CARNEGIE MELLON PORTUGAL PROGRAM
Débora Vanessa Campos Freire Diogo Filipe da Paz de Barros Francisco Freire do Nascimento Junior
Larissa Zabudowski Schroeder Rafael Luis Yanase de Rezende
Blockchain & Crypto Currency for Urban Solid Waste Management in a Circular Economy and Smart City Context, application proposal focusing on Portugal:
The BitBin Project
Lisbon 06 november 2020
Francisco Freire do Nascimento Junior Larissa Zabudowski Schroeder Rafael Luis Yanase de Rezende
Blockchain & Crypto Currency for Urban Solid Waste Management in a Circular Economy and Smart City Context, application proposal focusing on Portugal:
The BitBin Project
Paper presented as part of the Blockchain & Crypto Currency for Waste Management Master Class at the Bee2WasteCrypto project Summer School. That project is part of Carnegie Mellon Portugal Program, leding by Compta in partnership with NOVA Information Management School, Instituto Superior Técnico, and 3drivers, and it aims to create an innovative platform, using blockchain and cryptocurrency technology for MSW management.
Advisor: Ian Scott
Professor(a): Miguel de Castro Neto
Turma: Crypto Summer by
Lisbon 06 november 2020
Sustainable development is being addressed as a new economic paradigm that establishes a general context for organizations and institutions to develop their strategies and processes. Especially for public administration, contextualized in the current information society where the construction of this new paradigm points out the development of sustainable and intelligent cities through networks of complex operations and managed through data, aiming to optimize optimizing flows of materials, energy, people, public agents, among others. Depletion of fossil fuels and concern for environmental issues puts pressure on energy policies in the direction the increase in the use of renewable energies, with one of the alternatives being the improvement of the use of Municipal Solid Waste (MSW) through recycling, using raw material as part of a circular economy, and the generation of energy from organic waste, having a better use in a smart city context. This research addresses the problem of solid waste management in the cities, presenting The BitBin project that came to fill up a gap, and by doing so there was a need to develop a system to connect citizens and the other public and private stakeholders in a way that can be trusted by all the participants in the system, Blockchain was chosen to be this system as it is transparent and immutable, and brings trust and security to its users. This work also presents the state of the art and gather the existing information, within the established parameters, about waste management using concepts such as circular economy, through blockchain technology and integrated into a smart city scenario, and how this management has been applied in communities.
Figure 1 – The main phases of a circular economy model. . . 37
Figure 2 – Benchmarking of Waste And Recycling Projects. . . 46
Figure 3 – Online form to sign-up for WASTED Labs . . . 47
Figure 4 – Disposal of bags, users scans the WASTED QR code on a container. 47 Figure 5 – Uploading the picture of the WASTED bag by type of waste. . . 48
Figure 6 – The discounts available at WASTED website to be exchanged for WASTED coins. . . 48
Figure 7 – Cycle through which the cryptocurrency follows . . . 49
Figure 8 – European Waste Transportation on Blockchain Application . . . 50
Figure 9 – Wristband RFID reader and container with RFID. . . 52
Figure 10 – EOW vision of the circular economy. . . 54
Figure 11 – Blockchain sequence used by the EOW system. . . 54
Figure 12 – How Recereum Work. . . 56
Figure 13 – Tratolixo functions. . . 57
Figure 14 – Tratolixo cover area. . . 58
Graphic 1 – Percentage of recycled waste originating from solid urban waste in
the EU. . . 31
Graphic 2 – Average composted waste in the EU. . . 32
Graphic 3 – Waste destined for landfill in the EU . . . 32
Graphic 4 – Waste destined for landfill in the EU kilogram per capita. . . 33
Graphic 5 – Waste destined for energy production in the EU. . . 33
Graphic 6 – Urban waste destined for energy production by countries in the EU per kilogram per capita. . . 34
Graphic 7 – Energy generated from urban waste in the EU per Giga Watt hour. 34 Graphic 8 – Europe Union goals to achieve in Portugal. . . 35
Graphic 9 – Base value for pet. . . 61
Graphic 10 – Base value for PEAD. . . 62
Graphic 11 – Base value for Wrap . . . 62
Graphic 12 – Base value for paper . . . 62
Table 1 – Selected keywords in English and Portuguese . . . 14
Table 2 – Strings . . . 14
Table 3 – Search Results . . . 16
Table 4 – LSR Results. . . 19
1 Introduction . . . . 8
2 Research Characterization . . . . 9
3 Secondary Data Collection: Systematic Literature Review . . . . 10
3.1 Method . . . . 10
3.2 Step 1 - Research question . . . . 11
3.3 Step 2 - Location and selection of studies . . . . 11
3.3.1 Defining search parameters . . . 12
3.3.2 Keywords used to perform the SLR . . . 13
3.4 Steps 3 and 4 - Critical evaluation of studies and selection of data for analysis . . . . 19
3.5 Step 5 - Data analysis and presentation . . . . 27
3.6 Step 6 and 7 - Data interpretation, improvement and update . . . 27
4 Secondary Data Collection: Literature Review . . . . 28
4.1 Municipal Solid Waste Management . . . . 28
4.2 Circular Economy . . . . 36
4.3 Municipal Solid Waste Management Strategy in Smart City Context 40 4.4 Blockchain . . . . 41
4.4.1 Consensus Algorithm . . . 42
4.4.2 Mining and Validating nodes . . . 42
4.4.3 Bitcoin . . . 43 4.4.4 Ethereum . . . 43 4.4.5 Smart-contracts . . . 43 4.4.6 Hyperledger . . . 44 4.4.7 Substrate . . . 44 4.4.8 Polkadot . . . 45
4.4.9 Waste And Recycling Projects Review And Benchmarking . . . 45
220.127.116.11 Wasted Lab . . . 46
18.104.22.168 Swachhcoin . . . 49
22.214.171.124 European Waste Transportation on Blockchain . . . 50
126.96.36.199 RecycleGo . . . 51
188.8.131.52 Partitalia . . . 51
184.108.40.206 Plastic Bank . . . 52
220.127.116.11 End of waste (EOW) . . . 53
5 Primary and Secondary Data Collection: Scenario Survey . . . . 57
5.1 Screening facility overview: Tratolixo . . . . 57
5.1.1 Cover Area . . . 57
5.1.2 Processes Involved . . . 59
5.1.3 Main Challenges . . . 60
5.2 Generation of revenue from recyclable materials in Portugal . . . 60
6 BitBin: improving waste quality . . . . 64
6.1 Description . . . . 64
6.1.1 Application requirements . . . 65
6.1.2 Blockchain analysis . . . 65
6.2 Implementation . . . . 66
6.3 Conclusions & Future Work . . . . 66
The poor sorting of waste leads to certain materials which could be recycled to end up in landfills, and other more inappropriate destinations for waste such as the ocean. Now-a-days, citizens recycle for many reasons besides monetary incentives, besides there being rewarding schemes for returning cans and bottles and similar simple systems such as the previously mentioned.
There are no systems currently running that in a seamless way reward citizens for properly sorting their waste, the most similar project, called Swachhcoin is being developed in India however it never showed any signs of progress.
In this paper we present The BitBin project came to fill up that gap, and by doing so there was a need to develop a system to connect citizens and the other public and private stakeholders in a way that can be trusted by all the participants in the system.
Blockchain was chosen to be this system as it is transparent and immutable, and brings trust and security to its users. In this work the progress in building this system is explained and a more in depth look is taken at which types of blockchain were used and how they were tested.
