Costas Velis | University of Leeds (original) (raw)

Papers by Costas Velis

Environmental Science & Technology, Dec 5, 2013

Laner and Cencic 1 comment on Velis et al. (2013) 2 clarifying certain points on the use of the m... more Laner and Cencic 1 comment on Velis et al. (2013) 2 clarifying certain points on the use of the material flow analysis (MFA) software STAN 3. We welcome the correspondence and the opportunity this exchange provides to discuss optimal approaches to using STAN. In keeping with Velis et al. 2 these physically impossible, and otherwise insignificant, negative flows have enabled improvements to STAN. Here, we elaborate on the practicalities of using STAN in our research and on the correctness and validation of our results, notwithstanding the inclusion of negative flows. We explain the contribution of our approach to solid waste management and resource recovery. To our knowledge, discussion about physically impossible flows resulting from reconciliation in STAN was for the first time raised here 2. Laner and Cencic 1 state that "occurrence of negative flows [while applying STAN] indicates problems with input data, as contradictions in the mass balance equations lead to unrealistic results after data reconciliation." They also refer to "different approaches […] to handle uncertainties in MFA, differing in […] sophistication, mathematical rigor, and applicability" 1. We agree that detailed information and analysis on such approaches is missing and could enable the improved application of MFA software. We also contend that data quality in Velis et al. 2 employs best laboratory practice, as identified in the methodology sections 2, 4 , accounting for the nature of sampling MBT plants that treat municipal solid waste 5 (highly heterogeneous, dynamically evolving flows sampled with time differentials from hours to days). High between

Acta Horticulturae, 2016

A compost was produced by co-composting olive mill wastewater (OMW) and chicken manure (CM), with... more A compost was produced by co-composting olive mill wastewater (OMW) and chicken manure (CM), with green waste as a bulking agent. Two different variants of OMW compost were used in growth trials during the 2014 season in the UK, one twice composted and one that was composted three times. The composting was on a pilot scale in windrows. During the first composting procedure these windrows were turned 14 times. For the second composting CM and OMW were added to the compost from the first stage used as the bulking agent; this was turned 8 times. This compost was used as a bulking agent for the third composting, with CM and OMW added. Amounts of this product in ratios of 10, 25 and 50% were combined with substrate to create a soilless medium suitable for the growth of strawberry (Fragaria x ananassa). Fruits were assessed for quality by measuring sugar content and flesh firmness using a refractometer and penetrometer respectively. The extent of these trials was not enough to get an understanding of any consistent differences in the production of strawberries when grown in different substrates. Trials in 2015 will have greater scope to clarify if this substrate has an impact on marketable crop quality.

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

CEST, Aug 31, 2017

It is commonly accepted that the recycling and reuse of solid waste materials in developing count... more It is commonly accepted that the recycling and reuse of solid waste materials in developing countries has the potential to create many social, environmental and financial benefits. Given that the majority of recycling in these locations is carried out informally by waste pickers, it is also recognised that their inclusion into formal service provision could be the most efficient way of maintaining and increasing the recycling rates of a city. In the absence of sophisticated equipment, the informal recycling sector (IRS) has developed a wealth of self-taught knowledge and skills for manually identifying and processing waste materials. Using primary and secondary data gathered from a materials recovery facility (MRF) in Belo Horizonte, Brazil, this study describes the so called 'social technology' techniques used to sort municipal waste materials by a cooperative of informal sector recycling workers. This involves identifying and separating 17 types of plastic polymers by visual and tactile sorting skills. The methods presented are compared and contrasted with manual sorting techniques used mainly in the near past in the UK. To conclude, the study discusses whether these techniques provide a viable method for increasing recycling rates at scale in the Global South.

