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Black soldier fly larvae (BSFL) are widely used in recycling and upcycling of nutrients in agri-food by-products, but low and inconsistent BSFL rearing performance (i.e. larval growth, bioconversion rate, and substrate reduction) has been identified as a key challenge. The aims of this research were two-fold: (1) validate an existing closed rearing system design; and (2) assess whether a microbial inoculum derived from the rearing residue increases rearing performance. In controlled bench-scale experiments, BSFL were reared on tomato pomace (TP) and white wine pomace (WWP), along with food waste as control substrate. The two aims were assessed based on the following response variables: larval mass, substrate reduction, residue properties (i.e. pH, temperature, moisture content), and larval intestinal and residue microbiota. Higher BSFL mass (by 5.1 mg dry mass) at harvest on WWP and substrate reduction on TP (by 11.7% dry mass) in the closed system compared to the open system confirmed the potential of closed systems for rearing performance improvements of agri-food by-products. The rearing system also affected the residual moisture content and temperature, but only had a small effect on microbiota. Performance improvements by the closed rearing system design may be outweighed by insufficient aeration with pasty substrates and higher operational efforts for aeration and larval separation from the high-moisture residues. In contrast to the rearing system design, addition of the residue-derived microbial inoculum did not result in improved performance, nor did it alter intestinal and residue microbiota. Missing performance improvements could have been due to absent or low numbers of probiotic bacteria. The success of microbial substrate supplementation could be improved by studying effects of larval-associated microbes and developing cultivation methods that selectively amplify the beneficial (yet unknown) members of the microbial community. Our investigations aimed to increase the valorisation of low-value agri-food by-products in BSFL rearing.

A highly green fluorescent carbon quantum dots (CQDs) synthesized from food waste via one step green synthesis. As-synthesized colloidal CQDs are highly stable due to their surface functionality with homogeneous distribution. Structural characterization is examined using XRD analysis. The optical and physicochemical properties of CQDs exemplify the green-emission under an excitation wavelength of 390 nm in UV–Vis spectra, it showed two (π → π ∗ transition of C = C bonds and n → π ∗ transition of C = O bonds) peaks around 278 and 368 nm. Synthesized CQDs are to be used for next generation energy storage and bioengineering application.

In line with the increase in consciousness on sustainability in today’s global world, great emphasis has been attached to food waste management. Food waste is a complex issue to manage due to uncertainties on quality, quantity, location, and time of wastes, and it involves different decisions at many stages from seed to post-consumption. These ambiguities re-quire that some decisions should be handled in a linguistic and ambiguous environment. That forces researchers to benefit from fuzzy sets mostly utilized to deal with subjectivity that causes uncertainty. In this study, as a novel approach, the spherical fuzzy analytic hierarchy process (SFAHP) was used to select the best food treatment option. In the model, four main criteria (infrastructural, governmental, economic, and environmental) and their thirteen sub-criteria are considered. A real case is conducted to show how the proposed model can be used to assess four food waste treatment options (composting, anaerobic digestion, landfilling, and incineration). Also, a sensitivity analysis is generated to check whether the evaluations on the main criteria can change the results or not. The proposed model aims to create a subsidiary tool for decision makers in relevant companies and institutions.

In an endeavor to make Europe carbon-neutral, and to foster a circular economy, improving food waste management has been identified by the European Union (EU) as a key factor. In this study, we consider 21 pathways, covering: (i) prevention; (ii) reuse for both human consumption and animal feed; (iii) material recycling as an input into the food and chemical industries; (iv) nutrient recycling; and (v) energy/fuel recovery. To include all types of impact, a sustainability assessment, encompassing environmental, economic, and social pillars, is performed and complemented with societal life cycle costing. The results indicate that after prevention, reuse for human consumption and animal feed is the most preferred option, and, in most cases, nutrient recycling and energy recovery are favored over material recycling for chemical production. While highlighting that the food waste management hierarchy should be supported with quantitative sustainability analyses, the findings also illustrate that biochemical pathways should be improved to be competitive despite the fact that food waste valorization has the potential to satisfy the EU demand for the chemicals investigated. Yet, the results clearly show that the potential benefits of improving emerging technologies would still not eclipse the benefits related to food waste prevention and its redistribution.

