Waste Management & Research: The Journal for a Sustainable Circular Economy

With the rapid spread of coronavirus disease 2019 (COVID-19), the amount of used personal protective equipment (PPE) including face masks and protective clothes has significantly increased. This used PPE in a hospital can lead to the indirect infection by COVID-19. Accordingly, it has been recognized that the management of used PPE is very important to prevent the spread of COVID-19. Through the experience of spreading some infectious diseases such as severe acute respiratory syndrome, Middle East respiratory syndrome and Ebola virus in South Korea (Republic of Korea), a safe management method of waste related to infectious diseases has been developed. In addition, regarding waste related to COVID-19, the Ministry of Environment, SK, proposed special measures to strengthen the management process of waste related to COVID-19 based on principles such as sustainability, transparency and safety.

This work examines polycyclic aromatic hydrocarbon (PAH) concentrations in yard trash at various stages of the yard trash management cycle of collection, stockpiling, grinding and screening into mulch, and composting. Total extractable PAH concentrations were measured in yard trash at various management stages from 10 locations in Florida. The concentrations of 16 PAH compounds in processed yard trash ranged from 0.38 to 14 mg kg^-1. PAH concentrations were detected in vegetative material harvested from a residential neighborhood, but were below the United States Environmental Protection Agency residential regional screening levels (RSLs). PAH concentrations near or above the RSLs were common in both unprocessed and processed yard trash collected at waste management facilities. PAH concentrations were amongst the highest in newly ground yard trash samples and were amongst the lowest in composted yard trash samples. These findings are important because land application of some waste materials, such as construction and demolition debris fines and street sweepings, are sometimes limited due to PAH. If processed yard trash, which is commonly land applied in residential settings, possesses similar PAH concentrations, evaluation of current risk assessment practices for land-applied wastes may require further examination.

Healthcare waste generation is an integral part of healthcare operations. Improper healthcare waste management and disposal can be detrimental to humans and the environment. The objective of this paper is to investigate the healthcare waste management practices, aiming to provide needed data to inform policy decisions. The study was conducted using a cross-sectional study. Quantitative data was obtained from 497 respondents who worked in 25 major healthcare facilities. Data was analyzed using (SPSS) version 23.0. Results indicated that 52.4% of respondents had knowledge about healthcare waste management. However, only 12% of the respondents were open to training in healthcare/biomedical waste management. Less than half of the respondent (47.5%) practiced waste segregation at the sources of generation. There were significantly more healthcare waste disposal materials available (P = 0.001) in private than government and quasi-government hospitals. Based on the major findings of the study, we recommend that adequate training as well as Personal Protective Equipment (PPE’s) should be provided to healthcare professionals to improve healthcare waste management. Complacence in adhering to Healthcare waste disposal guideline must be addressed.

Accurate estimation of municipal solid waste (MSW) generation has become a crucial task in decision-making processes for the MSW planning and management systems. In this study, the Gaussian process regression (GPR) model tuned by Bayesian optimization was used to forecast the MSW generation of Turkey. The Bayesian optimization method, which can efficiently optimize the hyperparameters of kernel functions in the machine learning algorithms, was applied to reduce the computation redundancy and enhance the estimation performance of the models. Four socio-economic indicators such as population, gross domestic product per capita, inflation rate, and the unemployment rate were used as input variables. The performance of the Bayesian GPR (BGPR) model was compared with the multiple linear regression (MLR) and Bayesian support vector regression (BSVR) models. Different performance measures such as mean absolute deviation (MAD), root mean square error (RMSE), and coefficient of determination (R²) values were used to evaluate the performance of the models. The exponential-GPR model tuned by Bayesian optimization showed superior performance with minimum MAD (0.0182), RMSE (0.0203), and high R² (0.9914) values in the training phase and minimum MAD (0.0342), RMSE (0.0463), and high R² (0.9841) values in the testing phase. The results of this study can help decision-makers to be aware of social-economic factors associated with waste management and ensure optimal usage of their resources in future planning.