In this paper we present also the state of the art and gather the existing information, within the established parameters, about waste management using concepts such as circular economy, through blockchain technology and integrated into a smart city scenario, and how this management has been applied in communities and what economic, social and environmental impacts.
The present research has applied nature, due to the practical interest, aiming at usable results in the solution of real problems. Through an exploratory and descriptive research, it is sought to explore the problem, in order to provide information for a more precise investigation, as well as to make a description of the study object. Primary and secondary data are used, secondary data were obtained through systematic literature review and bibliographic review, for the primary data collection visits were made to companies that carry out the collection, separation, screening and disposal of waste in the municipalities.
2 Research Characterization
The present research has applied nature, due to the practical interest, aiming at usable results in the solution of real problems. The search for description, and understanding of processes related to the research object, characterizes the approach as qualitative, as well, as the research seeks through numerical valuation to estimate the evaluated technologies. It is also characterized as quantitative, being classified as quali-quantitative approach.
Through an exploratory and descriptive research, it is sought to explore the problem, in order to provide information for a more precise investigation, as well as to make a description of the study object. Thus, a method for the management of urban solid waste through the use of blockchain technology is proposed, with the purpose of evaluating and validating the proposed method, as well as identifying gaps and opportunities for further research that may also contribute to the management of urban solid waste within the context of smart cities.
Primary and secondary data are used, secondary data were obtained through systematic literature review and bibliographic review, through books, scientific articles and documentation made available by European Commission Environment, European Parliamentary Research Service, United Nation, The Platform for Accelerating the Circular Economy (PACE), Portuguese Environment Agency, annual reports of sorting and collection company of solid urban waste, among others.
For the primary data collection visits were made to companies that carry out the collection, separation, screening and disposal of waste in the municipalities, observing the steps and processes involved in waste management, as well as, with specialists belonging to the functional staff of these companies helping to understand the stages. Further details on data collection and content handling are presented in the following sections.
3 Secondary Data Collection: Systematic Literature Review
This section presents a Systematic Literature Review (SLR) to survey the state of the art and gather the existing information, within the established parameters, about waste management using concepts such as circular economy, through blockchain technology and integrated into a smart city scenario, and how this management has been applied in communities and what economic, social and environmental impacts. Through this search, a survey is carried out to identify authors and journals relevant to the study. Following a SLR method through a sequence of steps, this work intend to map the results of relevant studies on the research subject, as well as to identify possible gaps.
The SLR aims to survey the state of the art and gather the existing information, within the established parameters, about the research object. SLR must be carried out in an impartial and systematic manner, following a well-defined sequence and respecting a set of steps that must describe from the phase of collection of the studies to their analysis.
This systematic form makes future revisions feasible, provided that the same procedures adopted are used, thus being able to be repeated, which validates the SLR, making it auditable, impartial and exempt. According to DRESH, LACERDA, and J JUNIOR (2015), SLR is used, among other functions, to map the results of relevant studies on a subject, as well as to identify possible gaps.
The objective of this SLR is to identify the state of the art on waste management using concepts such as circular economy, through blockchain technology and integrated into a smart city scenario, and how this management has been applied in communities and what economic, social and environmental impacts.
It also aims to verify the feasibility of applying some existing concepts in other sciences to the object of study. For this, bibliometrics studies and bibliographic review could be carried out, aiming to identify the main authors, magazines and terms used within the context of the research object.
After choosing the terms, a systematic literature review should be carried out in different databases, according the relevance on the research theme, chosen based on pre-established criteria, in order to search the keywords combinations, within the research object, in published papers in the last years.
There are several methods to perform an SLR, in this research was chose the method developed by Cochrane Collaboration, due to the representativeness that it has in the academic environment with more than 9.000 SLRs already published in the health
area and available at the Cochrane Library (COCHRANE LIBRARY, 2020).
As it is a method with a consolidated structure for systematized research, it can be replicated in others of knowledge that require an SLR, not being restricted to applications in the health area. According to this method, 7 steps must be performed, which are:
1) Step 1 - Research question;
2) Step 2 - Location and selection of studies; 3) Stage 3 - Critical evaluation of the studies; 4) Step 4 - Selection of data for analysis; 5) Step 5 - Analysis and presentation of data; 6) Step 6 - Data interpretation;
7) Step 7 - Improvement and update.
Through SLR, it is intended to carry out research in a reference database, according to the attribution given by CAPES (2020), considering the areas of knowledge and the quantity of journals available, in order to search what is already published within the research object.
As an initial idea, the keywords chosen were: Blockchain; Waste Management; Smart City/Cities; Circular Economy. These keywords summarize the concepts necessary to work with the proposed theme and were used for the definition of search strings, which is a phrase with the keywords and logical operators, used to perform searches in databases.
Through this search, a survey is carried out to identify authors and journals relevant to the study. Following the sequence of the steps mentioned above, it is intended to finally map the results of relevant studies on the research subject, as well as to identify possible gaps.
3.2 Step 1 - Research question
This research aims to answer the question: What currently exists in solid waste management using blockchain technology and how is it being used in cities?
3.3 Step 2 - Location and selection of studies
This study sought to use research in studies completed in the format of a scientific article, which have wide visibility through specialized bibliographic databases.
The first stage of this study was to identify keywords, main authors and relevant journals for the research object. As well as what methods to use to perform these identifications, which make it possible to use specific methodological procedures and contribute to the establishment of indicators in the context of the research object.
According to Noronha and de M. Maricato (2008) metric science studies are carried out to establish or strengthen measures that make it possible to raise a profile of the scientific world and these measures have been used in several areas of knowledge, with a lot of use as tools for decision-making and formulation of public policies. Through these metrics, indicators of research trends can be identified, in addition to “pointing out theoretical and methodological weaknesses in this production, thus contributing to overcome them” (de Figueiras Gomes, 2006, p. 4).
According to Noronha and de M. Maricato (2008) bibliometrics studies provide significant subsidies that assist researchers in the search for the best references for their work. In this sense, “researching the nature and incident use of bibliographic citations used in a given scientific area, becomes a relevant task that allows the tracking of the path taken by scholars in this area”(Zanine, de S. Pinto, & Filippim, 2012, p. 125).
According to Guedes and Borschiver (2005), bibliometrics laws are the support for the metric study of science, being these: Bradford’s Law of 1934, which aims to measure the productivity of journals; Lotka’s Law, 1926, which aims to measure the productivity of authors and Zipf’s Law, 1949, which aims to measure the frequency of words in a text. Zipf’s law is the one to aid in the identification of keywords, as it is a law that aims to indicate the distribution of words in a text, helping to choose key words to perform the SLR on the on the selected databases.
The keywords also could be selected from literature review, choosing words with greatest affinity with the research question theme, that was the strategy used for the biggest part of the papers selected from the SLR and showed at table 4. Some authors prefers a mix between bibliometrics laws and literature review to choose the best keywords, as Freire (2019) did on hers thesis, where the bibliometrics laws were applied on the Web of Science database - main collection (Clarivate Analytics), accessed through the Capes journals website, CAPES (2020), using a mix between Zipf’s Law and bibliography review to choose the keywords.
3.3.1 Defining search parameters
For this step, the Web of Science database - main collection (Clarivate Analytics) were consulted, accessed through the Capes journals website, CAPES (2020). This base was chosen to carry out keyword analysis studies due to its representativeness in the academic environment and multidisciplinary characteristics. Were chosen expression as topic, stipulated time and categories, as described below.
