Elsevier

Waste Management

Volume 73, March 2018, Pages 26-38
Waste Management

Design, implementation, and evaluation of an Internet of Things (IoT) network system for restaurant food waste management

https://doi.org/10.1016/j.wasman.2017.11.054Get rights and content

Abstract

Catering companies around the world generate tremendous amounts of waste; those in China are no exception. The paper discusses the design, implementation, and evaluation of a sensor-based Internet of Things (IoT) network technology for improving the management of restaurant food waste (RFW) in the city of Suzhou, China. This IoT-based system encompasses the generation, collection, transportation and final disposal of RFW. The Suzhou case study comprised four steps: (1) examination of the required functionality of an IoT-enabled system in the specific context of Suzhou; (2) configuration of the system architecture, both software and hardware components, according to the identified functionality; (3) installation of the components of the IoT system at the facilities of the stakeholders across the RFW generation-collection-transportation-disposal value chain; and (4) evaluation of the performance of the entire system, based on data from three years of operation. The results show that the system had a strong impact. Positive results include: (1) better management of RFW generation, as evidenced by a 20.5% increase in RFW collected via official channels and a 207% increase in the number of RFW generators under official contract; (2) better law enforcement in response to RFW malpractice, enabled by the monitoring capabilities of the IoT system; and (3) an overall reduction in illicit RFW activities and better process optimization across the RFW value chain. Negative results include: (1) Radio-frequency identification (RFID) tags need to be renewed often due to the frequent handling of waste bins, thus increasing operating costs; (2) dynamic/automatic weight sensors had a higher degree of error than the more time-consuming static/manual weighing method; and (3) there were disagreements between the city’s government agencies about how to interpret data from the IoT system, which led to some inefficiencies in management. In sum, the Suzhou IoT system enabled data-driven management of RFW and had a net positive impact for the stakeholders involved.

Introduction

Catering companies around the world generate tremendous amounts of waste, not only of food, but also of paper, plastics, metals, wood, cardboard, and hazardous materials. “Restaurant food waste (RFW)”, the focus of our research, is produced by the catering industry and is composed of two segments: (1) food residue generated from commercial dining tables and kitchens; and (2) grease collected from oil-water separators and grease traps. In China, for instance, about 40 million tons of RFW were produced in 2014, accounting for 50% of all food waste that year (Wen et al., 2015). In Germany, 18 million tons of food waste are produced annually, with a significant fraction coming from restaurants (Pleissner et al., 2017). Such quantities of waste can lead to significant costs. In the United Kingdom, food waste represents a cost to the catering sector alone of 682 million GBP (WRAP, 2015). Due to its high organic matter and moisture content, RFW is rich in nutrients and can be an important source of organic fertilizer and bioenergy after proper treatment. On the other hand, treating RFW improperly can lead to serious food safety and environmental problems. These include: harm to public health as a result of strong odors, pathogenic microbes, and mycin from rotten RFW; sewer blockages due to directly discharged RFW; groundwater pollution, soil pollution, and methane emissions from RFW disposed of in landfills (Yang et al., 2013); and the spread of disease and threats to human health as a consequence of directly feeding untreated RFW to livestock.

In response to rapidly increasing amounts of RFW, numerous policies and laws have been implemented in countries around the world to promote the integrated utilization of such waste (De Clercq et al., 2016, De Clercq et al., 2017). While such policies are encouraging, further work is required to enhance RFW management. Turning RFW into useable and commercial resources requires coordination across the value chain, including generation, collection, transportation, disposal, and utilization. Management frameworks must take into account multiple stakeholder interests, such as those of catering companies, collection and transportation service providers, and disposal service providers.

In China, there are two traditional ways to treat RFW. The first involves selling RFW to illegal third-parties, who manufacture low-quality “gutter oil” (re-processed cooking oil) or pig feed. This presents significant food safety risks. The second traditional scheme involves collection of RFW mixed with other waste, which complicates subsequent treatment and leads to environmental problems (Pei, 2014). In addition, secondary pollution from the traditional method of collection and transportation is significant. In order to alleviate problems associated with traditional treatment methods, the Central Government issued a policy notice on “Organized Development of Municipal Food Waste Resource Utilization and Safe Disposal Pilot Projects”. This has led to the ratification of 100 “pilot cities” where pilot-scale RFW treatment projects are to be constructed. Under the 12th Five Year Plan, 242 projects were slated to be built across these pilot cities (De Clercq et al., 2017). Anaerobic digestion is the principal technology being implemented, given the positive environmental effects and the output of valuable products associated with this mature technology (Franchetti, 2013, Jin et al., 2015, Xu et al., 2015, Zhang et al., 2014, Vandermeersch et al., 2014, Villarroel Walker and Beck, 2014, Bernstad and la Cour Jansen, 2011). The economic potential of anaerobic digestion for nutrient-resource recovery from urban and agricultural wastes is, in fact, quite impressive (Villarroel Walker and Beck, 2014).

Despite these attempts to enhance RFW management in China, many issues persist. One significant problem is that the flow of RFW is difficult to control, so that the illegal trade and informal treatment of RFW is still very extensive in China. In addition to the aforementioned food safety and environmental problems, this also leads to under-capacity in respect of formal and legal treatment plants, which results in higher unit costs for these official RFW treatment paths. For instance, De Clercq et al. (2016) found that one major project in Beijing could only attain 27% of its designed capacity because of upstream waste collection problems. One of the main reasons for such persistent problems is the lack of effective supervision in the existing RFW management system.

