Towards sustainable textile waste management: Exploring valuable chemicals production through steam cracking in a dual fluidized bed

Steam cracking in a semi-industrial dual fluidized bed reactor: Tackling the challenges in thermochemical recycling of plastic waste

Crude tall oil is a by-product obtained from the manufacture of chemical wood pulp. The residue obtained after the distillation of this product is known as tall oil pitch (TOP). This complex fraction is a highly viscous liquid that consists mainly of free fatty acids, fatty acids derivatives, rosin acids and additives. Given its complex composition, it is commonly used as fuel for heat production. In this work, steam cracking is proposed as an alternative treatment for this residue. Steam cracking can convert TOP into a valuable product gas that can be used in different applications including the production of green chemicals, moving towards a carbon circular economy. The experimental tests were performed in the Chalmers pilot scale Dual Fluidized Bed, consisting of a steam cracker and a combustor. For these experiments, the thermochemical decomposition of 150–175 kg/h TOP was performed at the steam cracker at two different temperatures (775 and 825 °C) to evaluate the influence of this parameter on the obtained products. Wood pellets were also tested as reference material for the highest temperature. The distribution of the obtained products was analysed. Results show that TOP can be regarded as a by-product instead of a residue and used as feedstock for the recovery of chemical building blocks and syngas via thermochemical recycling. Between 40 and 50 % of the carbon present in the fuel is kept in the permanent gases, while about 20 % is in aromatic hydrocarbons. Compared to biomass, the aromatics yield obtained for TOP is much higher (190 g/kg for TOP and 13 g/kg for biomass). Among the species found, benzene, toluene and xylene, represent between 62 and 72 % of the total measured aromatics. Regarding the gas fraction, the production of valuable light hydrocarbons (such as ethylene and propylene) is more pronounced in the TOP residue than in the biomass. In addition, an energy balance over the system was estimated and showed that TOP thermochemical recycling can be self-sustained in a Dual Fluidized Bed if the non-valuable products are combusted. The results obtained in this work indicate that this TOP could be an appealing option to consider as a source of biorefinery revenue leading to the circular use of waste.

Sustainable Municipal Solid Waste management has remained a big challenge in Africa and other resource constrained settings. However, to achieve sustainability, the gaps in governance of waste management need to be addressed speedily as populations are expanding rapidly, far exceeding available infrastructure and resources. Ruiru subcounty has a rapidly expanding population which has not been matched with sustainable waste management in commercial and residential sectors. This study sought to establish the influence of governance on Sustainable Municipal Solid Waste management in Ruiru Sub-County. Mixed methods research approach and descriptive research design were used in both data collection and analysis. This involved administration of Questionnaires, interviews and observation checklist through an online platform Kobo Collect. Results of the study showed that the County Government and subsequent sub-counties are responsible for waste management. Despites this mandate there are heaps of waste remain in commercial and residential areas. This is attributed to various governance challenges such as lack of prioritization of waste management, limited financial and human resources, minimal community participation, disregard of informal players in waste management cycle, weak implementation and enforcement of waste management policies. While it is desirable to attain sustainable solid waste management in Ruiru, and while the national legal frameworks are in place, there are major challenges and gaps in solid waste governance. Therefore, this study concludes enforceability of mechanisms, adequacy of funding, wholistic involvement of all players remain daunting. Unless these are addressed, sustainable waste management will only remain an unattainable goal.

It is widely accepted that solid waste management is a global problem. This problem is even more pronounced in developing countries such as Nigeria where solid waste management is a major concern. In recent times, however, there has been a concerted effort towards engaging members of the public in solving the waste management crisis. This effort is centred on public participation in sustainable waste management practice across the country. Nevertheless, in Abuja there seems to be low public participation in sustainable wastes and environmental management practice. This paper therefore seeks to investigate the rate of participation in sustainable waste and environmental management activities in Abuja. In order to achieve the aim of the study, the paper relied on a sample of 57 participants to obtain some primary data. The paper employed a mixed method approach with the aid of a questionnaire. The questions were designed to gather data on demographics of the participants, their awareness and attitude to sustainable waste management, the barriers preventing public participation in a sustainable solid waste management and measures that can encourage public participation in sustainable waste management in Abuja. The study revealed that increase funding, provision of recycling collection points, enforcement of laws and policies, the development of effective policies and regulatory framework amongst others are some of the measures that can encourage public participation in sustainable waste management programs in Abuja.