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT, 2019

Plastics have become one of the most fundamental materials for industry and for everyday life. Th... more Plastics have become one of the most fundamental materials for industry and for everyday life. They offer great functional benefits at low cost. The use of plastics has increased 20-fold in the past 50 years and is expected to double in the next 20 years (PlasticsEurope, 2015). However, despite the many benefits that plastics bring to society, we also see that there are some drawbacks. As a majority of packaging items are used only once before being discarded, it is estimated that 95% of its value, USD 80-120 billion, is lost to the economy each year (The Ellen MacArthur Foundation, 2016). Additionally, plastic production emits global warming gasses, with it estimated that in a business as usual scenario, the entire plastics industry could be producing 15% of the annual carbon budget in 2050. An astounding 32% of plastic packaging also escapes collection systems, causing major environmental, social and economic loss by impacting natural systems such as the ocean (The Ellen MacArthur Foundation, 2016). Much of the plastic leakage is expected in the Global South and as suggested in recent studies is mainly a result of mismanaged waste (Wilson et al. 2013;Velis, 2014; Jambeck et al. 2015). A typical solid waste management system in a developing country displays an array of problems, including low collection coverage, irregular collection services, illegal open dumping, open burning without pollution control, and the handling and control of informal waste picking or scavenging activities (Ogawa, 2018). These general characteristics of the Global South often relate to inadequacies of waste management sector due to lower municipal budgets compared to the Global North. Expanding on the above, the Global South, with three quarters of the world populations, has access to onefifth of the world income (Therien, 2010). Corruption and poor environmental enforcement are features of the Global South. There are fewer trained people, and the best people tend to be concentrated in capitals rather than in field posts; equipment for monitoring and data gathering is scarce, and the basic data is unreliable (Bell and Russell, 2002). Moreover, the Global South lacks appropriate technology, political stability and the economies are disarticulated (Therien, 2010). These characteristics of the Global South, are compounded by the predictions of rapid urbanization rates and an increase in waste generation in the upcoming years. This makes the introduction of local decision-support tools as well as the implementation of locally adopted policy and engineering interventions to manage plastic pollution a great challenge. Here we outline the progress towards developing a decision-support tool for waste management authorities that quantifies the degree of plastic leakage into the environment. The tool builds on the outcomes of the ISWA MLTF report "Prevent Marine Plastic Litter-Now!" (Velis et. al. 2017). It is applicable at the city district-level and takes into account sources, factors that affect the location and quantity of potential plastic pollution, and potential mitigation interventions. It has also the capability to expand to quantification of loss of 'value' present in waste plastics via the combination with the Complex Value Optimisation for Resource Recovery (CVORR) approach (Iacovidou et. al. 2017). This approach assesses how value is created and destroyed in resource recovery from waste systems. It achieves this by taking into account environmental, economic, social and technical positive and negative impacts within the socio-political context of the specific regions (Iacovidou, et al. 2017). The decision-support tool estimates the quantity and type of plastic entering the environment from landbased sources under a variety of typical landscapes and conditions, using both a temporal and spatial approach. The principal of the model developed (Figure 1) is that the study region is split into different regions (modelling unit cells). These may be regular unit cells (i.e., 1 km 2 grid) or be related to geographical / political boundaries (i.e. constituencies, post codes etc.). Although the regular unit cells are likely to give a higher spatial resolution, the geographical / political modelling unit cells allow easier data collection / analysis as they provide more natural boundaries. The characteristics of the area under study is defined according to a number of typologies related to the relative land use of the area, the waste management system in place and the geographical and social conditions. The total amount of plastic waste arising is then calculated for each land use based on predicted waste generation rates and waste compositions. The summation of these gives the overall plastic waste generation in that modelling

22 Over the coming decades, a large additional mass of plastic waste will become available for 23... more 22 Over the coming decades, a large additional mass of plastic waste will become available for 23 recycling, as the world’s largest fast moving consumer goods companies step up efforts to 24 reduce plastic pollution and facilitate a circular economy. Finding ways to recover value from 25 this material is a substantial challenge that has prompted exploration of novel processes, such as 26 ‘chemical recycling’, as well as more established ones, such as incineration with energy 27 recovery. Many of these efforts will take place in the Global South, where plastic pollution and 28 due to mismanagement of waste are most acute. New infrastructure will need to be developed, 29 and it is important that the processes and systems chosen do not result in adverse effects on 30 human health and the environment. This concern is particularly acute in countries that lack 31 effective, well-resourced and independent systems for environmental regulation and the 32 protection of occupational and public...

