Food Waste to Valuable Resources: Applications and Management

Food Waste to Valuable Resources: Applications and Management compiles current information pertaining to food waste, placing particular emphasis on the themes of food waste management, biorefineries, valuable specialty products and technoeconomic analysis. Following its introduction, this book explores new valuable resource technologies, the bioeconomy, the technoeconomical evaluation of food-waste-based biorefineries, and the policies and regulations related to a food-waste-based economy. It is an ideal reference for researchers and industry professionals working in the areas of food waste valorization, food science and technology, food producers, policymakers and NGOs, environmental technologists, environmental engineers, and students studying environmental engineering, food science, and more.

• Presents recent advances, trends and challenges related to food waste valorization
• Contains invaluable knowledge on of food waste management, biorefineries, valuable specialty products and technoeconomic analysis
• Highlights modern advances and applications of food waste bioresources in various products’ recovery

• Language: English
• Publisher: Academic Press
• Release date: Apr 28, 2020
• ISBN: 9780128183540

Book preview

Chapter 1

Introduction: sources and characterization of food waste and food industry wastes

S. Kavitha¹, R. Yukesh Kannah¹, Gopalakrishnan Kumar², M. Gunasekaran³ and J. Rajesh Banu⁴,    ¹Department of Civil Engineering, Anna University Regional Campus Tirunelveli, Tirunelveli, India,    ²Institute of Chemistry, Bioscience and Environmental Engineering, Faculty of Science and Technology, University of Stavanger, Stavanger, Norway,    ³Department of Physics, Anna University Regional Campus Tirunelveli, Tirunelveli, India,    ⁴Department of Life Sciences, Central University of Tamil Nadu, Neelakudi, Thiruvarur, India

Abstract

Food waste (FW) consists of organic-rich resources for consumption which are then discarded, wasted, decomposed, or spoiled. The issue of FW is presently progressing, linking all divisions of waste management practices from assortment to clearance; the recognition of viable resolutions spreads to all players in the food supply chains, farming and business sectors, and sellers and the ultimate patrons. A sequence of resolutions can be executed in suitable FW handling, and highlighted in an analogous mode to the waste managing framework. The utmost desirable keys are signified by prevention and contribution of eatable portions of FW to food banks. FW can also be utilized in industries as substrates for biofuels and value-added products recovery. Additional steps enable nutrient retrieval by composting. Incineration and landfill are considered as less preferred practices. Significant researches have been performed on FW with the outlook of recovering bioenergy or value-added products. This introductory chapter summarizes an overview of FW, food loss, sources, origin, generation, management, and valorization strategies.

Keywords

Food waste; food loss; generation; quantification; food waste hierarchy; management practices

1.1 Food waste and food loss

Food waste (FW) have been defined as the byproducts or wastes originating from houses, canteens, hotels, restaurants, catering services, and several food-based industries, etc. FW are considered as the nonproduct streams of constituents where their economic worth is below the collection and retrieval cost, and hence they are thrown away as waste (United Nations Industrial Development Organization, 2012). About 89 million tons of FW are produced annually in the EU-27 (European Commission, 2010). Of this total, 80% has been recorded, with 38% created by the manufacturing sector and 42% by the household sector, emphasizing the generation of FW at each phase in the food supply chain (FSC). Generally, household FW generated by people at their homes signifies an issue from the logistics perspective.

Food loss is defined as food which accidentally deteriorates either qualitatively or quantitatively due to food spillage, spoilage, and/or drooping. Destruction is also caused by organization boundaries at the manufacturing, storing, handling, and circulation stages of the FSC. FW refers to any foodstuff and uneatable portions of food wasted from the FSC that can be recuperated or discarded. This comprises FW which is to be sent to landfill, managed via anaerobic digestion (AD), incinerated for bioenergy production, combusted, discarded to drainage, disposed to landfill, put in open dumps, or disposed of to water bodies.

Food losses can happen during the generation, packing, handling, distribution, and marketing phases, in addition to prior to or at the time or later stages of food preparation (Bio Intelligence Service et al., 2011). Food residuals include inevitably uneatable and partially unwanted products such as hides, stems, and foliage (Bio Intelligence Service et al., 2011; Foresight, 2010; WRAP, 2009). In addition, it comprises remains generated in eateries, hostelries, cafes, and some food facilities that do not plan for social utilization. A byproduct is a beneficial and saleable product or facility arising from a production stage which is not the main one generated (EEA, 2013). The eatable derivatives of food generated in the preparation and processing stages are usually taken from the human FSC and used as animal feed (Foresight, 2010). Food derivatives which are of animal origin include all organs or portions of animal bodies. FW comes under the heading of unnecessary waste. Disposed food, however, has worth and is very appropriate for utilization. Food products which are dropped, decayed, bruised, or crushed are referred to as FW. This comprises complete or sealed packets or separate foodstuffs that are not consumed (WRAP, 2008). In the FSC, FW cane be generated at any stage (Foresight, 2010) due to insufficient performance of food chain players (e.g., manufacturers, sellers, the food service sector, customers).

The European Commission (2014) released goals for the bioeconomy and FW handling in July 2014. They defined food waste as food products (as well as uneatable portions) lost from the FSC. This does not include food removed to value-added biomaterials, for example, biological materials, food for animals, or that directed for resupply. In addition, the member states of the European Union (EU) plan to launch agendas to assemble and provide reports about the FW level in every sectors. Up-to-date records are required to progress FW prevention strategies. These plans are intended to achieve the goal of decreasing FMW by nearly 30% from January 1, 2017, to December 31, 2025. The European Commission (EC) intends to approve executing directives by December 31, 2017, so as to launch perpetual circumstances for observing the execution of FW-preventive processes implemented by EU member states. The Commission has withdrawn the circular economy rules established from the EC’s program on December 16, 2014. This package discussed the strategy and future directions including FW reuse, combustion, and landfilling. The Food and Agricultural Organization (FAO, 2014) issued a worldwide intended agenda demarcating food loss as the reduction of food quantitatively or qualitatively, which is initiated mostly by food generation and supply system operation. Thus food loss happens during the FSC. In addition, the FAO differentiates FW as an essential portion of loss of food, that denotes the exclusion of food appropriate for utilization from the FSC from foodstuffs which have been left for spoilage or decay due to failings by the ultimate consumer at the household level.