Healthcare waste in Bangladesh: Current status, the impact of Covid-19 and sustainable management with life cycle and circular economy framework

PurposeThe study analyses the factors that promote pro-environmental intentions and sustainable electronic waste management among households in a developing country context.Design/methodology/approachBased on a quantitative survey, a cross-sectional study of households was conducted. Data from 652 respondents were collected using structured questionnaires and analysed with partial least squares structural equation modelling (PLS-SEM).FindingsAmong the findings, environmental values was the major influencer of pro-environmental intentions, accounting for 54.8% of its variance. Whilst pro-environmental intention was hypothesised as a key predictor of sustainable waste management behaviours, results showed that sustainable e-waste management is mainly influenced by perceived behavioural control (β = 0.546, p = 0.000), followed by pro-environmental intentions (β = 0.302, p = 0.000). Perceived behavioural control, on the other hand, was influenced by perceived producer responsibility (β = 0.340, p = 0.000) and facilitating conditions (β = 0.141, p = 0.0.034).Research limitations/implicationsFirst, the study used a quantitative approach. The use of a mixed-methods approach could provide deeper insights into the determinants of sustainable e-waste management practices in a specific cultural context. Also due to the quantitative nature of the study, sustainable e-waste management was based on self-reports. Future studies may adopt longitudinal studies to validate self-reported behaviours with observation. Finally, the study does not include all constructs proposed by planned behaviour and norm activation theory. This is because the main aim of the study was to examine perceived behavioural control as an extrinsic motivator and environmental values as an intrinsic motivator to engage in sustainable waste management practices.Practical implicationsWaste is best managed at source, so the study recommends that producers of electronic equipment must reconsider their role in sustainable waste management, by taking physical and economic responsibility for the environmental costs of their products. Pro-environmental intentions must be encouraged; however, it is not sufficient to cause sustainable waste management behaviours. Consequently, governments must promote and encourage sustainable e-waste management among households by providing enabling policy conditions such as convenient e-waste collection points and positively reinforcing waste reduction, reuse and recycling behaviours. Also, a culture of environmental conservation should be encouraged among households.Originality/valueThe study explores the role of environmental values and perceived behavioural control as a source of intrinsic and extrinsic motivation to engage in sustainable e-waste management. The inclusion of facilitating conditions and perceived producer responsibility is justified, based on the call for a collective approach towards electronic waste management. The results of the study throw more light on the tri-party approach, specifically, consumers, business and government role in developing and maintaining a sustainable approach towards the management of electronic waste in Ghana. Also, the study integrates planned behaviour and norm activation based on the strong sustainability argument.

