Analysis of Promotion Policies for the Valorization of Food Waste from Industrial Sources in Taiwan

: Growing concern about circular bioeconomy and sustainable development goals (SDGs) for the valorization of food waste has raised public awareness since 2015. Therefore, the present study focused on the promotion policies and regulatory measures for the valorization of mandatory recyclable food waste from industrial sources in Taiwan, including the animal/plant production farms and food-processing plants. According to the ofﬁcial data on the annual statistics during the period of 2015–2019, it showed that the food waste from alcoholic beverage manufacturers (i.e


Introduction
Growing concern about circular bioeconomy, hunger, resource conservation, and sustainable development associated with food loss and waste (FLW) has raised public awareness in recent years [1,2]. With t he changes in diet habits and the improvement of living standards, many food waste has been generated from residential, commercial, and institutional sources, such as retails, wholesales, restaurants, hospitals, schools, and hotels, as well as from industrial sources like food processing plants, animal-breeding farms, crop/vegetable/fruit farms, and employee lunchrooms [3,4]. The discarded food often contained vegetable leaves, leftover meals and grains, fruit peelings, dairy, oils/grease, salts, and water. Due to its constituents like lignocelluloses, protein, and oils and grease, such wastes without valorization for the production of value-added materials and/or bioenergy would imply the resource depletion and wastage. Moreover, the environmental concern could be derived from their compositions, which may cause negative effects on the environment (e.g., odors, vectors, emission gas emissions, or climate change) if they are illegally disposed of in dumping sites or fields [5]. In addition, these food discards may be rich in the moisture and nutrient compositions, thus causing wastewater discharge with high biochemical oxygen demand (BOD) and/or chemical oxygen demand (COD) values in the landfill leachate [6]. For these reasons, the valorization of food waste has become increasingly important in recent years due to the United Nations (UN) Sustainable Development Goals (SDGs) and national regulatory requirements [7]. Therefore, the reuse of food waste as a valuable resource for the production of materials, fertilizer, and biofuels has been reviewed recently [7,8].
As mentioned above, FLW has become one of vital issues raised by great public concern. In order to provide a target-oriented blueprint for peace and prosperity to all countries in the near future (2030), the United Nations (UN) announced 17 Sustainable SDGs on 25 December 2015 [9], reflecting the increased global awareness for the environmental issues. In this regards, the Target 12.3 of the SDGs, thus, calls for halving per capita global food waste at retail and consumer levels by 2030, as well as reducing food losses along the production and supply chains. In line with the international trends, the Taiwan government announced the Taiwan's Sustainable Development Goals in July 2019 [10], including the goals for 2030 and targets for 2020. Regarding FLW, the 12th Goal is "Responsible Consumption and Production", which involves the Goal 12.3 by reducing food lose in the supply-chain side and also reducing food wastage in the consumer side, and the Goal 12.4 by reducing (food) waste generation through green production and also promoting (food) waste valorization and its technological capacity. In addition, the 7th and 13th Goals in the Taiwan's SDGs aims at taking actions for providing renewable energy and combating climate change, respectively, which were also relevant to the food waste issue.
According to the official definition in Taiwan, waste can be categorized into general (urban) waste and industrial waste. Under the circular economy principle, the central governing agency (i.e., Environmental Protection Administration, EPA) in Taiwan has implemented the Four-in-One Resource Recycling Plan over the past two decades [11,12], which combined the efforts by communities, recycling enterprises, local governments, and the Recycling Fund. It showed that the urban waste recycling rate has increased from about 10% in 2000 to over 56% in 2019 [13]. Regarding the kitchen waste (including waste cooking oil) management, the Taiwan EPA promulgated the regulations of governing the valorization of food waste from non-industrial (urban) and industrial sources by designating it as a mandatory recyclable waste under the authorization of the Waste Management Act (WMA) [14,15]. Furthermore, over ten items of food waste valorization (or reuse) from industrial sources have defined by the central responsible agencies under the authorization of the WMA, including the Council of Agriculture (COA), Ministry of Finance (MOF), and Ministry of Economic Affairs (MOEA) [16]. Currently, most of the industrial food waste items were reused as valuable feedstocks for animal feed, organic fertilizer, or biomass energy. Meanwhile, the EPA also provided the subsidies for local governments to establish their valorization (animal feed) programs for the prevention of African swine fever (ASF) spread because the virus can persist in the kitchen waste without high-temperature (>90 • C) cooking [15]. Moreover, the burden on municipal solid waste (MSW) incineration plants and sanitary landfills can be reduced in recent years [15].
Regarding the regulatory and promotional measures for mandatory valorization of food waste from the industrial sources, few studies were discussed previously [4,17]. Mirabella et al. [4] reviewed the valuable compounds and fuels derived from the solid and liquid waste in the food processing industry but lacked the promotion policies or regulatory measures for the food waste valorization. Naziri et al. [17] reported the valorization of the major agrifood (i.e., olive oil, wine, and rice) industrial by-products and waste from Central Macedonia in Greece for the recovery of value-added compounds (e.g., antioxidants) for food applications. As compared to other countries [18,19], the food waste valorization with high recycling rate in Taiwan may be a learnable case due to the adaptation of "zero waste and resource recycling" policy. In the previous studies [15,20], the author focused on the regulatory and promotion measures for the valorization of food waste from the non-industrial sources like residential and service sectors. Therefore, the present study will put emphasis on the promotion policies and regulatory measures for the valorization of food waste from industrial sources (hereinafter industrial food waste) in Taiwan. Therefore, the aim of this study was twofold. First, the updated data on the statistics and status of industrial food waste generation and treatment in Taiwan will be addressed in Section 3.1 to analyze the trends. Second, the promotion policies and regulatory measures for industrial food waste valorization were studied subsequently based on the joint-efforts by the central governing authorities under the authorization of the WMA. In addition, a case study was addressed to highlight the environmental and economic benefits regarding the valorization of urban food waste for the production of bioenergy by anaerobic digestion in Taiwan.