According to the European Commission (2014), FW has been categorized into three groups: (1) Loss of food: foodstuffs that are lost at the production stage; (2) inevitable FW: foodstuffs that are lost at the consumption stage (e.g., peels of banana, cores of fruits); (3) unnecessary FW: foodstuffs that are not consumed, but lost at the consumption stage. Based on every stage of the FSC, Gustavsson et al. (2011) divided the generation of FW into the following production stages: agro-based FW generation, postharvest treatment and storing, handling, supply, and consumption. Parfitt et al. (2010) described FW as the loss of food during the absolute stage of FSC (marketing and ultimate consumption), that relates to seller and consumer behavior. Lipinski et al. (2013) defined FW as food products which possess better value and are appropriate for human utilization, that however are not utilized as they are disposed of prior to or after spoilage.

1.2 Food supply chain waste characterization

Food supply chain waste (FSCW) is product rich in organics generated for human utilization which is thrown away, subjected to loss, or decomposed chiefly at the production and marketing phases, comprising waste generated from pest-degraded food or spoiled food. FW is generated during all stages of the FSC, and is mainly apparent at the merchandizing and customer stages. The FAO has reported that nearly 51% of food generated is thrown away or unused prior to and after it reaches the customer (Parfitt et al., 2010). Nearly 1300 million tonnes of food is generated annually worldwide. This clearly illustrates a foremost socioeconomic and ecological issue (Gustavsson et al., 2011). The agri-based FSC includes a wide range of production processes that produce incremental amounts of diverse FW, particularly organic residues. The escalating requirement for value-added products and biofuels, along with additional drivers, is inspiring the reutilization and proficient biorefineries of organics from the FSC for the generation of new biomaterials, fine chemicals, and biofuels, as a harmonizing method to the traditional approaches (i.e., incineration, composting, animal feed, and landfill).

Industries move in the direction of greater sustainability to decrease costs and increase the effectiveness of processes to make innovative strategies economically sound for reutilization of FW. The progressively stringent European rules and principles and the expenses linked with their compliance (Landfill Directive in Europe) are the main drivers for the utilization of FSCW as a substrate to produce value-added products. Numerous methods can be considered to progress cutting-edge valorization approaches for the remains and derivatives of FW. This includes substantial amounts of biomolecules (i.e., proteins, polysaccharides, triglycerols, lipids, phenolic compounds), which are ample, easily obtainable, reutilized, and renewable. Numerous FW pools have value-added products that can be recuperated, resolved, and reutilized as useful foods, oils, and flavoring compounds. The expansion of valorization methods can solve the chief problems of the food industry, directing progress to more viable FSC and FW treatment schemes. They can resolve both the source and FW treatment issues, as the concerns linked with agro-based FW are significant, and include:

• reducing landfill;

• reducing greenhouse gas emissions;

• reducing water supply contamination through inorganic material leaching; and

• enhancing the effectiveness of traditional FW treatment approaches (i.e., composting and incineration).

The best examples of these systems include expansion of closed-loop models with regard to the supply chain (World Economic Forum, 2010). These models explain that every type of FW can be recycled in the FSC (e.g., packed FW can be reutilized).

FSC originate from an agricultural stage, continue through various industries and trades, and end with domiciliary consumption. Throughout this chain, food is wasted or lost due to technical, financial, and/or social causes. Scientist have disagreements about the descriptions of food waste and food loss in FSC. As stated by the Foresight Project report organized through the Government Bureau of Science (Foresight, 2011), FW is demarcated as eatable product planned for societal utilization which are thrown away, lost, decomposed, or used by nuisances when foodstuff are taken from farms to buyer. FSC and postharvest schemes are two other definitions under dispute in various reports. Postharvest loss is usually defined as loss of food and spoilage of food. Loss of food is defined as decrements in the volume and worth of food both quantitatively and qualitatively (Premanandh, 2011). Qualitative loss refers to a reduction in the calorific and nutritious value, with a reduction in quality that renders the product inedible (Kader, 2009). Loss of quantity is defined as a reduction in the eatable mass of food during the FSC.

1.3 Sources and origins of food waste

FW is generated mostly, but not absolutely, during the final consumer stage of the FSC (e.g., household waste). Food loss occurs at the processing, delivery, marketing, ultimate utilization, and postconsumption phases (FAO, 2014; Parfitt et al., 2010). Loss of food at the processing stage is typically caused by mechanical damage and/or spilling at harvesting (e.g., separating, fruitlet gathering, or crop categorization). Environmental factors such as changes in climate, for instance, temperature fluctuations and climate change and, in addition, financial issues such as rules, policies, and private or public principles for qualitative characteristics and look are key reasons for the loss of food (Kader, 2009). The stages during which loss of food occurs are postharvest, management, storing, handling, and distribution. Loss of food during the postharvesting stage happens because of leakage and decomposition, lack of storing amenities, and conveyance from the farm (Kader, 2009).

A substantial quantity of foodstuff is lost during storage and this largely occurs due to insects and microbes. Conversely, FW at processing occurs due to leakages or decomposition (for instance, juice preparation and canning). During the processing stage, generation of FW may also happen at cleaning, shredding, cutting, steaming, etc. During the distribution stage, FW occurs because of inappropriate conveyance, unsuitable packing, time limitations, and dealer/purchaser relations and poor organization. During the retailer stage, loss of food is typically denoted as FW as it is chiefly produced because of cognizant resolution to waste food. Such wasted food is however considered nontoxic and nutritive for human use, as stated by the Department of Environment Food & Rural Affairs (Defra, 2009). FW during the retailer stage occurs because of poor claim estimation, record mishandling, temperature changes, climate conditions during conveyance, discarding of unretailed food, unsuitable packing, and food guidelines and their lack of clarification.

Venders dispose of substantial amounts of food which have expired in periods with subsequent labels: best before, sell by, or use by. Some sellers unite with charities and redistribution bodies (for instance, food banks) to distribute unretailed food or to guide customers on how to avoid food wastage. FW occurs during the consumption stage because of single shopping practices, absence of cognizance, absence of awareness of effective food utilization, social problems, lack of awareness of suitable shopping estimation, packing, and other issues (Defra, 2009). Rules at the global level take decisions that aim to decrease food wastage by averting waste from landfill via directives, tax policies, and community awareness. During the postconsumer phase, FW has been categorized into three kinds (WRAP, 2009):

1. avoidable FW (food that is wasted as it is not needed or has reached its expiry date);

2. probably avoidable FW (some foods that will be eaten by some people but not others); and

3. unavoidable FW (food wasted during the preparation of food which is not eatable in any condition).