The choice of keywords was based on the research theme, as well as from the analysis of the most cited articles in the search carried out on the Web of Science, within the collections listed below, contextualized in the research, in order to answer the question of research. The bibliometrics laws were not applied, but a bibliographic review and analysis of keywords within the search.
In the search, the terms “Waste Management” and “Blockchain” were used in Topics. Estimated time of the last five years until 08/11/2020. Languages: English and Portuguese; Type of document: article. The most relevant results were in the collections: Scopus (Elsevier), with 215 results; Technology Research Database, with 173 results; Advanced Technologies & Aerospace Database, with 169 results; Materials Science & Engineering Database, with 161 results; Science Citation Index Expanded (Web of Science), with 142 results.
3.3.2 Keywords used to perform the SLR
In Table 1, the selected keywords are listed, accompanied by correspondence in the Portuguese language. These keywords, once defined, are organized in search strings in order to obtain greater specificity within the articles searched in the databases (Conforto, Amaral, & Silva, 2011).
From the combinations of keywords with logical operators, search strings are created for consultation in the databases. The terms are combined and used in English and Portuguese, resulting in the formation of 11 strings, the keywords are presented in Table 1 and the search strings in Table 2.
Table 1 – Selected keywords in English and Portuguese Keywords
GESTÃO DE RESÍDUOS WASTE MANAGEMENT
CIDADES INTELIGENTES / CIDADE INTELIGENTE SMART CITIES / SMART CITY
ECONOMIA CIRCULAR CIRCULAR ECONOMY
Elaborated by the authors.
For the strings’ formation, combinations are performed without repetition between terms, that is, combinatorial analysis. The first strings will be formed by combining 2 to 2 of 4 elements without repetition, represented by
C24 and indicating how many ways it is possible to choose 2 elements in a group of 4 elements. Equation 1 shows how the number of possible combinations was calculated for 4 elements combined 2 to 2 without repetition. Equation 1: C24 = (4!) (2! ∗ (4 − 2)!) = (4 ∗ 3 ∗ 2 ∗ 1) (2 ∗ 1 ∗ 2 ∗ 1) = 6 (3.1)
Using combinatorial analysis for the other possible combinations, which are: combination 3 to 3 of 4 elements without repetition, combination 4 to 4 of 4 elements without repetition, the values are respectively
= 1. Performing the sum of all possible combinations, that is, 6 + 4 + 1 = 11 possible strings, according to Table 2.
Table 2 – Strings Strings
1 ((blockchain) AND (waste management))
2 ((blockchain) AND (circular economy))
3 ((blockchain) AND (smart city OR smart cities))
4 ((smart city OR smart cities) AND (circular economy))
5 ((smart city OR smart cities) AND (waste management))
6 ((waste management) AND (circular economy)))
7 ((waste management) AND (circular economy) AND (smart city OR smart cities))
8 ((waste management) AND (circular economy) AND (blockchain))
9 ((waste management) AND (blockchain) AND (smart city OR smart cities))
10 (blockchain) AND (smart city OR smart cities) AND (circular economy)
11 ((waste management) AND (blockchain) AND (smart city OR smart cities) AND (circular economy)
Elaborated by the authors.
After defining the strings, it was verified which database would be searched. For this, the relevance of the bases was considered; areas of knowledge covered, taking into account the research object of this study and the amount of research available, according to the information provided by the CAPES (2020). In view of this analysis, 3 were the bases chosen, namely:
a) SCOPUS - Referential multidisciplinary database with abstracts. Covering several areas such as Biological, Health, Physical, Social and Engineering Sciences (CAPES, 2020).
b) Web of Science - Multidisciplinary database of referential type with abstracts that index the journals with the highest number of citations in their areas is composed of: SCI-EXPANDED, SSCI, A & HCI, CPCI-S, CPCI-SSH (CAPES, 2020).
c) IEEE - Database of complete texts and technical standards, within the areas of engineering, which provides journals; technical standards; conference and conference proceedings published by the Institute of Electrical and Electronic Engineers (IEEE) and the Institution of Engineering and Technology (IET) (CAPES, 2020).
After defining the search strings (Table 2) and the databases to be consulted, a relationship was made between the strings, the database consulted and the quantity of searches found, these data are detailed in the Table 3.
The strings were searched in topics, for Web of Science database; All Metadata for IEE and Article Title, Abstract ans Keywords for Scopus. Time base stipulated for searches: last five years until 08/11/2020. Languages: English and Portuguese. Type of document: article and proceedings paper.
String Number Strings Number of Occurrences SCOPUS Number of Occurrences Web of Science Number of Occurrences IEEE
1 ((blockchain) AND (waste management)) 31 10 15
2 (blockchain) AND (circular economy) 19 16 3
((blockchain) AND (smart city OR smart
cities)) 399 190 347
((smart city OR smart cities) AND (circular
economy)) 45 33 13
((smart city OR smart cities) AND (waste
String Number Strings Number of Occurrences SCOPUS Number of Occurrences Web of Science Number of Occurrences IEEE 6
((waste management) AND (circular
economy)) 1.244 1.104 46
((waste management) AND (circular
economy) AND (smart city OR smart cities)) 14 12 5
((waste management) AND (circular
economy) AND (blockchain)) 2 3 0
((waste management) AND (blockchain)
AND (smart city OR smart cities)) 3 1 3
(blockchain) AND (smart city OR smart
cities) AND (circular economy) 2 2 1
((waste management) AND (blockchain) AND (smart city OR smart cities) AND
String Number Strings Number of Occurrences SCOPUS Number of Occurrences Web of Science Number of Occurrences IEEE
Elaborated by the authors.
3.4 Steps 3 and 4 - Critical evaluation of studies and selection of data for analysis
The critical evaluation of the studies was carried out as follows: in the searches with 2 keywords, the titles of all documents were analyzed to verify which would be contextualized in the research, for the cases where the search returned with many documents, these were classified in decreasing order of number of citations in other articles and the titles of the 100 most cited were evaluated. Thus, within a total of 4.541 documents that returned from searches, the titles of 1.079 documents were verified.
For searches with 3 keywords, the titles and abstracts of all articles were checked. For the search performed with the 4 keywords, the articles should be read in full, however, the search in the 3 bases returned empty. This application resulted in the selection of 58 articles from the search with 2 keywords, and 20 articles from the search with 3 keywords, taking care not to be repeated.
For the selection of data for analysis, the 20 articles resulting from the search with 3 keywords were selected from the reading of the titles and abstracts. From the search with two keywords, the abstracts of the other 58 articles were obtained, previously selected by title. The result of this screen was the selection of 54 articles listed bellow to be read in full.
