Comparative analysis of anaerobically digested wastes flow properties

The flow curve of anaerobically digested wastes from different origins was determined through rheological measurements. Regardless of their origin, samples can be divided into two families: simple non-Newtonian liquids well modelled by basic power law below 10%DC and viscoelastic liquids with a yield stress, well modelled by a Herschel–Bulkley model above. In all the cases, the rheological behaviour is driven by both the organic content and the volatile fraction (organic content/solid content), indicating that anaerobic digestion tends to smooth the rheological characteristics of organic wastes, whichever their origins.     

Modelling agronomic properties of Technosols constructed with urban wastes

The greening of urban and suburban areas requires large amounts of arable earth that is a non-renewable resource. However, concentration of population in cities leads to the production of high amounts of wastes and by-products that are nowadays partly recycled as a resource and quite systematically exported out of urban areas. To preserve natural soil resources, a strategy of waste recycling as fertile substitutes is proposed. Eleven wastes are selected for their environmental harmlessness and their contrasted physico-chemical properties for their potential use in pedological engineering. The aim is (i) to demonstrate the feasibility of the formulation of fertile substrates exclusively with wastes and (ii) to model their physico-chemical properties following various types, number and proportions of constitutive wastes. Twenty-five binary and ternary combinations are tested at different ratios for total carbon, Olsen available phosphorus, cation exchange capacity, water pH, water retention capacity and bulk density. Dose–response curves describe the variation of physico-chemical properties of mixtures depending on the type and ratio of selected wastes. If these mixtures mainly mimic natural soils, some of them present more extreme urban soil features, especially for pH and P_Olsen. The fertility of the new substrates is modelled by multilinear regressions for the main soil properties.     

Assessment of medical wastes management practice: a case study of the northern part of Jordan

This study includes a survey of the procedures available, techniques, and methods of handling and disposing of medical waste at medium (between 100 and 200 beds) to large (over 200 beds) size healthcare facilities located in Irbid city (a major city in the northern part of Jordan). A total of 14 healthcare facilities, including four hospitals and 10 clinical laboratories, serving a total population of about 1.5 million, were surveyed during the course of this research. This study took into consideration both the quantity and quality of the generated wastes to determine generation rates and physical properties. Results of the survey showed that healthcare facilities in Irbid city have less appropriate practices when it comes to the handling, storage, and disposal of wastes generated in comparison to the developed world. There are no defined methods for handling and disposal of these wastes, starting from the personnel responsible for collection through those who transport the wastes to the disposal site. Moreover, there are no specific regulations or guidelines for segregation or classification of these wastes. This means that wastes are mixed, for example, wastes coming from the kitchen with those generated by different departments. Also, more importantly, none of the sites surveyed could provide estimated quantities of waste generated by each department, based upon the known variables within the departments. Average generation rates of total medical wastes in the hospitals were estimated to be 6.10 kg/patient/day (3.49 kg/bed/day), 5.62 kg/patient/day (3.14 kg/bed/day), and 4.02 kg/patient/day (1.88 kg/bed/day) for public, maternity, and private hospitals, respectively. For medical laboratories, rates were found to be in the range of 0.053-0.065 kg/test-day for governmental laboratories, and 0.034-0.102 kg/test-day for private laboratories. Although, based on the type of waste, domestic or general waste makes up a large proportion of the waste volume, so that if such waste is not mixed with patient derived waste, it can be easily handled. However, based on infections, it is important for healthcare staff to take precautions in handling sharps and pathological wastes, which comprises only about 26% of the total infectious wastes. Statistical analysis was conducted to develop mathematical models to aid in the prediction of waste quantities generated by the hospitals studied, or similar sites in the city that are not included in this study. In these models, the number of patients, number of beds, and hospital type were determined to be significant factors on waste generation. Such models provide decision makers with tools to better manage their medical waste, given the dynamic conditions of their healthcare facilities.     

Feasibility study of the separation of chlorinated films from plastic packaging wastes

This study describes the possible separation of chlorinated plastic films (PVC and PVDC) from other heavy plastic packaging waste (PPW) by selective twist formation and gravity separation. Twists formation was mechanically induced in chlorinated plastic films, whereas twist formation did not occur in PS and PET films. After twist formation, all the films had the apparent density of less than 1.0 g/cm³ and floated in water even though the true density was more than 1.0 g/cm³. However, the apparent density of the PS and the PET films increased with agitation to more than 1.0 g/cm³, whereas that of chlorinated plastic films was kept less than 1.0 g/cm³. The main reason would be the air being held inside the chlorinated plastic films which was difficult to be removed by agitation. Simple gravity separation after twist formation was applied for artificial film with 10 wt.% of the chlorinated films and real PPW films with 9 wt.% of the chlorinated films. About 76 wt.% of the artificial PPW films and 75 wt.% of real PPW films after the removal of PP and PE were recovered as settling fraction with 4.7 wt.% and 3.0 wt.% of chlorinated plastic films, respectively. These results indicate that simple gravity separation process after twist formation can be used to reduce the chlorinated plastic concentration from mixed heavy PPW films.     