In this Global Review on Safer End of Engineered Life, we take a long overdue and systematic look... more In this Global Review on Safer End of Engineered Life, we take a long overdue and systematic look at the scientific evidence around waste and resources management and the impact on human health and life. Surprisingly, this research appears to be the first of its kind anywhere in the world. We offer suggestions for immediate corrective action that should be taken and identify where engineering solutions could mitigate and prevent harm to human life and health. We also suggest where further research is required into the nature and magnitude of the problem.

Part 2 of 2 – This video entitled "Applying the Waste Flow Diagram" provides a technica... more Part 2 of 2 – This video entitled "Applying the Waste Flow Diagram" provides a technical explanation behind two of the critical methods within the Waste Flow Diagram toolkit – quantifying plastic leakage, and determining the fate of this plastic leakage in the environment. This is illustrated using the example of a dumpsite.

Part 1 of 2 - the "Introduction to the Waste Flow Diagram" video explains the rationale... more Part 1 of 2 - the "Introduction to the Waste Flow Diagram" video explains the rationale toolkit, as well as providing guidance on how the tool simply visualises solid waste management systems and waste flows. In addition, the video further advises on how the toolkit quantifies plastic waste leakages, what the data requirement are and explains the unique link between the Waste Flow Diagram and the Sustainable Development Goal 11.6.1 - Proportion of urban solid waste regularly collected and with adequate final discharge out of total urban solid waste generated, by cities.

The Waste Flow Diagram user manual provides an explanation of the Waste Flow Diagram toolkit and ... more The Waste Flow Diagram user manual provides an explanation of the Waste Flow Diagram toolkit and in-depth guidance on how to apply it. This includes information on data collection issues, how to estimate plastic leakages, how to run scenarios, and how to visualise the waste flows.

The Waste Flow Diagram toolkit is an excel-based model allowing users to perform a rapid assessme... more The Waste Flow Diagram toolkit is an excel-based model allowing users to perform a rapid assessment of municipal solid waste flows within a city or municipality. The tool maps these waste flows using Sankey diagrams and quantifies the plastic waste that is emitted from the solid waste management system and its eventual fate in the environment. The toolkit is specifically designed to integrate with SDG 11.6.1 by informing on the sub-indicators, and can be operated either as a baseline assessment or used for scenario forecasting.

Supplemental material, WMR941085_supp_mat for Characterisation and composition identification of ... more Supplemental material, WMR941085_supp_mat for Characterisation and composition identification of waste-derived fuels obtained from municipal solid waste using thermogravimetry: A review by Spyridoula Gerassimidou, Costas A Velis, Paul T Williams and Dimitrios Komilis in Waste Management & Research

Over the coming decades, a large additional mass of plastic waste will become available for recyc... more Over the coming decades, a large additional mass of plastic waste will become available for recycling, as the world’s largest fast moving consumer goods companies step up efforts to reduce plastic pollution and facilitate a circular economy. Finding ways to recover value from this material is a substantial challenge that has prompted exploration of novel processes, such as ‘chemical recycling’, as well as more established ones, such as incineration with energy recovery. Many of these efforts will take place in the Global South, where plastic pollution and due to mismanagement of waste are most acute. New infrastructure will need to be developed, and it is important that the processes and systems chosen do not result in adverse effects on human health and the environment. This concern is particularly acute in countries that lack effective, well-resourced and independent systems for environmental regulation and the protection of occupational and public health. Here, we present a rapid...