1 Environmental Aspects Of The Waste
Management Technologies In Bulgaria And EU Nikolai Vitkov
WSX - European Waste Services Exchange, Instrument To Start The Transition Towards Circular Economy
3 Quality Improvement in Organic Food Supply Chain Using Blockchain Technology
G. Balakrishna Reddy; K. Ratna Kumar
A Sustainable Circular Economy Approach for Smart Waste Management System to achieve sustainable development goals: Case Study in Indonesia
Yun Arifatul Fatimah; Kannan Govindan; Rochiyati Murniningsih; Agus Setiawan
5 Ageing population of cities – Implications for circular economy in the Czech Republic
Kristýna Rybová; Jan Slavík; Jan Evangelista
6 From Smart Campus to Smart City : Monastir Living Lab
Ahmed Noureddine Helal Sofien Benltoufa; Fadhel Jaafar; Mohsen Maraoui; Lamia Said; Mounir Zili; Hassen Hedfi; Mohamed Labidi; Abdelkader Bouzidi; Besma belhaj jrad; Hedi Belhadj Salah
7 Digital waste management using LoRa network a business case from lab to fab
Michail J. Beliatis; Hussam Mansour; Szabolcs Nagy; Annabeth Aagaard; Mirko Presser
The Management of Municipal Waste through Circular Economy in the Context of Smart Cities Development
Mirela Ionela Aceleanu; Andreea Claudia Erban; Marta-Christina Suciu; Teodora Ioana BiToiu
9 An Architecture for Blockchain over Edge-enabled IoT for Smart Circular Cities
Amalia Damianou; Constantinos Marios Angelopoulos; Vasilis Katos
10 IOT based Smart Waste Bin to Track Dustbin and
Public Complaint Management System Ajmal Khan; Sandeep kumar Agrawal
11 Blockchain and IoT Based Formal Model of Smart Waste Management System Using TLA+
Saba Latif; Aniqa Rehman; Nazir Ahmad Zafar
12 Proposing applied processes to achieve the Circular Economy model in the textile sector
Abeer Hussein Salem; Omnia Abed Mahmoud
Assessment of municipal solid waste
management system using a mixing index as indicative for urban sustainability analysis
Ricardo Morel Hartmanna; Luis Evelio Garcia Acevedo; Edson Bazzo
14 At the Nexus of Blockchain Technology, the Circular Economy, and Product Deletion
Mahtab Kouhizadeh; Joseph Sarkis; Qingyun Zhu
LCA-Based Comparison of Two Organic Fraction Municipal Solid Waste Collection Systems in Historical Centres in Spain
Jara Laso; Isabel García-Herrero; María Margallo; Alba Bala; Pere Fullana-i-Palmer; Angel Irabien; Rubén Aldaco
A Door-to-DoorWaste Collection System Case Study: A Survey on its Sustainability and Efectiveness
Nicola Laurieri; Andrea Lucchese; Antonella Marino; Salvatore Digiesi
Big Data Manifestation in Municipal Waste Management and Cryptocurrency Sectors: Positive and Negative Implementation Factors
Tadas Limba; Andrejus Novikovas; Andrius Stankeviˇcius; Antanas Andruleviˇcius; Manuela Tvaronaviˇcien˙e
18 Towards a Circular Economy–A Zero Waste Programme For Europe
Dana Corina Deselnicu; Gheorghe Militaru; Vioricadeselnicu; Gabriel Z ˘ainescu; Lumini¸ta Albu
Application of Blockchain Technology in Incentivizing Efficient Use of Rural Wastes: A case study on Yitong System
Blockchain-based life cycle assessment: An implementation framework and system architecture
Abraham Zhang; Ray Y Zhong; Muhammad Farooque; Kai Kang; V G Venkatesh
A Technological Alternative for Solid Waste Utilization with a Emphasis on Closed Production Cycles in Circular Economy
Amanda Marina Lima Batista; Fernando Zatt Schardosin; Clerilei Aparecida Bier; Carlos Roberto De Rolt; Henrique Fell Lautert; Denilton Luiz Darold
Dynamic visualisation of municipal waste management performance in the EU using Ternary Diagram method
R. Pomberger; R. Sarc; K.E. Lorber
23 Energy Balance of Waste Management Systems:
A Case Study Alberto Bellini; Alessandra Bonoli
24 A Romanian Zero Waste Strategy: Salacea and Cociuba Mare Case Study
Zoltán PÁSZTAI; Ferenc BRANNER; Klára HÜBNE; Tiberiu APOSTOL; Constantin STAN; Diana Mariana COCÂRT,A; Constantin STRECHE˘
25 A World Without Waste MICHAEL T. TIMKO
26 From Waste Management to Resource Efficiency—The Need for Policy Mixes
Henning Wilts; Nadja von Gries; Bettina Bahn-Walkowiak
27 Solid Waste and the Circular Economy A Global Analysis of Waste Treatment and Waste Footprints
Alexandre Tisserant; Stefan Pauliuk; Stefano Merciai; Jannick Schmidt; Jacob Fry; Richard Wood; Arnold Tukker
Do We Have the Right Performance Indicators for the Circular Economy? Insight into the Swiss Waste Management System
Melanie Haupt; Carl Vadenbo; Stefanie Hellweg
Municipal solid waste management and waste-to-energy in the context of a circular economy and energy recycling in Europe
J. Malinauskaite; H. Jouhara; D. Czajczy nska; P. Stanchev; E. Katsou; P. Rostkowski; R.J. Thorne; J. Col; S. Ponsa; F. Al-Mansour; L. Anguilano; R. Krzy_zy nska; I.C. L opez; A.
30 Use of Gamification Techniques to Encourage Garbage Recycling. A Smart City Approach
Alfonso González Briones; Pablo Chamoso; Alberto Rivas; Sara Rodríguez; Fernando De La Prieta; Javier Prieto; Juan M. Corchado
An integrated node for Smart-City applications based on active RFID tags; Use case on waste-bins
Dimitris Karadimas; Andreas
Papalambrou; John Gialelis; Stavros Koubias
32 Recycle.io: An IoT-Enabled Framework for Urban Waste Management
Eyhab Al-Masri; Ibrahim Diabate; Richa Jain; Ming Hoi Lam; Swetha Reddy Nathala
An IoT-based smart cities infrastructure architecture applied to a waste management scenario
Patric Marques; Diogo Manfroi; Eduardo Deitos; Jonatan Cegoni; Rodrigo Castilhos; Juergen Rochol; Edison Pignaton; Rafael Kunst
Developing criteria for performance assessment in municipal solid waste
A.P. Rodrigues, M.L. Fernandes, M.F.F. Rodrigues, S.C. Bortoluzzi, S. Gouvea Da Costa, E. Pinheiro De Lima
35 Utilization of energy from waste potential in Turkey as distributed secondary renewable energy source
Burhan Baran; Mehmet Salih Mamis; Baris Baykant Alagoz
The Use of Led Technology and Biomass to Power Public Lighting in a Local Context: The Case of Baeza (Spain)
Valentín Molina-Moreno; Pedro Núñez-Cacho Utrilla; Francisco J. Cortés-García; Antonio Peña-García
37 Circular ecosystem innovation: An initial set of principles
Jan Konietzko; Nancy Bocken; Erik Jan Hultink
38 A Research and Innovation Agenda for Zero-Emission European Cities
Francesco Fuso Nerini; Adriaan Slob; Rebecka Ericsdotter Engström; Evelina Trutnevyte
39 Blockchain and the circular economy: potential tensions and critical reflections from practice
Mahtab Kouhizadeh; Joseph Sarkis; Qingyun Zhu
From Trash to Cash: How Blockchain and Multi-Sensor-Driven Artificial Intelligence Can Transform Circular Economy of Plastic Waste?
