Research

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14 pages, 3675 KiB

Open AccessArticle

Theoretical Study on the Production of Environment-Friendly Recycled Cement Using Inorganic Construction Wastes as Secondary Materials in South Korea

by Jihoon Kim, Sungho Tae and Rakhyun Kim

Sustainability 2018, 10(12), 4449; https://doi.org/10.3390/su10124449 - 27 Nov 2018

Cited by 19 | Viewed by 5923

Abstract

The cement industry endeavors to reduce CO₂ emissions from cement manufacturing by utilizing industrial by-products as alternative fuels and developing secondary concrete products from construction wastes. With these efforts, the cement industry is attempting to become more eco-friendly and reduce environmental load. [...] Read more.

The cement industry endeavors to reduce CO₂ emissions from cement manufacturing by utilizing industrial by-products as alternative fuels and developing secondary concrete products from construction wastes. With these efforts, the cement industry is attempting to become more eco-friendly and reduce environmental load. This study analyzed the possibility of using inorganic construction wastes to produce environmentally friendly recycled cement using the process of proportioning. To this end, the types and production trends of recyclable construction wastes and previous studies on the development of recycled cement using such construction wastes were analyzed. Based on this analysis, recyclable inorganic construction wastes were selected, and real waste was collected. The chemical composition of each inorganic construction waste was analyzed using X-ray fluorescence, and the composition of ordinary commercial cement was used as the baseline. After the collected inorganic construction wastes were mixed, they were fired using the Bogue formula. The mineral components of clinker, which was generated from the firing process, were predicted and analyzed. Waste gypsum board and ceiling materials were shown to contain large amounts of CaO, which could substitute limestone—a key component of cement. These results suggested that if the limestone content was greater than 85 wt %, mixing inorganic construction wastes in appropriate proportions could be used to develop various types of Portland cement. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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20 pages, 6564 KiB

Open AccessArticle

Cross-Laminated Secondary Timber: Experimental Testing and Modelling the Effect of Defects and Reduced Feedstock Properties

by Colin M. Rose, Dan Bergsagel, Thibault Dufresne, Evi Unubreme, Tianyao Lyu, Philippe Duffour and Julia A. Stegemann

Sustainability 2018, 10(11), 4118; https://doi.org/10.3390/su10114118 - 09 Nov 2018

Cited by 34 | Viewed by 6830

Abstract

The construction industry creates significant volumes of waste timber, much of which has residual quality and value that dissipates in conventional waste management. This research explored the novel concept of reusing secondary timber as feedstock for cross-laminated timber (CLT). If cross-laminated secondary timber [...] Read more.

The construction industry creates significant volumes of waste timber, much of which has residual quality and value that dissipates in conventional waste management. This research explored the novel concept of reusing secondary timber as feedstock for cross-laminated timber (CLT). If cross-laminated secondary timber (CLST) can replace conventional CLT, structural steel and reinforced concrete in some applications, this constitutes upcycling to displace materials of greater environmental impacts. The fabrication process and mechanical properties of CLST were tested in small-scale laboratory experiments, which showed no significant difference between the compression stiffness and strength of CLST and a control. Finite element modelling suggested that typical minor defects in secondary timber have only a small effect on CLST panel stiffness in compression and bending. Mechanically Jointed Beams Theory calculations to examine the potential impacts of secondary timber ageing on CLST panels found that this has little effect on compression stiffness if only the crosswise lamellae are replaced. Since use of secondary timber to make CLST has a more significant effect on bending stiffness, effective combinations of primary and secondary timber and their appropriate structural applications are proposed. The article concludes with open research questions to advance this concept towards commercial application. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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20 pages, 2465 KiB

Open AccessFeature PaperArticle

Environmental-Economic Analysis of Integrated Organic Waste and Wastewater Management Systems: A Case Study from Aarhus City (Denmark)

by Marianne Thomsen, Daina Romeo, Dario Caro, Michele Seghetta and Rong-Gang Cong

Sustainability 2018, 10(10), 3742; https://doi.org/10.3390/su10103742 - 17 Oct 2018

Cited by 22 | Viewed by 5513

Abstract

This study presents a comparative analysis of the environmental and economic performances of four integrated waste and wastewater management scenarios in the city of Aarhus in Denmark. The purpose of this analysis is to deliver decision support regarding whether (i) the installation of [...] Read more.