Data Mining
In this work, the statistical database, promotion policies, and regulatory measures, and case study relevant to industrial food waste valorization were accessed on the official yearbooks and relevant websites, which were briefly summarized below.
• Activity (statistics and status) of industrial food waste generation According to the annual yearbook of environmental protection statistics [13], the updated data on the statistics and status of industrial food waste generation and treatment in Taiwan were analyzed in the present study.

• Promotion policies and regulatory measures for industrial food waste valorization
The information about the promotion policies and regulatory measures for industrial food waste valorization was accessed on the relevant website [16], which was built by the Ministry of Justice (MOJ).

•
Case study: Production of bioenergy from the anaerobic digestion of urban food waste An official plan for establishing biogas-to-power plants from the urban food waste was addressed to highlight the environmental and economic benefits of food waste valorization by anaerobic digestion in Taiwan [21].

Status of Industrial Food Waste Generation in Taiwan
According to the project ("Food Use for Social Innovation by Optimizing Waste Prevention Strategies") funded by the European Commission [22], the definition of food waste refers to "any food, and inedible parts of food, removed from the food supply chain to be recovered or disposed". In this regards, food waste will be often generated from the retailers, consumers, and food service providers or food processing manufacturers due to the expiration, discard during the sorting operation, leftover, and other wastage reasons [23]. Figure 1 shows the categories of food waste based on its generation sources. In the present study, the industrial sources referred to the agricultural farms (e.g., s laughterhouse, hatchery, oyster farm, aquafarm, and truck farm), and animal-based or plant-based food processing plants or sites. By contrast, the non-industrial sources included the residential, commercial (e.g., office, retail, wholesale, warehouse and distribution, hotel, and restaurant), and service (e.g., hospital) and institutional (school) facilities [3]. In order to manage food waste from the industrial sources efficiently, the Taiwan EPA announced that the se sources with over specified amount of food waste generated annually were required to submit their industrial waste management plans by on-line reporting system based on the requirements of the WMA. According to the on-line reports during the period of 2015-2019 [24], Table 1 listed the reported amounts of industrial food waste, showing that the organic food waste from alcoholic beverage manufacturers (i.e., lees, dregs, or alcohol mash) and inorganic food waste from oyster farms (i.e., waste oyster shell) accounted for about half (about 250,000 metric ton) of industrial food waste generation in Taiwan. Table 2 showed the reported amounts of kitchen waste and waste cooking oil during the period of 2015-2019, which were categorized into the industrial sources and non-industrial sources. Obviously, the amount of kitchen waste generation was mostly from the non-industrial sources, indicating a stable amount of about 600,000 metric tons. It should be noted that the significant increases in kitchen waste generation from industrial sources and waste cooking oil from non-industrial sources in 2017 was attributed to the regulatory requirements due to the "food safety scandal" event and circular bioeconomy promotion [14,15]. It can be seen that total reported amounts of waste cooking oil significantly increased from 12,877 metric tons in 2015 to 29,507 metric tons in 2019.

