A Perspective on Emerging Inter-Disciplinary Solutions for the Sustainable Management of Food Waste

Abstract

Since food waste is a contemporary and complicated issue that is widely debated across many societal areas, the world community has designated the reduction of food waste as a crucial aspect of establishing a sustainable economy. However, waste management has numerous challenges, such as inadequate funding, poor waste treatment infrastructure, technological limitations, limited public awareness of proper sanitary practices, and inadequate legal and regulatory frameworks. A variety of microorganisms participate in the process of anaerobic digestion, which can be used to convert organic waste into biogas (e.g., methane) and nutrient-rich digestate. In this study, we propose a synergy among multiple disciplines such as nanotechnology, omics, artificial intelligence, and bioengineering that leverage anaerobic digestion processes to optimize the use of current scientific and technological knowledge in addressing global food waste challenges. The integration of these fields carries with it a vast amount of potential for improved waste management. In addition, we highlighted the relevance, importance, and applicability of numerous biogas-generating technologies accessible in each discipline, as well as assessing the impact of the COVID-19 epidemic on waste production and management systems. We identify diverse solutions that acknowledge the necessity for integration aimed at drawing expertise from broad interdisciplinary research to address food waste management challenges.

1. Introduction

According to the Food Waste Index Report 2021 published by the United Nations Environment Programme (UNEP), approximately 17% of the world’s food production is lost or thrown away [1]. Almost 61% of this loss occurs in private households, 26% in food service establishments, and 13% in retail businesses. In most cases, food is discarded due to various errors made within the food supply chain [2], threatening food security by affecting food availability and costs. The food supply chain comprises the following elements: agriculture, post-harvest management, processing, distribution/retail/service, and consumer consumption [3]. More food losses occur in developing countries during the production and post-harvest steps than in developed ones.

In contrast, a more significant proportion is wasted in developed countries’ distribution and consumption stages [4]. As a result, the food waste reduction plans in developed countries primarily promote better retail management and food consumption behaviour, among other factors responsible for food waste [5]. In the context of a sustainable economy, the issue of food waste is fundamental; hence the Sustainable Development Goal Target 12.3 aims to significantly (+50%) reduce global per capita food waste by 2030. Indeed, food waste reduction is a crucial element of a sustainable food economy (along with several others, e.g., aerobic and anaerobic digestion) seeking to address the challenges of waste management and circular economy around the globe [6,7,8]. In the context of a circular economy in the food waste treatment sector, the recovery and reuse of resources are fundamental in reducing waste and improving energy efficiency [9]. Moreover, composting and anaerobic digestion are prioritized in the circular economy principles [10] and the waste management hierarchy [11] above alternative waste management methods such as incineration and landfilling [12].

When waste is disposed of or recycled safely, ethically, and responsibly, this helps reduce its negative impacts on the environment. Traditional landfills have been broadly utilized for waste disposal, despite the adverse environmental repercussions they have caused, including contamination of the air, leachate generation and methane emissions [13]. When waste is burned at high temperatures, the chemical composition is changed via thermal conversion [14]. However, maintaining thermal conversion technologies, such as gasification and pyrolysis [15], may be challenging due to their complexity and affordability [14].

Dalla Vecchia et al. [16] acknowledge that recuperating renewable energy via biogas using anaerobic digestion while simultaneously decreasing biodegradable waste from industrial, municipal, and agricultural operations is a highly efficient waste management solution. Indeed, aerobic digestion (composting) of food waste by microorganisms such as bacteria and fungi in the presence of oxygen has been a common approach of biological food waste treatment [17]. However, protein-rich organic wastes (such as meat, fish, etc.) and prepared foods make digestion challenging [18]. Although composting improves the soil structure and equilibrium [19], the nuisance nature of the composting process is usually problematic to the surrounding inhabitants.

Due to its economic and environmental benefits, such as the generation of renewable energy, the recycling of nutrients, and the decrease in waste volumes, the anaerobic digestion of food waste has become increasingly used [20]. As a result, most developed countries are becoming environmentally mindful by discontinuing food waste transfer to landfills and air pollution-associated treatments such as incineration or gasification [21]. Despite this, there is a pressing need for more exploration into the development of anaerobic digesters to improve the overall effectiveness of the methane gas generation process [22]. Composting and anaerobic digestion are generally preferred over other methods because both have the potential to provide beneficial soil transformation by enhancing the soil’s physical, chemical, and microbiological properties [19]. This kind of transformation would positively impact the viability of sustainable food systems over a more extended period.

The production of biogas from waste has attracted a variety of energy-efficient, resource-saving, and environmentally beneficial approaches; nevertheless, the majority of these approaches still face challenges in terms of their feasibility on a technical, economic, and social level [5]. Many such strategies focus on system stability and process efficiency for improved biogas yield while also optimizing several parameters such as foaming, NH₃ concentrations, co-digestion feasibility, digester designs, microbial community, and feedstock [23,24,25,26,27].