Loss of food that occurs from the manufacturer to the supplier stage is calculated to being sufficient to provide food for 1 billion people (Tomlinson, 2013). Loss of food is considered as the wastage of food arising due to human inputs, farm efforts, incomes, money inputs, and limited natural sources, for example, water. FW and loss of food are mainly linked with upstream FSC (manufacture to delivery) in low-income nations. The loss of food and FW in developed countries are highly associated with the downstream FSC. For example, minimizing loss of food in Africa is utmost of significance because of the organization of the FSC. In these places, loss of food originates from extensive technological and decision-making boundaries in harvesting, storage, conveyance, handling, cooling amenities, infrastructure, packing, and selling.

Efforts have been taken to calculate FW and loss of food globally. However, because of differences in practices, evaluation extent, and foodstuffs, it is problematic in calculating definitive records (Premanandh, 2011). The loss of food and FW are mainly derived from the manufacturing and marketing stages in the developed nations of Europe. Consumer-stage FW and loss of food are chiefly problems in Oceania, Europe, North America, and industrialized Asia. The minimum FW occurs at the consumer stage and major loss of food occurs during the manufacturing to marketing stages in South Asia, Southeast Asia, and sub-Saharan Africa. In developed countries, loss of food and FW occur through the FSC. This can be initiated by poor decision-making, market indications, inappropriate technologies, governing outlines and their miscomprehension, social standards, and unsuitable FW management approaches.

1.4 Food waste generation

In 2009 the United Nations FAO calculated and reported that 32% of generated foodstuffs were wasted or lost globally (Gustavsson et al., 2011). Fig. 1.1 represents the quantity of worldwide FW generation, contrasting sharply with the 0.87 billion persons described as recurrently malnourished. Roughly 1300 million tonnes annually that is, one-third of the food generated for consumption, is unexploited worldwide. In the United States, approximately 0.061 billion tonnes of FW is produced annually (GMA, 2012). Dee (2013) quantified the rate of FW generation in Australia as approximately 4 million tons annually. FW generation records in 2010 showed that South Korea generated 0.00624 billion tonnes, with 0.0924 billion tonnes of FW generated in China (Lin et al., 2011), and 0.021 billion tonnes generated annually in Japan.

Figure 1.1 Quantity of worldwide food waste generation.

The generation of FW in Europe is calculated to be 0.09 billion tonnes annually (European Commission, 2013). Reports showed that in Europe, the amount of FW generation was found to be more than 0.014 billion tonnes in 2013 (WRAP, 2013). Quested et al. (2013) estimated that, in the United Kingdom, FW generation was 160 kg per household annually, implying that 12% of food and drink arriving at homes and 30% of overall domiciliary food in the United Kingdom was wasted. Nellemann et al. (2009) implied that 25%–50% of food prepared is lost through the FSC. The scale and extent of FW production is constant and is not restricted to industrialized nations. Gustavsson et al. (2011) documented records of FW production in various regions, illustrating that production of FW showed an analogous directive of extent in developed and emerging nations. However, developed and emerging nations varied considerably.

More than 40% of food was lost during the postharvest and processing stages in developed countries, whereas in developing countries nearly 40% of food was lost during the marketing and consumption stages. Based on per capita income, much more food is lost in developed countries than developing countries (Gustavsson et al., 2011). The reasons for loss and wastage of food in underdeveloped countries are mostly associated with technical, economical, and managerial limits in harvesting, packing, and chilling services. Numerous small agronomists in emerging nations survive on the boundaries of food uncertainty, and a decrease in the amount of food loss can have an instant and considerable effect on their quality of life. FSCs in developing countries must be supported, boosting small agriculturalists to establish, expand, and upscale their manufacture and selling of foods. The reasons for food loss and wastage in average/high-income countries are related primarily to customer activities in addition to an absence of harmonization among the numerous players in the FSC.

The sales agreement among farmers and buyers could contribute en route to farm crop wastage. Food wastage can also occur because of a lack of value standards (foodstuffs which lack appropriate shape or form would be excluded). At the consumer stage, insufficient scheduling and expiration of best before date also create an enormous quantity of FW. This occurs due to the careless attitudes of consumers. FW in developed countries could be minimized by increasing awareness among sellers, food processing industries, and customers. This infers the redundant utilization of enormous quantity of sources utilized in the production of food, and the subsequent upsurge in greenhouse gas emissions (Gustavsson et al., 2011).

Generation of FW is articulated using, for instance, the total quantity of FW generated annually (tonnes per year) and per capita (kilograms per year or kilograms per day). The FW generated by buyers per capita in the United States and Europe was estimated to be 95–115 kg/year, and 6–11 kg/year in Asia and Africa (Gustavsson et al., 2011). Dung et al. (2014) estimated that FW in industrialized and developing nations per capita were 107 and 57 kg/year, respectively. These data illustrated that the generation of FW among industrialized and developing countries is reasonably tied to advanced livelihood standards causing elevated FW production (Lipinski et al., 2013). This has resulted in enormous quantities of FW production to meet food value requirements, for example, enormous amounts of constituents are required to prepare better value food. In addition, buyers might impact the quantity of FW generated by sellers. FW is foodstuffs which are not retailed or products that reach their expiry date and are discarded in preference to contributing it to food stores or charities (European Commission, 2014). Societies with poor hygiene values have low requirements for food preparation, and hence, the associated generation of FW per capita is less. However, due to the impact of increasing populations and growing financial restraints, it is anticipated that overall wasted foodstuff quantities in emerging nations is less than in industrialized countries.

The Agriculture Organization of the United Nations (2014) has documented that yearly overall quantities of FW generated worldwide are about 1300 million tonnes/year. These data do not showed noticeable variations when comparing industrialized (0.67 billion tonnes) and emerging (0.63 billion tonnes) nations. These data are due to the greater populations and greater number of developing nations (hypothesizing that there is poorly developed financial prudence in developing nations). Presently, the global population in highly industrialized countries is 1.2 billion, with 6 billion in poorly developed nations. At a global level, about 137 countries are developing and 49 are industrialized nations. Among the developing nations, 37% of the overall global population is in China and India. Fig. 1.2A and B illustrates the populations, FW, and different types of FW generated by various countries (developed and developing) around the world.