Environmental Science & Technology, Dec 5, 2013

Laner and Cencic 1 comment on Velis et al. (2013) 2 clarifying certain points on the use of the m... more Laner and Cencic 1 comment on Velis et al. (2013) 2 clarifying certain points on the use of the material flow analysis (MFA) software STAN 3. We welcome the correspondence and the opportunity this exchange provides to discuss optimal approaches to using STAN. In keeping with Velis et al. 2 these physically impossible, and otherwise insignificant, negative flows have enabled improvements to STAN. Here, we elaborate on the practicalities of using STAN in our research and on the correctness and validation of our results, notwithstanding the inclusion of negative flows. We explain the contribution of our approach to solid waste management and resource recovery. To our knowledge, discussion about physically impossible flows resulting from reconciliation in STAN was for the first time raised here 2. Laner and Cencic 1 state that "occurrence of negative flows [while applying STAN] indicates problems with input data, as contradictions in the mass balance equations lead to unrealistic results after data reconciliation." They also refer to "different approaches […] to handle uncertainties in MFA, differing in […] sophistication, mathematical rigor, and applicability" 1. We agree that detailed information and analysis on such approaches is missing and could enable the improved application of MFA software. We also contend that data quality in Velis et al. 2 employs best laboratory practice, as identified in the methodology sections 2, 4 , accounting for the nature of sampling MBT plants that treat municipal solid waste 5 (highly heterogeneous, dynamically evolving flows sampled with time differentials from hours to days). High between

Acta Horticulturae, 2016

A compost was produced by co-composting olive mill wastewater (OMW) and chicken manure (CM), with... more A compost was produced by co-composting olive mill wastewater (OMW) and chicken manure (CM), with green waste as a bulking agent. Two different variants of OMW compost were used in growth trials during the 2014 season in the UK, one twice composted and one that was composted three times. The composting was on a pilot scale in windrows. During the first composting procedure these windrows were turned 14 times. For the second composting CM and OMW were added to the compost from the first stage used as the bulking agent; this was turned 8 times. This compost was used as a bulking agent for the third composting, with CM and OMW added. Amounts of this product in ratios of 10, 25 and 50% were combined with substrate to create a soilless medium suitable for the growth of strawberry (Fragaria x ananassa). Fruits were assessed for quality by measuring sugar content and flesh firmness using a refractometer and penetrometer respectively. The extent of these trials was not enough to get an understanding of any consistent differences in the production of strawberries when grown in different substrates. Trials in 2015 will have greater scope to clarify if this substrate has an impact on marketable crop quality.

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

CEST, Aug 31, 2017

It is commonly accepted that the recycling and reuse of solid waste materials in developing count... more It is commonly accepted that the recycling and reuse of solid waste materials in developing countries has the potential to create many social, environmental and financial benefits. Given that the majority of recycling in these locations is carried out informally by waste pickers, it is also recognised that their inclusion into formal service provision could be the most efficient way of maintaining and increasing the recycling rates of a city. In the absence of sophisticated equipment, the informal recycling sector (IRS) has developed a wealth of self-taught knowledge and skills for manually identifying and processing waste materials. Using primary and secondary data gathered from a materials recovery facility (MRF) in Belo Horizonte, Brazil, this study describes the so called 'social technology' techniques used to sort municipal waste materials by a cooperative of informal sector recycling workers. This involves identifying and separating 17 types of plastic polymers by visual and tactile sorting skills. The methods presented are compared and contrasted with manual sorting techniques used mainly in the near past in the UK. To conclude, the study discusses whether these techniques provide a viable method for increasing recycling rates at scale in the Global South.