Promotion Policies for the Valorization of Food Waste from Industrial Sources
Regarding the on-line reporting amount and the regulatory measures for the reuse (or valorization) status of food waste from the non-industrial (residential and commercial) sources in Taiwan, the data during the period of 2010-2017 have been addressed in the previous study [15]. Table 3 further updated the data [13], indicating that the increasing trend in composting valorization during the period of 2015-2019 could be due to the driving force by the "food safety scandal" event in September 2014 and the prevention of African swine fever (ASF) spread since 2019 [25]. Under the authorization of the WMA, the Taiwan EPA subsequently promulgated and/or revised some promotion policies for the valorization of mandatory recyclable food waste (including kitchen waste and waste cooking oil) from all sources to avoid entering the food chain and the 24 larger-scale MSW incineration plants [14]. According to the regulatory definition, the valorization (or reuse) of food waste refers to the production of value-added resources like organic fertilizer, animal feed, and biomass energy. From the regulatory joint-efforts by the central governing authorities [16], including EPA, COA, MOF, and MOEA, Tables 4 and 5 summarized the regulatory measures for the valorization (or reuse) options of urban food waste (kitchen waste and waste cooking oil) and industrial food waste, respectively.

Promotion Policies for the Production of Value-Added Materials from Food Waste
Over the past two decades, industrial ecology concepts, including Cradle to Cradle (C2C) and circular economy, played a prevailing role in the waste management [4]. The approach for the "zero waste" aimed at reusing the food waste as raw material (or feedstock) for new products and applications. In Taiwan, the promotion policies for the production of value-added materials from food waste were based on the legislations by the governing authorities, including the Council of Agriculture (COA), the Ministry of Economic Affairs (MOEA), and the EPA [16]. Therefore, the central governing agency (i.e., COA) jointly promulgated some regulatory measures for ensuring the bio-products from the food waste valorization under the acts, including the Fertilizer Management Act, the Feed Management Act, and the Animal Industry Act. Based on the Fertilizer Management Act, the organic fertilizer produced from food waste must meet the specifications for the soil-based nutrients/compositions like organic matter, nitrogen and phosphorus, and the limits of toxic metals, including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn).  Due to its richness in moisture, carbohydrate polymers and other constituents (e.g., protein, and lipids), food waste has been used as an excellent feedstock for the production of various kinds of value-added biobased materials and/or biobased products via microbial conversion, including methane, hydrogen, ethanol, organic acids, and bio-fertilizers [26,27]. More importantly, the production of bioenergy from food waste would not only solve the environmental hazards from the MSW incineration plants and sanitary landfill sites but will also mitigate the emissions of greenhouse gases while replacing the usage of fossil fuels by bioenergy. In Taiwan, the promotion policy for the production of bioenergy from food waste was based on the legislation of the Renewable Energy Development Act (REDA) in 2009, which was recently revised in 2019. Among the promotion measures in the REDA, the central governing agency (i.e., MOEA) shall announce the so-called feed-in tariff (FIT) rates for all types of renewable energy annually, which were reviewed or amended in considering related factors like technical progress in power generation, changes in cost and renewable electricity goal achievement. Table 6 listed the FIT rates for promoting electricity generation from biomass-to-power (via anaerobic digestion process or not) and waste-to-power in Taiwan since 2010. It showed an increasing trend from 2.0615 NT$/kW-h in 2010 to 5.1176 NT$/kW-h in 2021 for the biomass-to-power by anaerobic digestion. The MOEA will open up the business model for the direct supply and transfer of green power generation, and also guarantee the fixed 20-year rate which renewable electricity can be converted at the feed-in tariff (FIT) officially announced. Table 6. Variations of feed-in tariff (FIT) for biomass-to-power and waste-to-power in Taiwan  In order to diversify food waste treatment options and also reduce the burdens on the MSW incineration plants and sanitary landfills in Taiwan, the EPA revised the relevant regulation ("Regulations for Collection, Clean-up and Treatment of General Waste") on 3 November 2017 and announced the new regulation ("Management Regulations for Reuse of Common Industrial Waste") on 8 January 2018. The former regulation added the energy recovery of food waste and other organic residues to one of the specified treatment methods. The food waste and waste cooking oil were listed for the industrial waste reuse items in the latter regulation. Their reuse options have been listed in Table 4. Afterwards, the EPA further launched the Resource Recycling and Reuse Plan in 2018, which was based on the cross-departmental action strategies and promotion measures under the Taiwan's SDGs [10]. In this regards, the EPA has assisted five municipal governments to build food waste bioenergy plants since 2018, which will be further addressed as a case study to discuss their environmental and economic benefits in the subsequent section.