This study presents a comparative analysis of the environmental and economic performances of four integrated waste and wastewater management scenarios in the city of Aarhus in Denmark. The purpose of this analysis is to deliver decision support regarding whether (i) the installation of food waste disposers in private homes (AS1) or (ii) separate collection and transport of organic waste to biogas plants is a more viable environmental and economic solution (AS2). Higher environmental benefits, e.g., mitigation of human health impacts and climate change, are obtained by transforming the existing waste combustion system into scenario (ii). Trade-offs in terms of increased marine eutrophication and terrestrial ecotoxicity result from moving up the waste hierarchy; i.e., from waste incineration to biogas production at wastewater treatment plants with anaerobic sludge digestion. Scenario (i) performs with lower energy efficiency compared to scenario (ii). Furthermore, when considering the uncertainty in the extra damage cost to the sewer system that may be associated to the installation of food waste disposers, scenario (ii) is the most flexible, robust, and less risky economic solution. From an economic, environmental, and resource efficiency point of view, separate collection and transport of biowaste to biogas plants is the most sustainable solution. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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19 pages, 747 KiB

Open AccessArticle

Use of Organic Wastes and Industrial By-Products to Produce Filamentous Fungi with Potential as Aqua-Feed Ingredients

by Sajjad Karimi, Nasrollah Mahboobi Soofiani, Amir Mahboubi and Mohammad J. Taherzadeh

Sustainability 2018, 10(9), 3296; https://doi.org/10.3390/su10093296 - 14 Sep 2018

Cited by 55 | Viewed by 6544

Abstract

Organic-rich waste and industrial by-product streams, generated in enormous amounts on a daily basis, contain substantial amounts of nutrients that are worthy of recovery. Biological conversion of organic-waste streams using filamentous fungi is a promising approach to convert nutrients into value-added bioproducts, such [...] Read more.

Organic-rich waste and industrial by-product streams, generated in enormous amounts on a daily basis, contain substantial amounts of nutrients that are worthy of recovery. Biological conversion of organic-waste streams using filamentous fungi is a promising approach to convert nutrients into value-added bioproducts, such as fungal biomass. High-protein fungal biomass contains different kinds and levels of amino acids, fatty acids, immunostimulants, antioxidants, pigments, etc., which make it a potential choice for application in animal feed supplementation. Considering the challenges long faced by the aquaculture industry in fishmeal production due to the increasing prices and environmental concerns, the aquaculture industry is forced to provide alternative protein-rich sources to replace conventional fishmeal. In this review, the possibilities of utilization of filamentous fungi biomass cultivated on organic-rich waste streams, as an alternative nutrient source in fish feed, were thoroughly reviewed. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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14 pages, 2626 KiB

Open AccessArticle

Proposal for Feasibility Assessment Model for Landfill Mining and Its Implementation for Energy Generation Scenarios

by Algimantas Bučinskas, Mait Kriipsalu and Gintaras Denafas

Sustainability 2018, 10(8), 2882; https://doi.org/10.3390/su10082882 - 14 Aug 2018

Cited by 7 | Viewed by 4145

Abstract

New approaches to waste management and requirements of a circular economy have changed landfill management. Therefore, the updating on these subjects is required. To benefit from landfill mining, information about composition and properties of disposed waste should be gathered. Decay of landfilled waste [...] Read more.

New approaches to waste management and requirements of a circular economy have changed landfill management. Therefore, the updating on these subjects is required. To benefit from landfill mining, information about composition and properties of disposed waste should be gathered. Decay of landfilled waste over time primarily determines the amount of recyclable and combustible matter as well as the amount of landfill gas formation. In this paper, we propose scenarios for landfill management and we create a conceptual model on their basis. A conceptual model is formulated and theoretical calculations are performed and compared with field research results in order to understand changes in the composition of landfilled waste. Correlations between theoretical and actual results were determined. Correlations of theoretical and actual results for the Torma (EE) and Alytus (LT) landfills were 0.68 and 0.78, respectively. In addition, the changes of refuse-derived fuel resources in Alytus landfill during the previous 10-year period were calculated. Finally, four different landfill closure and aftercare scenarios with respect to energy generation were created, assessed, and compared. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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13 pages, 1585 KiB

Open AccessArticle

A Practical Approach to Reduce Greenhouse Gas Emissions from Open Dumps through Infrastructure Restructuring: A Case Study in Nanjing City, China

by Jing Ma, Zhanbin Luo, Fu Chen, Qianlin Zhu, Shaoliang Zhang and Gang-Jun Liu

Sustainability 2018, 10(8), 2804; https://doi.org/10.3390/su10082804 - 08 Aug 2018

Cited by 5 | Viewed by 3583

Abstract

A new environmental ban has forced the restructure of open dumps in China since 1 July 2011. A technical process was established in this study that is feasible for the upgrade of open dumps through restructuring. The feasibility of restructuring and the benefit [...] Read more.

