SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Waste picker

28

A landfill reclamation project was considered to recover landfill airspace and soil, reduce future groundwater impacts by removing the waste buried in the unlined area, and optimize airspace use at the site. A phased approach was utilized to evaluate the technical and economic feasibility of the reclamation project; based on the results of these evaluations, approximately 6.8ha of the unlined cells were reclaimed. Approximately 371,000 in-place cubic meters of waste was mined from 6.8ha in this project. Approximately 230,600 cubic meters of net airspace was recovered due to beneficial use of the recovered final cover soil and reclaimed soil as intermediate and daily cover soil, respectively, for the current landfill operations. This paper presents the researchers' landfill reclamation project experience, including a summary of activities pertaining to reclamation operations, an estimation of reclamation rates achieved during the project, project costs and benefits, and estimated composition of the reclaimed materials.

Concepts: Waste management, Waste picker, Estimation, Recycling, Soil, Land reclamation, Daily cover, Landfill

28

This work presents the enforcement performance of recent Haulien County, Taiwan municipal solid waste (MSW) recycling management programs. These programs include: Mandatory Refuse Sorting and Recycling, Diverse Bulk Waste Reuse, Pay-as-you-Discharge, Total Food Waste Recycling, Restricted Use on Plastic Shopping Bags & Plastic Tableware, Recycling Fund Management, and Ash Reuse. These programs provide incentives to reduce the MSW quantity growth rate. It was found that the recycled material fraction of MSW generated in 2001 was from 6.8%, but was 32.4% in 2010 and will increase stably by 2-5% yearly in the near future. Survey data for the last few years show that only 2.68% (based on total MSW generated) of food waste was collected in 2001. However, food waste was up to 9.7 % in 2010 after the Total Food Waste Recycling program was implemented. The reutilization rate of bottom ash was 20% in 2005 and up to 65% in 2010 owing to Ash Reuse Program enforcement. A quantified index, the Total Recycle Index, was proposed to evaluate MSW management program performance. The demonstrated county will move toward a zero waste society in 2015 if the Total Recycle Index approaches 1.00. Exact management with available programs can lead to slow-growing waste volume and recovery of all MSW.

Concepts: Waste management concepts, Incineration, Waste picker, Reuse, Waste hierarchy, Waste management, Waste, Recycling

27

Most of Israel’s waste is disposed in landfills, threatening scarce land resources and posing environmental and health risks. The aim of this study is to estimate the expected costs of transferring municipalities to solid waste source separation in Israel, aimed at reducing the amount of waste directed to landfills and increasing the efficiency and amount of recycled waste. Information on the expected costs of operating a solid waste source separation system was gathered from 47 municipalities and compiled onto a database, taking into consideration various factors such as costs of equipment, construction adjustments and waste collection and disposal. This database may serve as a model for estimating the costs of entering the waste source separation system for any municipality in Israel, while taking into consideration its specific characteristics, such as size and region. The model was used in Israel for determining municipalities' eligibility to receive a governmental grant for entering an accelerated process of solid waste source separation. This study displays a user-friendly and simple operational tool for assessing municipalities' costs of entering a process of waste source separation, providing policy makers a powerful tool for diverting funds effectively in promoting solid waste source separation.

Concepts: Das Model, Municipality, Policy, Waste picker, Estimator, Recycling, Waste, Waste management

27

The objective of this study is to discuss the role of networks formed of waste-picker cooperatives in ameliorating problems of final disposal of solid waste in the city of Rio de Janeiro, since the city’s main landfill will soon have to close because of exhausted capacity. However, it is estimated that in the city of Rio de Janeiro there are around five thousand waste-pickers working in poor conditions, with lack of physical infrastructure and training, but contributing significantly by diverting solid waste from landfills. According to the Sustainable Development Indicators (IBGE, 2010a,b) in Brazil, recycling rates hover between 45% and 55%. In the municipality of Rio de Janeiro, only 1% of the waste produced is collected selectively by the government (COMLURB, 2010), demonstrating that recycling is mainly performed by waste-pickers. Furthermore, since the recycling market is an oligopsony that requires economies of scale to negotiate directly with industries, the idea of working in networks of cooperatives meets the demands for joint marketing of recyclable materials. Thus, this work presents a method for creating and structuring a network of recycling cooperatives, with prior training for working in networks, so that the expected synergies and joint efforts can lead to concrete results. We intend to demonstrate that it is first essential to strengthen the waste-pickers' cooperatives in terms of infrastructure, governance and training so that solid waste management can be environmentally, socially and economically sustainable in the city of Rio de Janeiro.

