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Recent sustainable development goals of food security, environmental protection, material and energy efficiency are the key drivers of the valorization of food waste. In the present work, the production of biosurfactant sophorolipids from several (food) waste streams was investigated, using the non-pathogenic yeast Starmerella bombicola. From a preliminary screening, restaurant food waste emerged as the most suitable feedstock compared to bakery waste, textile waste, used corn oil, animal fat and lipid fraction of hydrolyzed food waste. Restaurant food waste was subsequently used for sophorolipids production in a laboratory-scale bioreactor. Food waste obtained from a local restaurant was subjected to enzymatic hydrolysis for 16 h, yielding a hydrolysate containing about 100 g/L glucose and 2.4 g/L free amino nitrogen. High SL process efficiency was achieved by fed-batch fermentation using the restaurant food waste hydrolysate as the complete batch medium, i.e. without any supplementation of additional medium components such as vitamins, salts, nitrogen or phosphate. Controlled feeding of glucose and oleic acid to the culture was performed after the batch phase. A sophorolipids titer of 115.2 g/L was obtained in a fermentation time of 92 h resulting in an overall volumetric productivity of 1.25 g/L.h. These results achieved for sophorolipids productivity using hydrolyzed food waste are in the same order of magnitude as the reported values using traditional (complex) fermentation media. This indicates the suitability of the developed process using food waste for the advancement of waste-based bio-processes for the production of sophorolipids.

This paper presents an efficient, green and sustainable approach for succinic acid (SA) fermentation, in which glucose-rich hydrolysates from various waste streams were used as the substrate for SA production by Yarrowia lipolytica without pH control for the first time. First, Y. lipolytica PGC202 was found to be able to consume glucose-rich mixed food waste (MFW) hydrolysate for SA production with high efficiency. After medium optimization, a SA titer at 31.7 g/L with a yield of 0.52 g/g and productivity of 0.60 g/L/h was obtained from isFBB fermentation when using 60 g/L glucose-containing MFW hydrolysate as the carbon source supplemented with 3% tryptone. When glucose-rich hydrolysate from other waste streams was used, the highest SA yield of 0.61 g/g via yeast fermentation at low pH was achieved, which demonstrated the extensive substrate adaptability and great potential of Y. lipolytica. By feeding concentrated MFW hydrolysate, SA titer up to 71.6 g/L was achieved from fed-batch fermentation with pH decreased naturally to 2.8. Finally, with the revised recovery method, 68.3% of the total SA with purity between 89.5% and 91.0% was recovered from the acidic fermentation broth with only low input of acid for acidification, which demonstrated the great advantages of SA production at low pH over that under neutral conditions in terms of economic improvement and environmental sustainability. In general, this study overcomes one of the major economic drawbacks for future feasible large-scale fermentative SA production, and it also illustrates a promising prospective for bio-SA production.

Techno-economic analysis was conducted to evaluate a food and beverage (F&B) waste valorisation process for sugar syrup production via integrated biorefinery. A comprehensive process model was developed with a capacity of 10 metric tons (MT) hour−1 of food waste and 14 MT hour−1 of beverage waste. Three scenarios were proposed with different types of sugar syrups as the main products: Scenario I) fructose syrup, Scenario II) high fructose syrup-42, and Scenario III) glucose-rich syrup. Mass balance showed conversion yields of 0.24 MT sugar syrups per MT of F&B waste, while lipids (0.07 MT per MT of F&B waste) and insect feed (0.44 MT per MT of F&B waste) were the co-products proposed to be used for other industrial biorefinery processes. All scenarios were observed to be economically self-sustainable with net profit generation (US$11-26 million year−1) and positive net present values (US$92-294 million). Along with the net production costs (US$443-665 MT−1), the sugar syrups derived from the F&B waste have relatively low minimum selling prices of US$157-747 MT−1 at a 5% discount rate. Lastly, sensitivity analysis was performed which found that the prices of sugar syrups were the largest determinants of their profitability. This study proposes a significant techno-economic basis for F&B waste biorefinery, which offers a successful demonstration for food and drink industries adopting these biotechnological processes for the same plant size.

As a platform chemical with various applications, succinic acid (SA) is currently produced by petrochemical processing from oil-derived substrates such as maleic acid. In order to replace the environmental unsustainable hydrocarbon economy with a renewable environmentally sound carbohydrate economy, bio-based SA production process has been developed during the past two decades. In this review, recent advances in the valorization of solid organic wastes including mixed food waste, agricultural waste and textile waste for efficient, green and sustainable SA production have been reviewed. Firstly, the application, market and key global players of bio-SA are summarized. Then achievements in SA production by several promising yeasts including Saccharomyces cerevisiae and Yarrowia lipolytica are detailed, followed by calculation and comparison of SA production costs between oil-based substrates and raw materials. Lastly, challenges in engineered microorganisms and fermentation processes are presented together with perspectives on the development of robust yeast SA producers via genome-scale metabolic optimization and application of low-cost raw materials as fermentation substrates. This review provides valuable insights for identifying useful directions for future bio-SA production improvement.

