Environmental and health impacts of using food waste as animal feed: a comparative analysis of food waste management options

Development of a pragmatic framework to help food and drink manufacturers select the most sustainable food waste valorisation strategy

Food waste is a significant contemporary issue in the UK, with substantial environmental, social and economic costs to the nation. Whilst efforts to reduce food waste are laudable, a significant proportion of food and drink manufacturer waste is unavoidable. On the one hand, there is a drive from industry to reclaim as much value from this waste as possible, for example, by conversion to valuable products in what is known as "valorisation". At the same time, growing social and legislative pressures mean that any attempts to valorise food waste must be performed in a sustainable manner. However, for every company and its specific food wastes, there will be multiple valorisation possibilities and few tools exist that allow food and drink manufacturers to identify which is most profitable and sustainable for them. Such a decision would need to not only consider environmental, social and economic performance, but also how ready the technology is and how well it aligns with that company's strategy. In response, this paper develops and presents a hybrid framework that guides a company in modelling the volumes/seasonality of its wastes, identifying potential valorisation options and selecting appropriate indicators for environmental, social and economic performance as well as technological maturity and alignment with company goals. The framework guides users in analyzing economic and environmental performance using Cost-Benefit Analysis and Life Cycle Assessment respectively. The results can then be ranked alongside those for social performance, technological maturity and alignment with company goals using a weighted sum model variant of Multi-Criteria Decision Analysis to facilitate easy visual comparison. This framework is demonstrated in the form of a case study with a major UK fruit consolidator to identify the optimal strategy for managing their citrus waste. Possibilities identified included sale of imperfect but still edible waste via wholesale at a significantly reduced profit and the investment in facilities to extract higher value pectin from the same waste stream using a microwave assisted pectin extraction process. Results suggest that continued sale of waste to wholesale markets is currently the most beneficial in terms of economic viability and environmental performance, but that in the medium to long term, the projected growth in the market for pectin suggests this could become the most viable strategy.

Sustainable management practices of food waste in Asia: Technological and policy drivers

The policies and technological drivers to manage food waste in Asia have been shaped by the increasing awareness of the countries to this issue, their commitment to national and international development goals, their socio-economic constraints, and their recognition of the potency to recover nutrients and energy from food waste. The concept of reduce, reuse and recycle (the 3R principles) streamline the existing food waste management policies, and scrutinising the gaps and challenges led to a conclusion that most of the countries emphasise food waste segregation and treatment instead of prevention at source itself. Furthermore, a qualitative SWOT analysis of five prevailing treatment options led to a conclusion that animal feeding, incineration, and landfilling are unsustainable since they pose various health and environmental hazard risks. It was further concluded that anaerobic digestion was the preferred option than aerobic digestion (composting) considering the characteristics of the available food waste in Asia as well as the underlying environmental and economic benefits. Moreover, decentralised, community-scale, anaerobic digestion system has been gaining traction over centralised, large-scale system because of their lower energy footprint, ease of operation, need for lesser resources, lower operation and maintenance costs, and higher chances of public acceptance. It was also observed that the policy to gain energy from segregated food waste is a larger driving force for the efforts to promote anaerobic digestion and thereby manage food waste sustainably.

The Life-Cycle Environmental Impact of Recycling of Restaurant Food Waste in Lanzhou, China

The recycling of restaurant food waste can bring environmental benefits and improve food safety for urban residents. We here assessed the entire life cycle of the anaerobic digestion–aerobic composting technique of restaurant food waste recycling using Lanzhou as a case study. We used the CML2001 method provided with the Gabi software and compared the results to those produced using the traditional treatment techniques (landfill and incineration). This work includes a sensitivity analysis of the results. It is here concluded that the anaerobic digestion–aerobic composting technique had the smallest environmental impact of the methods here examined. The life cycle of anaerobic digestion–aerobic composting primarily consumes water, clay, coal, crude oil, and natural gas. The pre-processing phase consumes the most resources, and anaerobic digestion showed the greatest environmental impact. Specific environmental impacts in order from the highest to lowest potential to exacerbate global warming were found to be photochemical ozone production, acidification, eutrophication, marine aquatic ecotoxicity, human toxicity, freshwater aquatic ecotoxicity, and terrestrial ecotoxicity. The main factors associated with different environmental impacts and the environmental impacts themselves were found to differ across different phases. Some environmental impacts were shown to be sensitive to electricity, and the eutrophication potential and photochemical ozone creation potential showed the least sensitivity to all variables. To reduce the environmental impact of the anaerobic digestion–aerobic composting treatment technique, the energy structure and consumption of electricity, water, and diesel need to be optimized.