Waste management is an emerging focus in Pakistan. Specifically, waste-to-energy (WtE) projects are conceived to obtain benefits from municipal waste collection in metropolitan cities. This study provides a brief background of WtE potential, waste collection statistics, type of generated wastes, and current measures to build the confidence of investors in WtE projects. In addition, a brief overview of government efforts for WtE and delineation of licensing requirements for power generation are discussed. The parameters laid down for the determination of tariffs for municipal waste management power projects and the cost accounted for each parameter are analyzed in detail. Similarly, this study deliberates on observations among stakeholders and compares Pakistan tariffs with those of neighboring countries.

The building industry is responsible for a large amount of waste, and the measurement and modelling of this waste could be used to develop better waste management plans. Several theoretical models explain the relationships between waste and building characteristics, but local practices may result in different behaviours. This study aimed to measure and analyse the waste generated through construction. It was based on the analysis of 18 building sites located in the region of Porto Alegre, Brazil. Waste was measured at these sites, and the results showed an average waste generation rate of 0.151 m³ m^-2. A regression analysis of the collected data presented a satisfactory performance in two models. The first model was developed to explain total waste generation, including the effects of certain attributes, with an R² = 0.81. The changes in waste generated during construction were estimated. The second model considered time schedules and examined the effect of the construction stage on waste generation, and reached an R² = 0.91. The model with time indicated an S-shaped relationship. The models presented satisfactory statistical parameters and could be used to produce better waste management plans in the preconstruction stage.

Municipal solid waste incineration generates large quantities of bottom ash that should be recycled. Current use of municipal solid waste incineration bottom ash (MSWI-BA) in cementitious materials is mostly in Ordinary Portland Cement (OPC). This paper considers using MSWI-BA as sand substitution in Calcium Sulfoaluminate Cement (CSA) as an alternative to OPC. A comparison between OPC and CSA mortars containing 0–2 mm MSWI-BA is conducted. The MSWI-BA used was treated to remove the ferrous and non-ferrous metals in order to obtain a better mineral fraction. Different percentages (0%, 25%, 50%, 75%, and 100%) of standard sand were substituted by MSWI-BA based on equivalent volume. Experimental results showed that the compressive strength and porosity of the CSA mortars were superior to OPC after substitution at 1, 7, 28, and 90 days. The compressive strength of OPC mortars with 25% substitution decreased by 40% compared to 11% for CSA mortars at 90 days. This is due to the difference in pH between the two cement pastes as OPC in contact with the MSWI-BA leads to a reaction with the aluminum content which releases hydrogen gas, increases the porosity, and decreases the compressive strength.

The management of dredged sediments poses serious environmental and economic problems because of their geochemical properties and in particular their pollutant content. In this research, marine sediments from Tunisian harbors were collected to study their beneficial reuse as construction materials using an eco-friendly polymer binder. Experimental investigations include the determination of physicochemical, mineralogical, and environmental parameters of sediments from the Sidi Mansour and Sidi Youssef areas in Tunisia. Prismatic mortar samples (4 × 4 × 16 cm) were prepared at laboratory scale using normalized sand and epoxy resin. Then their composition was modified by including a sediment fraction in the substitution of sand at rates ranging from 10 to 50% in dry mass. After a 7-day curing period, mortar samples were submitted to mechanical, physicochemical, and environmental analyses. Mortar samples including sediment fractions displayed lower strength than sand mortar used as control. This result is explained by the increase of porosity values in the mortar samples when sediment samples were incorporated. A positive relationship between porosity and compressive strength values was evidenced, suggesting that the compactness of granular skeleton could play an important role in the preparation of materials. From an environmental point of view, the mortar samples containing sediment fractions showed relatively low leaching levels, which confirms their suitability for the manufacturing of construction materials.