Waste streams have emerged as potential feedstocks for biofuel production via microbial bioconversion. Metabolic engineering of the microalga Phaeodactylum tricornutum in its lipid biosynthetic pathways has been conducted with an aim to improve lipid production. However, there has been only limited achievement in satisfying biofuel demands by utilising extracellular organic carbons from low-cost waste streams. Herein, we present a successive staged cultivation mode, based on a previously engineered strain that co-overexpresses two key triacylglycerol biosynthesis genes. We first optimised microalgal biomass and lipid production by using food waste hydrolysate and crude glycerol as the cultivation media. Food waste hydrolysate (5% v/v) is a low-cost organic carbon source for enhanced microalgal biomass production, and the resulting lipid concentration was 1.08-fold higher with food-waste hydrolysate than that of the defined medium. Additionally, the resultant lipid concentration after using crude glycerol (100 mM) was 1.24-fold higher than that using the defined medium. Two carbon feeding modes (hybrid and sequential) were also performed to investigate the potential of engineered P. tricornutum with preliminary mechanistic analyses. The biodiesel properties of lipids produced in the hybrid mode were evaluated for potential application prospects. Collectively, this study demonstrates a waste stream utilisation strategy for efficient and sustainable microalgal biofuel production.

Investigation of composition of biomass is an important pre-requisite for determining its suitability for various downstream applications. In recent times, food waste has emerged as a valuable biomass feedstock which could be valorized for production of fuels, chemicals and materials. Prior to use as a feedstock, it is pertinent to perform a detailed composition analysis and gather critical information about nutrient content including carbon, nitrogen and lipid. Additionally, analysis of minor constituents in food waste is significant to understand the possibility of their toxic or inhibitory effects during biotechnological conversions. Another abundant biomass source is manure which primarily arises from animal feeding operations. The major application of manure is land-applied fertilizer besides the recent investigations for fuel and energy. These intended applications demand complete characterization of nutrient content and quality. Thus, this chapter is focused on characterization and analysis of food waste and manure. Methods for sampling, handling and pretreatment of food waste and manure are discussed. Furthermore, a detailed nutrient analysis and equipment used for analysis is described. We further discuss the application of food waste processing techniques which could facilitate the characterization, treatment and product recovery.

A sustainable food waste valorisation process was proposed by designing a plant with a capacity of 10 metric tons (MT) hour−1 of food waste powder with a 20-year lifetime. Three scenarios were proposed with different products: Scenario I) lactic acid, Scenario II) lactide, Scenario, and III) poly(lactic acid) (PLA). Mass balance showed conversion yields of 3.1 MT of 80% lactic acid, 1.7 MT of lactide, and 1.3 MT of poly(lactic acid) from 10 MT of food waste powder. All scenarios were economically feasible, but Scenario I had the highest annual net profits (US$ 22,184,169), internal rate of return (31.1%), net present value (US$234,803,060) and the shortest payback period (5.1 years) at a discount rate of 5%. The minimum selling prices of lactic acid, lactide and poly(lactic acid) were US$943 MT−1, US$2073 MT−1 and US$3330 MT−1, respectively. Sensitivity analysis showed that the prices of lactic acid, lactide and poly(lactic acid) were the largest determinants of the profitability in the plant while the sale of by-products (animal feed) was also critical to the plant's economics. This work has cast insights on the techno-economic performance of a sustainable food waste treatment under a decentralised approach in urban areas.

The review presents the recent trends in green and sustainable chemistry, as well as waste valorization and their applicability to understand and realize the concept of a circular economy. It also provides a comprehensive global perspective of the linear plastics economy and makes the case for its transformation into a circular plastics economy. Furthermore, bioconversion in a food waste biorefinery to produce fructose as an example of a high value-added product is given as a case study to demonstrate the feasibility of a circular economy.

Food waste contains complex nutrients such as carbohydrates, fats, proteins which could be broken down into simpler substrates such as sugars (e.g., glucose), lipids and proteins (e.g., free amino nitrogen). These components can be used for conversion into useful bio-based products such as chemicals, materials and fuels. This research aimed at the development of bio-based polyurethane (PU) materials using food waste-derived lipids. Since the quality of lipid plays an important role in polyol synthesis, optimal extraction procedures were developed to select the most appropriate method for polyol synthesis. From obtained lipids, two polyol synthesis methods were used, lipid transamidation with diethanolamine (DEOA or DEA) and lipid epoxidation and subsequent epoxy ring opening with trimethylolpropane. Bio-polyol obtained in transamidation reaction was used to obtain rigid PU foams with three different isocyanate indices of 130; 150 and 200 while bio-polyol form epoxy ring opening was used to obtain rigid PU foams with an isocyanate index of 150. The initial formulations were suitable to produce good quality rigid PU foam samples at a laboratory scale. The resultant rigid PU foams are promising for further studies and development of thermal insulation materials.

Bioconversion of food waste into sophorolipid-based biosurfactants is a promising emerging technology. It is important to evaluate the environmental impacts associated with the latest advancements in sophorolipid production as it matures to maximize sustainability on scale-up. This study takes a dynamic Life Cycle Assessment (dLCA) approach to address the inherent uncertainties and evaluate the environmental performances. It demonstrates the dLCA framework by conducting the new traversal of food waste-derived industrial-scale sophorolipid production, with the combination of Techno-Economic Analysis (TEA). A systematic investigation of the environmental-economic implications of the two pathways to produce SL crystals and syrup. The global warming potential (GWP) for 1 kg of SL crystals and syrup was 7.9 kg CO2 eq. and 5.7 kg CO2 eq., respectively. The Ashby-like charts based on the LCA and TEA results at the pilot plant highlighted the trade-offs between systemic environmental costs and economic benefits for design decisions.