Improving the recycling technology of waste cooking oils: Chemical fingerprint as tool for non-biodiesel application

Samples of sunflower Waste Cooking Oils (WCOs) subjected to several cycles of frying were treated with water under four different combinations of temperature and pH. Several aspects of the chemical composition of edible, non-treated and processed samples was determined by three different analytic techniques: headspace Solid-Phase Microextraction (HS-SPME) coupled with gas-chromatography (GC), ¹H NMR spectroscopy and ESI-MS spectrometry. Thus, a characteristic chemical fingerprint of each sample was derived and proposed as useful set of tools for the optimization of recycling of WCOs. On the basis of the presented results, a mini-plant for the production of bio-lubricants and bio-solvents with a circular economy approach was designed and herein described.

Turning food waste to energy and resources towards a great environmental and economic sustainability: An innovative integrated biological approach

Food waste (FW) management is a global conundrum because of the rapid population growth and growing economic activity. Currently, incineration and landfill are still the main means for FW management, while their environmental sustainability and economic viability have been in question. Recently, the biological processes including anaerobic digestion, aerobic composting, bioethanol fermentation, feed fermentation etc. have attracted increasing interest with the aims for energy and resource recovery from FW. However, these biological approaches have inherent drawbacks, and cannot provide a comprehensive solution for future FW management. Therefore, this review attempts to offer a critical and holistic analysis of current biotechnologies for FW management with the focus on the challenges and solutions forward. The biological approaches towards future FW management should be able to achieve both environmental sustainability and economic viability. In this instance, the concept of zero solid discharge-driven resource recovery has thus been put forward. According to which, several innovative biological processes for FW management are further elucidated with critical analysis on their engineering feasibility and environmental sustainability. It turns out that is an urgent need for turning current single task-orientated bioprocess to an integrated biological process with multiple tasks of concurrent recovery of water, resource and energy together with zero-solid discharge.

Production of bioplastic through food waste valorization

The tremendous amount of food waste from diverse sources is an environmental burden if disposed of inappropriately. Thus, implementation of a biorefinery platform for food waste is an ideal option to pursue (e.g., production of value-added products while reducing the volume of waste). The adoption of such a process is expected to reduce the production cost of biodegradable plastics (e.g., compared to conventional routes of production using overpriced pure substrates (e.g., glucose)). This review focuses on current technologies for the production of polyhydroxyalkanoates (PHA) from food waste. Technical details were also described to offer clear insights into diverse pretreatments for preparation of raw materials for the actual production of bioplastic (from food wastes). In this respect, particular attention was paid to fermentation technologies based on pure and mixed cultures. A clear description on the chemical modification of starch, cellulose, chitin, and caprolactone is also provided with a number of case studies (covering PHA-based products) along with a discussion on the prospects of food waste valorization approaches and their economic/technical viability.

Rearing of Hermetia Illucens on Different Organic By-Products: Influence on Growth, Waste Reduction, and Environmental Impact

The aim of the study was to evaluate the use of three by-products as growing substrates for Hermetia illucens (Black Soldier Fly (BSF)) larvae: okara, maize distiller, brewer's grains, and a control hen diet. The study focused on larval growth and bioconversion performance, production of methane by larvae and environmental burden of larvae production, using Life Cycle Assessment (LCA) on a lab scale. Chemical composition of substrates differed: okara had the highest crude protein and ether extract contents, while brewer's grains showed the highest fiber content. Larvae fed on a hen diet and maize distiller exhibited the highest final weights (2.29 and 1.97 g, respectively). Larvae grown on okara showed the highest indexes for waste reduction and efficiency of conversion of the ingested feed. The BSF larvae did not produce any detectable traces of CH4. LCA evaluation showed that larvae production on a hen diet resulted in the most impact for most of environmental categories, for the inclusion of soybean meal in the diet (for climate change, 5.79 kg CO2 eq/kg dry larvae). Feed production activities resulted in the main contributions to environmental impact. In order to compare the larvae production obtained on all substrates, an environmental impact was attributed to okara and brewer's grain through a substitution method, and, by this approach, the best sustainable product resulted from the larvae grown on the maize distiller.