Evaluation of recycled textile wastes with E-glass fabric in bio-based epoxy matrix composites: investigation of the mechanical properties

Journal of Material Cycles and Waste Management - The goal of this study is to recycle diverse textile wastes and use them as cutting-edge and sustainable raw materials in composite structures. In...     

The effects of using reprocessable material on the durability and mechanical properties of landfill leachate collection HDPE pipes

This paper investigated the durability and mechanical properties of landfill leachate collection HDPE pipes which had been made of different weight percent amounts of virgin and reprocessable HDPE compounds (VC and RC). Durability is reported base on the chemical properties, obtained through oxidative induction time (OIT) and melt flow index (MFI) measurements, at the temperature of 50 °C and over a period of 12 months immersion in a synthetic leachate. Mechanical properties are also described according to tensile and pressure tests which had been conducted on the pipes samples. All of the factors were examined had been affected by the addition of RC, but for the special combination the antioxidant depletion was significantly affected by the experimental aging condition and no important changes had been observed in the other pipe properties. The results from OIT tests indicate that the rate of antioxidant depletion is reduced by an increase in the weight percent amounts of RC, during the experimental aging condition. This reduction is probably attributed to the extraction of antioxidants from RC in their recovery process. Finally, although these results are related to the particular HDPE compound, antioxidant formulation and condition examined, but it can be said that the use of clean own reprocessable material for the production of landfill leachate pipes shall be permitted without limitations.     

Management of agricultural biomass wastes: Preliminary study on characterization and valorisation in clay matrix bricks

In this work the feasibility of using woody agricultural biomass wastes as grapes and cherries seeds, sawdust, as pore forming agent, and sugar cane ash, as silica precursor, in bricks, were reported.Sawdust and grapes and cherries seeds, thanks to their organic substances content, during their combustion, bring an energetic support in the bricks firing phase and act as pore forming agent. Usually the addition of this kind of waste is limited to 10 wt.% in order to reach an equilibrium between positive (weight and shrinkage decrease and porosity increase) and negative (increase of water absorption and mechanical resistance decrease) effects. The results show that grapes and cherries seeds, added in a percentage of 5 wt.% to a brick formulation, have better influence with respect to the sawdust, maintaining the mechanical properties of the fired brick (950 °C), showing modulus of rupture around 21–23 MPa with a weight reduction of 3–10% (respect to the standard one). Regarding the sugar cane ash, the addition of 5 wt.% improves the mechanical properties (modulus of rupture around 27 MPa) and no weight decrease is observed. These results confirmed the role played by this kind of agricultural waste, which thanks to its high silica content (61 wt.%) is capable to demonstrate a filler and plasticity reducing effect on the brick bodies. Tests carried out highlighted that the addition of these by-products (5 wt.%) do not change negatively the main technological properties measured (water absorption, linear shrinkage, flexural resistance, etc.) and permit to hypothesize their use to obtain bricks with both insulating and higher mechanical properties using a pore agent forming or silica carrier alternative raw materials, respectively.     

Managing post-conflict demolition wastes in Gaza Strip: a case study on May 2021 conflict

Gaza Strip is considered as one of the armed conflicts prone areas in Middle East. Several intensive conflicts occurred in Gaza Strip in 2008, 2012, 2014 and 2021. These conflicts caused massive destroying the infrastructures, facilities, and buildings, which affected all services and activities in Gaza Strip. One of the major post-conflict issues in Gaza strip is the management of resulted demolition waste including its removal, sorting, recycling, and material recovery. In May 2021, over than 370,000 tons of demolition waste composed of rubbles and debris was generated during 11 days of armed conflict. The accumulated previous experience of rubbles and debris removal and recycling in Gaza Strip supported to perform a quick management approach for safe removal of the post-conflict demolition waste and reuse/recycle the resulted waste materials in various applications. The sorting and transporting process of concreate and non-concreate rubble elements of the waste were carried out in cooperation between local and international agencies as emergency recovery-funded projects. The most proportion of rubbles are concrete aggregates, thus, the material recovery was conducted through crushing process for concrete rubbles and then reusing it for road rehabilitation or producing concrete building blocks. The large concrete blocks reused to be placed for shoreline protection for specific area along Gaza beach. The recycling of post-conflict demolition waste management projects in Gaza Strip brought economic and social benefits through the reuse and recycle of resources and creation of job opportunities. In conclusion, although the post-conflict demolition waste management is quite different from municipal/industrial waste management in Gaza Strip, it is conducted through applying similar techniques of disaster waste management in waste removal, and those of construction and demolition (C&D) waste management in sorting, crushing, and sieving for recycling.