Algal cells are known for improved accumulation of long chain fatty acids when grown in continuous flow cultures under conditions where nutrients, such as nitrogen and/or phosphorous, are limited. Food waste has been shown to be an appropriate source of carbon, nitrogen and phosphorous compounds to be used as nutrients in heterotrophic microalgal biomass production. Food waste, however, has unpredictable contents of the three mentioned compounds, which makes an application in continuous flow cultures where defined concentrations of nutrients are required challenging. Therefore, this study aimed on developing continuous flow cultures of the heterotrophic microalga Chlorella pyrenoidosa solely based on mixed restaurant food waste for improved fatty acid production. Food waste was enzymatically digested using amylolytic or proteolytic enzymes, and the obtained hydrolysate was used for the cultivation of C. pyrenoidosa in continuous flow cultures under nitrogen and/or phosphate limitation. In a nutrient sufficient batch culture, C. pyrenoidosa contained 103.8 mg g−1 lipids, while up to three times more lipids was found in biomass cultured under nutrient limited conditions. C. pyrenoidosa also accumulated up to 619.0 mg g−1carbohydrates. With decreasing dilution rate and increasing nutrient stress, the carbohydrate content could be decreased to 390.9 mg g−1. The outcomes of this study extended our understanding on how to utilize complex media in continuous flow cultures of algal cells which are carried out under specific nutrient limitation for improved fatty acid accumulation.

This study investigates the prospective of utilizing kitchen wastewater and food wastes, biofuels industry byproducts as alternative water and carbon sources. Kitchen wastewater did not impede cellular growth rate of the evolved Phaeodactylum strain E70, which indicates its potential as an alternative to freshwater resources. Among the organic wastes assessed, food waste hydrolysate significantly increased cell growth. Supplement of crude glycerol in cultivation medium enhances the total fatty acid content. Mixed food waste hydrolysate and crude glycerol remarkably increased both the cell density and total fatty acid content. Also, the supplement of butylated hydroxytoluene alleviated the oxidative stress induced by impurities in organic wastes and concomitantly increased microalgal total fatty acids and polyunsaturated fatty acids content. The experimental results reported in this study show that a waste-based biorefinery could lead to utilization of organic waste resources for the efficient production of value-added products.

Dunaliella salina is a promising microbial host for the sustainable production of bioenergy and valuable compounds. D. salina can be mixotrophically cultivated using a pure organic carbon source. However, pure organic carbon sources remarkably enhance the cost of cultivation and constrain the development of upscale microalgal cultivation. This study examined the feasibility of using low-value food waste supplemented with fulvic acid in D. salina mixotrophic cultivation for lipid and carotenoid accumulation. The glucose-rich hydrolysate was first obtained via enzymatic hydrolysis from selected food waste. This hydrolysate was an appropriate source of organic carbon for microalgal mixotrophy based on a two-stage cultivation strategy for investigating the biomass and accumulation of valuable products. In addition, fulvic acid, which contains oxygen-rich and carbon-poor functional groups, was used in the second stage to maximise the production of biomass (3.1 ± 0.2 g/L), lipids (0.75 ± 0.03 g/L) and carotenoids (0.52 ± 0.03 g/L). The biodiesel quality of the lipid derived from D. salina biomass based on food waste hydrolysate met the previously approved standards. These data illustrate a sustainable and efficient algal-based food waste biorefinery strategy for the co-production of bioenergy and bioactive compounds, and offer key insights to address the issues of global food waste and algal-based resource utilisation.

Microbial biosurfactants are surface-active molecules that are naturally produced by a range of microorganisms. They have certain advantages over chemical surfactants, such as lower toxicity, higher biodegradability, anti-tumor, and anti-microbial properties. Sophorolipids (SLs) in particular are one of the most promising biosurfactants, as they hold the largest share of the biosurfactant market. Currently, researchers are developing novel approaches for SL production that utilize renewable feedstocks and advanced separation technologies. However, challenges still exist regarding consumption of materials, enzymes, and electricity, that are primarily fossil based. Researchers lack a clear understanding of the associated environmental impacts. It is imperative to quantify and optimize the environmental impacts associated with this emerging technology very early in its design phase to guide a sustainable scale-up. It is necessary to take a collaborative perspective, wherein life cycle assessment (LCA) experts work with experimentalists, to quantify environmental impacts and provide recommendations for improvements in the novel waste-derived SL production pathways. Studies that have analyzed the environmental sustainability of microbial biosurfactant production are very scarce in literature. Hence, in this work, we explore the possibility of applying LCA to evaluate the environmental sustainability of SL production. A dynamic LCA (dLCA) framework that quantifies the environmental impacts of a process in an iterative manner, is proposed and applied to evaluate SL production. The first traversal of the dLCA was associated with the selection of an optimal feedstock, and results identified food waste as a promising feedstock. The second traversal compared fermentation coupled with alternative separation techniques, and highlighted that the fed-batch fermentation of food waste integrated with the in-situ separation technique resulted in less environmental impacts. These results will guide experimentalists to further optimize those processes, and improve the environmental sustainability of SL production. Resultant datasets can be iteratively used in subsequent traversals to account for technological changes and mitigate the corresponding impacts before scaling up.