Future global pig production systems according to the Shared Socioeconomic Pathways

Global pork production has increased fourfold over the last 50 years and is expected to continue growing during the next three decades. This may have considerable implications for feed use, land requirements, and nitrogen emissions. To analyze the development of the pig production sector at the scale of world regions, we developed the IMAGE-Pig model to describe changes in feed demand, feed conversion ratios (FCRs), nitrogen use efficiency (NUE) and nitrogen excretion for backyard, intermediate and intensive systems during the past few decades as a basis to explore future scenarios. For each region and production system, total production, productive characteristics and dietary compositions were defined for the 1970-2005 period. The results show that due to the growing pork production total feed demand has increased by a factor of two (from 229 to 471Tg DM). This is despite the improvement of FCRs during the 1970-2005 period, which has reduced the feed use per kg of product. The increase of nitrogen use efficiency was slower than the improvement of FCRs due to increasing protein content in the feed rations. As a result, total N excretion increased by more than a factor of two in the 1970-2005 period (from 4.6 to 11.1 Tg N/year). For the period up to 2050, the Shared Socio-economic Pathways (SSPs) provide information on levels of human consumption, technical development and environmental awareness. The sustainability of pig production systems for the coming decades will be based not only on the expected efficiency improvements at the level of animal breeds, but also on four additional pillars: (i) use of alternative feed sources not competing with human food, (ii) reduction of the crude protein content in rations, (iii) the proper use of slurries as fertilizers through coupling of crop and livestock production and (iv) moderation of the human pork consumption.

Energy, amino acid, and phosphorus digestibility and energy prediction of thermally processed food waste sources for swine

Recycling energy and nutrients from food waste into animal feed decreases the environmental impact of food animal production. However, recycling energy and nutrients from various food waste sources into swine feeding programs is constrained by the high variability and lack of data on the digestibility of energy and nutrients. Therefore, the objectives of this study were to evaluate the digestibility of energy, amino acids, and phosphorus in thermally dried food waste sources fed to growing pigs and to compare in vivo determined digestibility values with those obtained from in vitro digestibility procedures and published prediction equations to determine the accuracy of using these nutritional evaluation methods. Pigs (n = 36; initial body weight = 16.37 ± 1.9 kg) were utilized to determine digestible energy (DE) and metabolizable energy (ME) content, as well as standardized total tract digestibility (STTD) of phosphorus and standardized ileal digestibility (SID) of amino acids in three sources of dehydrated food waste in three separate trials. Initial body weight of pigs at the beginning of each digestibility trial was used as the blocking factor in a randomized complete block design. Diets were formulated to contain 30% food waste derived from fish waste (FW), supermarket waste (containing bakery, fruits and vegetables, meat, and deli foods from a single supermarket; SMW), and fruit and vegetable waste (FVW). The DE and ME content of FW (DE = 5,057 kcal/kg; ME = 4,820 kcal/kg) and SMW (DE = 5,071 kcal/kg; ME = 4,922 kcal/kg) were not different (P > 0.05), whereas FVW had the least (P < 0.05) DE (2,570 kcal/kg) and ME (2,460 kcal/kg) content compared with FW and SMW. Digestibility of crude protein and amino acids was greater (P < 0.05) in FW and SMW compared with FVW. The in vitro digestibility procedure can be used to approximate the digestibility of dry matter (DM) and energy in SMW, FW, and FVW compared with in vivo estimates, but significant error exists depending on the chemical characteristics of each food waste source. However, use of the prediction equations and digestibility data obtained from the in vitro procedure resulted in high accuracy in estimating DE content of FW (observed = 5,058 kcal/kg DM vs. predicted = 4,948 kcal/kg DM), SMW (observed = 5,071 kcal/kg DM vs. predicted 4,978 kcal/kg DM), and FVW (observed = 2,570 kcal/kg DM vs. predicted 2,814 kcal/kg DM) sources.