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT, 2019

Plastics have become one of the most fundamental materials for industry and for everyday life. Th... more Plastics have become one of the most fundamental materials for industry and for everyday life. They offer great functional benefits at low cost. The use of plastics has increased 20-fold in the past 50 years and is expected to double in the next 20 years (PlasticsEurope, 2015). However, despite the many benefits that plastics bring to society, we also see that there are some drawbacks. As a majority of packaging items are used only once before being discarded, it is estimated that 95% of its value, USD 80-120 billion, is lost to the economy each year (The Ellen MacArthur Foundation, 2016). Additionally, plastic production emits global warming gasses, with it estimated that in a business as usual scenario, the entire plastics industry could be producing 15% of the annual carbon budget in 2050. An astounding 32% of plastic packaging also escapes collection systems, causing major environmental, social and economic loss by impacting natural systems such as the ocean (The Ellen MacArthur Foundation, 2016). Much of the plastic leakage is expected in the Global South and as suggested in recent studies is mainly a result of mismanaged waste (Wilson et al. 2013;Velis, 2014; Jambeck et al. 2015). A typical solid waste management system in a developing country displays an array of problems, including low collection coverage, irregular collection services, illegal open dumping, open burning without pollution control, and the handling and control of informal waste picking or scavenging activities (Ogawa, 2018). These general characteristics of the Global South often relate to inadequacies of waste management sector due to lower municipal budgets compared to the Global North. Expanding on the above, the Global South, with three quarters of the world populations, has access to onefifth of the world income (Therien, 2010). Corruption and poor environmental enforcement are features of the Global South. There are fewer trained people, and the best people tend to be concentrated in capitals rather than in field posts; equipment for monitoring and data gathering is scarce, and the basic data is unreliable (Bell and Russell, 2002). Moreover, the Global South lacks appropriate technology, political stability and the economies are disarticulated (Therien, 2010). These characteristics of the Global South, are compounded by the predictions of rapid urbanization rates and an increase in waste generation in the upcoming years. This makes the introduction of local decision-support tools as well as the implementation of locally adopted policy and engineering interventions to manage plastic pollution a great challenge. Here we outline the progress towards developing a decision-support tool for waste management authorities that quantifies the degree of plastic leakage into the environment. The tool builds on the outcomes of the ISWA MLTF report "Prevent Marine Plastic Litter-Now!" (Velis et. al. 2017). It is applicable at the city district-level and takes into account sources, factors that affect the location and quantity of potential plastic pollution, and potential mitigation interventions. It has also the capability to expand to quantification of loss of 'value' present in waste plastics via the combination with the Complex Value Optimisation for Resource Recovery (CVORR) approach (Iacovidou et. al. 2017). This approach assesses how value is created and destroyed in resource recovery from waste systems. It achieves this by taking into account environmental, economic, social and technical positive and negative impacts within the socio-political context of the specific regions (Iacovidou, et al. 2017). The decision-support tool estimates the quantity and type of plastic entering the environment from landbased sources under a variety of typical landscapes and conditions, using both a temporal and spatial approach. The principal of the model developed (Figure 1) is that the study region is split into different regions (modelling unit cells). These may be regular unit cells (i.e., 1 km 2 grid) or be related to geographical / political boundaries (i.e. constituencies, post codes etc.). Although the regular unit cells are likely to give a higher spatial resolution, the geographical / political modelling unit cells allow easier data collection / analysis as they provide more natural boundaries. The characteristics of the area under study is defined according to a number of typologies related to the relative land use of the area, the waste management system in place and the geographical and social conditions. The total amount of plastic waste arising is then calculated for each land use based on predicted waste generation rates and waste compositions. The summation of these gives the overall plastic waste generation in that modelling

22 Over the coming decades, a large additional mass of plastic waste will become available for 23... more 22 Over the coming decades, a large additional mass of plastic waste will become available for 23 recycling, as the world’s largest fast moving consumer goods companies step up efforts to 24 reduce plastic pollution and facilitate a circular economy. Finding ways to recover value from 25 this material is a substantial challenge that has prompted exploration of novel processes, such as 26 ‘chemical recycling’, as well as more established ones, such as incineration with energy 27 recovery. Many of these efforts will take place in the Global South, where plastic pollution and 28 due to mismanagement of waste are most acute. New infrastructure will need to be developed, 29 and it is important that the processes and systems chosen do not result in adverse effects on 30 human health and the environment. This concern is particularly acute in countries that lack 31 effective, well-resourced and independent systems for environmental regulation and the 32 protection of occupational and public...