     

Life-cycle assessment of municipal solid wastes: development of the WASTED model

This paper describes the development of the Waste Analysis Software Tool for Environmental Decisions (WASTED) model. This model provides a comprehensive view of the environmental impacts of municipal solid waste management systems. The model consists of a number of separate submodels that describe a typical waste management process: waste collection, material recovery, composting, energy recovery from waste and landfilling. These submodels are combined to represent a complete waste management system. WASTED uses compensatory systems to account for the avoided environmental impacts derived from energy recovery and material recycling. The model is designed to provide solid waste decision-makers and environmental researchers with a tool to evaluate waste management plans and to improve the environmental performance of solid waste management strategies. The model is user-friendly and compares favourably with other earlier models.     

内蒙古环境承载力与工业三废间关系的实证研究

在国内外学者对环境承载力与工业三废关系研究的基础上,探究了内蒙古环境承载力与工业三废间的关系.数据统计分析说明环境承载力与工业三废间存在长期稳定关系,但二者间不存在短期或长期的因果关系.实证分析说明近年来内蒙古环境承载力水平较低,但保持着稳步上升的趋势,缓解了工业三废带来的负外部效应.     

Characteristics of healthcare wastes

A comprehensive understanding of the quantities and characteristics of the material that needs to be managed is one of the most basic steps in the development of a plan for solid waste management. In this case, the material under consideration is the solid waste generated in healthcare facilities, also known as healthcare waste. Unfortunately, limited reliable information is available in the open literature on the quantities and characteristics of the various types of wastes that are generated in healthcare facilities. Thus, sound management of these wastes, particularly in developing countries, often is problematic. This article provides information on the quantities and properties of healthcare wastes in various types of facilities located in developing countries, as well as in some industrialized countries. Most of the information has been obtained from the open literature, although some information has been collected by the authors and from reports available to the authors. Only data collected within approximately the last 15 years and using prescribed methodologies are presented. The range of hospital waste generation (both infectious and mixed solid waste fractions) varies from 0.016 to 3.23kg/bed-day. The relatively wide variation is due to the fact that some of the facilities surveyed in Ulaanbaatar include out-patient services and district health clinics; these facilities essentially provide very basic services and thus the quantities of waste generated are relatively small. On the other hand, the reported amount of infectious (clinical, yellow bag) waste varied from 0.01 to 0.65kg/bed-day. The characteristics of the components of healthcare wastes, such as the bulk density and the calorific value, have substantial variability. This literature review and the associated attempt at a comparative analysis point to the need for worldwide consensus on the terms and characteristics that describe wastes from healthcare facilities. Such a consensus would greatly facilitate comparative analyses among different facilities, studies and countries.     

Thermogravimetric analysis and kinetic study on large particles of printed circuit board wastes

Pyrolysis of large printed circuit board (PCB) waste particle was conducted on a specially designed laboratory-scale thermobalance (Macro-TG) with sample loading of 30 g under dynamic nitrogen atmosphere. The effects of heating rate (10, 15, 20 and 25 °C min^?1) and particle size (1 mm × 1 mm, 5 mm × 5 mm, 10 mm × 10 mm and 10 mm × 20 mm) were examined. To compare the different decomposition behavior of fine and large one, the thermal decomposition of PCB waste powder (approximately 5 mg) was also performed on a thermogravimetric analyzer (common TG) under various heating rates (10, 15, 20 and 40 °C min^?1) and particle size ranges (0.198–0.165 mm, 0.165–0.074 mm, 0.074–0.055 mm and 0.055–0.047 mm). Experimental results show that large particle has a pyrolysis reaction retardancy compared to fine one. The distributed activation energy model was used to study the pyrolysis kinetics. It was found that during pyrolysis process, values of frequency factor (k₀) changed with different activation energy (E) values. On common TG, the E values range from 156.95 to 319.37 kJ mol^?1 and k₀ values range from 2.67 × 10¹³ to 2.24 × 10²⁷ s^?1. While, on Macro-TG, the range of E was 31.48–41.26 kJ mol^?1 and of the frequency factor was 19.80–202.67 s^?1.     