Aditya Chidepatil; Prabhleen Bindra; Devyani Kulkarni; Mustafa Qazi; Meghana Kshirsagar; Krishnaswamy Sankaran
41 Tokenizing coopetition in a blockchain for a
transition to circular economy Rumy Narayan; Annika Tidström
Evaluation of Waste Electronic Product Trade-in Strategies in Predictive Twin Disassembly Systems in the Era of Blockchain
Özden Tozanlı; Elif Kongar; Surendra M. Gupta
44 Blockchain-based Smart Waste Management System
Satvik Shrivastava; Ankush Tripathi; R. Yamini
45 The future of waste management in smart and sustainable cities: A review and concept paper
Behzad Esmaeilian; Ben Wang; Kemper Lewis; Fabio Duarte; Carlo Ratti; Sara Behdad
46 Towards blockchain-based urban planning: Application for Waste Collection Management
Mohamed Ridda LAOUAR; Zaineb TOUATI HAMAD; Sean EOM
47 E-waste Management Using Blockchain based
Smart Contracts Neha Gupta; Punam Bedi
48 Custom Block Chain Based Cyber Physical System for Solid Waste Management
Ayush Thada; Uday Karan Kapur; Saif Gazali; Nikhil Sachdeva; Shridevi.S
Case study analysis of e-waste management systems in Germany, Switzerland, Japan and India: a RADAR chart Approach
Karishma Chaudhary; Prem Vrat
50 Blockchain Based Waste Management Preethi Gopalakrishnan; Ramaguru R
51 A Refuse Management System and Blockchain: A Practical View
Rohana Sham; Amir A’Atieff Hussin; Noranita Abdamia; Suhana
Mohamed; Won Jet Rou
52 Blockchain-based E-waste Management in 5G Smart Communities
Amit Dua; Akash Dutta; Nishat Zaman; Neeraj Kumar;
53 Blockchain-based Smart Contracts in Waste Management: A Silver Bullet?
GUIDO ONGENA; KOEN SMIT; JARNO BOKSEBELD; GERBEN ADAMS; YORIN ROELOFS; PASCAL RAVESTEIJN
54 Proposing the use of blockchain to improve the solid waste management in small municipalities
A.S.L. França; J. Amato Neto; R.F. Gonçalves; C.M.V.B. Almeida
Elaborated by the authors.
3.5 Step 5 - Data analysis and presentation
The papers selected allowed the literature review presented at chapter 2. The data analysis showed there are several papers describing the Blockchain technology and how that could be used for waste management but no one selected at the SLR showed a case of a real application for urban solid waste.
3.6 Step 6 and 7 - Data interpretation, improvement and update
The data interpretation showed the selected papers are about concepts and theoretical ideas, there is a lack of applied case studies presenting researches and data about how to improve waste management for urban solid waste in a smart city context through blockchain technology improving circular economy. An applied case could validate the ideas presented in the papers about the use of blockchain for waste management, showing the strengths and weaknesses for this application and fulfill a knowledge gap with a practical result.
4 Secondary Data Collection: Literature Review
The generation of solid urban waste has been gradually increasing in recent years worldwide, the main factors being the global increase in the human population, urbanization and the increase in the population’s purchasing power. In view of this increase, countries have been investing in ecologically safe treatment of domestic waste, through investments in technologies, infrastructure and economical destination of final products. European countries are among the leaders in implementing these technologies (Vitkov, 2019).
4.1 Municipal Solid Waste Management
With regard to the management of urban solid waste, recycling impacts the reduction of the need for primary raw materials and energy for its production, the amount of waste deposited in landfills and the environmental impact. The disposal of materials without proper recycling is also counterproductive when considering the complexity of the resource extraction processes and the energy expenditure for processing the obtained raw material.
“In Europe, 16 tons of material are consumed per person per year, of which 6 tons are transformed into waste, 36% of all waste generated is recycled, the rest goes to landfill or burned, in some countries, 80% of all household waste goes to landfills” (Batista et al., 2020, p. 2).
In developing countries this situation is much worse, in Brazil, for example, in 2018, 79 million tons of waste were generated and, although 70% is collected by the Government, 40% of the collected waste is disposed of in landfills, part of that landfills do not receive adequate treatment to avoid environmental damage and health risks to the population (Batista et al., 2020). Beyond the environmental risks, when the waste is not reused, products that could be used as row material are lost.
In this sense, the World Economic Forum of the year 2019, held in Davos, Switzerland addressed, among urgent actions to the environment, the need for the rational use and recycling of materials to combat climate change. Graphic 1 shows the growth of recycled materials in the European Union (EU), compared to that produced from solid urban waste.
The waste and landfill Directives allows a better uniformity of EU law application and intends to minimize negative impacts on the environment and human health, according to the 7th Environmental Action Program, the priority objectives of European policy will be: to reduce the total waste generated; maximize recycling and reuse; limit the burning of unused materials; gradually eliminate the landfill for non-recyclable products and non-recoverable waste; ensure the implementation of these objectives in
waste management in all Member States (EUROPEAN COMMISSION ENVIRONMENT, 2020).
Non-recyclable and thermally processed urban solid waste is disposed of in landfills, most of the time in open places, without impermeable protections, being the most harmful way of treating waste to the environment. In Europe, because of the actions of the European Union (EU), acting as a supra-national institution, the garbage sent to landfills has been decreasing in recent years in Europe, as shown in Graphic 3.
The EU “has been able to affect policies within the majority of its member countries. In the field of waste management, The Thematic Strategy on the Prevention and Recycling of Waste includes the main policies, general objectives and action principles. (Costa, Massard, & Agarwal, 2010, p. 7).
“The EU influences member countries through regulations (laws applied in full throughout the Community), directives (binds members to achieve objectives; however, they are free to address their local distinctiveness while incorporating the objectives into their legal system) and decisions (binds particular individuals, firms or member states, to perform or refrain from an action, confer rights or impose obligations)“ (Costa et al., 2010, p. 7).
Even with the EU policies application, as we can see in the graphics bellow, there is differences between countries. Where the percentage of recycled waste is high, such as Bulgaria, this can be explained by the financial interest in its commercial realization. Most metals, plastics, paper and cardboard are recycled, as they do not require specialized processing, and are sold directly as raw material. Other wastes such as wood and textiles are not as commercial, as they are not subject to direct use (Vitkov, 2019).
Another countries has a historical directives and regulations on environment and nowadays they have better efficiency on waste management, as graphic 6 shows with Denmark leads this ranking with more than 400 kilos per capita of urban waste destined for energy production, and as shown in Graphic 7, regarding the production of energy from solid urban waste with Germany leading the ranking.
In Portugal the EU directives and regulations are the base of Portuguese waste legislation, despite this, in 2019, 3 out of 5kg of urban waste were sent to landfills in Portugal. According to the EU goals, this year Portugal should recycle 50% of all the packaging and improve even further. Although, last year it recycled 41%, an increase of only 1% from the previous year. Another important goal is to reduce to 10% all waste destined to landfills until the year of 2035, nowadays Portugal sent 58% of all waste destined to landfills, as shown in Graph 8 (AGÊNCIA PORTUGUESA DO AMBIENTE, I.P. DEPARTAMENTO DE RESÍDUOS, ANA MARCAL, & CRISTINA FERREIRA, 2020, Jul.; Coentrão, 2020, Ago. 3).
The waste management legislation in Portugal follows the EU guidelines, the national waste management plans follow methodological guidelines for regional development adopted through European financing programs, with construction and operation in the municipalities of waste incineration facilities, including the use of the energy generated.