A new environmental ban has forced the restructure of open dumps in China since 1 July 2011. A technical process was established in this study that is feasible for the upgrade of open dumps through restructuring. The feasibility of restructuring and the benefit of greenhouse gas emission reductions were assessed according to field surveys of five landfills and four dumps in Nanjing. The results showed that the daily processing capacities of the existing landfills have been unable to meet the growth of municipal solid waste (MSW), making restructuring of the landfills imperative. According to an assessment of the technical process, only four sites in Nanjing were suitable for upgrading. Restructuring the Jiaozishan landfill effectively reduced the leachate generation rate by 5.84% under its scale when expanded by 60.7% in 2015. CO₂ emissions were reduced by approximately 55,000–86,000 tons per year, in which biogas power generation replaced fossil fuels Fossil fuels accounted for the largest proportion, up to 45,000–60,000 tons. Photovoltaic power generation on the overlying land has not only reduced CO₂ emissions to 26,000–30,000 tons per year but has also brought in continuing income from the sale of electricity. The funds are essential for developing countries such as China, which lack long-term financial support for landfill management after closure. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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13 pages, 3649 KiB

Open AccessArticle

System Dynamics versus Agent-Based Modeling: A Review of Complexity Simulation in Construction Waste Management

by Zhikun Ding, Wenyan Gong, Shenghan Li and Zezhou Wu

Sustainability 2018, 10(7), 2484; https://doi.org/10.3390/su10072484 - 16 Jul 2018

Cited by 82 | Viewed by 10100

Abstract

The environmental impacts caused by construction waste have attracted increasing attention in recent years. The effective management of construction waste is essential in order to reduce negative environmental influences. Construction waste management (CWM) can be viewed as a complex adaptive system, as it [...] Read more.

The environmental impacts caused by construction waste have attracted increasing attention in recent years. The effective management of construction waste is essential in order to reduce negative environmental influences. Construction waste management (CWM) can be viewed as a complex adaptive system, as it involves not only various factors (e.g., social, economic, and environmental), but also different stakeholders (such as developers, contractors, designers, and governmental departments) simultaneously. System dynamics (SD) and agent-based modeling (ABM) are the two most popular approaches to deal with the complexity in CWM systems. However, the two approaches have their own advantages and drawbacks. The aim of this research is to conduct a comprehensive review and develop a novel model for combining the advantages of both SD and ABM. The research findings revealed that two options can be considered when combining SD with ABM; the two options are discussed. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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15 pages, 1940 KiB

Open AccessArticle

Microbial Strategies for Cellulase and Xylanase Production through Solid-State Fermentation of Digestate from Biowaste

by Laura Mejias, Alejandra Cerda, Raquel Barrena, Teresa Gea and Antoni Sánchez

Sustainability 2018, 10(7), 2433; https://doi.org/10.3390/su10072433 - 12 Jul 2018

Cited by 37 | Viewed by 4983

Abstract

Solid-state fermentation (SSF) is a promising technology for producing bioproducts from organic wastes. The objective of this study is to assess the feasibility of using digestate as substrate to produce hydrolytic enzymes, mainly cellulase and xylanase, by exploring three different inoculation strategies: (i) [...] Read more.

Solid-state fermentation (SSF) is a promising technology for producing bioproducts from organic wastes. The objective of this study is to assess the feasibility of using digestate as substrate to produce hydrolytic enzymes, mainly cellulase and xylanase, by exploring three different inoculation strategies: (i) SSF with autochthonous microbiota; (ii) non-sterile SSF inoculated with Trichoderma reesei and (iii) sequential batch operation to select a specialized inoculum, testing two different residence times. Native microbial population did not show a significant cellulase production, suggesting the need for a specialized inoculum. The inoculation of Trichoderma reesei did not improve the enzymatic activity. On the other hand, inconsistent operation was achieved during sequential batch reactor in terms of specific oxygen uptake rate, temperature and enzymatic activity profile. Low cellulase and xylanase activities were attained and the main hypotheses are non-appropriate biomass selection and some degree of hydrolysis by non-targeted proteases produced during fermentation. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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16 pages, 3189 KiB