Activated Carbon from Prickly Pear Seed Cake: Optimization of Preparation Conditions Using Experimental Design and Its Application in Dye Removal

In the present study, the experimental design method was used to optimize the preparation conditions of an activated carbon from prickly pear seed cake by phosphoric acid activation. The parameters studied include impregnation ratio, carbonization temperature, and carbonization time. The optimal conditions for the preparation of the activated carbon with high adsorption capacity for methylene blue were identified to be an impregnation ratio of 2.9, carbonization temperature of 541°C, and carbonization time of 88 min. The obtained activated carbon was characterized by SEM/EDX, FTIR, pHpzc, and its capacity to adsorb methylene blue. FTIR analysis and pHPZC showed the acidic character of the activated carbon surface. The adsorption capacity of the optimal activated carbon was found to be 260 mg·g−1 for methylene blue. The adsorption equilibrium of methylene blue was well explained by the pseudo-second-order model and Freundlich isotherm. Furthermore, the performance of the produced activated carbon was examined by the methyl orange removal.

Current status of food waste generation and management in China

The current status of FW generation, including its characteristics, management, and current challenges in China, were analyzed, and further suggestions were made with regards to improvement. About 19.50% of the FW generated could be treated under the current designs for treatment capacity in China. FW characteristics show great variability in different economic regions in China, where both treatment efficiency and FW management are poor. Combined pretreatment and three-phase separation is the most used pretreatment method, and of the current FW pilot projects, anaerobic digestion is the most prevalent, accounting for 76.1% of all projects. Significant regional characteristics have been identified regarding FW generation and the treatment capacity for FW processing. Possible factors influencing FW management in China were also discussed. Finally, detailed suggestions are given for further development of FW treatment capacity, particularly regarding potential technical routes and management measures.

Support amongst UK pig farmers and agricultural stakeholders for the use of food losses in animal feed

While food losses (foods which were intended for human consumption, but which ultimately are not directly eaten by people) have been included in animal feed for millennia, the practice is all but banned in the European Union. Amid recent calls to promote a circular economy, we conducted a survey of pig farmers (n = 82) and other agricultural stakeholders (n = 81) at a UK agricultural trade fair on their attitudes toward the use of food losses in pig feed, and the potential relegalisation of swill (the use of cooked food losses as feed). While most respondents found the use of feeds containing animal by-products or with the potential for intra-species recycling (i.e. pigs eating pork products) to be less acceptable than feeds without, we found strong support (>75%) for the relegalisation of swill among both pig farmers and other stakeholders. We fit multi-hierarchical Bayesian models to understand people's position on the relegalisation of swill, finding that respondents who were concerned about disease control and the perception of the pork industry supported relegalisation less, while people who were concerned with farm financial performance and efficiency or who thought that swill would benefit the environment and reduce trade-deficits, were more supportive. Our results provide a baseline estimate of support amongst the large-scale pig industry for the relegalisation of swill, and suggest that proponents for its relegalisation must address concerns about disease control and the consumer acceptance of swill-fed pork.