Figure 1.2 (A) Population and food waste generation in developed and developing countries. (B) Different types of food waste generated in various countries.

The generation of FW in emerging nations is lesser and those requires a smaller amount food for utilization. However, overall generation of FW in emerging nations is almost equivalent to that generated in industrialized nations. FW in emerging countries is estimated to be 55% of municipal waste. Among the total municipal solid waste, the percentages of FW in Malaysia, India, Mexico, and Brazil were estimated to be 55%, 51%, 52%, and 54.9%, respectively. The greater fraction of organics illustrates the great accessibility of composting, an FW management practice in emerging countries. Furthermore, municipal FW worldwide is anticipated to increase by 44% between 2005 and 2025. Because of the rapid economic growth which is anticipated in Asia, it is expected that there will be a drastic increase in the generation of FW from 0.278 to 0.416 billion tonnes. This could lead to worldwide environmental pollutant emissions increasing by 8%–10%.

The generation of FW takes place at different stages in the FSC, beginning at the farm itself even prior to product entering the market (WRAP, 2008). Preharvest losses occur because of great climate impacts (e.g., water scarcity) or pest incursions. FSC wastes are produced during the harvesting stage and are usually exposed to technological changes comprising augmented modernization, equipment faults, and new treatment approaches. Economic factors, which disturb manufacturers’ readiness to take their products to market, are also a general root of FSC waste generation. Food is also exposed to extra losses when it departs the farm for the market. Instances of comparable losses comprise bread, meat, and other associated related foodstuffs manufactured by eateries or caterers that are never distributed, along with the discarding of stained, poorly labeled/packed, improperly stored/conveyed, or overripened foodstuffs that are not able to be sold but remain nutritious and safe for consumption. An essential element of food loss during the retail stage of FSC is stock cleared from markets when the commodity reaches its expiry date (WRAP, 2008). Dairy products which are manufactured freshly and extra unpreserved products frame a major portion of marketing food loss. Kader calculated that nearly one-third of all fruit and vegetables which are generated globally are lost prior to reaching the consumer (Kader, 2009). These data have been calculated to constitute 9% in the United Kingdom. FW is also an essential constituent of domestic waste, covering an estimated 20% of total domestic waste (WRAP, 2009).

1.5 Food waste quantification

Quantifying the extent of FW is crucial for the progression of active, well-organized FW treatment strategies. This could be employed to decide if future FW recovery and preventive measures significantly modify the remaining leftover materials. Knowledge about the amount of FW could afford motivation for societies to modify their outlooks and possibly their activities toward FW. On the other hand, descriptional problems, the lack of complete quantifying approaches, and an overall lack of imperious or governmental drive have paved the way for substantial records gaps concerning FW quantification (Parfitt et al., 2010). A variety of approaches have been employed for quantifying FW. Some of these have some disadvantages. Some methodologies, which include sorting based on waste characterization and modeling of material flow analysis, have attempted to calculate the quantity of FW mixed with municipal solid waste (i.e., wastes generated from marketable, household, and official divisions). Other approaches, such as food records, quality level analyses/meetings, and FSC and food statistics evaluation place an emphasis on overall FW quantities produced from particular divisions (for instance, residential and eateries) or target related disposal quantities with social activities. Few investigations emphasize simply official waste and reject waste that are discharged via routes other than the conventional FW treatments (e.g., FW sent to landfill, FW which is composted at home, and FW used as animal feed).

1.6 Types of food waste and food processing wastes

Bioenergy and biofuel production from FW mainly utilize mixed/domestic FW but the recovery of value-added products is dependent on the particular FW type. The valorization of both FW and food processing wastes are described below. PURAC (2015) reported the utilization of colorful fruits, olive leaves, and tomatoes for the generation of polyphenols, phenols, fibers, carotenoids, and antioxidants. Likewise, waste originating from dairy processing food industries and slaughter houses was used as a substrate in the production of lactic acid and the abstraction of proteins. Generally, fruits contain high amount of vitamins, fibers, and different bioactive components. A huge amount of wastes are generated from fruit processing industries, including peelings, kernels, cores, and flesh. These can be valuable products in larger amounts.

Extraction of pectin from fruit processing industrial waste, recovery of phenolics and organic acids from kernels of mango and pigments such as carotenoids, polyphenolic compounds, vitamins, dietary fibers, and enzymes from peels of mango; extraction of biocompounds such as bromelain from the stem of pineapple; extraction of protein powder from coconut processing industrial waste, etc. have been investigated widely. Likewise, a food additive, pectin, which is primarily utilized in chemical, pharmaceutical, and food industries is chiefly extracted from FW which includes pomace of apples, orange peel, and sugar beet pulp waste. It has been found that dried peels of lemon, grapes, and oranges contain 20%–30% pectin. Apple pomace has 10%–15% pectin on a dry weight basis.

1.7 Food waste hierarchy

The major principles of FW hierarchy have been linked to European policies in the early 1970s, and the 1975 rules on waste (European Parliament Council, 1975), and to the EU’s second environment action program in 1977 (European Commission, 1977). In 1989 the FW hierarchy was clearly described in the European regulation’s public policy for the treatment of waste (European Parliament Council, 1989). In the meantime, the FW pyramid was implemented globally as the chief waste managing agenda. Other agendas supported by many Asian countries and Japan include the 3Rs, which affords a comparable method for managing waste by highlighting the possibilities of reducing, reusing, and recycling FW. The objective of the FW hierarchy is to find the best probable routes to provide eminent and complete favorable ecological consequences. Fig. 1.3 shows the FW hierarchy. As shown in Fig. 1.3, the most appropriate choice is prevention, and the least appropriate choice is disposal, which is presented at the bottom of the upturned hierarchy pyramid.

Figure 1.3 Food waste hierarchy.