The Internet of Things (IoT) refers to network technology which permits sensor-based information exchange between objects. The technology offers significant advantages in terms of traceability, adaptability, real-time monitoring, and more (ITU, 2005, EPoSS., 2008, Atzori et al., 2010). Given these technological advantages, IoT opens up opportunities for alleviating the difficulties cited above and enhancing the management of RFW. IoT applications to the food supply chain and food waste have accordingly been gaining more attention in recent years, although research on applications to RFW in particular is notably lacking. The innovative contribution of this article is thus the application of IoT to RFW management via a large-scale case study in an important metropolitan region.

Wang and Yue (2017) developed an IoT-supported infrastructure framework that provides an early warning system for food safety risks across the food supply chain. Nychas et al. (2016) have also explored the potential of using information technology across the food chain, including cloud computing and IoT, primarily for food safety management. Regarding food waste, Hong et al. (2014) proposed an IoT-based smart garbage system (SGS) to improve the effectiveness and efficiency of a “Pay as You Throw” management scheme in South Korea. They implemented it as a pilot project in the Gangnam district, Seoul, for a one-year period. The experiment shows that the SGS, along with the adaptive user-oriented policy, results in not only food waste reduction of about 33%, but also energy savings of 16%.

In the United States, IoT systems (such as Grind2Energy) are enabling disposal service providers to identify wasteful habits and fix equipment before it breaks. This is expected to result in a reduction of tipping fees associated with composting or more traditional forms of food waste disposal. It also enables food waste collection bins to be proactively emptied according to fill level, rather than at pre-arranged collection times, in order to reduce time delays and manual interventions. In addition, some companies in the USA are using IoT to reduce the amount of water and electricity required to break down organic materials in food waste during the oxidative conversion process (Clancy, 2017).

China began to explore applications of IoT in RFW management around 2010. Focusing on disposal sites, the Shanghai municipality has developed a real-time RFW monitoring system by using RFID technology and database management (Guo et al., 2013). In addition, Taking Yichang City in Hubei province as an example of small and mid-sized cities, an innovative “grid” management method based on IoT technology has been adopted. The local government established a five-level management system, vertically segmented by “city level”, “district level”, “sub-district level”, “community level” and “grid level”. The manager of each grid was equipped with IoT devices for real-time acquisition and transmission of information regarding food waste generation and collection. Measurements collected included time, weight, position, and more (Shu et al., 2013).

Most of the existing literature only briefly introduces ideas pertaining to system design, and most studies focus on just one of the stakeholders in the RFW management chain, as shown in Table 1. The shortage of rigorous methodology coupled with effective process implementation and subsequent performance evaluation, is evident from Table 1. Detailed discussion of RFW management policies is also lacking in the literature. As a result, this paper represents an innovative and valuable contribution to the expanding literature on food waste management. In the face of China’s mounting food waste challenge, this type of research is especially timely.

In contrast, therefore, our research has developed an IoT-based RFW management system that encompasses the entire process: from RFW generation, through collection and transportation, and on to final disposal. This system has been operating as a pilot program in Suzhou City since 2012. After several years of operation, the results show that the system has significantly strengthened RFW management, improved enforcement of RFW management regulations, and formalized the entire RFW treatment process. The IoT-based system extended and upgraded the traditional low-tech method of RFW management, and enabled data-driven management of RFW. Operational limits of the system were also identified; and recommendations have been provided (and implemented) to enhance its overall effectiveness.

Section snippets

Background and motivation

Suzhou City, which is one of China’s first “Municipal Food Waste Resource Utilization and Safe Disposal Pilot Cities”, has been chosen as a demonstration site for this research. The research group of Tsinghua University’s Research Center for Industry of Circular Economy (CICE) has engaged in research on RFW management problems based on pilot projects since 2006 in this region (Wen et al., 2015, Wen et al., 2016).

Design methodology of the IoT-based RFW management system

Together with a team of engineers, the authors developed an IoT-based system covering the entire RFW collection-transportation-disposal process in order to enhance the Suzhou City government’s capacity to manage this vital urban system effectively. The details of the system are presented in detail below.

System implementation and performance results

The IoT-enabled system has been operating in the urban area of Suzhou City as a pilot program since 2012. Up to December 2015, 6265 catering companies had participated in the scheme. 36,084 trash bins had been fitted with RFID tags, and the government-commissioned disposal company had used 28 smart collection trucks equipped with RFID readers, weight sensors, GPS, GIS, and wireless video surveillance cameras. Lastly, on-line monitoring of recovered products and pollutant emissions has been

Discussion

Our IoT-based system has extended the traditional scope of RFW supervision: from what was once supervision of the disposal process alone to now the entire train, from generation, through collection and transportation, to disposal. This clearly remedies the problem of focusing solely on disposal, while ignoring source control. In addition, it advances the establishment of a long-term RFW regulatory mechanism for the entire train. Moreover, it enables the pro-active management of RFW based on

Conclusion

In order to solve the problem of inadequate RFW management, an IoT-based system has been developed and applied in the city of Suzhou, China. It encompasses the generation, collection, transportation and final disposal of RFW and its development has involved research on both the software and hardware components of the system. They have been designed, implemented, and then tested over a period of three years of operation.

The components of the developed system cover the entire RFW management chain:

Acknowledgements

The authors gratefully acknowledge the financial support of the National Key Research and Development Program of China (2011BAC06B10, 2016YFC0502802) and the National Natural Science Fund for Outstanding Young Scholars of China (71522011). The contents of this paper reflect the views of the authors and do not necessarily indicate the views of the sponsors.

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