Naturally occurring limestone and samples from a lab scale dual fluidized bed (DFB) calcium looping (CaL) test facility were analysed in a thermo gravimetric analyser (TGA). The reactivity of the samples evaluated at typical carbonation conditions prevailed in the carbonator was compared with raw samples. Carbonations were carried out at 600, 650 &700°C and 5, 10 &15 vol-% CO2 atmosphere using a custom designed sample holder that provided ideal conditions for solid gas contact in a TGA. The rate of carbonation and carbonation capacity of the samples were compared with respect to the following three categories: number of calcination-carbonation cycles, carbonation temperature and CO2 concentration. Notable differences in total conversion (XCaO) and the rates of conversions were observed between the raw and DFB samples in all three cases. It is suspected the much lower activity of the DFB sample is attributed to the differences in experimental conditions: ie., partial carbonation of the DFB particles, fast heating rate in the calciner and thus a rapid calcination reaction, and particle attrition in the CFB calciner riser. These harsh conditions lead sintering and thus a loss of surface area and reactivity. Sintered DFB samples showed low (nearly 1/3 of the raw samples) but stable conversions with increasing number of cycles. The sorbent taken from the DFB facility did not decrease with respect to carbonation rate or maximum conversion over 4 cycles whereas the fresh limestone changed significantly over 4 cycles. Hydration was used as an attempt to regenerate the lost capture capacity of partially carbonated DFB sample. Hydration of the sintered DFB sample was successful in increasing the maximum capture capacity in the fast reaction regime to values almost as high as that of a fresh sample in its first carbonation cycle. Although more investigation is required to investigate the effect of hydration on the CaO particle morphology, a process modification to enhance the CO2 capture efficiency of the carbonator via particle hydration was proposed.

Simplified modeling of circulating flow of solids between a fluidized bed and a vertical pneumatic transport tube reactor connected by orifices

Naturally occurring limestone and samples from a lab-scale dual fluidized bed (DFB) calcium looping test facility were analyzed in a thermogravimetric analyzer. The reactivity of the samples evaluated at typical carbonation conditions prevailed in the carbonator was compared with raw samples. The rate of carbonation and carbonation capacity of the samples were compared with respect to the following three categories: number of calcination-carbonation cycles, carbonation temperature, and CO2 concentration. It is suspected that the much lower activity of the DFB sample is attributed to the differences in experimental conditions, i.e., partial carbonation of the DFB particles, fast heating rate in the calciner and thus a rapid calcination reaction, and particle attrition in the circulating fluidized bed calciner riser. These harsh conditions lead to sintering and thus a loss of surface area and reactivity. Sintered DFB samples showed low (nearly one-third of the raw samples) but stable conversions with increasing number of cycles. Hydration was used as an attempt to regenerate the lost capture capacity of partially carbonated and sintered DFB sample. Hydration of the DFB sample was successful in increasing the maximum capture capacity in the fast reaction regime to values almost as high as that of a fresh sample in its first carbonation cycle. Although more investigation is required to investigate the effect of hydration on the CaO particle morphology, a process modification to enhance the CO2 capture efficiency of the carbonator via particle hydration was proposed.

A multi-floor manufacturing in residential districts of huge city promotes decongestion of urban traffic and satisfy the population’s demand for essential goods. City manufacturing and its supply chain entail several challenges related to the sustainable development of a large agglomeration. Environmental problems impose significant constraints on such manufacturing activities and production waste in the urban environment poses a real problem that needs to be addressed by special research. This paper discusses integrated sustainable production waste management for a city multi-floor manufacturing cluster, consisting of a group of production buildings and a supporting logistics node. In line with the theory of integrated sustainable waste management, three key components are addressed: waste management stakeholders, components of the waste management system, and the technical, environmental and legal aspects of a city multi-floor manufacturing cluster. The goal of the paper is to develop a concept for a model of environmental sustainable waste management in a city multi-floor manufacturing cluster, aimed at ensuring the system safety: human - technical facility - environment. This model can serve as a basis for the development of appropriate logistics chains for production waste management considering their hazardousness indicator. The versatility of the model will allow it to be widely used, and when its stages and working principles are embedded in the practice of city multi-floor manufacturing, proper control over the waste management process can be achieved. The application of the proposed model of integrated sustainable production waste management in the practice of the city multi-floor manufacturing clusters will contribute to the environmental sustainability of its operation.