Bioconversion of food waste into value-added products is a promising way to tackle the global food waste management problem. In this study, a novel valorisation strategy for bioenergy and lutein production via microalgal fermentation was investigated. Significant amount of glucose was recovered from enzymatic hydrolysis of food waste. The resultant hydrolysate was then utilised as culture medium in mixotrophic cultivation of Chlorella sp. to obtain high levels of lipid and lutein, whose accumulation patterns were consistent with molecular analyses. The resultant algal lipid derived from microalgal biomass using food hydrolysate was at high quality in terms of biodiesel properties. Further, in semi-continuous fermentation, the average algal biomass was 6.1 g L-1 with 2.5 g L-1 lipid and 38.5 mg L-1 lutein using hydrolysate with an initial glucose concentration of 10 g L-1. Meanwhile, the resultant algal biomass was 6.9 g L-1 with 1.8 g L-1 lipid and 63.0 mg L-1 lutein using hydrolysate with an initial glucose concentration of 20 g L-1, which suggests food waste hydrolysate could trigger algal products preferences. The experimental results of this study suggested the potential of microalgae as a platform for bioconversion of food waste into high-value products, especially sustainable bioenergy.

This study evaluates the techno-economic feasibility of sophorolipid (SL) production process that co-utilizes food waste, glucose and oleic acid as substrates. Two variables are considered in terms of (a) Plant construction: Purchasing equipment either from the US or Mainland China and (b) Production: to produce SL crystals (about 97% active) or a concentrated SL liquid/syrup (about 78% active). Hence, four scenarios are generated: Scenario I: equipment made in the USA + SL crystals; Scenario II: equipment made in the USA + SL syrup; Scenario III: equipment made in China + SL crystals; Scenario IV: equipment made in China + SL syrup. It is found that all scenarios are economically feasible and Scenario I has the highest net profit. Scenario III has the highest internal rate of return, net present value and the shortest payback period at a 7% discount rate. Finally, comparison of food waste-related techno-economic studies was conducted.

Until now, the production of microbial biosurfactants has been limited to the use of first-generation (food) substrates. Moreover, the results on sophorolipids yield and productivity reported by state-of-the-art fed-batch processes for sophorolipids production remain unsatisfactory and lead to a significantly high cost per kg of the product. With an aim to address these problems, this study demonstrates a long-term and high-efficiency sophorolipids production method using a semi-continuous integrated production-separation system which utilizes food waste as a substrate. An average volumetric productivity of 2.43 g L−1 h −1 and the overall sophorolipids yield on the substrate (i.e. the combination of glucose and oleic acid as carbon source) of 0.73 g g−1 was achieved within 240 h by fed-batch and separation fermentation. Moreover, the potential of sustaining high production efficiency during long-term fermentation times (480 h) was investigated. No reduction in process efficiency was observed, i.e. average volumetric productivity and an overall sophorolipids yield of 2.39 g L−1 h −1 and 0.73 g g−1 were obtained, respectively. Notably, a very high biomass concentration of 117.2 g L−1 was observed in fed-batch fermentation and separation, which is the highest cell density ever reported for Starmerella bombicola. The separation efficiency was also calculated to evaluate the in-situ separation performance of the developed process quantitatively. In 480-h fermentation, the average separation efficiency of 74.3% and overall separation efficiency of 93.0% was achieved after six separation cycles, suggesting that both separation design and process control were successful in laboratory-scale fermentation. These findings demonstrate the potential of the developed sophorolipids fermentation-separation system for application at industrial scale.

Recovering valuable materials from food waste by applying the concept of a bio-refinery is attracting considerable interest. To this effect, we investigated the possibility of enhancing the enzymatic hydrolysis of food waste using ultrasonic technology. The effect of pre-treating blended food waste with high-intensity ultrasound (20 kHz) on subsequent hydrolysis by glucoamylase was investigated as a function of sonication time and temperature. Particle sizing by laser diffraction, and imaging via scanning electronic microscopy showed that ultrasonic pre-treatment could reduce the particle size of the blended food waste significantly, resulting in a better interaction with the enzyme. As a consequence, the glucose yield of enzymatic hydrolysis was ∼10% higher for food waste pre-sonicated using the most intensive ultrasonication conditions studied (5 min sonication at a power of 0.8 W/mL at 20 °C) than for the untreated control. In addition, the time required to achieve high yields of glucose could be more than halved using ultrasonic pre-treatment. This could enable the hydrolysis reactor size or the enzyme usage to be reduced by more than 50%. Therefore, an ultrasound-assisted bioconversion process from food waste into a value-added product has been demonstrated.