Owing to the significant contributions accomplished by different disciplines in addressing the issues of waste management, the current perspective comprehensively traverses disciplines of omics, bioengineering/bioprocessing, and nanotechnology by further advocating for an inter/multidisciplinary approach for waste management. Indeed, omics techniques have provided exceptional opportunities for exploring microbial communities (meta-omics), genes (transcriptomic), proteins (proteomics), and metabolites (metabolomics) by enhancing the efficiency of biogas production during the anaerobic digestion process. Next-generation sequencing, mass spectrometry, in silico modelling, microarrays, and other cutting-edge technologies are applied in omics to produce valuable biological data on microbes and their cellular activities, as well as on critical biomolecules involved in waste bioremediation [28,29,30].

Researchers are also unremittingly exploring the use of nanotechnology for efficient waste management [31,32,33]. Nanomaterials (<100 nm) with enhanced specificity, responsiveness for adsorption, redox reactions, and treatment efficacy are used in nanotechnology applications [34]. Moreover, the capability of nanotechnology to efficiently bypass numerous conventional treatment phases is essential for minimizing the amount of energy, operating costs, and treatment time required throughout the waste treatment process [34]. To a significant extent, the effectiveness and sustainability of nanotechnology in waste management is contingent on the choice of suitable nanomaterials, such as metal (mainly iron) and carbon-based nanomaterials.

Additionally, bioengineering/bioprocess technologies are currently employed to address issues relating to waste management by specifically improving process design and operating conditions during anaerobic digestion [35]. For instance, in the context of bioengineering, there is a current interest in achieving high degradability through the use of dual digestion systems (anaerobic and aerobic thermophilic processes), which is considered novel in dealing with the management of various waste for an efficient circular economy [35].

Furthermore, machine learning techniques based on statistics and computational intelligence are currently used to identify functional patterns and models [36]. Machine learning has emerged as a ground-breaking and fascinating new technology for constructing models that can effectively assess and manage the performance of many anaerobic processes [37]. As a result of the advances in machine learning techniques, these may now be used to accurately forecast digester performance. Anaerobic digestion is a complicated yet effective renewable energy source and waste management technique that relies on the interplay of several operational and monitoring factors [38]. Fortunately, modern anaerobic digestion systems may be considerably improved by applying advanced data analysis, process optimization, and control techniques. For example, mathematical models [39] and low-cost machine learning techniques may be used to monitor critical process parameters and then utilize the simulation model to forecast, optimize, and control processes [40]. Continuous monitoring, which artificial intelligence can perform, is perhaps the most crucial component in ensuring that processes are optimized, and quality standards are met [41]. In addition, artificial intelligence can be utilized to evaluate the features of biomass feedstock, the primary quantities of products, and the overall performance of anaerobic digestion systems [42].

Process failure can be attributed to the lack of automated, rapid, and cost-effective monitoring and control (e.g., biomass feedstock, fermenter volume, substrate, biofuel properties, temperature, pH, and pressure controls) in biogas plants [42,43]. Process modelling is important because it provides a better understanding of the ideal operating conditions by controlling and forecasting a system’s behaviour and outcomes [38]. Indeed, various computational methods and machine learning algorithms have been employed to guarantee that anaerobic digestion systems stay relevant in the face of existing and anticipated challenges. On the other hand, more technical interventions are required to develop new modelling concepts while enhancing old techniques or even integrating tools from other areas [39]. Fortunately, mechanistic models such as Anaerobic Digestion Model 1 (ADM1) have considerably enhanced the scientific community’s capacity to forecast digestion performance and biogas output [44]. Relevant to this study and also valuable to waste management efforts, artificial intelligence techniques such as artificial neural networks (ANNs) and adaptive neural fuzzy inference systems (ANFIS) are currently put to use in the predictive modelling of wastewater treatment, anaerobic digestion, and biogas synthesis [45,46,47].

Despite the tremendous efforts that have been made to optimize food waste management technology, many problems still exist connected to the systems or processes involved. Consequently, there is an urgent need for numerous disciplines to focus on these challenges, which is why the interdisciplinary approach systems are widely recommended and continue to be seen as essential to accomplishing the vision of a circular economy [48]. In the context of anaerobic digestion, scientific data is generated from meta-omics, omics, bioengineering, bioprocessing technology, and nanotechnology. Most findings recommend further process/system optimization for improved anaerobic digestion technologies. To fully explore food waste management in the context of anaerobic digestion processes, the current review provides essential developments made by the disciplines mentioned above, as well as a critical perspective on several promising and plausible multi/interdisciplinary partnerships in dealing with the challenges of food waste management.

Very little interdisciplinary research aimed at enhancing anaerobic digestion processes has been conducted to date. However, the few attempts that have been made recognize the significance of interdisciplinarity, which this study advocates. For instance, Casals et al. [49] coupled nanotechnology and bioengineering by creating the novel concept of exploiting surface-state engineering by administering Fe₃O₄-engineered nanoparticles to increase biogas production by 234% using wastewater sludge. The authors anticipated that, since small nanoparticles are unstable, they can be designed in a regulated manner, which would result in the greatest increase in biogas production yet observed. In an effort to further deepen the interdisciplinarity between nanotechnology and bioengineering, Dalla Vecchia et al. [16] used magnetite nanoparticles in batch and continuous flow mesophilic anaerobic digestion to increase biogas yield from food waste. They were able to increase the batch and continuous biogas yields by 33% and 8%, respectively.