Open AccessArticle

Integration of Membrane Bioreactors with Edible Filamentous Fungi for Valorization of Expired Milk

by Rahul Thunuguntla, Amir Mahboubi, Jorge A. Ferreira and Mohammad J. Taherzadeh

Sustainability 2018, 10(6), 1940; https://doi.org/10.3390/su10061940 - 10 Jun 2018

Cited by 10 | Viewed by 4811

Abstract

Around 29 million tons of milk end as waste yearly in Europe, representing an environmental issue but also a potential substrate for biological valorization given its nutritional value. Aspergillus oryzae and Neurospora intermedia are edible filamentous fungi with dissimilar metabolism when grown in [...] Read more.

Around 29 million tons of milk end as waste yearly in Europe, representing an environmental issue but also a potential substrate for biological valorization given its nutritional value. Aspergillus oryzae and Neurospora intermedia are edible filamentous fungi with dissimilar metabolism when grown in expired milk. Neurospora intermedia is more devoted to lactose consumption; 68 and 57% of lactose was consumed after cultivation in expired milk and its liquid fraction, respectively. Aspergillus oryzae consumed less lactose in expired milk (14%), but led to better microfiltration characteristics of the final effluent due to fat and protein degradation. A two-stage fed-batch cultivation using membrane bioreactors (MBRs) was developed, bringing together both fungal metabolic characteristics when grown in 70% diluted expired milk. In the first MBR, A.oryzae degraded fat and protein, improved microfiltration, and produced ca 11 g/L of biomass. In the second MBR, N. intermedia consumed the remaining lactose in the permeate and originated ca 7 g/L of biomass. The developed system was successful for valorization of non-sterile milk due to the balance between consumption of bacterial growth-derived acids, consequent pH, and fungal enzymatic activities. Besides, a final clear effluent (83% reduction of COD) was obtained, which is of interest considering wastewater treatment. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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19 pages, 5287 KiB

Open AccessEditor’s ChoiceArticle

Effects of the Use of Ornamental Plants and Different Substrates in the Removal of Wastewater Pollutants through Microcosms of Constructed Wetlands

by Luis Carlos Sandoval-Herazo, Alejandro Alvarado-Lassman, José Luis Marín-Muñiz, Juan Manuel Méndez-Contreras and Sergio Aurelio Zamora-Castro

Sustainability 2018, 10(5), 1594; https://doi.org/10.3390/su10051594 - 16 May 2018

Cited by 47 | Viewed by 6369

Abstract

The high costs involved in treating wastewater are problems that developing countries confront, mainly in rural areas. Therefore, Constructed Wetlands (CWs), which are composed of substrate, vegetation, and microorganisms, are an economically and ecologically viable option for wastewater treatment in these places. There [...] Read more.

The high costs involved in treating wastewater are problems that developing countries confront, mainly in rural areas. Therefore, Constructed Wetlands (CWs), which are composed of substrate, vegetation, and microorganisms, are an economically and ecologically viable option for wastewater treatment in these places. There is a wide variety of possibilities for substrates and ornamental plants that have not yet been evaluated to be implemented in future CW designs. The goal of this study was to evaluate the process of adaptation and removal of wastewater pollutants in CW microcosms using different terrestrial ornamental plants (Lavandula sp., Spathiphyllum wallisii, and Zantedeschia aethiopica). Those plants were sown in two types of substrate: red volcanic gravel (RVG) and polyethylene terephthalate (PET). CWs with vegetation reduced 5-day biochemical oxygen demand (BOD₅) by 68% with RVG substrate and 63% with PET substrate, nitrates 50% in RVG substrate and 35% in PET substrate, phosphates 38% in RVG substrate and 35% in PET substrate, and fecal coliforms 64% in RVG and 59% in PET substrate). In control microcosms without vegetation, reductions were significantly lower than those in the presence of plants, with reduction of BOD₅ by 61% in RVG substrate and 55% in PET substrate, nitrates 26% in RVG substrate and 22% in PET substrate, phosphates 27% in RVG substrate and 25% in PET substrate. Concerning fecal coliforms 62% were removed in RVG substrate and 59% in PET substrate. Regarding the production of flowers, Lavandula sp. did not manage to adapt and died 45 days after sowing and did not produce flowers. Spathiphyllum wallisii produced 12 flowers in RVG and nine flowers in PET, while Zantedeschia aethiopica produced 10 in RVG and 7 in PET. These results showed that the use of substrates made of RVG and PET is a viable alternative to be implemented in CWs. In addition, the reuse of PET is an option that decreases pollution by garbage. The plants Spathiphyllum wallisii and Zantedeschia aethiopica remarkably contribute in the removal of pollutants in wastewater. Additionally, the use of ornamental plants, with commercial interest such as those evaluated, enables an added value to the CW to be given, which can be used for flower production purposes on a larger scale and favor its acceptance within rural communities. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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Review