1.8 Management and valorization of food waste

FWs have varying chemical compositions based on their generation and origin. Thus, FWs contain a mixture of proteins, carbohydrates, and lipids. If the FW is produced from particular agro-based industries, then it will be rich in one of the above-mentioned components. Various biofuels are thus generated from FW either biologically or thermochemically based on their composition. In addition, FW valorization pathways involve both extraction of value-added products from FW. Fig. 1.4 illustrates the types of FW, their valorization routes, and applications. The management of FW and food industry waste includes various treatments such as chemical, physical, mechanical, and biological techniques, which have numerous benefits and drawbacks. For example, valorizing food processing industry waste as animal feed is the most conventional technique. Proteinaceous and lipid-rich FW is appropriate for animal feed, while FW rich in cellulosic composition can be appropriate for cattle feed. On the other hand, the possible occurrence of toxic products that have antinutritious influence and instable compositions of nutrients might threaten the health of both humans and animals (Murugan and Ramasamy, 2013). The conveyance price (because of the distance of the FW generating site and consumption site) regularly makes this source of feed as expensive as traditional animal feed. The various FW management practices are valorizing FW as animal feed, composting, incineration, landfill, and biofuel production (Banu et al., 2018a,b,c, 2019; Kannah et al., 2017a,b, 2019).

Figure 1.4 Types of food waste and valorization route.

1.8.1 Animal feed

Animal feed is commonly the best inexpensive valorization route for FSCW, on the other hand, in some cases, it is restricted by governing problems besides the characteristics of byproducts produced in the process. Composting is referred to as a general land spreading or injection process and is a promising and long-term approach. It is an eco-friendly process and it diverts FW from landfill and decreases planters’ requirements (e.g., for fertilizers).

1.8.2 Landfill

Strategies for the management of FW raise considerable ecological issues. Discarding of FW to landfill creates influences both economically and environmentally through greenhouse gas emissions (methane and carbon dioxide) directly and indirectly. For instance, 4.2 tonnes of carbon dioxide are released during FSC from 1 tonne of FW produced. This includes emissions to air, water, and soil (World Economic Forum, 2010). Recovery of heat energy via incineration is not economically viable. This is usually due to the loss of energy to vaporize the higher water content of FW. However, in recent years, the utilization of FW as a compost or soil enhancer has emerged. Tuck et al. (2012) validated the economic benefit related to FW valorization to fine products. The typical cost of FW conversion to fine chemicals and biofuels was calculated to be approximately 1000 and 200–400 USD/tonne FW, respectively. Relatively, the animal feed and power were calculated to be in the range of 70–200 and 60–150 USD/tonne FW, respectively.

A typical waste disposal approach is the landfill as it is a cost-effective treatment route. Landfill is described as the dumping, solidity, and spreading of FW at suitable locations and comprises four general phases, namely, hydrolysis or aerobic digestion, hydrolysis and fermentation, acidogenic, and methanogenic phases. During this process, the organic matter in FW is oxidized and decomposed, ultimately causing methane production and pollution of groundwater. This could be mainly because of organic matter and metal ions. Various policies have focused on FW treatment approaches to divert FW from landfill. Directives have attempted to flourish in this objective via rules, taxes, and communal alertness. In relation to the EU waste scheme, the amount of FW sent to landfill has been calculated as:

• 25% decrease in FW sent to landfill was achieved in 2010 in comparison to 2006;

• 60% decrease in FW sent to landfill was achieved in 2013 in comparison to 2006; and

• 90% decrease in FW sent to landfill will be achieved in 2020 in comparison to 2006 (European Commission, 2010).

Likewise, the FW regulations of the United Kingdom aim at nearly 85% of waste originating from food processing industries to be spread on land (Sanders and Crosby, 2004). Generally, the best strategies aim to shift FW management from landfill to avoidance, reutilization, and recovery. Thus, a stable strategy comprises joint actions, for example, (1) FW landfilling is banned, (2) taxes on landfilling boost diversion and enhance the use of alternate managements, (3) expansion of composting or AD options, (4) expansion of the requisite setup, and (5) establishing an inclusive management system.

1.8.3 Bioenergy and biofuel conversion approaches

Wastes generated from food processing industries consist of an enormous amount of organic matter that can be transformed into energy. This energy then can be used for heat or electrical energy. AD and thermal practices (e.g., incineration, ignition, and pyrolysis) are considered as the chief bioenergy-generating processes (Murugan et al., 2013). FW with a moisture content below 50% is appropriate for thermochemical processes, which transform the organic-rich content of FW into gas or liquid. For example, incineration is a heat-based process which involves oxidization of ignitable components of FW for heat energy generation. Incineration is a feasible process for FW with comparatively less moisture (<50% by quantity). On the other hand, these processes have certain environmental impacts such as greenhouse gas emissions, severe ecological effects, and elevated cost (Murugan et al., 2013).

AD is an extensively employed approach (Kavitha et al., 2014, 2015, 2019) for treating FW which has higher moisture content and organic content in excess of 50%. In AD, diverse groups of microbes are involved in treating and stabilizing the FW in an anaerobic environment. Simultaneously, biogas is generated. Biogas is a blend of CH4, carbon dioxide, and water with H2S or H2. Biogas is utilized to produce electricity through the heat generated and is currently decreasing the utilization of fossil fuels and the release of carbon dioxide.

Numerous feedstocks have been assessed as possibly appropriate substrates for production of biohydrogen via a dark fermentative process. Among the above-mentioned substrates, FW may be a comparatively cheap and suitable choice of decomposable organics for biohydrogen generation, chiefly owing to its high amount of sugar and abundant nature. This process can be integrated into various biological practices resulting in bioenergy production. The potential of biohydrogen production is influenced by numerous factors such as the type of inoculum treatment, fermenter type, substrate loading, fermentation time, temperature, and medium pH. FW can be utilized as an inexpensive, renewable, and extensively available substrate for bioethanol production.

Pretreatments are commonly employed to increase the hydrolysis of sugar-enriched FW (Kannah et al., 2018; Kavitha et al., 2017), as the yeast biomass lack the potential to hydrolyze and ferment complex starch or cellulosic molecules into bioalcohol. Cekmecelioglu and Uncu (2013) established the viability of dropping the cost of ethanol recovery by using household FW as feedstock, without using the carbon sources that are conventionally utilized in the fermentation process. Pretreatment is not needed before enzymatic hydrolysis to obtain more glucose from household FW as the carbon and sugar contents in FW afford an adequately nutritious medium for the inoculum to yield more ethanol (Cekmecelioglu and Uncu, 2013). Kim et al. (2011) have obtained enhanced bioethanol production by utilizing carbohydrates containing FW in which the yield ranged from 300 to 400 mg ethanol/1000 mg total solids.