In this study, an advanced biorefinery technology that uses mixed bakery waste has been developed to produce l-lactic acid using an adaptively evolved Thermoanaerobacterium aotearoense LA1002-G40 in a non-sterilized system. Under these conditions, mixed bakery waste was directly hydrolysed by Aspergillus awamori and Aspergillus oryzae, resulting in a nutrient-rich hydrolysate containing 83.6g/L glucose, 9.5 g/L fructose and 612 mg/L free amino nitrogen. T. aotearoense LA1002-G40 was evaluated and then adaptively evolved to grow in this nutrient-rich hydrolysate. Using a 5-L fermenter, the overall lactic acid production from mixed bakery waste was 0.18 g/g with a titer, productivity and yield of 78.5 g/L, 1.63 g/L/h and 0.85 g/g, respectively. This is an innovative procedure involving a complete bioconversion process for l-lactic acid produced from mixed bakery waste under non-sterilized conditions. The proposed process could be potentially applied to turn food waste into l-lactic acid in an economically feasible way.

A techno-economic study of food waste valorization via fungal hydrolysis, microalgae cultivation and production of plasticizer, lactic acid and animal feed was simulated and evaluated by Super-Pro Designer®. A pilot-scale plant was designed with a capacity of 1 metric ton day−1 of food waste with 20 years lifetime. Two scenarios were proposed with different products: Scenario (I) plasticizer & lactic acid, Scenario (II) plasticizer & animal feed. It was found that only Scenario I was economically feasible. The annual net profits, net present value, payback period and internal rate of return were US$ 422,699, US$ 3,028,000, 7.56 years and 18.98%, respectively. Scenario II was not economic viable due to a deficit of US$ 42,632 per year. Sensitivity analysis showed that the price of lactic acid was the largest determinant of the profitability in Scenario I, while the impact of the variables was very close in Scenario II.

In this study, glucoamylase extract was produced from various bakery wastes under solid state fermentation by Aspergillus awamori and Aspergillus oryzae. The highest glucoamylase activities obtained from bread and cake waste with A. awamori were 240.7 U/g of bread (db) and 134.9 U/g of cake (db), respectively, and 83.3 U/g of pastry (db) using A. oryzae. Kinetic studies showed that glucoamylase obtained from bakery wastes should have at least two conformations under the two temperature ranges of 30–55 °C and 60–70 °C. Thermodynamics stated that the range 30–55 °C was considered to be the optimal temperature for glucoamylase activity and subsequent food waste hydrolysis. The crude enzyme extracts were then used in the hydrolysis of restaurant food waste to produce a glucose-rich hydrolysate. It was found that using combined crude glucoamylase (produced from A. awamori and A. oryzae) could achieve higher glucose production (0.515 g of glucose/g of food waste) than using glucoamylase alone (produced from A. ...

Staggering amounts of food waste are being generated in Asia by means of agricultural processing, food transportation and storage, and human food consumption activities. This along with the recent sustainable development goals of food security, environmental protection, and energy efficiency are the key drivers for food waste valorization. The aim of this review is to provide an insight on the latest trends in food waste valorization in Asian countries such as India, Thailand, Singapore, Malaysia and Indonesia. Landfilling, incineration, and composting are the first-generation food waste processing technologies. The advancement of valorisation alternatives to tackle the food waste issue is the focus of this review. Furthermore, a series of examples of key food waste valorization schemes in this Asian region as case studies to demonstrate the advancement in bioconversions in these countries are described. Finally, important legislation aspects for food waste disposal in these Asian countries are also reported.

Sustainability consists of three major components, namely economic, ecological and social impacts. The most important driver for food waste based biorefinery is whether the proposed design is profitable. The development of highly efficient and cost-effective biorefineries is a prerequisite for such a bio-based economy. There are many factors that influence the overall costs and returns of the food waste based biorefinery process, and affect the overall economic performance as well. In this chapter, the economic and environmental impacts of food waste based biorefinery is evaluated by using Techno-economic Study and Life Cycle Assessment (LCA) in terms of non-renewable energy use (NREU) and greenhouse gases (GHG) emission. Special focus on the economics of Green Chemistry, and the current status of LCA studies on succinic acid and thermochemical processes for biomass conversion to biofuels are covered.

The global plastic production has reached 299 million tons per year, of which more than 95% is petroleum-based plastic. With the consideration of the environmental degradation caused by petroleum-based plastics and the depletion of fossil resources, there is an increasing interest driving the development of bioplastics, which offer numerous advantages over petroleum-based plastics, e.g., less greenhouse gas emission, biodegradation, and use of renewable substrates. This chapter discusses two types of the most common bioplastics, namely polyhydroxybutyrate and poly(lactic acid), with their histories, properties, synthesis, and current status on the commercial market and the low-cost waste materials that are identified for production.

Heterotrophic cultivation of Chlorella vulgaris was investigated in food waste hydrolysate. The highest exponential growth rate in terms of biomass of 0.8 day−1 was obtained in a hydrolysate consisting of 17.9 g L−1 glucose, 0.1 g L−1 free amino nitrogen, 0.3 g L−1 phosphate and 4.8 mg L−1 nitrate, while the growth rate was reduced in higher concentrated hydrolysates. C. vulgaris utilized the nutrients recovered from food waste for the formation of biomass and 0.9 g biomass was produced per gram glucose consumed. The microalgal biomass produced in nutrient sufficient batch cultures consisted of around 400 mg g−1 carbohydrates, 200 mg g−1 proteins and 200 mg g−1 lipids. The conversion of nutrients derived from food waste and the balanced biomass composition make C. vulgaris a promising strain for the recycling of food waste in food, feed and fuel productions.