The development of waste legislation in Portugal takes place only at the national level, the two main documents that guide this regulation are: Law 11/87, National Law of the Environment that establishes the general principles of environmental protection having in its article 24 the disposal of waste and its reuse / recycling as raw material and energy; and Decree-Law no. 178/2006, which establishes the provisions for activities related to transportation, treatment, storage and disposal of waste (Costa et al., 2010).
“In policy terms, there is one national waste plan and four plans for specific waste flows (e.g. urban, industrial, medical, agricultural), covering targets and instruments. For urban waste, regional plans are also developed. National recycling networks also exist, each dedicated to one of eight types of waste materials. Each system is managed by a not-for-profit entity, formed by representatives of producers and recyclers” (Costa et al., 2010, p. 12).
The graphic bellow shows some numbers in Europe, related to waste management, as we can see in some of them, Portugal occupied a bad position, being the 8th worst country in kilograms per capita sent to landfills, regarding the production of energy from solid urban waste, Portugal in 2016 produced 92 kilos per capita while Denmark leads this ranking with more than 400 kilos per capita of urban waste destined for energy production. It seems that in addition to legislation and public policies Portugal needs an innovative solution to achieve the EU goals.
Graphic 1 – Percentage of recycled waste originating from solid urban waste in the EU.
Own elaboration, adapted from Vitkov (2019).
High humidity biodegradable municipal waste is usually composted with energy recovery for the production of biogas and biofertilizer. The resulting biogas is used as a fuel with a slightly lower calorific value than methane in combustion plants. The waste from biogas production is used for composting. Composting without biogas recovery, only as a biofertilizer, is not advisable from an environmental point of view, since the methane produced is released into the atmosphere as gas greenhouse effect, in addition to the value not generated by energy production (Vitkov, 2019).
The economic viability of biogas conversion projects and the use of gas in combustion plants is determined by the value of the investment and the possibility of profitable realization of the energy produced. The average percentage of composted waste for the EU in the period from 2008 to 2017 is shown in Graphic 2, where there is stability with an increase from 14 to 17% during the period.
Graphic 2 – Average composted waste in the EU.
Own elaboration, adapted from Vitkov (2019).
Graphic 3 – Waste destined for landfill in the EU
Own elaboration, adapted from Vitkov (2019).
Graphic 4 shows the comparison of landfills in different EU countries, showing differences in absolute units, kilograms per capita, with major differences between the more developed and less developed countries. In 2016, Portugal occupied 8th place, behind only Cyprus, Malta, Greece, Croatia, Bulgaria, Spain and Slovakia.
Graphic 4 – Waste destined for landfill in the EU kilogram per capita.
Own elaboration, adapted from Vitkov (2019).
A significant part of solid urban waste is used for energy generation. Over the period considered, the relative share of MSW for energy in the EU increased by around 10%, from 16 to 27%, as shows Graphic 5. Open burning of waste without energy recovery has not been practiced in the EU since 2014 (Vitkov, 2019).
Graphic 5 – Waste destined for energy production in the EU.
Graphic 6 shows that Denmark leads this ranking with more than 400 kilos per capita of urban waste destined for energy production, Portugal in 2016 produced 92 kilos per capita.
Graphic 6 – Urban waste destined for energy production by countries in the EU per kilogram per capita.
Own elaboration, adapted from Vitkov (2019).
Regarding the production of energy from solid urban waste, Germany leads the ranking, as shown in Graphic 7, Portugal occupies the 14th position.
Graphic 7 – Energy generated from urban waste in the EU per Giga Watt hour.
Graphic 8 – Europe Union goals to achieve in Portugal.
The researched articles point out to the need to change the mentality in relation to urban solid waste at all levels, from ordinary citizens to responsible institutions. Citizens are becoming aware that waste cannot be disposed of irresponsibly, being an immediate threat to the environment and their own health.
On the other hand, waste is a potential raw material reused for products and for energy production. The implementation of financial instruments, incentives and sanctions are other measures little used by which the government has the opportunity to influence the population to maximize the use of waste and minimize its negative impact on public health and the environment.
When the waste is sent for recycling, that material generates considerable incomes. In Brazil, for example, “A single referral program for packaging recycling called Give a Hand to the Future, with the recovery of 22% of packaging that was placed on the market only by partner companies, handled around C 13.5 million” (Batista et al., 2020, p. 2).
Some actions that can be mentioned show that the practices are being adopted, the Netherlands has developed a blockchain-based platform for waste management and transportation. In Greece, special consideration is given to the use of innovative technologies for waste processing and energy recovery. In Sweden, burning waste helps to heat buildings, as a substitute for fossil fuels, every 4 tonnes of waste has energy equivalent to 1 ton of oil (Batista et al., 2020; Flinders, 2018; Ringhof, 2020; Yee, 2018).
should consider the entire ecosystem with innovative actions bringing together different actors in a circular economy context. There are several forms to start the Ecosystem innovation, different technology organizations could form a consortium, for example, it is important to have policy organizations and research institutions.
Konietzko, Bocken, and Hultink (2020, p. 6) points out “ecosystem innovation can be initiated by bringing together new and previously unconnected actors, from business, research, policy and civil society. Involving new actors stimulates ‘out-of-the-box’ thinking: it ensures that the participants approach a problem from multiple and previously unrecognized angles“. In the next topic the theme is addressed in a broader view of Circular Economy.
4.2 Circular Economy
In the last few decades, there has been an increase in research and efforts aimed at reorganizing socioeconomic structures with a view to preserving the environment and circular economic growth through a sustainable society. However, the actual mode of production remains destructive, based on excessive consumption in an accelerated cycle of production and disposal, with a growing volume of municipal solid waste.
Since the industrial revolution, the world had worked as a one-way model of production and consumption as ‘take-make-consume and dispose’ pretending that resources are abundant, accessible, and affordable to throw away. This system caused negative environmental impacts with the increase on consumption due to the world’s population growth.
“Circular economy systems keep the added value in products for as long as possible and eliminates waste. They keep resources within the economy when a product has reached the end of its life, so that they can be productively used again and again and hence create further value” (“Communication from the Commission to The European Parliament, The Council, The European Economic and Social Committee And The Committee of the Regions. COM(2014) 398 final”, 2014, p. 2).
On the illustration bellow from “Communication from the Commission to The European Parliament, The Council, The European Economic and Social Committee And The Committee of the Regions. COM(2014) 398 final” (2014) it is possible to visualize the major stages of a circular economy where in each of them costs and dependence on natural resources can be reduced. All the processes on the diagram are interlinked, as materials are reused on all phases. The goal is to optimize the system by reducing resources that escapes from the circle.
Figure 1 – The main phases of a circular economy model.
European Commission Environment, 2014 .
According Konietzko et al. (2020, p. 1) “a circular economy maximizes the value of material resources and minimizes greenhouse gas emissions, resource use, waste and pollution“, ”(. . . ) transitioning to a circular economy therefore requires product, business model and ecosystem innovation“.
In 2019, according to THE PLATFORM FOR ACCELERATING THE CIRCULAR ECONOMY (PACE) (2019), only 9% of the global economy is circular, which means that less than 10% of the 92.8 billion tons of materials used in production processes are reused.
To change the current paradigm, circular economy approaches are increasingly discussed, through regenerative systems in which the consumption of resources, waste production, carbon emissions and energy losses are minimized through practices of closed production cycles in Circular Economy and Industrial Ecology as recycling, remanufacturing, reuse, repair, maintenance and new business models (Konietzko et al., 2020).