A multi-criteria assessment of scenarios on thermal processing of infectious hospital wastes: A case study for Central Macedonia

In Greece more than 14,000 tonnes of infectious hospital waste are produced yearly; a significant part of it is still mismanaged. Only one off-site licensed incineration facility for hospital wastes is in operation, with the remaining of the market covered by various hydroclave and autoclave units, whereas numerous problems are still generally encountered regarding waste segregation, collection, transportation and management, as well as often excessive entailed costs. Everyday practices still include dumping the majority of solid hospital waste into household disposal sites and landfills after sterilization, still largely without any preceding recycling and separation steps. Discussed in the present paper are the implemented and future treatment practices of infectious hospital wastes in Central Macedonia; produced quantities are reviewed, actual treatment costs are addressed critically, whereas the overall situation in Greece is discussed. Moreover, thermal treatment processes that could be applied for the treatment of infectious hospital wastes in the region are assessed via the multi-criteria decision method Analytic Hierarchy Process. Furthermore, a sensitivity analysis was performed and the analysis demonstrated that a centralized autoclave or hydroclave plant near Thessaloniki is the best performing option, depending however on the selection and weighing of criteria of the multi-criteria process. Moreover the study found that a common treatment option for the treatment of all infectious hospital wastes produced in the Region of Central Macedonia, could offer cost and environmental benefits. In general the multi-criteria decision method, as well as the conclusions and remarks of this study can be used as a basis for future planning and anticipation of the needs for investments in the area of medical waste management.     

Medical wastes management in the south of Brazil

In developing countries, solid wastes have not received sufficient attention. In many countries, hazardous and medical wastes are still handled and disposed together with domestic wastes, thus creating a great health risk to municipal workers, the public and the environment. Medical waste management has been evaluated at the Vacacai river basin in the State of Rio Grande do Sul, Brazil. A total of 91 healthcare facilities, including hospitals (21), health centers (48) and clinical laboratories (22) were surveyed to provide information about the management, segregation, generation, storage and disposal of medical wastes. The results about management aspects indicate that practices in most healthcare facilities do not comply with the principles stated in Brazilian legislation. All facilities demonstrated a priority on segregation of infectious-biological wastes. Average generation rates of total and infectious-biological wastes in the hospitals were estimated to be 3.245 and 0.570 kg/bed-day, respectively.     

An IR study to investigate the structural relationship of lignin-like matter and lignosulphonates obtained from animal-vegetable wastes

Lignin-like matter (I) from rice hull residues and humin-like matter and (II) from rice hull-fecal matter compost yield, upon sulphonation by SO(3), the lignosulphonates III and IV, respectively. The solid state IR spectra of I and II are analysed and interpreted based on the functional groups content values obtained for III and IV by solution NMR spectroscopy. IR absorbance values at five selected wavelengths for I and II correlate well with functional groups content values for III and IV according to Beer's law. It is concluded that the sulphonated derivatives, aside from the -SO(3)H content, reflect well the chemical structure of the parent materials. No side reaction of I or II with SO(3), other than C sulphonation, is apparent. The above correlation may be useful for waste management purposes.     

Investigations into the landfill behaviour of pretreated wastes

Mechanical-biological treatment of municipal solid waste has become popular throughout the UK and other parts of Europe to enable compliance with the Landfill Directive. Pretreatment will have a major influence on the degradation and settlement characteristics of the waste in landfills owing to the changes in the composition and properties of the wastes. This paper presents and compares the results of long term landfill behaviour of the UK and German MBT wastes pretreated to different standards. The gas generating potential, leachate quality and settlement characteristics are highlighted. The results reveal that it is possible to achieve stabilisation of MBT waste within a year and the biogas yield and leachate strength of German MBT waste was significantly reduced compared with the UK MBT waste. The settlement resulting from mechanical creep is more significant than the biodegradation induced settlement in both cases.     

In-vessel composting of household wastes

The process of composting has been studied using five different types of reactors, each simulating a different condition for the formation of compost; one of which was designed as a dynamic complete-mix type household compost reactor. A lab-scale study was conducted first using the compost accelerators culture (Trichoderma viridae, Trichoderma harzianum, Trichorus spirallis, Aspergillus sp., Paecilomyces fusisporus, Chaetomium globosum) grown on jowar (Sorghum vulgare) grains as the inoculum mixed with cow-dung slurry, and then by using the mulch/compost formed in the respective reactors as the inoculum. The reactors were loaded with raw as well as cooked vegetable waste for a period of 4 weeks and then the mulch formed was allowed to maturate. The mulch was analysed at various stages for the compost and other environmental parameters. The compost from the designed aerobic reactor provides good humus to build up a poor physical soil and some basic plant nutrients. This proves to be an efficient, eco-friendly, cost-effective, and nuisance-free solution for the management of household solid wastes.