Water use intensity of Canadian beef production in 1981 as compared to 2011

The amount of beef produced per animal in Canada increased significantly from 1981 to 2011, due to enhanced production efficiency and increased carcass weight. This study examined the impact of improvements in production efficiency on water use intensity over this period. Temporal and regional differences in cattle categories, water use for drinking, feed production and meat processing, feeding systems, average daily gains, and carcass weight were considered in the analysis. Potential evapotranspiration (PET) was estimated by the National Drought Model (NDM) from 679 weather stations across Canada using the Priestley and Taylor equation. To adjust PET estimates for each crop included in cattle diets, FAO crop coefficients were used to calculate total feed water demand. Estimates of drinking water consumed by a given class of cattle accounted for physiological status, body weight and dry matter intake as well as ambient temperature. In both years, drinking water accounted for less than 1% of total water use with precipitation (i.e., green water) included for feed and pasture production. With exclusion of green water, drinking water accounted for 24% and 21% of total water use for Canadian beef production in 1981 and 2011, respectively. The estimated intensity of blue water (surface and groundwater) use per kilogram of boneless beef was 577L in 1981 and 459 in 2011, a 20% decline. The observed reduction in water use intensity over the past three decades is attributed to an increase in average daily gain and slaughter weight, improved reproductive efficiency, reduced time to slaughter as well as improvements in crop yields and irrigation efficiency. Given that feed production accounts for the majority of water use in beef production, further advances may be achieved by improving feeding efficiencies and reducing water use per unit of feed crop and pasture production.

Prioritizing and optimizing sustainable measures for food waste prevention and management

Food waste has gained prominence in the European political debate thanks to the recent Circular Economy package. Currently the waste hierarchy, introduced by the Waste Framework Directive, has been the rule followed to prioritize food waste prevention and management measures according to the environmental criteria. But when considering other criteria along with the environmental one, such as the economic, other tools are needed for the prioritization and optimization. This paper addresses the situation in which a decision-maker has to design a food waste prevention programme considering the limited economic resources in order to achieve the highest environmental impact prevention along the whole food life cycle. A methodology using Life Cycle Assessment and mathematical programing is proposed and its capabilities are shown through a case study. Results show that the order established in the waste hierarchy is generally followed. The proposed methodology revealed to be especially helpful in identifying "quick wins" - measures that should be always prioritized since they avoid a high environmental impact at a low cost. Besides, in order to aggregate the environmental scores related to a variety of impact categories, different weighting sets were proposed. In general, results show that the relevance of the weighting set in the prioritization of the measures appears to be limited. Finally, the correlation between reducing food waste generation and reducing environmental impact along the Food Supply Chain has been studied. Results highlight that when planning food waste prevention strategies, it is important to set the targets at the level of environmental impact instead of setting the targets at the level of avoided food waste generation (in mass).

Use of food waste, fish waste and food processing waste for China's aquaculture industry: Needs and challenge

China's aquaculture industry is growing dramatically in recent years and now accounts for 60.5% of global aquaculture production. Fish protein is expected to play an important role in China's food security. Formulated feed has become the main diet of farmed fish. The species farmed have been diversified, and a large amount of 'trash fish' is directly used as feed or is processed into fishmeal for fish feed. The use of locally available food waste as an alternative protein source for producing fish feed has been suggested as a means of tackling the problem of sourcing safe and sustainable feed. This paper reviews the feasibility of using locally available waste materials, including fish waste, okara and food waste. Although the fishmeal derived from fish waste, okara or food waste is less nutritious than fishmeal from whole fish or soybean meal, most fish species farmed in China, such as tilapia and various Chinese carp, grow well on diets with minimal amounts of fishmeal and 40% digestible carbohydrate. It can be concluded that food waste is suitable as a component of the diet of farmed fish. However, it will be necessary to revise regulations on feed and feed ingredients to facilitate the use of food waste in the manufacture of fish feed.

Sustainable food systems-a health perspective

Malnutrition in all forms, ranging from undernourishment to obesity and associated diet-related diseases, is one of the leading causes of death worldwide, while food systems often have major environmental impacts. Rapid global population growth and increases in demands for food and changes in dietary habits create challenges to provide universal access to healthy food without creating negative environmental, economic, and social impacts. This article discusses opportunities for and challenges to sustainable food systems from a human health perspective by making the case for avoiding the transition to unhealthy less sustainable diets (using India as an exemplar), reducing food waste by changing consumer behaviour (with examples from Japan), and using innovations and new technologies to reduce the environmental impact of healthy food production. The article touches upon two of the challenges to achieving healthy sustainable diets for a global population, i.e., reduction on the yield and nutritional quality of crops (in particular vegetables and fruits) due to climate change; and trade-offs between food production and industrial crops. There is an urgent need to develop and implement policies and practices that provide universal access to healthy food choices for a growing world population, whilst reducing the environmental footprint of the global food system.