In addition, several other works have coupled bioengineering with omics techniques to maximise biogas yield. For instance, Bremges et al. [50] analyzed metagenome and metatranscriptome of a complex biogas-producing microbial community isolated from agricultural waste. In their strategy, they were able to produce an enhanced biogas yield of 810.5 I/kg oDM from wet biogas fermentations and 698.2 I/kg oDM from dry biogas fermentations. In another study, using metagenomic and metabolomic approaches, magnetite nanoparticles, and rice paddy and acetate supplemented-continuously agitated anaerobic cultures from organic waste, Inaba et al. [51] improved the biogas output from organic waste. Indeed, this is another viable prospective inter-disciplinary effort to solve waste challenges, which the present perspective endorses and encourages.

Lastly, artificial intelligence and machine learning is yet another promising field that can be utilized in an integrative manner to improve anaerobic digestion processes. For instance, by using an artificial neural network model for active sludge technology and separated closed fermentation chambers, Sakiewicz et al. [52] were able to achieve a maximum biogas production of 4050 m³/day.

The remaining part of the paper (as shown in Figure 1) is organized as follows: Section 2 reviews the literature that deals with food waste in the global context: - this section provides an overview of the impact of food waste on the environment, economy, and natural resources on a global scale. Section 3 then discusses the impact of the COVID-19 pandemic on food waste generation: this section briefly highlights the impact of COVID-19 on global economic losses, waste management, and circular economy. Section 4 reports on food waste management, regulations, and biological treatment technologies: - this section briefly discusses waste management and policy challenges, consumer awareness as a technique for reducing food waste, and anaerobic digestion as a viable alternative to food waste management, energy generation, and nutrient generation. Section 5 provides a comprehensive overview of the current and future interdisciplinary waste management initiatives utilizing anaerobic digestion systems: - this section discusses potential and emerging collaborations from multiple disciplines (such as bioengineering, artificial intelligence, omics, and nanotechnology) to address the various waste management crises. Section 6 then details the review’s conclusions and recommendations.

2. Food Waste in the Global Context

Food waste is described by the United Nations Food and Agriculture Organization (FAO) as food wastage that happens at the end of the food chain, attributable to the actions of both consumers and retailers [53]. The Sustainable Development Target 12.3 intends to significantly reduce the quantity of food waste by 2030. Indeed, there is an urgent need to meet this goal since food waste currently overburdens waste management systems, exacerbates the food insecurity crisis, and places a burden on the environment and economy. The 2021 Food Waste Index of the United Nations Environment Programme indicates that 931 million tonnes of food is wasted annually by households, stores, and the food service industry [1]. To put this into perspective, roughly 570 million tonnes of this worldwide wastage comes from households. In comparison, the food service industry contributes 244 million tonnes, and the retail sector contributes 118 million tonnes, respectively. The total household food waste produced in selected countries is presented in Figure 2. Here, China (91 million tonnes/annum), India (68 million tonnes/annum), Nigeria (37 million tonnes/annum), Indonesia (20 million tonnes/annum), United States (19 million tonnes/annum) were the most significant contributors to food waste. In comparison, Australia (0.25 million tonnes/annum) generates remarkably low amounts.

It is common knowledge that most food waste in developed countries (e.g., the US and Europe) occurs during the consumer phase of the supply chain [54]. In contrast, in most developing countries (e.g., Asia and Africa) it occurs during packaging and processing [55]. Food waste has a monetary value of approximately USD 936 billion, without considering the social and environmental costs incurred because of this wastage [56]. A country’s income, urbanization, and economic growth affect the amount of food waste it generates [57]. Poor practices, technological limitations, labour, financial constraints, and insufficient transportation and storage infrastructure are primarily responsible for food waste in less-developed countries [58]. In any case, the fact that food waste occurs primarily because of consumer behaviour, routines, practices, beliefs, habits, and attitudes is real, even in developed countries where 40% of food waste occurs during the consumption stage [59,60]. Hence, food waste severely affects the environment, economy, and natural resources [61]. From an environmental point of view, when food waste is dumped into landfills, a significant percentage of it is transformed into carbon dioxide and methane, both potent greenhouse gases with direct consequences for global warming [62]. Furthermore, food waste reduction programs might lower food costs [63], increase supply chain efficiency [64], and enhance access to healthy meals for low-income families [58]. Food waste is an interdisciplinary topic that draws on research from various areas, including agriculture, science, environmental studies, logistics, and business [65]. In an attempt to deal with food waste challenges (which this present perspective seeks to contextualize using an integrated approach), many studies have independently looked at the significant causes of food waste at various points of the food supply chain by focusing on research constraints [66,67], policy implications [61] and sustainable food waste management [65].

