital drivers for attaining environmental protection and improved health and well-being. The presence of a local level motivator may promote household waste segregation and ultimately pro-environmental behaviour. The present cluster randomized control trial aims to understand if volunteer based information on waste segregation (I-MISS) can effectively promote increased waste segregation practices at the household level when compared with existing routine waste segregation information in an urban Indian setting.

METHODS

This paper describes the protocol of an 18 month two-group parallel,cluster randomised controlled trialin the urban setting of Ujjain, Madhya Pradesh, India. Randomization will be conducted at ward level, which is the last administrative unit of the municipality. The study will recruit 425 households in intervention and control groups. Assessments will be performed at baseline (0 months), midline (6 months), end line (12 months) and post intervention (18 months). The primary outcome will be the comparison of change in proportion of households practicing waste segregation and change in proportion of mis-sorted waste across the study period between the intervention and control groups as assessed by pick analysis. Intention to treat analysis will be conducted. Written informed consent will be obtained from all participants.

DISCUSSION

The present study is designed to study whether an external motivator, a volunteer selected from the participating community and empowered with adequate training, could disseminate waste segregation information to their community, thus promoting household waste segregation and ultimately pro-environmental behaviour. The study envisages that the volunteers could link waste management service providers and the community, give a local perspective to waste management, and help to change community habits through information, constant communication and feedback.

TRIAL REGISTRATION

The study is registered prospectively with Indian Council of Medical Research- Clinical Trial Registry of India ( CTRI/2020/03/024278 ).

Restructuring municipal solid waste management and governance in Hong Kong: Options and prospects

From the chronological analytical review regarding municipal solid waste management (MSWM) and governance optimisation progress in Hong Kong since 2002, it is noted that the policy outcomes have seriously deviated from the original policy goals under the hitherto lack of effective development in bureaucratic and economic policy cultures in municipal solid waste (MSW) strategies formulation and related programmes implementation. The policy analysis specially stated that although the MSW recycling ratio (30%) is not particularly poor, the recovered percentage of plastics, glass and food waste in Hong Kong are extremely low. Based on the unfavourable outcomes and consequences for MSWM and governance in Hong Kong, a conclusion of negative correlation between the per capita MSW disposal rate and bureaucratic policy culture development, as well as positive correlation between recycling rate of low value items and economic policy culture development, can be made. With considering the key factors of benchmark indicators, socio-economic factors, driving force, and communication of MSW policy, conducive options and prospects are also developed for the attempt to provide insights to restructure MSWM and governance in Hong Kong in the next decade. First, the government can build up strategic innovation from a global benchmark case - MSWM and governance improvement from the South Korea case. Second, to create opportunities and conditions to develop high value biofuel from waste through flexible local environmental policies formulation and implementation. Third, shifting a front-line MSWM for governance structure reform.

Improving the non-sterile food waste bioconversion to hydrogen by microwave pretreatment and bioaugmentation with Clostridium butyricum

This work targeted the energy recovery from food waste (FW), aiming at the implementation of a potentially participative process of FW conditioning before the non-sterile biological conversion to hydrogen (H₂). Food waste conversion was initially performed under sterile conditions, achieving a maximum H₂ productivity of 249.5 ± 24.6 mL H₂ (L h)^-1 and a total H₂ production to 4.1 ± 0.2 L L^-1. The non-sterile operation was implemented as a way of process simplification, but the total H₂ production decreased by 59% due to the FW native microorganisms. To counteract this effect, FW was submitted to acid, microwave (MW), and combined acid and MW pretreatment. The application of 4 min MW, 550 W, efficiently controlled the FW microbial counts. The Clostridium butyricum bioaugmented conversion of MW-pretreated FW accelerated the H₂ production to 406.2 ± 8.1 mL (L h)^-1 and peaked the total H₂ production and conversion yield to 4.6 ± 0.5 L L^-1 and 234.6 ± 55.6 mL (g sugar)^-1, respectively. These results exceeded in 63, 12 and 4%, respectively, the H₂ productivity, total production and sugar conversion yield obtained under sterile conditions, and are encouraging for the future implementation of increasingly responsible waste valorisation practices.