Fruits waste have also been considered as a suitable feedstock for production of bioalcohol. For instance, waste from bananas or spoiled bananas, peelings, and poor-value berries have been widely considered as feedstocks for bioethanol. Another biofuel, biodiesel, is defined as the alkyl esters (methyl/ethyl esters) of long-chain fatty acids and short-chain alcohols. This could be obtained from natural lipid-rich FW, such as plant-based oils or fats from animal-based origins, through a process called transesterification. This biodiesel is suitable for application in traditional diesel appliances and circulated via available energy infrastructure. Any FW rich in fatty acids could be used as a feedstock in the production of biodiesel.

1.8.4 Composting

Composting is an effective approach in treating FW in emerging nations. In India, presently, over 70 composting treatment amenities are handling mixed municipal solid waste, and reprocess nearly 5.9% of the total FW to produce around 0.0043 billion tonnes of compost annually. Mostly composting amenities treat a mixture of wastes, except the facilities in Vijayawada and Suryapet. These facilities treat FWs which are source separated. This practice is generally employed for the treatment of sugar-rich wastes in Thailand. Presently, as per Pollution Control Department and Ministry of Natural Resources and Environment (2010), exploitation approaches reprocess around 0.00059 billion tons of FW which has been composted to biofertilizers and biomethane. Nationwide 3Rs approaches implement AD and composting to enhance utilization of FW. In Malaysia, the government has implemented a prime initial plan to generate biofertilizer utilizing FW. In contrast, in most developing countries, there are issues with composting due to impure wastes which are the byproducts of source-segregated FW. Thus, the marketing of composting has dropped and FW composts which compete with chemical-based fertilizers create problems for the processes and investments of composting amenities. Global NGOs have provided plans to support the economical needs by implementing small-scale composting in emerging countries. Though steps have been taken to improve the awareness of FW reutilization in some African and Asian nations, the value of compost has not been enhanced.

1.8.5 Value-added products recovery

Household or domestic FWs can be used as substrate to recover value-added products. These value-added products include fine chemicals, nutraceuticals, biopolymers, biopeptides, antibiotics, high-fructose syrup, levulinic acid, bionanocomposites, single-cell proteins, polysaccharides, activated carbon adsorbent, chitosan, antioxidants, bioactives, corrosion inhibitors, industrial enzymes, films, vermicompost, mushroom cultivation, organic acids, pigments extraction, sugars, wax esters, and xanthan gum. This book covers in depth the recovery of valuable resources, their applications, and management. An overall concept diagram for this book and the topics covered is presented in Fig. 1.5.

Figure 1.5 Overall concept diagram for chapters in this book (food waste to valuable resources: applications and management).

1.9 Conclusion

The expansion of viable resolutions for managing FW is a foremost issue for the general public. These resolutions must be proficient for utilizing the valuable resources signified in FW to accomplish communal, economic, and ecological advantages. Perfect and commonly recognized descriptions of FW and associated definitions are not yet completed, and approximations on the produced quantities are not still finalized. The production of FW can be preferably be achieved with an appropriate balance between the generation and utilization of FW. However, optimal organization remains distant. A viable managing practice for the surplus generation of eatable food could be its redistribution to food banks. The food donation approach aims at provision from directives to ease the acquisition by food banks or societal amenities. Food processing residuals and domestic FW are not appropriate for social utilization and could be employed as a substrate for biopolymer and bioenergy recovery, along with the abstraction of value-added products. This necessitates a lively contribution from the scientific community to finalize appropriate source-separated FW to be converted into reserves.

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Chapter 2

Valorization of food waste for biogas, biohydrogen, and biohythane generation

T.M. Mohamed Usman¹, S. Kavitha¹, J. Rajesh Banu² and S. Kaliappan³,    ¹Department of Civil Engineering, Anna University Regional Campus, Tirunelveli, India,    ²Department of Life Sciences, Central University of Tamil Nadu, Neelakudi, Thiruvarur, Tamil Nadu, India,    ³Department of Civil Engineering, Anna University, Chennai, India

Abstract

Appropriate management of food waste (FW) is essential to decrease its environmental impact and to reduce hazards to human health. However, commonly adopted techniques are aimed to address mainly the disposal issues which consider FW as waste rather than an energy resource, yet require additional energy to process. FW can be conventionally combusted or incinerated for heat and energy recovery. These conventional techniques use natural resources, and adversely affect the environment, causing consequences such as air pollution and loss of the chemical value of FW during combustion. With this in mind, converting FW to bioenergy using greener technologies such as anaerobic digestion and dark fermentation is an appropriate and sustainable way to handle FW. This chapter covers the various greener technologies available for producing bioenergy from FW, as well as the challenges associated with the commercialization of technologies.

Keywords

Biohydrogen; biomethane; biohythane; anaerobic digestion; dark fermentation

2.1 Introduction

Food waste (FW) is considered to be a valuable substrate with increased potential to recover bioenergy. FW is mainly generated from homes, restaurants, and the food industry, and includes cereals, milk, fruits, meat, oilseed, vegetables, and seafood that are rich in nutrients such as carbohydrates (starch, cellulose, and hemicelluloses), proteins, lipids, organic acids, and lignin. The high organic matter, high moisture content, and biodegradability potential of FW make it a suitable candidate for bioenergy recovery (Zhang et al., 2011). FW is generally disposed of in landfill sites. Fig. 2.1 shows the most popular practices for FW management. Improper disposal or stacking of FW in landfills can cause serious health-related issues as well as other environmental problems such as odor, emissions of greenhouse gases like methane, and groundwater pollution (Kim and Shin, 2008; Kim et al., 2009; Lee et al., 2010a). A study by the United States Environmental Protection Agency (EPA) revealed that manmade emissions of methane were calculated as 282.6 million tons during the year 2000, where 13% of emissions were from landfills (Ren et al., 2018). On other hand, proper landfill disposal requires a larger area and high capital investment. In general, food production requires energy and nutrients, which makes these processes uneconomical and inappropriate (Uçkun Kiran and Liu, 2015). In addition to landfills, conventional treatment methods such as incineration or combustion are practiced to treat FW and to generate energy and heat. During combustion, the high moisture content of FW may lead to the generation of toxic compounds such as dioxin. FW incineration also can induce air pollution and, as a result, the chemical assets of FW may be lost.