Jump to: Research

27 pages, 1737 KiB

Open AccessReview

A Review of Waste Management Decision Support Tools and Their Ability to Assess Circular Biowaste Management Systems

by Eldbjørg Blikra Vea, Veronica Martinez-Sanchez and Marianne Thomsen

Sustainability 2018, 10(10), 3720; https://doi.org/10.3390/su10103720 - 16 Oct 2018

Cited by 26 | Viewed by 5318

Abstract

The circular economy concept offers a number of solutions to increasing amounts of biowaste and resource scarcity by valorising biowaste. However, it is necessary to consistently address the environmental benefits and impacts of circular biowaste management systems (CBWMS). Various decision support tools (DST) [...] Read more.

The circular economy concept offers a number of solutions to increasing amounts of biowaste and resource scarcity by valorising biowaste. However, it is necessary to consistently address the environmental benefits and impacts of circular biowaste management systems (CBWMS). Various decision support tools (DST) for environmental assessment of waste management systems (WMS) exist. This study provides a review of life cycle assessment based WMS-DSTs. Twenty-five WMS-DSTs were identified and analysed through a shortlisting procedure. Eight tools were shortlisted for the assessment of their applicability to deliver sustainability assessment of CBWMS. It was found that six tools model key properties that are necessary for assessing the environmental sustainability of CBWMSs, including waste-specific modelling of gaseous emissions, biogas generation or bioproduct composition. However, only two tools consider both waste-specific heavy metals content in bioproducts and the associated implications when applied on soil. Most of the shortlisted tools are flexible to simulate new technologies involved in CBWMS. Nevertheless, only two tools allow importing directly new background data, which is important when modelling substitution of new bioproducts developed in emerging biowaste refineries. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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22 pages, 1367 KiB

Open AccessReview

Citrus and Winery Wastes: Promising Dietary Supplements for Sustainable Ruminant Animal Nutrition, Health, Production, and Meat Quality

by Tawanda Tayengwa and Cletos Mapiye

Sustainability 2018, 10(10), 3718; https://doi.org/10.3390/su10103718 - 16 Oct 2018

Cited by 30 | Viewed by 5068

Abstract

Citrus and grapes are the most widely grown fruits globally, with one-third of total production used for juice and wine making. The juice and winemaking processes generate large quantities of solid organic wastes including citrus pulp and grape pomace. These fruit wastes pose [...] Read more.

Citrus and grapes are the most widely grown fruits globally, with one-third of total production used for juice and wine making. The juice and winemaking processes generate large quantities of solid organic wastes including citrus pulp and grape pomace. These fruit wastes pose serious economic, environmental, and social challenges, especially in low-to-middle-income countries due to financial, technological, and infrastructural limitations. They are, however, rich in valuable compounds which can be utilized in the ruminant livestock industry as novel, economical, and natural sources of cellulose, polyunsaturated fatty acids, and phytochemicals, which have nutritional, anthelmintic, antioxidant, and antimicrobial properties. Despite citrus and grape fruit wastes having such potential, they remain underexploited by the livestock industry in low-to-middle-income countries owing to lack of finance, skills, technology, and infrastructure. Inclusion of these fruit wastes in ruminant diets could combine the desirable effects of enhancing animal nutrition, health, welfare, production, and meat quality attributes with the prevention of challenges associated with their disposal into the environment. The current review explores the valorization potential of citrus and winery wastes as dietary supplements to sustainably enhance ruminant animal nutrition, health, welfare, production, and meat quality. Full article

(This article belongs to the Special Issue The New Paradigm of Waste Management: Waste as Resources)

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