Concepts: Incineration, Waste hierarchy, Waste picker, Sustainability, Landfill, Waste, Waste management, Recycling

24

Landfills are the final stage in the life cycle of many products containing per- and polyfluoroalkyl substances (PFASs) and their presence has been reported in landfill leachate. The concentrations of 70 PFASs in 95 samples of leachate were measured in a survey of U.S. landfills of varying climates and waste ages. National release of PFASs was estimated by coupling measured concentrations for the 19 PFASs where more than 50% of samples had quantifiable concentrations, with climate-specific estimates of annual leachate volumes. For 2013, the total volume of leachate generated in the U.S. was estimated to be 61.1 million m3, with 79% of this volume coming from landfills in wet climates (> 75 cm/yr precipitation) that contain 47% of U.S. solid waste. The mass of measured PFASs from U.S. landfill leachate to wastewater treatment plants was estimated to be between 563 and 638 kg for 2013. In the majority of landfill leachate samples, 5:3 fluorotelomer carboxylic acid (FTCA) was dominant and variations in concentrations with waste age affected total estimated mass. There were six PFASs that demonstrated significantly higher concentrations in leachate from younger waste compared to older waste, while no PFAS demonstrated significant variation with climate.

Concepts: Climate, Waste picker, Waste management, Recycling, Sewage treatment, Anaerobic digestion, Leachate, Landfill

23

Mercury (Hg)-containing waste from various industrial facilities is commonly treated by incineration or stabilization/solidification and retained in a landfill at a managed site. However, when highly concentrated Hg waste is treated using these methods, Hg is released into the atmosphere and soil environment. To eliminate these risks, Hg recovery technology using thermal treatment has been developed and commercialized to recover Hg from Hg-containing waste for safe disposal. Therefore, we developed Hg recovery equipment to treat Hg-containing waste under a vacuum of 6.67kPa (abs) at 400°C and recover the Hg. In addition, the dust generated from the waste was separated by controlling the temperature of the dust filtration unit to 230°C. Additionally, water and Hg vapors were condensed in a condensation unit. The Hg removal rate after waste treatment was 96.75%, and the Hg recovery rate as elemental Hg was 75.23%.

Concepts: Waste treatment technology, Landfill, Waste picker, Pollution, Atmosphere, Incineration, Recycling, Waste management

1

Public festivals and events generate a tremendous amount of waste, especially when they involve food and drink. To reduce contamination across waste streams, we evaluated three types of interventions at a public event. In a randomized control trial, we examined the impact of volunteer staff assistance, bin tops, and sample 3D items with bin tops, on the amount of contamination and the weight of the organics, recyclable containers, paper, and garbage bins at a public event. The event was the annual Apple Festival held at the University of British Columbia, which was attended by around 10,000 visitors. We found that contamination was the lowest in the volunteer staff condition among all conditions. Specifically, volunteer staff reduced contamination by 96.1% on average in the organics bin, 96.9% in the recyclable containers bin, 97.0% in the paper bin, and 84.9% in the garbage bin. Our interventions did not influence the weight of the materials in the bins. This finding highlights the impact of volunteers on reducing contamination in waste streams at events, and provides suggestions and implications for waste management for event organizers to minimize contamination in all waste streams to achieve zero waste goals.