There is a lot of definitions for circular economy, Kirchherr, Reike, and Hekkert (2017) identified 114 definitions and formulated an understanding about the concept as an economic system operating in all levels, as production, consumption, industrial, regions, replacing the end of life cycle of materials though actions aimed at recovering materials as recycling, with the aim of creating a more sustainable society with social equity and environmental quality.
Kirchherr et al. (2017) approach is based on three principles: “preserving and revitalizing ecosystems by controlling non-renewable resources and balancing flows of renewable resources, prolonging use and optimizing the yield of product and material components and promoting system efficiency by achieving their difficulties“ (Batista et al., 2020, p. 3).
In fact circular economy is a theme that brings together several schools of thought, Industrial Ecology (IE) is one of that ideas that most aligns with this work, aiming to make productions closed with the cooperation between the actors, “closing their production cycles by reusing or entering waste from one into the other’s production process, generating an economically and environmentally viable industrial symbiosis” (Batista et al., 2020, p. 3).
The literature also reveals three concepts that should have attention for business ecosystems in a circular economy context: innovation ecosystems, focusing on the value proposition of the solution through multiple actors acting together but with one actor playing the rule of the ’orchestrator’ for example, the owner of a platform; service ecosystems, focusing on services as the basis of the exchanges, actors interecting and depending of each other, co-creating value and sometimes facing complexites because different rules and beliefs; platform ecosystems, focusing on different actors acting together through a coomon market-oriented platform, “the more actors join, the more attractive the platform becomes, which in turn attracts more actors“ (Konietzko et al., 2020, p. 3).
Through literature review, Konietzko et al. (2020) identified three groups of principles for the innovation of the circular ecosystem, these being through: collaboration, on how organizations can interact; experimentation, about how organizations can structure actions oriented towards trial and error processes; and through platforms, on how organizations can organize social and economic interactions through online platforms. “Ecosystem innovation seeks to change how a set of actors collaborate and relate to each other to contribute to a collective outcome“ (Konietzko et al., 2020, p. 3).
To promote Circular Economy some entities appears in order to promote collaboration, helping companies to find partners to reuse the waste and avoiding landfill disposal, promoting actions as commercialization of waste and the incentive to the use of recycled products, the National Industrial Symbiosis Programme (NISP) is an example in the United Kingdom and the Organized Waste Market (OWM) in Portugal (Costa et al., 2010).
In attempt to rich the actors involved at the transactions on line platforms also appears in market places formats, using Apps and platforms where all transactions occur in an e-commerce model. Batista et al. (2020) realized a benchmarking of some platforms, showed at table 1, witch fulfilled the categories of Circular Economy Application, the common Functional Requirements for that solutions are “User profile;
Geolocation; Photos; Product Listing; Chat between seller and buyer; Payment methods; Purchases historic (Batista et al., 2020, p. 4)“.
Table 5 – Benchmarking Circular Economy marketplaces.
A. M. L. Batista et al., 2020
To make possible that the innovative approaches works it is important to have a look in the entire innovation ecosystem, not waiting to the perfect actors, as Konietzko et al. (2020, p. 6) points out different actors will bring also conflicts due to different interests, but studies cases shows that “Similar values appear to be especially important for a normative goal like a circular ecosystem (Konietzko et al., 2020, p. 6).“
Konietzko et al. (2020) realized an ecosystem innovation case study, including 20 interview with eleven key individuals over the course of 15 months, from that it is possible to observe some important points to highlight about partners participation:
1) Establishing and maintaining trust between partners is critical.
2) Commitment from partners to ensure that the initial project proposals are met on time.
3) Align the different interests so that even if there are conflicts, everyone works with the same goals.
4) Clear roles and responsibilities for all actors even if they need to be redefined, the terms and boundaries of role changes must be made clear, lack of clear responsibilities generate frustrations.
5) To have a collaborative and decentralized governance enabling all stakeholders to participate in the decision-making process.
6) Make it clear how partners will benefit from the joint project through clear legal frameworks.
4.3 Municipal Solid Waste Management Strategy in Smart City Context
According UNITED NATIONS, DEPARTMENT OF ECONOMIC AND SOCIAL AFFAIRS POPULATION DIVISION (2015) by 2050 almost two-thirds of the world’s population will be living in urban areas. Large cities with ever-increasing populations will need smart services to assist management, thereby meeting citizens’ needs. The technology could deal with this scenario in a smart city context, with the convergence of information and communication technologies to provide solutions in fields as waste management, infrastructure, transports, energy, surveillance, etc.
“A smart city is an urban development vision to integrate multiple information and communication technology (ICT) solutions in order to manage a city’s assets. City’s assets may include, but not limited to, local departments information systems, schools, libraries, transportation systems, hospitals, power plants, law enforcement, vehicle traffic, waste management and other community services. The goal of building a smart city is to improve quality of life by using technology to improve the efficiency of services and meet residents’ needs.“ (Karadimas, Papalambrou, Gialelis, & Koubias, 2016, p. 1).
This becomes reality through the use of systems and sensors in real time, with data being collected through devices and processed, generating information that helps in the better management of cities.
In the waste management context, several papers propose solutions for intelligent garbage collection using the concepts of Internet of Things (IoT), that involves waste bins, providing information collection at the point of waste disposal, such as filling variations and locations.
Shyam, Manvi, and Bharti (2017) presented a solution that provides intelligence to waste bins, it is an IoT-based system with sensors that measures the level of waste in residential waste bins and sends this data to a server, aiming at improving garbage collecting routes in big cities. The authors tried to replicate the scenario using Open Data from the city of Pune, India.
Hong et al. (2014) presented an IoT-based system that is currently implemented in South Korea. When the citizen is going to discard the waste the solution identifies them through RFID cards in the bins. The waste is weighed and the information is sent to a server that processes the data for billing purposes.
Besides these examples, there is several papers presenting solutions for smart bins. According to Marques et al. (2019, p. 1), despite very relevant “the proposals currently found in the literature are mainly focused on garbage collection, not taking into account another important aspect, which is the correct waste separation considering the characteristics of the disposed products“. The authors also identified a lack of evaluations of solutions implemented in the real world.
Marques et al. (2019) implemented a solution through Raspberry Pi hardware, to improve sort waste. The garbage bins were equipped with RFID readers, collecting data from tags located in the products, witch provides the identification of the product to be disposed off. When a person approaches the bins the system queries the products database and consequently open the correct bin. After the disposal, information about the product, such as its type and weight are uploaded to the database, based on the amount and kind of disposed products the garbage collection routes also could be improve.
The biggest part of the papers analyzed consists of smart bins equipped with sensors to detect the level of waste in real time. Determining the filling level for bins in real-time to improve waste management, optimizing the routes for waste collection.
Others projects aims to improve the waste sorting though products identification, that could be before of the product be disposed off, guiding the citizen, as showed in Marques et al. (2019) or after the disposal as the Recycle.io project, Al-Masri, Diabate, Jain, Lam, and Nathala (2018), where cameras are attached to waste bins that capture images of disposed items. These cameras are connected to edge devices that are capable of processing images locally at the edge of a network and check any violation. All of them requires IoT systems and sensors, involving hardware and software innovation.
In this section we give a brief overview of what is blockchain, Bitcoin and cryptocurrencies, Ethereum and smart-contracts, and finally Hyperledger and its variants. For now we will only present the key features and distinguishing factors between them, but later on we will discuss how each one relates and eventually changed the course of The BitBin Project.