The amount of food being thrown away despite being in an edible condition has become alarming in countries with populations with medium and high incomes. Changes in consumer behaviour, such as overbuying, are some of the major impetuses of food waste. This study aimed to examine the relationship between food waste and social media usage, neuroticism, and impulse buying. The mediating role of impulse buying and the moderating role of neuroticism on food waste during the coronavirus (COVID-19) pandemic were also uncovered in this study. A self-administered online survey was distributed to a total of 274 consumers who had experienced a lockdown during the COVID-19 outbreak and were also regular buyers of food. Empirical findings supported the fact that social media usage, neuroticism, and impulse buying were positively related to food waste. Impulse buying mediates the relationship between social media usage and food waste, as well as between neuroticism and food waste. The study results also revealed that neuroticism positively moderates the relationship between social media usage and food waste. This paper offers new insights into efforts for sustainable food consumption to tackle the issue of food waste.

The COVID-19 pandemic caused unprecedented disruptions to food systems, leading to both food shortages and food waste across the supply chain. These disruptions have, in turn, altered how people consume and then ultimately discard food. To better understand these impacts, their underlying drivers, and their sustainability implications, this study surveyed U.S. consumers about food purchasing, use, and waste behaviors during the pandemic. Survey respondents reported an increase in overall food purchases and a slight decrease in food waste generation due to the pandemic, but the linkages between these outcomes and underlying behaviors were complex. For instance, reduced household food waste was significantly correlated with an increase in behaviors such as meal planning, preserving foods, and using leftovers and shelf-stable items. On the other hand, behaviors aimed at self-sufficiency, including bulk purchasing and stockpiling, were significantly correlated with increased food purchase, which in turn led to increased waste. Results may offer insight for future resource and waste management strategies. For example, over 60% of respondents who started or increased efficient food use behaviors stated an intent to continue these activities after the pandemic. In contrast, less than 10% of respondents reported that they began or increased separating or composting food waste during the pandemic, and many stopped altogether due to suspension of local curbside composting services. Findings suggest that it may be easier to shift food consumption and use behaviors but more challenging to alter food waste separation behaviors, particularly those influenced by external factors, such as infrastructure that may be vulnerable to disruption. Identifying ways to facilitate ongoing behavior change and foster robust food waste management systems can contribute to resilience of food systems now and once the immediate threat of the pandemic has subsided.

The efficient use of waste from food processing industry is one of the innovative approaches within sustainable development, because it can be transferred into added value products, which could improve economic, energetic and environmental sectors. In this context, the squid pen waste from seafood industry was used as raw material to obtain nanofibrous β-chitin films. In order to extend functionality of obtained films, elderberry extract obtained from biomass was added at different concentrations. The tensile strength of chitin-elderberry extract films was improved by 52%, elongation at break by 153% and water vapor barrier by 65%. The obtained material showed distinct color change when subjected to acidic or basic solutions. It was proven by CIELab color analysis that all color changes could be easily perceived visually. In addition, the obtained nanofibrous film was successfully used to monitor the freshness of Hake fish. Namely, when the film was introduced in a package that contained fresh fish, its color was efficiently changed within the time during the storage at 4 °C. The obtained results demonstrated that food processing waste could be efficiently valorized, and could give sustainable food package design as a spoilage indicator of high protein food.

Turning the food waste into a fuel source such as charcoal briquette was one of the alternatives in managing the food wastes disposal. In this present work, food waste was converted into charcoal by microwave irradiation technique. Application of binders such as potato starch and carboxymethyl cellulose (CMC) at ratios of 5%,10% and 15% for briquetting purpose were investigated in terms of its chemical and physical characteristics. Result showed that the briquette formed using the starch as the binder performed better in combustion quality than that of carboxymethylcellulose (CMC). A good quality of charcoal briquette has capability to withstand impact during packaging, handling, and transportation. Standard physical characteristic that was tested for briquette includes moisture content, compressive strength, and impact resistance. Calorific value of briquette was studied to analyse energy content in the briquette. The study showed that food waste charcoal has calorific value comparable to that of the commercial charcoal. However, the addition of binders showed some reduction in the energy content, with more reduction when CMC is added. In terms of combustion characteristic, the addition of binders does not alter the combustion profile in comparison to the raw food waste charcoal’s profile. The ignition and burnout temperatures of the food waste charcoal briquette showed a better performance with and without binders as compared to the commercial charcoal. In terms of physical characteristics, CMC has showed as an excellent binder with highest shatter index value. Overall, in terms of chemical properties, addition of 10% starch showed a better performance, while addition of 10% CMC showed a better performance in terms of physical characteristics. This finding is beneficial for briquette industry in the development of green product using biomass, but further research is essential before production of briquette take place.