3. Food Associated Waste Generation during the COVID-19 Pandemic

Significant global economic losses and biosecurity risks are expected to occur from COVID-19 disruptions [68], calling for a more comprehensive strategy to improve food supply chain efficiency by lowering food loss and enhancing waste management in food supply chains challenged by shifts in consumer behaviour brought on by pandemics [69]. Changes in lifestyle and consumption, disruptions in supply chains and logistics, cheaper oil, and lower demand for recycled waste are just some of the aspects of the COVID-19 pandemic which have impacted waste management, recycling, and the circular economy worldwide [6,7,8,54], as well as many other facets of sustainability [70]. Schanes et al. [71] also found that employment in the United States is typically associated with a higher level of consumer food waste; thus, the higher food costs and lower wages during the post-COVID era should lead to a reduction in food waste. Considering that COVID-19 has recently had a massive impact on hunger and food insecurity, it is essential to determine if global household food waste increased or reduced through the epidemic. Despite a surge in global food purchases, the level of household food waste in Italy (for example) reduced during the COVID-19 lockdown. This finding might indicate that the population’s understanding or awareness of the importance of minimizing or at least decreasing food waste improved throughout the lockdown period in many impacted communities worldwide.

During the COVID-19 crisis, a 12% increase in household food wastage was observed globally [69]. It is undeniable that the existing food delivery networks exacerbated food waste during the COVID-19 pandemic because they could not swiftly adapt to changes in consumer preferences [72]. In other places, such as Spain, fruit and vegetable crops were damaged because of labour shortages caused by illness or the fear of becoming ill among agricultural and food processing workers [73]. It is expected that government intervention may lessen the effect of the COVID-19 pandemic on wasted food. However, it is the objective of government policies that establishes how successful they will be. Di Marcantonio et al. [74] discovered a connection between lowering the amount of wasted food and enacting policies that stimulate innovation to dampen the impact of adverse occurrences on food sources.

It has also been found that companies that adjusted their business approach could boost their production efficiency while also lowering the amount of wasted food. In Italy, Pappalardo et al. [75] performed a nationwide assessment of household food consumption and discovered a substantial reduction in food waste when people resorted to buying more non-perishable items. As a consequence of this, behaviour changes in food handling were brought about as a result of the reality of the COVID-19 crisis, which eventually contributed to an improvement in the burden of waste management. Their findings show that consumers are becoming more conscious of food waste, which might positively affect the environment by lowering greenhouse gas emissions and groundwater contamination if worldwide populations adopt the same practices, including beyond the COVID-19 era.

4. Food Waste Management, Regulations, and Biological Treatment Technologies

The global food system significantly contributes to climate changing greenhouse gas emissions. It significantly influences the surrounding ecosystem, including through the destruction of biodiversity, water loss, and the emission of pollutants [76]. Policymakers are becoming increasingly conscious of the need to address these issues. Moreover, they are increasingly confronted with food security and nutrition-related concerns. As a significant contributor to global warming, many global policymakers view the food system as one of the most severe environmental challenges. Food waste management is inherently challenging since it necessitates numerous coordinated measures involving several public and local governments [77,78,79,80].

Given that a circular economy fosters the reduction of environmental effects and increases resource efficiency, Aramyan et al. [81] and Chiaraluce et al. [82] believe that reforming the behaviour of individuals is fundamental to engage them in the transition to a circular economy. The circular economy aims to reduce waste and unnecessary resource consumption by turning waste into value-added products [83], and policy instruments that incentivize behaviour supporting circular food systems are critical for systemic behavioural change. For instance, European cities have collaborated to share lessons learned in market incentives, public awareness campaigns, and producing renewable energy and agricultural bio-fertilizers [84]. According to Colombian law (Resolution 0754_2014), once a waste management plan is implemented, the local authority is responsible for controlling, updating, optimizing, and improving the plan to ensure an efficient waste management service [85]. To guarantee effective urban food waste policies, over two-thirds of the 169 Sustainable Development Goals (SDG) require adequate participation and cooperation with local and regional governments [86,87,88]. Food packaging materials are now given significant attention as part of global efforts to dramatically reduce food waste, with legislation being modified to encourage the adoption of ecologically friendly, reusable, and recyclable packaging solutions [89].

Furthermore, the European Commission is constantly updating marketing guidelines to highlight the importance of sustainable food consumption and strengthen educational messaging about the importance of reducing food waste in school systems [69]. According to research by ReFED [90], consumer awareness programs have become one of the most utilized interventions for achieving economic and environmental benefits from food waste reduction in the United States. Moreover, intelligent waste management initiatives including smart bins [91,92], bin-cams [93], fridge-cams [94], and awareness campaigns such as Canada’s “Love Food Hate Waste” [95] have previously been found to improve waste management significantly.