Figure 2.1 Commonly practiced food waste disposal methods.

This turns the research focus into appropriate FW reduction and valorization. In this context, several studies have been conducted on the conversion of food to bioenergy, value-added products, and fine chemicals. Life cycle assessment of FW carried out by Schott and Andersson (2015) shows that an alternative FW management to replace incineration and landfill is anaerobic digestion (AD). AD could greatly reduce the global warming problem. Dark fermentation and AD were widely studied technologies for bioenergy production from FW (Sen et al., 2016). A number of studies have been conducted on the production of methane, which pushes this concept into an industrial-scale application. In addition, biohydrogen-based studies are slowly evolving (Girotto et al., 2015). Also, a blend of hydrogen and methane (biohythane) can be produced from various organic wastes (e.g., FW) through a two-stage sequential digestion process, that is, a first step of a dark fermentation process is followed by a second step of AD for hydrogen and methane yield (Algapani et al., 2018). Thus, this biological process provides an effective pathway to recover energy and nutrients from FW which compensates for early invested energy in food production. This chapter provides an overview of energy recovery (biogas, biohydrogen, and biohythane) from FW, factors affecting the bioenergy recovery, and the challenges affecting commercialization.

2.2 Anaerobic digestion of food waste

FW is rich in nutrients such as proteins, carbohydrates, and lipids. Organic-rich FW can be used as a suitable substrate for AD (Lee et al., 2019). AD is a biological treatment commonly adopted for FW treatment in many developed countries since 2006 (Abbasi et al., 2012b), yet developing countries remain unable to adopt this technique widely. During AD the complex waste material can be biodegraded into simpler compounds to produce rich calorific biogas as the end product. The AD process is illustrated in Fig. 2.2 (Chinellato et al., 2013). AD is a perfect choice of process for treating high moisture feedstock (up to 90%) such as FW (Brennan and Owende, 2010). AD demands less energy compared with other biological process and also has less of an atmospheric effect compared with other processes such as incineration and pyrolysis. The AD process involves various biochemical reactions mediated by diverse group of microbes. The biochemical reactions involved in AD are commonly divided into four stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis (Krishna and Kalamdhad, 2014). The first stage, hydrolysis, is mediated by fermentative bacteria, which convert macromolecules such as proteins, fats, and polysaccharides into smaller compounds such as peptides, fatty acids, and monosaccharides or simple sugars. Hydrolysis is followed by the second stage, acidogenesis, during which the hydrolyzed simpler compounds are converted into volatile fatty acids (VFAs) by acidogenic microbes (Kumar et al., 2016). The third step in AD is acetogenesis, during which acetogens convert the VFAs into acetic acid, hydrogen, and carbon dioxide. At the end of this stage the methanogenic process occurs, during which the acetic acid is converted into methane and carbon dioxide. The energy-rich biogas produced at the end of AD mainly contains methane, carbon dioxide, and a small amount of hydrogen sulfide (H2S). Methane is one of the best-known bioenergies produced in-house. Household production of methane using kitchen waste (FW) has been studied intensively for the last few decades. Studies on AD shows that parameters such as temperature, pH, C/N ratio (Zeshan et al., 2012), VFA (Xu et al., 2014), organic loading rate (OLR), reactor design (Krishna and Kalamdhad, 2014), and inoculum type (Deepanraj et al., 2017) affect the process dynamics, as discussed in detail in the forthcoming sections.

Figure 2.2 Anaerobic digestion process dynamics.

Based on various studies, it is noted that FW would be an appropriate choice of substrate as compared with agricultural residues for production of biofuels such as biohydrogen and biomethane (Dung et al., 2014). A study conducted on cafeteria FW by Chen et al. (2010) showed 0.61 Nm³/kg volatile solids (VS) of specific biogas yield. The results also clearly showed that biogas generated from these feedstocks contains a maximum 59% methane content and the remaining portion was carbon dioxide. The various benefits obtained through biological degradation of FW are volume reduction in organic matter, biogas production, water recovery, and valuable end products such as soil conditioner. Methane is the main component of biogas which has commercial value (Dahiya et al., 2018).