Residents’ waste management practices in a developing country: A social practice theory analysis

Hydrodynamic analysis of a 10 kW th Calcium Looping Dual Fluidized Bed for post-combustion CO 2 capture

Aims: To Identify sustainable Biomedical solid waste management practices in the context of limited resources in selected HCFs in Douala, Cameroon.
 Study Design: A cross-sectional survey with quantitative and qualitative study design was adopted for data collection from workers in the HCFs and also identifying the process of waste management.
 Place and Duration of Study: This study was carried out in the some selected HCFs in the Douala region of Cameroon between January 2023 to June 2023.
 Methodology: Study respondents were working in different sections of the HCFs and comprised of the following categories: doctors, laboratory scientists, cleaners, nurses and administrative/clerical workers. Field visitations and interactions with HCFs officials took place during the random sampling technique which was used in determining the sample size of 200 workers, Out of the sample size of 200 who were given questionnaires in order to provide data for the study, 150 valid mail questionnaires were retrieved and used for analysis. Every questionnaire was verified by validity. There’s also questions related funds, facilities availability, training and personal protective equipment. All of the data were coded and analyzed. The results were calculated based on sums and percentages of variables with SPSS vers.26 software and chi-square analysis with the level significance of p-value less than 0.05 was analyze
 Results: This finding could also indicate that imbibing sustainable biomedical wastes management practices increases with higher experience in the hospital. Furthermore, communal bin disposal of biomedical wastes was the only statistically significant category under disposal method, indicating that waste disposal may be lacking in terms of sustainable practices. [30] also identified biomedical wastes disposal in open dumps among health workers in Saudi Arabia, attributable to poor sustainable waste training and lack of regulatory frameworks. I PCA results indicate that there are two dimensions of prevalent biomedical wastes in the hospital studied, as explicated by the two components retained
 Conclusion: The limited resources and government policies and local councils influences sustainable waste management practices and this paper aimed at identifying some of the solutions towards improving Sustainable waste management policies. The practice of biomedical waste management in the study area was low. Level of education, taking training on biomedical waste management, availability of color-coded three bins, and attitude of health care workers were significantly associated with biomedical waste management practices. Hence, in-service training is recommended to improve biomedical waste management practices.

Solid waste management is a pressing issue worldwide and small islands developing states (SIDS) are no exception. While many SIDS are now moving towards sustainable waste management, several among these small island developing economies still adopt illegal dumping and backyard burning as their waste disposal option as they are unaware of the negative health and environmental impacts caused by these practices. Furthermore, lack of financial and technical means and land scarcity are some of the main barriers that hamper the development of an integrated and sustainable waste management system in SIDS. Among the different SIDS, Mauritius is one of the few small islands that possesses a sanitary landfill. In 2017, over 480,000 tons of solid wastes were disposed at the only landfill in Mauritius, located at Mare Chicose. Besides landfilling, recycling and home composting are being practised to some extent. The potential waste management options in Mauritius, based on the waste composition, include composting and anaerobic digestion with recycling representing another avenue for sustainable waste management. Nonetheless, a sustainable solid waste management strategy and action plan should be developed and implemented as this will be the cornerstone of the setting-up of any future waste management technology.

The increase in global municipal solid waste (MSW) generation, with a significant portion being improperly managed, has resulted in detrimental socio-ecological effects. This paper addresses the challenge of implementing effective waste management practices for achieving sustainability, particularly in urban areas where the majority of global waste is generated. It emphasizes the need for a multidimensional, multiscale, and long-term approach that surpasses local solutions and linear strategies. The approach recognizes the broader impacts of waste management beyond city boundaries and promotes circularity by incorporating waste reduction, reuse, recycling, and proper disposal practices. Through an analysis of the literature on waste from 1992 to 2022, this paper aims to identify the key concepts, propose solutions, and explore sustainable waste management scenarios. This paper introduces the m-SWM4Cities model for sustainable waste management in urban areas, highlighting its methodology and application in Mexico City (mD-SWM4CDMX). The models presented in this paper incorporate essential elements and interactions, providing a comprehensive understanding of the transition to sustainable waste management. The findings highlight the importance of monitoring waste management indicators and offer insights into the waste system of Mexico City. The m-SWM4Cities model can be adapted to address specific city contexts and thus serves as a valuable tool for assessing and improving waste management practices.