1. 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.
2. 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.
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.
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).
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].
4. 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 CO2/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.