Research on different alternative liquid fuels is rapidly growing because of the environmental concerns and depletion of fossil fuels. As the world confronts a reported food shortage and rising fuel prices, researchers are engaged in developing biofuels that would not convert food crops into energy. In addition, it is apparent that the demand for biodiesel is expected to rise over the coming years. To date, many edible oils are used for biodiesel production. Thus, increasing demand of biodiesel will have a direct impact on food shortage. This underlines the need to use waste materials for biodiesel preparation. In this regard, lipid fraction which can be obtained after hydrolysis of food waste with an enzyme system accumulated in the solid state fungal culture is considered inedible and can be used as a potential source to produce biodiesel.

Mixed food waste, which was directly collected from restaurants without pretreatments, was used as a valuable feedstock in succinic acid (SA) fermentation in the present study. Commercial enzymes and crude enzymes produced from Aspergillus awamori and Aspergillus oryzae were separately used in hydrolysis of food waste, and their resultant hydrolysates were evaluated. For hydrolysis using the fungal mixture comprising A. awamori and A. oryzae, a nutrient-complete food waste hydrolysate was generated, which contained 31.9 g L(-1) glucose and 280 mg L(-1) free amino nitrogen. Approximately 80-90 % of the solid food waste was also diminished. In a 2.5 L fermentor, 29.9 g L(-1) SA was produced with an overall yield of 0.224 g g(-1) substrate using food waste hydrolysate and recombinant Escherichia coli. This is comparable to many similar studies using various wastes or by-products as substrates. Results of this study demonstrated the enormous potential of food waste as renewable resource in the production of bio-based chemicals and materials via microbial bioconversion.

Food waste is currently generated in signifi cant quantities worldwide. While most of this has generally few uses different from landfi lling or composting, advanced valorization alternatives should be developed to maximize the value derived from such an important waste source. This contribu- tion aims to illustrate a series of examples and current valorization strategies proposed in different countries in order to tackle the food waste issue. Proposed processing schemes involve biorefi nery approaches based on both chemical and biological technologies. Important legislation aspects in dif- ferent countries are also presented. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd

In this paper, the techno-economic study for a pilot-scale production of succinic acid from food waste via fermentation was evaluated. The pilot plant was based in Hong Kong and designed for converting 1 tonne/day of bakery waste into succinic acid. The mass and energy balance of the process was simulated by computer package SuperPro Designer ® . The total capital investment for the plant and the total production cost were US$ 1,118,243 and US$ 230,750/year respectively. Overall revenue generated from the process was US$ 374,041/year. The return on investment, payback period and internal rate of return of the project were 12.8%, 7.2 years and 15.3% respectively. The findings indicated that the fermentative succinic acid production from bakery waste was feasible. This is important for attracting investment and industrialization interest on the biorefinery process using domestic wastes as raw materials.

When it is not consumed, bread presents a major source of food waste, both in terms of the amount and its economic value. However, bread also possesses the characteristics of an ideal substrate for solid state fermentation. Yet nearly all wasted bread ends up in landfill sites, where it is converted into methane by anaerobic digestion. Governments are finally taking action and, according to the EU Landfill Directive, for example, biodegradable municipal waste disposed into landfills must be decreased to 35% of 1995 levels, by 2020. Solid state fermentation of waste bread for the production of value added products is a novel idea, which could help with the achievement of this target. In this study, glucoamylase and protease production from waste bread pieces, via solid state fermentation, was investigated in detail. The optimum fermentation conditions for enzyme production were evaluated as, 20 mm particle size, 1.8 (w/w, db) initial moisture ratio, and duration of 144 h. Under these conditions, glucoamylase and protease activities reached up to 114.0 and 83.2 U/g bread (db), respectively. This study confirms that waste bread could be successfully utilised as a primary raw material in cereal based biorefineries.

The feasibility of using pastry waste as resource for glucoamylase (GA) production via solid state fermentation (SSF) was studied. The crude GA extract obtained was used for glucose production from mixed food waste. Our results showed that pastry waste could be used as a sole substrate for GA production. A maximal GA activity of 76.1 ± 6.1 U/mL was obtained at Day 10. The optimal pH and reaction temperature for the crude GA extract for hydrolysis were pH 5.5 and 55 °C, respectively. Under this condition, the half-life of the GA extract was 315.0 minutes with a deactivation constant (kd) 2.20 × 10−3 minutes−1. The application of the crude GA extract for mixed food waste hydrolysis and glucose production was successfully demonstrated. Approximately 53 g glucose was recovered from 100 g of mixed food waste in 1 h under the optimal digestion conditions, highlighting the potential of this approach as an alternative strategy for waste management and sustainable production of glucose applicable as carbon source in many biotechnological processes.