Official Plan for the Production of Bioenergy from the Anaerobic Digestion of Urban Food Waste
In Taiwan, industrial waste refers to waste that is generated from industrial activities (or sources), but excludes waste generated by the employees themselves. In this regards, food waste (e.g., kitchen waste and waste cooking oil) derived from industrial sources can be listed as general (urban) waste. In order to reduce the negative impacts of food waste on MSW incineration plants and/or sanitary landfills, the Taiwan EPA has been funding local governments in developing diverse treatment options to increase the food waste processing capacity. For instance, the EPA has subsidized the installation of over 50 sets of food waste pretreatment (i.e., shredding and drying) composting plants since 2003. In recent years, the EPA is subsidizing the establishments of food waste-to-bioenergy plant in the five special municipalities, including Taichung City, Taoyuan City, Taipei City, New Taipei City, and Kaohsiung City [21]. Table 7 listed the comparisons of five municipalities in Taiwan, showing that the variations of food waste generated per capita in 2019 were very large. Among these biogas-to-power plants, the first case in Taichung City has been completed and was in operation because this site was to revitalize the old composting plant. Taoyuan City planned to finish the construction of its plant by the end of July 2021, and all plants were estimated to be completed by 2024. Upon completion, these plants can process 230,000 metric tons of food waste per year for about 14.5 million citizens and also generate 41,970,000 kW-h electricity per year. The expected power generation not only gains an annual revenue of NT$214.79 million from selling electricity based on the FIT rate of 5.1176 NT$/kW-h, but also reduces the emissions of carbon dioxide by 21,363 metric tons according to the official carbon emission factor of 0.509 kg CO 2 /kW-h [28].

Conclusions
In Taiwan, industrial food waste was listed as one of "mandatory" recyclables under the authorization of the WMA for the production of biobased products like organic fertilizer, animal feed, and bioenergy (or biogas). This circular bioeconomy option would not only solve the environmental hazards from the traditional treatment options but will also mitigate the emissions of greenhouse gases while replacing the usage of fossil fuels by biobased materials and bioenergy. In this work, the findings showed that the organic food waste from alcoholic beverage manufacturers (i.e., lees, dregs, or alcohol mash) and inorganic food waste from oyster farms (i.e., waste oyster shell) accounted for about half (about 250,000 metric ton) of industrial food waste generation in Taiwan during the period of 2015-2019. Under the jointly efforts and legislations by the central governing agencies (i.e., EPA, COA, and MOEA), current regulatory and technological measures for converting industrial food waste into organic fertilizers, animal feed, biofuels, or electricity have resulted in the significant benefits from the environmental and economic viewpoints. In order to achieve the Taiwan's SDGs, one of official plans was to build five large-scale bioenergy plants at local governments via anaerobic digestion of food waste, which were estimated to process 230,000 metric tons annually and also generate 41,970,000 kW-h electricity per year. On completion by 2024, the expected power generation not only gains an annual revenue of NT$214.79 million from selling electricity based on the FIT rate of 5.1176 NT$/kW-h, but also reduces the emissions of carbon dioxide by 21,363 metric tons according to the official carbon emission factor of 0.509 kg CO 2 /kW-h. Obviously, the regulatory measures for industrial food waste valorization in Taiwan play a critical role in providing environmental, economic and energy benefits, which will be more adopted in industries.

Conflicts of Interest:
The authors declare no conflict of interest.