Blockchain is a list of records, called blocks, that are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data (usually represented as a Merkle Tree) (SELFKEY FOUNDATION, 2020; WIKIPEDIA, 2020a). The most important property of a blockchain structure is that in order to change one block, all subsequent blocks must be altered as well.
agree on a protocol for communication and block validation. In this sense, blockchain is used as a distributed ledger, where all nodes synchronize to the same state. Due to its cryptographic nature, blockchain is usually considered “secure by design”, which is a key factor when we talk about distributed systems due to Byzantine faults, to which blockchain has high tolerance to.
Blockchain is one of the most innovative technologies of our time changing our perception of how we approach topics such as transparency of information, distributed databases, trust and consensus. In a blockchain, data is stored following a certain timeline: data is grouped together in what we visualize as blocks and then cryptographically secured using a hash function. Every block needs to be validated by the nodes that store, preserved and spread blockchain data. The network has to reach consensus on the final state of the chain having every node get a copy of the next valid block.
A critical part of every blockchain is the consensus, used to achieve agreement between participants of the network. Bitcoin for example, uses Proof of Work (PoW) that makes use of electricity for heavy computations to find a valid hash. Since Bitcoin other types of consensus, like Proof of Authority (PoA), have been idealized in order to increase scalability and efficiency compared to it.
4.4.1 Consensus Algorithm
As stated before, nodes agree on a way to communicate information between them, but most importantly, the way all nodes in the network validate a block to add it to the blockchain. This is called the consensus algorithm.
The consensus algorithm defines many more things than just communication. For example, a computation heavy algorithm will consequently make the network consume more energy, and if it promotes competition between nodes, this effect will be more noticeable. In short, the consensus algorithm is the core of a blockchain, and to have a good blockchain, it is required to have a good algorithm as well.
4.4.2 Mining and Validating nodes
In some blockchains there are other concepts for nodes based on their behavior. The most common are mining nodes and validating nodes.
Mining nodes, ’mine’ the blockchain for rewards (usually a cryptocurrency). This serves as an incentive for the addition of nodes to the network that will ultimately make it more secure. These usual nodes represent the majority of the network and are the ones responsible to add new blocks and transactions to the blockchain.
Validating nodes are much simpler than mining nodes, these ones just validate that the blockchain is in a correct state and that the defined protocols are being followed.
Validating the blockchain is very important, but because it’s an easier job and one that does not wield any rewards, they are in much less quantity.
Bitcoin is one of the most known blockchains in the world. It was first introduced by an unknown author/group named Satoshi Nakamoto in 2008. This blockchain was created as a “purely peer-to-peer version of electronic cash” that can “be sent directly from one party to another without going through a financial institution” (Nakamoto & Bitcoin, 2008).
In the BitBin project, the most relevant part of Bitcoin is its consensus algorithm, known as Proof-of-Work (PoW). For miner nodes to mine blocks they have to brute force a hash, or in other words, guess a random number by trial and error. Using PoW means that a miner must expend energy in order to mine a block, and this amount increases with the difficulty of the network (that increases the more mining nodes and transactions exist).
Because of this, hardware specifically designed for bitcoin mining were created to be more cost effective and mass-produced. Nowadays, Bitcoin mining consumes more energy than what its rewards are worth. Another important note is that Bitcoin is a very inflexible protocol. The Bitcoin protocol is very strict and very difficult to create systems on top of it. Therefore, Bitcoin serves as an inspiration for our work.
Ethereum is very similar to Bitcoin, but adds a native application layer on top. Where Bitcoin was inflexible in use cases, Ethereum provides a platform for developing decentralized applications (dApps), in the form of scripts (smart-contracts), with the blockchain keeping its state (Buterin, 2014; Wood, 2014).
Another technical aspect that is worth talking is the hashing algorithm it uses for its PoW consensus. Unlike the Bitcoin SHA-256, Ethereum uses a custom hashing algorithm called ETHash with the intent of being ASIC-resistant via memory-hardness (WIKIPEDIA, 2020b).
Smart-contracts are, in short, scripts that run on the blockchain. When developing a smart-contract, we specify what information is kept in the blockchain, which computations are made, etc. This is an amazing feature for applications where availability is important and parties don’t trust each other. But all of this comes at a cost.
The act of deploying a smart-contract or interacting with an existing one, costs ethereum (the cryptocurrency used in Ethereum) based on complexity and data stored.
In low value transactions fees might be an issue, however, for high value transactions fees represent a low percentage and therefore those applications are viable. Due to this, there are several dApps running in the Ethereum mainnet from finance and exchange to gambling and games.
“Hyperledger is an open source collaborative effort created to advance cross-industry blockchain technologies”. Hyperledger is a project under The Linux Foundation that offers several solutions for different environments. These options are developed by big companies such as Intel, IBM, Microsoft, Oracle, etc (HYPERLEDGER, 2020) .
Unlike Bitcoin and Ethereum, Hyperledger allows to define what type of blockchain the project wants to build. It’s important to note that overall, Hyperledger is focused on enterprise blockchain solutions. The BitBin Project looked at Hyperledger Fabric and Sawtooth which are similar, that will be discuss later.
Substrate is a platform for the development of custom blockchain applications in an easy and effective way. It utilizes a modular framework to simplify development time and effort. The substrate core is the runtime where the custom logic of the blockchain is built. In the runtime you can change the current state of the blockchain and make it programmable to emit events and make it dynamic (SUBSTRATE DEVELOPER HUB, 2020).
The core substrate codebase take advantage of the Framework for Runtime Aggregation of Modularized Entities (FRAME) is a group of modules referred to as pallets and support libraries, inside these pallets the developer can implement domain-specific logic and can later on integrate it with other pallets. Inside the pallet there are storage items, functions and types that define the desired functionality of the program. The runtime determines which pallets and components are going to be used. Substrate has pre-build libraries which are used commonly in blockchains (SUBSTRATE DEVELOPER HUB, 2020).
The BitBin project aim to create a system reward utilizing a token which will be exchangeable with other assets. To reach this goal we use the Substrate framework to build the blockchain making use of the pre-built libraries and the integration we can make with network protocols such as Polkadot.
It is a network protocol which connects different blockchains in a standard. Composed of a relay chain, parachains, parathreads and bridges. The first one is the core of the system which has its own governance model. Parachains are the blockchains which will be using this protocol and parathreads are similar but utilizes a pay-as-you model. The so called bridges connect these blockchains making it an ecosystem of blockchains which can interact with each other (POLKADOT, 2020; Wood, 2020).
The BitBin Project main blockchain where the token reward system will be implemented, will communicate with another blockchain holding the waste animals. The users will be able to trade these digital unfungebla tokens using the rewards gained. 4.4.9 Waste And Recycling Projects Review And Benchmarking
To define the platform’s functionalities proposed in that paper, a benchmarking was carried out in search of the best characteristics for the technological alternative, using the same keywords of the SLR, 10 results were obtained, they are: Wasted Lab; Swachhcoin; European Waste Transportation on Blockchain; RecycleGo; Partitalia; Plastic Bank; End of waste (EOW); Arep; Recereum; Circulor.
From the experience of analyzing the 10 solutions found, we identified the best examples of functionalities, business models ans use cases, were also possible to identify the lack of them, the details of which one are described on the next topics. The figure bellow shows which of that projects attend the Waste Management System (WMS), Circular Economy, Smart City and Blockchain areas.