In this Global Review on Safer End of Engineered Life, we take a long overdue and systematic look... more In this Global Review on Safer End of Engineered Life, we take a long overdue and systematic look at the scientific evidence around waste and resources management and the impact on human health and life. Surprisingly, this research appears to be the first of its kind anywhere in the world. We offer suggestions for immediate corrective action that should be taken and identify where engineering solutions could mitigate and prevent harm to human life and health. We also suggest where further research is required into the nature and magnitude of the problem.

Part 2 of 2 – This video entitled "Applying the Waste Flow Diagram" provides a technica... more Part 2 of 2 – This video entitled "Applying the Waste Flow Diagram" provides a technical explanation behind two of the critical methods within the Waste Flow Diagram toolkit – quantifying plastic leakage, and determining the fate of this plastic leakage in the environment. This is illustrated using the example of a dumpsite.

Part 1 of 2 - the "Introduction to the Waste Flow Diagram" video explains the rationale... more Part 1 of 2 - the "Introduction to the Waste Flow Diagram" video explains the rationale toolkit, as well as providing guidance on how the tool simply visualises solid waste management systems and waste flows. In addition, the video further advises on how the toolkit quantifies plastic waste leakages, what the data requirement are and explains the unique link between the Waste Flow Diagram and the Sustainable Development Goal 11.6.1 - Proportion of urban solid waste regularly collected and with adequate final discharge out of total urban solid waste generated, by cities.

The Waste Flow Diagram user manual provides an explanation of the Waste Flow Diagram toolkit and ... more The Waste Flow Diagram user manual provides an explanation of the Waste Flow Diagram toolkit and in-depth guidance on how to apply it. This includes information on data collection issues, how to estimate plastic leakages, how to run scenarios, and how to visualise the waste flows.

The Waste Flow Diagram toolkit is an excel-based model allowing users to perform a rapid assessme... more The Waste Flow Diagram toolkit is an excel-based model allowing users to perform a rapid assessment of municipal solid waste flows within a city or municipality. The tool maps these waste flows using Sankey diagrams and quantifies the plastic waste that is emitted from the solid waste management system and its eventual fate in the environment. The toolkit is specifically designed to integrate with SDG 11.6.1 by informing on the sub-indicators, and can be operated either as a baseline assessment or used for scenario forecasting.

Supplemental material, WMR941085_supp_mat for Characterisation and composition identification of ... more Supplemental material, WMR941085_supp_mat for Characterisation and composition identification of waste-derived fuels obtained from municipal solid waste using thermogravimetry: A review by Spyridoula Gerassimidou, Costas A Velis, Paul T Williams and Dimitrios Komilis in Waste Management & Research

Over the coming decades, a large additional mass of plastic waste will become available for recyc... more Over the coming decades, a large additional mass of plastic waste will become available for recycling, as the world’s largest fast moving consumer goods companies step up efforts to reduce plastic pollution and facilitate a circular economy. Finding ways to recover value from this material is a substantial challenge that has prompted exploration of novel processes, such as ‘chemical recycling’, as well as more established ones, such as incineration with energy recovery. Many of these efforts will take place in the Global South, where plastic pollution and due to mismanagement of waste are most acute. New infrastructure will need to be developed, and it is important that the processes and systems chosen do not result in adverse effects on human health and the environment. This concern is particularly acute in countries that lack effective, well-resourced and independent systems for environmental regulation and the protection of occupational and public health. Here, we present a rapid...