2.2.1 Pretreatments employed

During AD of FW, hydrolysis is considered to be the rate-limiting step due to the presence of complex macromolecules which take more time to biodegrade or resist biodegradation. Pretreatment helps to improve the biodegradability and positively improves biogas production. Chemical, thermal, ultrasonic, and microwave pretreatments are commonly adopted for the enhancement of FW solubilization and biomethane production. The effect of pretreatment can be evaluated by its mode of mechanism on FW and its composition (Krishna and Kalamdhad, 2014). Ultrasonic pretreatment mainly reduces the particle size in FW through the cavitation effect and microbubble expansion. Thermal pretreatments have been reported widely for hydrolyzing macromolecular components in various FW (Papadimitriou, 2010). Thermal pretreatment breaks the chemicals bonds in FW through the thermal effect and induces solubilization (Krishna and Kalamdhad, 2014). A study by Ma et al. (2011) clearly showed that macromolecules in FW can be disintegrated after thermal hydrolysis, which improves solubilization, however biodegradability may be limited. Thermochemical pretreatment achieved a maximum of 615 mL/g VS where thermal treatment achieves 602 mL/g VS biogas production (Prabhudessai et al., 2009). Chemical pretreatment recorded the lowest biogas production rate of 410 mL/g VS (Prabhudessai et al., 2009). Combining thermal pretreatment with chemicals could efficiently enhance the biodegradability of substrate and biogas production. For example, Chandra et al. (2012) showed an improved maximum of 441 mL/g VS biogas production through combined thermal-chemical pretreatment of FW, compared with sole thermal pretreatment (357 mL/g VS) and chemical pretreatment (293 mL/g VS). A similar increment in biogas production (441 mL/g VS) was obtained through thermochemical pretreatment of cottage cheese waste (Chandra et al., 2012). Hydrothermal pretreatment is another effective physical pretreatment which results in enhanced solubilization of FW. Qiao et al. (2011) obtained 0.67 Nm³/kg VS specific biogas yield after pretreating FW with a hydrothermal pretreatment. In another study, Salminen et al. (2003) combined thermal with enzymatic treatment so that the methane yield improved from 37% to 51%, whereas the individual enzymatic pretreatment achieved only 32% of the maximum methane production (Salminen et al., 2003; Qiao et al., 2011). Ariunbaatar et al. (2014) worked on low-temperature thermal pretreatment (80°C for 1.5 h) of FW. The authors obtained a higher methane production of 52% than untreated food. Li and Jin (2015) reported that the biogas production rate was increased from 50.88% to 147% after pretreating FW with an elevated temperature. FW normally contains highly biodegradable, and easily volatile carbohydrates. However, studies have highlighted that long-chain fatty acids present in the lipid compounds of FW increase the lag period for methane production. Yet, it is a temporary problem as evolving microbes in the anaerobic process can consume long-chain fatty acids (Cirne et al., 2007; Li and Jin, 2015). The negative impacts of thermal pretreatment of FW include the caramelization of fermentable sugars due to extended treatment time. Therefore, to obtain better biomethane production, balance should be maintained between degrading compounds of substrate (carbohydrate, protein, and lipid) (Vavilin et al., 2008; Ariunbaatar et al., 2014). In addition, thermal and chemical pretreatment was not appropriate for pretreating slaughterhouse waste due to the highly biodegradable nature of the substrate. In contrast, Salminen et al. (2003) reported a significant improvement in chemical oxygen demand (COD) solubilization of meat waste after chemical, ultrasonic, and low thermal pretreatment. However, the study showed mixed results as some of the meat industrial effluents showed improved biodegradability after pretreatment and others showed reduced biodegradability due to the intermediate formation of inhibitory compounds, which require further treatment.

Ratanatamskul et al. (2015) ran an on-site single-stage anaerobic digester for biogas production. An experiment conducted for different hydraulic retention time (HRT) and OLR was carried out to determine its effect. At minimal HRT of 19 days, maximum biogas production was achieved with a 70% reduction in total volatile solids (Ratanatamskul et al., 2015). Grimberg et al. (2015) compared a pilot-scale study for mesophilic digestion with single- and two-stage reactors for kitchen waste. The study showed that two-stage mesophilic digestion performed better for methane production than a single-stage digester (Grimberg et al., 2015). Similarly, Kim et al. (2014b) investigated the utilization of FW leachate as the substrate in a two-phase anaerobic digester and achieved a maximum methane yield of 0.85 Nm³/kg of reduced VS. Ahamed et al. (2015) conducted a study on a multiphased anaerobic baffled pilot-scale reactor (MP-ABR) with FW as the substrate to produce biogas. In this study, the authors achieved a biogas yield of 215.57 mL/g VS removed per day (Kim et al., 2014b; Ahamed et al., 2015).

2.3 Factors affecting anaerobic digestion of food waste

A number of environmental factors are known to influence AD, through improving or obstructing operational parameters such as growth of microbes, death rate, biogas generation, utilization of substrate, and start-up. These factors could significantly improve biomethane production (Fig. 2.3). Some of these factors are described below.

Figure 2.3 Factors affecting the anaerobic process.

2.3.1 pH

pH is an important parameter to be optimized in an anaerobic digester and its value and stability are essential because methanogenic processes continue at a considerable extent only at a neutral range of pH. The AD process deteriorates at elevated (values greater than 8.2) and lower pHs (values below 6.5). The efficient methanogenic microbes are active at pH ranges from 7.2 to 8.5. A pH value of 5.5 was found to hinder methane generation in reactors. This could be due to VFA accumulation in the reactors. Lower pH and extreme generation and accumulation of VFA lead to displacement of the neutral pH–carbonate buffer system and methanogenic activity. Operational parameters such as pH also affect methane production. At pH 7, methane production is improved compared to pH 8, at the same time applying thermal pretreatment improves hydrogen production by restricting methane fermentation. Due to this methane yield dropped to 0.385 from 0.446 Nm³/kg VS.

2.3.2 Temperature

To ensure maximum growth of methanogens in reactors it is necessary to maintain optimum temperature conditions. Temperature ranges of 25°C–450°C, that is mesophilic temperature, are normally maintained in AD systems as the presence of the thermophilic microbial population is greatly reduced. The optimum range of temperature for AD is 30°C–400°C and when the employed temperature is below or above this optimal level, the AD process is hindered for each level of decrement in temperature. The biodegradation potential of AD is reported to be higher in thermophilic conditions as compared to mesophilic conditions. The benefits of thermophilic AD are improved destruction of pathogenic microbes and enhanced substrate biodegradation. Methanogenic bacteria are more highly sensitive to alterations in temperature than other microbes. AD is usually inappropriate for diluted wastewater treatment and at lower temperatures.

2.3.3 Hydraulic retention time

HRT is one of the most important processing parameters affecting the process efficiency. Shi et al. (2017) showed that stable performance occurred at higher HRT than lower HRT; however, reduced methane yield was reported in this study at increasing HRT due to substrate reduction. Lafitte-Trouqué and Forster (2000) conducted an experiment on a two-stage anaerobic codigester with confectionery waste combined with sewage sludge. The study showed maximum performance at 12 days HRT, which produced a better specific methane yield as 82% in biogas. Reduced HRT leads to a reduction in methane formation due to less methanogenic bacteria. In a single-stage digester system less than 20 days of HRT washed out methanogenic bacteria, reducing methane yield. Liu et al. (2018) stated that higher HRT at the initial stage accelerated the microorganism activity and produced a better biogas yield. At the same time, excess HRT could adversely affect the system due to a reduction in the microorganism population in the reactor concentration. This study also stated that higher HRT produced higher VFA and ammonic nitrogen which accumulated in the system, and which could affect the reactor performance. Shorter HRT reduces the production of methane as the growth of methanogenic bacteria was affected (Lafitte-Trouqué and Forster, 2000; Hawkes et al., 2007; Shi et al., 2017; Liu et al., 2018). Many studies have reported that by maintaining HRT between 2 and 10 h methane production was controlled significantly. However, optimal HRT can be defined only based on the substrate composition, OLR,