The study of household food waste has also attracted increasing interest, as has that of viable options for treating processing wastes and valorizing them into usable goods. Nonetheless, the high costs of processing organic materials compel the search for low-cost raw materials to synthesize valuable chemicals [96,97]. This technique can address fuel supply constraints and reduce the waste created by food processing businesses in a cost-effective manner [98]. Technology, on the other hand, may be used by businesses to, among other things, increase the number of viable options for valorizing food waste [99], better evaluate the true worth of waste, boost waste reduction and recovery techniques [100], and expand professional awareness [101]. Surprisingly, many researches on food waste reduction neglect the relative importance of technologically sustainable solutions for food-service organizations. However, Martin-Rios et al. [102] emphasized the need to adopt long-term technical innovations, such as using new technologies to quantify waste, its characteristics, and its uses to address the sustainability challenges.

In light of the world’s growing energy and waste management demands, it is indisputable that anaerobic digestion has emerged as one of the most environmentally friendly and viable approaches for managing food and generating energy [103]. Compared to many other processes, anaerobic treatment of food waste is a better option.

While Mutungwazi et al. [104] provide a more in-depth discussion of the anaerobic digestion process, we have included a summary of the critical biochemical and microbial activities herein. Figure 3 depicts the multistage process of anaerobic digestion, which includes the sequential steps of hydrolysis, acidogenesis, acetogenesis, and methanogenesis in the breakdown of biodegradable material to produce biogas [105]. Indeed, the anaerobic digestion technology has enormous potential for treating solid organic waste, slurries, sludge, industrial wastewater, and sewage [106]. Hydrolysis is generally the rate-determining step in anaerobic digestion processes [107], since it is required to break down complex solid chemical bonds that are often responsible for resistance to degradation, notably of lignin. Amylases, cellulases, xylanases, lipases, and proteases are all examples of hydrolytic enzymes that may be found in microbes, protozoa, and fungi proliferating in anaerobic digestion systems [108,109]. Cellulolytic and xylanolytic microorganisms generate xylanases that degrade complex cellulose and xylan into glucose and xylose. In contrast, proteolytic bacteria produce extracellular proteases that break down peptide bonds of proteins or polypeptide chains.

Additionally, lipolytic bacteria secrete lipases, which break down lipids (fats and oils) into valuable products like long-chain fatty acids and glycerol [110]. In the acidogenesis phase of anaerobic digestion, hydrogen, alcohol, carbon dioxide, and acids, including isobutyric, propionic, and lactic acid, are produced by oxidizing carbohydrates and organic molecules produced during hydrolysis [111]. On the other hand, acetogenesis is the process by which acetogenic bacteria and obligatory hydrogen-producing bacteria convert acidogenesis products into acetate and hydrogen gas [110,112,113]. Thereafter, acetogenic bacteria convert volatile fatty acids and alcohol into hydrogen, carbon dioxide, and acetate, while homoacetogenic bacteria convert carbon dioxide and hydrogen into acetate [114]. Moreover, propionate decomposers, butyrate decomposers, and acid formers also play a significant role in anaerobic digestion processes [110]. Methanogenesis is the final step in the anaerobic digestion process. This stage occurs when acetic acid is converted to methane gas [115]. Methanogenesis can take place via two primary pathways: the hydrogenotrophic pathway, in which hydrogen and carbon dioxide gasses are converted into methane; and the acetotrophic pathway, in which acetate is eventually converted to biogas (methane) [116,117,118]. The methane generated by either method can be used in combined heat and power generators [119].

In light of diminishing fossil fuel reserves and ever-increasing oil prices, food waste provides a remarkable opportunity to tap into a vast renewable energy resource and reservoir of valuable compounds. Positive indicators for the future of sustainable development include the possibility of increased use of biofuels to decrease greenhouse gas emissions, ameliorate climate change, enhance waste management, and boost the utilization of renewable resources using environmentally acceptable techniques [120,121]. There are several techniques for optimizing biogas output through anaerobic digestion, but each approach has a distinct mode of application and generates various amounts of biogas in the form of methane [122]. For example, it is challenging to find the best lignocellulose pre-treatment techniques for commercial biogas digesters [120]. Typically, controlling chemical, mechanical, biological pre-treatment options, or a combination thereof, is crucial in achieving a successful digestion process with optimal biogas generation. Divya et al. [105] also indicated that optimizing several factors (e.g., substrate pre-treatment, microbial valorization potential, microbial profiles, biomass utilization, and process technology) is critical for improving the efficiency of anaerobic digestion.

Therefore, anaerobic digestion has received significant attention from researchers worldwide as an effective waste-treatment strategy for a broad range of practical, ecological, and financial reasons [123]. However, significant challenges still exist in developing small-scale anaerobic digesters, mainly due to high response times and inadequate methane gas output [22]. Consequently, improving methane output for commercial use requires a focus on regulating key operating factors (including feedstock, temperature, pH, buffering capacity, and feedstock concentrations), studying the microbiota that drives anaerobic digestion, and modelling anaerobic processes [124].

5. Current and Prospective Interdisciplinary Food Waste Management Initiatives Utilizing Anaerobic Digestion Systems

According to our analyses, the most efficient waste management systems should provide nutritional and economical solutions that are both sustainable and equitable. Of note, the hierarchical structure of the present perspective encourages expertise from various disciplines to collaborate to address issues relating to waste management throughout the food supply chain. A multi-technological strategy that includes government initiatives and advances in bioengineering/bioprocess engineering, omics, artificial intelligence, and nanotechnology is crucial for waste management, and vital for maximizing its efficiency. The most successful waste management solution on a global scale remains the incorporating of current and emerging cutting-edge technology while promoting government accountability (legislation, regulations, etc.). Figure 4 depicts the recommended multidisciplinary approach system that is thoroughly discussed in the subsequent sections.