Increasingly tighter regulations regarding organic waste, and the demand for renewable chemicals and fuels, are pushing the manufacturing industry toward higher sustainability to improve cost-effectiveness and meet customers’ demand. Food waste valorization is one of the current research areas that has attracted a great deal of attention over the past few years as a potential alternative to the disposal of a wide range of residues in landfill sites. In particular, the development of environmentally sound and innovative strategies to process such waste is an area of increasing importance in our current society. Landfill, incineration and composting are common, mature technologies for waste disposal. However, they are not satisfactory to treating organic waste due to the generation of toxic methane gas and bad odor, high energy consumption and slow reaction kinetics. In fact, research efforts have also been oriented on novel technologies to decompose organic waste. However, no valuable product is generated from the decomposition process. Instead of disposing and decomposing food waste, recent research has focused on its utilization as energy source (e.g., for bioethanol and biodiesel production). Organic waste is also useful to generate useful organic chemicals via biorefinery or white biotechnology (e.g., succinic acid and/or bio-plastics). This article is aimed to summarize recent development of waste valorization strategies for the sustainable production of chemicals, materials, and fuels through the development of green production strategies. It will also provide key insights into recent legislation on management of waste worldwide as well as two relevant case studies (the transformation of corncob residues into functionalized biomass-derived carbonaceous solid acids and their utilization in the production of biodiesel-like biofuels from waste oils in Philippines, as well as the development of a bakery waste based biorefinery for succinic acid and bioplastic production in Hong Kong) to illustrate the enormous potential of biowaste valorization for a more sustainable society. Future research directions and possible sustainable approaches will also be discussed with their respective proofs of concept.

Food waste is a global problem. Each year food worth billions of dollars is wasted by the developed economies of the world. When food is wasted, the problem does not end at that point. More than 95% of the food waste ends at landfill sites, where converted into methane, carbon dioxide and other greenhouse gasses by anaerobic digestion. The impact of food waste to climate change is catastrophic. Food waste problem tends to increase in next 25 years due to economic and population growth mainly in Asian countries. In addition, when food wastes buried at landfill sites their energy content is lost. Although food waste is a huge problem, its global size and extent has recently become a hot topic in the academic community. This paper summarises the size of the global food waste problem together with the estimation of the amount of energy lost when food wastes dumped at landfill sites. Calculations in this study also revealed that energy lost at landfill sites equals to 43% of the delivered energy used for the preparation of foods in the US, 37% of the hydroelectric power generation of Japan, and more than 100% of the current annual renewable energy demand of UK industries.

Food waste recycling via fungal hydrolysis and lactic acid (LA) fermentation has been investigated. Hydrolysates derived from mixed food waste and bakery waste were rich in glucose (80.0-100.2gL(-1)), fructose (7.6gL(-1)) and free amino nitrogen (947-1081mgL(-1)). In the fermentation with Lactobacillus casei Shirota, 94.0gL(-1) and 82.6gL(-1) of LA were produced with productivity of 2.61gL(-1)h(-1) and 2.50gL(-1)h(-1) for mixed food waste and bakery waste hydrolysate, respectively. The yield was 0.94gg(-1) for both hydrolysates. Similar results were obtained using food waste powder hydrolysate, in which 90.1gL(-1) of LA was produced with a yield and productivity of 0.92gg(-1) and 2.50gL(-1)h(-1). The results demonstrate the feasibility of an efficient bioconversion of food waste to LA and a decentralized approach of food waste recycling in urban area.

Depletion of fossil fuels and environmental problems are encouraging research on alternative fuels of renewable sources. Biodiesel is a promising alternative fuel to be used as a substitute to the petroleum based diesel fuels. However, the cost of biodiesel production is high and is attributed mainly to the feedstock used which leads to the investigation of low cost feedstocks that are economically feasible. In this paper, we report on the utilization of lipid obtained from food waste as a low-cost feedstock for biodiesel production. Lipid from food waste was transesterified with methanol using base and lipase as catalysts. The maximum biodiesel yield was 100% for the base (KOH) catalyzed transesterification at 1:10 M ratio of lipid to methanol in 2 h at 60 °C. Novozyme-435 yielded a 90% FAME conversion at 40 °C and 1:5 lipid to methanol molar ratio in 24 h. Lipid obtained from fungal hydrolysis of food waste is found to be a suitable feedstock for biodiesel production.

Demand for biofuels is rapidly growing worldwide as petroleum based fuels are finite reserves. In this context, biodiesel and bioethanol are popular biofuels that are commercially available in various countries. Biofuels can be prepared from edible biomass. However, this is already generating food versus fuel debate among the members of civil societies. Therefore, there are needs to synthesize biofuels from nonedible waste materials. Food wastes can be utilized as resources for the production of biodiesel and bioethanol since they contain significant amount of lipids and carbohydrates. In future, industrial production of biodiesel and bioethanol from food waste can contribute to resolve the waste disposal, energy scarcity and energy security problems.

In recent years, there have been increased concerns about the disposal of food waste. The amount of food waste generated globally is staggering, with about 1.3 billion tonnes per year and the figures are rising. In Hong Kong, about 3000 tonnes of food waste have been generated every day over the past 10 years with a significant increasing trend. With the waste-to-landfill approach, huge amounts of food waste is being dumped to landfills, making food waste a significant component of municipal solid waste (MSW) and losing a potentially valuable food source or regenerated resource (e.g. energy recovery, composting and animal feed). In addition, many other environmental problems are associated with the disposal of food waste to landfill. In this chapter, attempts are made to review the current food waste disposal system in Hong Kong and some food waste valorization technologies, which have been practiced in other counties or regions, along with their advantages and limitations so as to improve the present food waste disposal system from a technological perspective. Our recommendations includes a comprehensive system to facilitate different approaches to recycle such important protein and carbon sources into valuable products from biofuels to animal feeds.