Review: Feed demand landscape and implications of food-not feed strategy for food security and climate change

The food-feed competition is one of the complex challenges, and so are the ongoing climate change, land degradation and water shortage for realizing sustainable food production systems. By 2050 the global demand for animal products is projected to increase by 60% to 70%, and developing countries will have a lion's share in this increase. Currently, ~800 million tonnes of cereals (one-third of total cereal production) are used in animal feed and by 2050 it is projected to be over 1.1 billion tonnes. Most of the increase in feed demand will be in developing countries, which already face many food security challenges. Additional feed required for the projected increased demand of animal products, if met through food grains, will further exacerbate the food insecurity in these countries. Furthermore, globally, the production, processing and transport of feed account for 45% of the greenhouse gas emissions from the livestock sector. This paper presents approaches for addressing these challenges in quest for making livestock sector more sustainable. The use of novel human-inedible feed resources such as insect meals, leaf meals, protein isolates, single cell protein produced using waste streams, protein hydrolysates, spineless cactus, algae, co-products of the biofuel industry, food wastes among others, has enormous prospects. Efficient use of grasslands also offers possibilities for increasing carbon sequestration, land reclamation and livestock productivity. Opportunities also exist for decreasing feed wastages by simple and well proven practices such as use of appropriate troughs, increase in efficiency of harvesting crop residues and their conversion to complete feeds especially in the form of densified feed blocks or pellets, feeding as per the nutrient requirements, among others. Available evidence have been presented to substantiate arguments that: (a) for successful and sustained adoption of a feed technology, participation of the private sector and a sound business plan are required, (b) for sustainability of the livestock production systems, it is also important to consider the consumption of animal products and a case has been presented to assess future needs of animal source foods based on their requirements for healthy living,

Polar aprotic solvent-water mixture as the medium for catalytic production of hydroxymethylfurfural (HMF) from bread waste

Valorisation of bread waste for hydroxymethylfurfural (HMF) synthesis was examined in dimethyl sulfoxide (DMSO)-, tetrahydrofuran (THF)-, acetonitrile (ACN)-, and acetone-water (1:1v/v), under heating at 140°C with SnCl₄ as the catalyst. The overall rate of the process was the fastest in ACN/H₂O and acetone/H₂O, followed by DMSO/H₂O and THF/H₂O due to the rate-limiting glucose isomerisation. However, the formation of levulinic acid (via rehydration) and humins (via polymerisation) was more significant in ACN/H₂O and acetone/H₂O. The constant HMF maxima (26-27mol%) in ACN/H₂O, acetone/H₂O, and DMSO/H₂O indicated that the rates of desirable reactions (starch hydrolysis, glucose isomerisation, and fructose dehydration) relative to undesirable pathways (HMF rehydration and polymerisation) were comparable among these mediums. They also demonstrated higher selectivity towards HMF production over the side reactions than THF/H₂O. This study differentiated the effects of polar aprotic solvent-water mediums on simultaneous pathways during biomass conversion.

A new approach for concurrently improving performance of South Korean food waste valorization and renewable energy recovery via dry anaerobic digestion under mesophilic and thermophilic conditions

Dry semicontinuous anaerobic digestion (AD) of South Korean food waste (FW) under four solid loading rates (SLRs) (2.30-9.21kg total solids (TS)/m³day) and at a fixed TS content was compared between two digesters, one each under mesophilic and thermophilic conditions. Biogas production and organic matter reduction in both digesters followed similar trends, increasing with rising SLR. Inhibitor (intermediate products of the anaerobic fermentation process) effects on the digesters' performance were not observed under the studied conditions. In all cases tested, the digesters' best performance was achieved at the SLR of 9.21kg TS/m³day, with 74.02% and 80.98% reduction of volatile solids (VS), 0.87 and 0.90m³ biogas/kg VS_removed, and 0.65 (65% CH₄) and 0.73 (60.02% CH₄) m³ biogas/kg VS_fed, under mesophilic and thermophilic conditions, respectively. Thermophilic dry AD is recommended for FW treatment in South Korea because it is more efficient and has higher energy recovery potential when compared to mesophilic dry AD.