Indeed, there is evidence of and prospects for multidisciplinary collaboration initiatives to address food waste by utilizing biological systems (e.g., anaerobic digestion) in conjunction with other cutting-edge technologies.

Table 1. A snapshot of some of the multidisciplinary research pioneered in addressing waste treatment.

Bioprocess Engineering Techniques	Nanotechnology Techniques	Omics Techniques	Artificial Intelligence	Treatment Method	Biogas Yield/% Increase	References
Surface-state engineering	Fe3O4 (magnetite) nanoparticles (MNPs)	TNA	TNA	Wastewater sludge	234%	[49]
Batch and continuous-flow mesophilic anaerobic digestion	Magnetite nanoparticles	TNA	TNA	Food waste	Batch = 33% Continuous = 8%	[16]
Wet biogas fermentations Dry biogas fermentations	TNA	Comparative metagenomics	TNA	Agricultural waste	810.5 I/kg oDM 698.2 I/kg oDM	[50]
Two-phased anaerobic digestion (TPAD)	TNA	TNA	Digester and Biomethanation sub models	Cattle manure Maize silage	Biogas production from 9.06 to 9.59%	[125]
Active sludge technology–BIODENIPHO Separated closed fermenting chambers-SCFC	TNA	TNA	Artificial neural networks model	Wastewater treatment plant (WWT)	Max yield = 4050 m3/day	[52]
Rice paddy and acetate-supplemented continuously agitated anaerobic cultures	Magnetite nanoparticles	Metagenomics, Metatranscriptomics and Metabarcoding	TNA	Organic waste	BYER	[51]
20% w:v FOG Laboratory scale digesters	TNA	Metagenomics: Metabolomics	TNA	Wastewater treatment plant	264.1 ± 76.5 mL/day	[126]
Pressurised anaerobic tubes	Conductive nanomaterials	Tandem mass tag (TMT) proteomics technology	TNA	Mineral salt media	BYER	[127]

TNA= Not Applied. BYER= biogas yield enhancement reported.

provides an overview of a few of those transdisciplinary research initiatives.

5.1. Initiatives Founded on the Discipline of Nanotechnology

Several researchers have amalgamated nanotechnology with other disciplines to improve anaerobic digestion. Conductive nanomaterials such as magnetite have been shown to improve methanogenesis by facilitating the interspecies electron transfer between acetogenic bacteria and methanogenic archaea, resulting in enhanced biogas outputs [51,126]. Inaba et al. [51] investigated the impact of magnetite nanoparticles (MNPs) on methanogenesis in anaerobic cultures generated from the soil. They observed increased methanogenesis when MNPs were applied in optimized agitated and static cultures.

Meanwhile, Eduok et al. [128] demonstrated the use of nanoparticles for better sludge digestion. By spiking waste sludge with aged, designed nanoparticles and combining silver oxide, titanium dioxide, and zinc oxide, they increased sludge digesting efficiency.

There are several additional revelations about attempts to enhance anaerobic digestion systems utilizing nanoparticle oxides of other metals [129] including transition metals, TiO₂, Fe₂O₃–TiO₂, and NiO–TiO₂ [98], and various nanoparticles, such as cobalt (Co) and nickel (Ni) nanoparticles [130]. As in many previous concerted attempts, the initial studies did not seek to establish an overview of concurrent optimization of system conditions for dealing with waste management.

While the use of nanoparticles in anaerobic digestion has for some time been indicated, the process cannot be efficient without optimizing the operation of the biogas plant. Optimization of bioreactors can encompass a wide variety of multidisciplinary features (for example, bioengineering, nanotechnology, and so on), algorithms (artificial intelligence), and biological processes (e.g., omics). From the revelations made throughout this study, it is abundantly clear that more multidisciplinary collaborative efforts are required to improve our knowledge of anaerobic digestion processes and process performance.

5.2. Initiatives Supported by Omics and Bioengineering Disciplines

Opportunities for the development of new high-throughput systems for efficiently identifying uncultivable microorganisms, unknown genes, and pathways involved in biogas production from a wide range of biomass resources have been greatly enhanced by recent advances in omics technologies such as metagenomics, transcriptomics, proteomics, and metabolomics [131]. Most of the microorganisms and genes involved in biogas generation from different forms of biomass remain unknown due to a lack of optimum anaerobic reactor conditions essential for optimal microbial growth, despite the staggering number of research articles dedicated to identifying them.

On the other hand, meta-omics approaches are potent instruments for analyzing microbial communities’ gene, metabolite, and protein expression patterns that might be used as possible indicators of process performance during anaerobic digestion. Several contributions [126,132,133,134,135] were able to provide a comprehensive evaluation of various meta-omics approaches. However, these meta-omics methods continue to rely on basic techniques such as transcriptomic, proteomics, and metabolomics; despite all of these being relevant, an overreaching approach specifically applicable to food waste management is still needed.