Potential of fungal hydrolysis in submerged fermentation by Aspergillus awamori and Aspergillus oryzae as a food waste treatment process and for preparation of fermentation feedstock has been investigated. By fungal hydrolysis, 80–90% of the initial amount of waste was reduced and degraded within 36–48 h into glucose, free amino nitrogen (FAN) and phosphate. Experiments revealed that 80–90% of starch can be converted into glucose and highest concentration of FAN obtained, when solid mashes of A . awamori and A . oryzae are successively added to fermentations at an interval of 24 h. A maximal solid-to-liquid ratio of 43.2% (w/v) of food waste has been tested without a negative impact on releases of glucose, FAN and phosphate, and final concentrations of 143 g L −1 , 1.8 g L −1 and 1.6 g L −1 were obtained in the hydrolysate, respectively. Additionally, fungal hydrolysis as an alternative to conventional treatments for utilization of food waste is discussed.

Restructuring conventional cereal-based processes is essential in order to create viable biorefineries for the production of fuels, chemicals and materials. Advanced biorefinery schemes should exploit the full potential of cereal grains by exploiting every component and residue to produce a wide spectrum of commodity and speciality products. This chapter presents generic biorefinery approaches that utilize the wheat grain for the production of bioethanol, polyhydroxybutyrate, succinic acid and various added-value products (e.g., arabinoxylans). Cereal-based food by-product or waste streams generated from primary processing of cereals, households, restaurants and catering services could be used for the development of second-generation biorefineries.

Glucose, free amino nitrogen (FAN), and phosphate were recovered from food waste by fungal hydrolysis using Aspergillus awamori and Aspergillus oryzae . Using 100 g food waste (dry weight), 31.9 g glucose, 0.28 g FAN, and 0.38 g phosphate were recovered after 24 h of hydrolysis. The pure hydrolysate has then been used as culture medium and nutrient source for the two heterotrophic microalgae Schizochytrium mangrovei and Chlorella pyrenoidosa , S. mangrovei and C. pyrenoidosa grew well on the complex food waste hydrolysate by utilizing the nutrients recovered. At the end of fermentation 10–20 g biomass were produced rich in carbohydrates, lipids, proteins, and saturated and polyunsaturated fatty acids. Results of this study revealed the potential of food waste hydrolysate as culture medium and nutrient source in microalgae cultivation.

In this paper, bakery waste, including cakes and pastries from Starbucks Hong Kong, was evaluated for the potential of succinic acid (SA) production. Through simultaneous hydrolysis and fungal autolysis, both cake and pastry hydrolysates were found to be rich in glucose (35.6 and 54.2 g L−1) and free amino nitrogen (685.5 and 758.5 g L−1), whereas the protein hydrolysis yields were 23.2 and 22.5%, respectively. These cake and pastry hydrolysates, together with magnesium carbonate (10 g L−1) were subsequently used as feedstock in Actinobacillus succinogenes fermentation, and the resultant SA concentrations were 24.8 and 31.7 g L−1, respectively. A cation-exchange resin-based process (via vacuum distillation and crystallisation) was subsequently used to recover the SA crystals from fermentation broth, and a high SA crystal purity (96–97.7%) was obtained. Results of the present work successfully demonstrated the novel use of bakery waste as the generic feedstock for the sustainable production of SA as a platform chemical in food waste biorefinery.

Increasing demand for fuels and chemicals, driven by factors including over-population, the threat of global warming and the scarcity of fossil resources, strains our resource system and necessitates the development of sustainable and innovative strategies for the chemical industry. Our society is currently experiencing constraints imposed by our resource system, which drives industry to increase its overall efficiency by improving existing processes or finding new uses for waste. Food supply chain waste emerged as a resource with a significant potential to be employed as a raw material for the production of fuels and chemicals given the abundant volumes globally generated, its contained diversity of functionalised chemical components and the opportunity to be utilised for higher value applications. The present manuscript is aimed to provide a general overview of the current and most innovative uses of food supply chain waste, providing a range of worldwide case-studies from around the globe. These studies will focus on examples illustrating the use of citrus peel, waste cooking oil and cashew shell nut liquid in countries such as China, the UK, Tanzania, Spain, Greece or Morocco. This work emphasises 2nd generation food waste valorisation and re-use strategies for the production of higher value and marketable products rather than conventional food waste processing (incineration for energy recovery, feed or composting) while highlighting issues linked to the use of food waste as a sustainable raw material. The influence of food regulations on food supply chain waste valorisation will also be addressed as well as our society's behavior towards food supply chain waste. “There was no ways of dealing with it that have not been known for thousands of years. These ways are essentially four: dumping it, burning it, converting it into something that can be used again, and minimizing the volume of material goods – future garbage – that is produced in the first place.” William Rathje on waste (1945–2012) – Director of the Tucson Garbage project.

The bioeconomy era will rely on efficient fractionation of renewable resources via integrated biorefineries. The food supply chain waste, despite its inherent variability, could evolve into an important industrial feedstock on account of its availability, versatility, and sustainability, for the production of bio-based products. Waste streams generated from all stages of the life cycle of food products could be refined into different fractions, which will be either purified to high-value molecules or converted via green chemical and/or biotechnological routes for the production of bio-based products. A working group of the EUBis COST Action TD1203 is taking steps to gather a critical mass of knowledge and expertise to create innovation and technological breakthroughs.