The construction sector in Costa Rica produces approximately 100 kg per square meter of residues, of which wood waste comprises 30%. Utilization of these wastes is still limited, but options are being sought and biomass is one of them. The aim of this work was to evaluate the characteristics of biomass produced from wood waste from construction, its energy potential, and its appropriateness for pellet manufacturing by determining its energy, physical, and mechanical characteristics. It was found that wood waste from construction is composed of different species with densities below 0.5 g/cm³, 26% moisture content, and 10% ash content; contamination with cement and nails can reach 6%. The process of pellet manufacturing can adapt adequately to using wood waste from construction, with an efficiency or yielding of 33%. Pellets presented a calorific value of 19573 kJ/kg, a bulk density of 1.25 g/cm³, an apparent density of 700 kg/m³, a failure force in compression of 467 N, and durability of 94.28%. According to different standards, the results obtained for biomass from wood waste are within the range established for pellet quality; therefore, wood waste from construction can be used to produce pellets, despite the disadvantage of it presenting high ash content.

To evaluate the combustion characteristics of raw or torrefied bamboo wastes and coal blends, the co-firing process determined by cone and pollutant emission was investigated by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The results showed that torrefaction improved the fuel properties of bamboo wastes. Torrefied bamboo had a lower volatile fuel ratio, H/C and O/C ratios, pollutant emission and a higher heating value. They further affected the co-firing process of raw or torrefied bamboo and coal. All blends had a lower ignition temperature and a more stable flame than coal. Torrefied bamboo and coal blends had a lower percentage of quality loss, a higher heat release rate (HRR), total heat release (THR) and total smoke release (TSR). With an increase in the proportion of torrefied bamboo in the blends, the HRR, THR, TSR and percentage of quality loss increased. The main pollutant emissions included CO₂, CO, SO₂ and NO _x . All blends of torrefied bamboo and coal had a lower pollutant emission. The optimum blend suggested was 20% torrefied bamboo/80% coal.

In this study, the pyrolysis behaviour of nonmetal fraction of waste printed circuit boards (NMF-WPCBs) was studied based on five model-free methods and distributed activation energy model (DAEM). The possible decomposition mechanism was further probed using the Criado method. Thermogravimetric analysis indicated that the NMF-WPCBs pyrolysis process could be divided into three stages with temperatures of 37–330°C, 330–380°C and 380–1000°C. The mass loss at different heating rate was determined as 26.85–29.98%, 13.47–24.21% and 20.43–23.36% for these stages, respectively. The activation energy (E_α) from various model-free methods first increased with degree of conversion (α) increasing from 0.05 to 0.275, and then decreased beyond this range. The coefficient (R) from the Flynn–Wall–Ozawa (FWO) method was higher, and the resulting E_α fell into the range of 214.947–565.660 kJ mol⁻¹. For the DAEM method, the average E_α value was determined as 337.044 kJ mol⁻¹, comparable with 329.664 kJ mol⁻¹ from the FWO method. The thermal decomposition kinetics of NMF-WPCBs could be better described by the second-order reaction.

The consumption of lithium iron phosphate (LFP)-type lithium-ion batteries (LIBs) is rising sharply with the increasing use of electric vehicles (EVs) worldwide. Hence, a large number of retired LFP batteries from EVs are generated annually. A recovery technology for spent LFP batteries is urgently required. Compared with pyrometallurgical, hydrometallurgical and biometallurgical recycling technologies, physical separating technology has not yet formed a systematic theory and efficient sorting technology. Strengthening the research and development of physical separating technology is an important issue for the efficient use of retired LFP batteries. In this study, spent LFP batteries were discharged in 5 wt% sodium chloride solution for approximately three hours. A specially designed machine was developed to dismantle spent LFP batteries. Extending heat treatment time exerted minimal effect on quality loss. Within the temperature range of 240°C–300°C, temperature change during heat treatment slightly affected mass loss. The change in heat treatment temperature also had negligible effect on the shedding quality of LFP materials. The cathode material and the aluminium foil current collector accounted for a certain proportion in a sieve with a particle size of −1.25 + 0.40 mm. Corona electrostatic separation was performed to separate the metallic particles (with a size range of –1.5 + 0.2 mm) from the nonmetallic particles of crushed spent LFP batteries. No additional reagent was used in the process, and no toxic gases, hazardous solid waste or wastewater were produced. This study provides a complete material recovery process for spent LFP batteries.