Elsewhere, Hahnke et al. [136] used maize silage (feedstock) in combination with pig/cattle dung in an optimized continuously stirred tank reactor (CSTR) in which biogas was produced. The dominant species in the CSTR system was determined to be Porphyromonadaceae bacterium using next-generation sequencing (NGS) technology, i.e., Illumina MiSeq system, whereby the bacteria’s entire genome sequence was established. Numerous researchers have also concentrated on transcriptomic-linked bioprocessing engineering systems used in biogas production. Transcriptomics studies an organism’s whole transcriptome (RNA or mRNA). Transcriptomics analysis may be critical in identifying the essential microbes with the relevant genes and metabolites. In biogas generating systems, for instance, Clostridia were shown to be the predominant class of hydrolytic organisms, playing a crucial role in the first stages of biomass degradation as evidenced by transcriptome analysis [137,138,139,140]. It is evident from these explorations that the use of transcriptomic approaches in conjunction with other technologies may aid in the advancement of our understanding of anaerobic digestion.

Proteomics often refers to the comprehensive analysis of an organism’s protein components. In contrast, “metaproteomics” refers to the study of all the proteins expressed by complex microbial communities in a given environment and at a given time [133]. For instance, proteins extracted from anaerobic digesters may be isolated and sequenced using tandem mass spectrometry (MS/MS) [133,139,141]. Several authors [127,142,143,144,145] have attempted to integrate proteomics during anaerobic digestion processes. Perhaps the most outstanding discoveries were made by Liu et al. [127], who used tandem mass tag (TMT) proteomics to determine the amount of Methanosarcina spp. proteins that were changed by carbon nanotubes (CNTs). Numerous genes involved in KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways were differentially expressed, indicating a direct involvement of carbon nanotubes in cell structure and function. These findings contributed to yet a greater understanding of the effect of conductive materials on the biomethane formation process, highlighting the need to incorporate proteomic techniques into studies of biomethane production.

Furthermore, process improvement and increased biogas production efficiency may be possible via the discovery of metabolic pathways within microbial communities that may be uncovered through the characterization of intracellular metabolites generated during anaerobic fermentation [146]. Since metabolomics is a comprehensive study that identifies and quantifies all of an organism’s metabolites in a specific environment under specified conditions, these metabolites are frequently identified and quantified using a variety of chromatographic methods, including GC-MS, NMR, Fourier-transform infrared (FTIR) spectroscopy, and HPLC [147]. In a stable and degraded methanogenic reactor, Sasaki et al. [147] successfully compared microbiome metabolite profiles and provided critical context for the metabolomics approach by finding changes in intracellular metabolites implicated in the Embden–Meyerhof and pentose phosphate processes.

Several researchers have also integrated omics and bioengineering disciplines to improve anaerobic digestion. For example, laboratory-size digesters were used to mimic possible shocks to a wastewater treatment plant’s anaerobic digestion process [126]. Metagenomic and metabolomic techniques were then employed to characterize the influence of operational shocks on digestion parameters during biogas generation. These omics tools could characterize the microbial makeup and metabolic activity throughout the anaerobic digestion process. In summary, the value of using omics methodologies in an anaerobic digestion process setting cannot be overstated.

In light of the information presented above, the purpose of this section is to try to summarize the significance of using a variety of omics technologies in the process of producing biogas. While further research must be done to fully realize the potential of this area of research, it is already well established that combining omics and other technologies gives a significant potential for boosting the efficiency of creating biogas from various wastes. This might be a beneficial development, particularly concerning the management of a wide variety of wastes. Moreover, the generation of biogas from organic matter is becoming a more attractive source of bioenergy. Recent breakthroughs in omics technology have enhanced our capacity to identify and analyze genes, encoded transcripts, proteins, metabolites, and metabolic pathways involved in anaerobic digestion. Finally, as previously stated, the co-application of omics and other technologies may result in a greater knowledge of the process of anaerobic digestion, as well as the generation of biogas that is more efficient and cost-effective to address the difficulties posed by global food waste.

5.3. Initiatives Founded on Artificial Intelligence and Machine Learning

In artificial intelligence and machine learning, neural networks have widely recognized patterns and delivered predictions based on previous experiences and acquired information [148]. The deployment of a neural network model enables data projection that could support the development of a machine learning algorithm to provide a more accurate estimation of results for biogas generation. Elsewhere, Sakiewicz et al. [52] successfully used artificial neural networks (ANNs) to simulate an anaerobic fermentation process for biogas creation in combination with wastewater purification in a modern wastewater treatment plant. This was accomplished in a contemporary wastewater treatment facility. The study illustrates the critical need to integrate artificial intelligence with bioprocess engineering. Furthermore, when modelling and optimizing biogas production, artificial neural networks may be used with genetic algorithms (GA) to address complex bioengineering challenges [119]. Of interest to this inter/multidisciplinary perspective, many studies have been conducted on the potential of artificial neural networks (ANNs) in the field of anaerobic digestion [149,150,151,152,153,154,155,156], and they have been able to predict the biogas output with a good correlation coefficient. Others [157,158,159] have also used Fuzzy Logic systems to predict wastewater treatment, anaerobic digestion, and biogas production.