Concepts: Waste picker, Reducing agent, Waste collection, Festival, Randomized controlled trial, Waste, Waste management, Recycling

0

One of the most common and economical methods for waste disposal is landfilling. The landfill cover system is one of the main components of landfills which prevents waste exposure to the environment by creating a barrier between the waste and the surrounding environment. The stability and integrity of the landfill cover system is a fundamental part of the design, construction, and maintenance of landfills. A reinforced tapered landfill cover system can be considered as a practical method for improving its stability; however, the simultaneous effects of seismic and seepage forces in the reinforced tapered landfill cover system have not been studied. The current paper provides a solution based on the limit equilibrium method in order to evaluate the stability of a reinforced tapered landfill cover system under seismic and seepage (both horizontal and parallel seepage force patterns) loading conditions. The proposed analytical approach is applied to different design cases through parametric study and the obtained results are compared to those derived from literature. Parametric study is performed to illustrate the sensitivity of the safety factor (FS) to the different design parameters. The obtained results reveal that parameters which describe the geometry have limited effects on the stability of the landfill cover system in comparison to the rest of the studied design parameters. Moreover, the comparisons between the derived results and available methods demonstrate good agreement between obtained findings with those reported in the literature.

Concepts: Soil, Mechanical biological treatment, Landfill, Waste picker, Pollution, Waste management, Recycling

0

In Europe over 5.25 billion tonnes of waste has been landfilled between 1995 and 2015. Among this large amount of waste, plastic represents typically 5-25 wt% which is significant and has the potential to be recycled and reintroduced into the circular economy. To date there is still however little information available of the opportunities and challenges in recovering plastics from landfill sites. In this review, the impacts of landfill chemistry on the degradation and/or contamination of excavated plastic waste are analysed. The feasibility of using excavated plastic waste as feedstock for upcycling to valuable chemicals or liquid fuels through thermochemical conversion is also critically discussed. The limited degradation that is experienced by many plastics in landfills (>20 years) which guarantee that large amount is still available is largely due to thermooxidative degradation and the anaerobic conditions. However, excavated plastic waste cannot be conventionally recycled due to high level of ash, impurities and heavy metals. Recent studies demonstrated that pyrolysis offers a cost effective alternative option to conventional recycling. The produced pyrolysis oil is expected to have similar characteristics to petroleum diesel oil. The production of valuable product from excavated plastic waste will also increase the feasibility of enhanced landfill mining projects. However, further studies are needed to investigate the uncertainties about the contamination level and degradation of excavated plastic waste and address their viability for being processed through pyrolysis.

Concepts: Carbon, Waste picker, Incineration, Waste management, Pyrolysis, Landfill, Recycling, Petroleum

0

This quantitative research aims to compare environmental and human health impacts associated with two recycling technologies of CFRP waste. The ‘baseline’ recycling technology is the conventional thermolysis process via pyrolysis and the ‘alternative’ recycling technology is an emerging chemical treatment via solvolysis using supercritical water (SCW) to digest the thermoset matrix. Two Gate-to-Gate recycling models are developed using GaBi LCA platform. The selected functional unit (FU) is 1 kg CFRP waste and the geographical boundary of this comparative LCIA is defined to be within the U.S. The results of this comparative assessment brought to light new insights about the environmental and human health impacts of CFRP waste recycling via solvolysis using SCW and, therefore, helped close a gap in the current state of knowledge about sustainability of SCW-based solvolysis as compared to pyrolysis. Two research questions are posed to identify whether solvolysis recycling offers more environmental and human health gains relative to the conventional pyrolysis recycling. These research questions lay the basis for formulating two null hypotheses (H0,1and H0,2) and their associated research hypotheses (H1,1and H1,2). LCIA results interpretation included ‘base case’ scenarios, ‘sensitivity studies,’ and ‘scenarios analysis.’ The results revealed that: (a) recycling via solvolysis using SCW exhibits no gains in environmental and human health impacts relative to those impacts associated with recycling via pyrolysis and (b) use of natural gas in lieu of electricity for pyrolyzer’s heating reduces the environmental and human health impacts by 37% (lowest) and up to 95.7% (highest). It is recommended that on-going experimental efforts that focus only on identifying the best solvent for solvolysis-based recycling should also consider quantification of the energy intensity as well as environmental and human health impacts of the proposed solvents.

Concepts: Null hypothesis, Scientific method, Waste picker, Carbon, Waste, Hypothesis, Waste management, Recycling