Meanwhile, Sakiewicz et al. [52] improved biogas production efficiency by applying a mathematical model that took into account the layout of a classic anaerobic digestion system and its two adaptations—two-phase anaerobic digestion (TPAD) and autogenerative high-pressure digestion (AHPD). Here, TPAD raised total biogas output from 9.06 to 9.59%. This is another example demonstrating the value of mathematical models in optimizing anaerobic digestion systems. Many other studies [160,161,162] also demonstrated the use of mathematical modelling of anaerobic digestion processes for biogas production under a variety of digester settings.

Optimizing full-scale biogas plant operation is critical to make biomass a viable renewable energy source. Among the most often implemented optimization methods is the Nonlinear Model Predictive Control (NMPC). According to Gaida et al. [163], so as to predict biogas production in a full-scale biogas plant, and allow for optimal control and operating decisions based on the actual state of the plant, its operation necessitates an online estimation of its operating state, e.g., anaerobic digestion model No.1 (ADM 1). The ability of the scientific community to accurately estimate digestion performance has substantially increased due to the development of mechanistic models such as the ADM 1, according to Wang et al. [44]. For instance, the management of present biological data (e.g., omics) pertaining to the anaerobic digestion process, as well as emerging data that is growing at an accelerating rate, is highly dependent on many other disciplines, of which artificial intelligence and machine learning [164] will play a significant role by combining such data with mathematical models in the near future.

However, Sin and Al [164] argue that to achieve thoughtful fusion and integration of data sources and knowledge competencies, an extensive research effort is required to develop new artificial intelligence-based techniques and community-wide and interdisciplinary collaboration to address several open and fundamental questions regarding food waste management in combination with anaerobic digestion. The discovery of likely functional linkages between genes from single-transcriptomic data using multivariate information demonstrates the feasibility of combining machine learning with mechanistic modelling in cell biology. However, the lack of progress in integrating machine learning and mechanistic modelling techniques in biological research must be addressed at an interdisciplinary level. To effectively combat food waste, educating a new generation of researchers with expertise in all these domains will be essential. Only then can artificial intelligence be used effectively in anaerobic digestion systems. Based on the current analysis, it is clear that more future collaborations or multidisciplinary work is critical to overcoming waste management challenges, as evidenced by some of these emerging contributions in artificial intelligence and other technologies that have a long association with bioprocessing of various wastes.

6. Conclusions and Recommendations

The present perspective anticipates a collaborative approach since many existing technologies are not used to their fullest potential. In addition, given the enormity of food waste problems, addressing global policy concerns, and minimizing food loss and waste should be prioritized for effective food waste management. It is recommended that, to address food waste management challenges, a comprehensive multidisciplinary research effort be undertaken that draws on the knowledge of various stakeholders and disciplines.

The present perspective encourages the inclusion of artificial intelligence and machine learning technologies with other disciplines since they deploy neural networks that are capable of making predictions based on past experiences to enhance anaerobic digestion processes. Omics techniques such as proteomics, metaproteomics, metabolomics, and transcriptomics present opportunities for the development of new high-throughput systems capable of efficiently identifying uncultivable microorganisms, unknown genes, proteins, and pathways involved in biogas production from a wide variety of biomass resources. Incorporating these techniques with those of other fields such as bioengineering, artificial intelligence and nanotechnology has significantly improved anaerobic digestion and is also viewed as the future solution to waste challenges. Utilizing and combining conductive nanomaterials such as magnetite and other designed nanoparticles has improved sludge digestion and efficiency while facilitating interspecies electron transfer, especially when anaerobic digestion was also optimized using bioengineering techniques that were predicted by artificial intelligence systems.

The message we sought to portray is interdisciplinarity, hence, it was necessary to highlight (with examples) the significance of each field before advocating for a merger. Unfortunately, the aspect of interdisciplinarity is limited and rare, and it cannot be widely demonstrated due to its scarcity in practice. Currently, many of these disciplines function independently towards food waste management, and this perspective aims to educate researchers and explore the impact of collaboration (with limited examples) across the fields of bioengineering, nanotechnology, artificial intelligence, and omics in order to address waste management. Many researchers in each subject are unaware of these interdisciplinary projects, nor are they aware that these methodologies may be combined to solve food waste challenges. This approach likewise highlights successful efforts but suggests a more multidisciplinary effort that relies on expertise from several other sectors. Indeed, there is information about each discipline, but it is not feasible to find research that combines omics, nanotechnology, AI/machine learning, and bioprocessing to enhance anaerobic digestion processes. While each subject has its own science (which has been assessed in several reviews), our approach encourages the integration of future studies, which few to-date have considered could be blended at the level of research.

On the other hand, present and future research on food waste management must also focus on strengthening government policies and improving various technologies.