Food waste is a global issue costing roughly US$ 680 billion annually in industrialized countries. Food spoilage is a major contribution to food waste but artificial food preservatives are often not well accepted by the public. The use of natural alternatives to control spoilage is therefore of interest to the food industry. Lactiplantibacillus plantarum B21, originally isolated from a Vietnamese fermented meat product, produces an antimicrobial bacteriocin peptide which is pH and temperature stable and capable of inhibiting spoilage and pathogenic bacterial strains, including Listeria. In this study the sources of nitrogen and Tween are demonstrated to be essential for growth and bacteriocin production in L. plantarum B21. Conversely, carbohydrate source was not critical for bacteriocin production but was essential for growth. The bacteriocin was found to interact with cell membranes of target microorganisms resulting in cell leakage and subsequent cell death. This study provides insight into the growth conditions needed for the potential development of L. plantarum B21 as a natural biopreservative for food products.

[Background]: Reduction of food waste provides important environmental and economic benefits. Valorization of food by-products into edible materials is one of the most interesting strategies in this field. However, food by-products and wastes can contain chemical contaminants or potential pathogens that may endanger consumers’ health. Therefore, assuring quality and safety of these by-products is of utmost importance to take advantage of this valorization strategy., [Scope and approach]: In this review, safety evaluation of valorized by-products intended for human and animal consumption has been revised and critically discussed. With this aim, the most relevant applications of valorized by-products intended for livestock feed or food, nutraceutical, and pharmaceutical industries, in which quality and safety were assessed have been compiled. Moreover, the most common strategies for the analysis and removal of undesirable substances in these valorized by-products have been pointed out, as well as the requirements established by current regulations., [Key findings and conclusions]: Despite the great number of applications found on food by-products valorization, only in a reduced number of works safety evaluation studies, such as physicochemical and microbiological assessments or the determination of toxic contaminants, were carried out. Among them, the development of decontamination procedures and processing approaches that avoid the generation of such undesirable substances, as well as effective analysis methods have been reported. However, in most cases the evaluation of results has been very complex and difficult due to the lack of specific legislation that regulates the suitability and safety of the new products to guarantee consumers’ safety., B.S.-R., G.A.-R. and A.V. would like to acknowledge the Spanish Ministry of Science, Innovation and Universities for their “Juan de la Cierva” postdoctoral grants. The authors also thank the support from the AGL 2017-89417-R project (Ministry of Economy and Competitiveness (MINECO, Spain).

The modern age is an era of fast-growing technology, all thanks to the Internet of Things. The IoT becomes a prime factor of human life. As in this running world, no one cares about the wastage of food. However, this causes environment pollution as well as loss of many lives. A lot of researchers help in this era by introducing some great and beneficial projects. Our work is introducing a new approach by utilizing some low-cost sensors. In this work, Arduino UNO is used as a microcontroller. We use the eNose system that comprises MQ4 and MQ135 to detect gas emission from different food items, i.e., meat, rice, rice and meat, and bread. We collect our data from these food items. The MQ4 sensor detects the CH4 gas while the MQ135 sensor detects CO2 and NH3 in this system. We use a 5 kg strain gauge load cell sensor and HX711 A/D converter as a weight sensor to measure the weight of food being wasted. To ensure the accuracy and efficiency of our system, we first calibrate our sensors as per recommendations to run in the environment with the flow. We collect our data using cooked, uncooked, and rotten food items. To make this system a smart system, we use a machine learning algorithm to predict the food items on the basis of gas emission. The decision tree algorithm was used for training and testing purposes. We use 70 instances of each food item in the dataset. On the rule set, we implement this system working to measure the weight of food wastage and to predict the food item. The Arduino UNO board fetches the sensor data and sends it to the computer system for interpretation and analysis. Then, the machine learning algorithm works to predict the food item. At the end, we get our data of which food item is wasted in what amount in one day. We found 92.65% accuracy in our system. This system helps in reducing the amount of food wastage at home and restaurants as well by the daily report of food wastage in their computer system.

An incentives-based residential recycling programme was designed and implemented for improving residential waste sorting in Shanghai city, but showed very limited success in its performance. To identify why, this study systematically analysed each step of implementation using key informant interviews and site observations. Results show that policy intentions were retained in the policy devolution processes from Municipality to District, and then to Street (ward) levels, but the incentives concepts were effectively nullified in the further devolution to community-level governance. The local implementers focused on formal key performance indicators (KPIs) in order to satisfy inspections. However, the KPIs, which had been devised to allow ease of measurement, were found to unintentionally cause divergence from the policy intention of incentivisation of residents. Furthermore, high scores for these KPIs masked the implementation failure. This identification of the effective derailing of a policy via conscientious implementation is worth highlighting for avoidance in other programmes, in recycling or elsewhere.

Economic development has improved people’s daily diets in China, but food waste has increased significantly. China faces severe natural resource constraints, and reducing food waste is important for ensuring national food security. Based on 1634 survey samples from 28 provinces in China, this study assessed food waste in rural China and empirically analyzed the main factors affecting rural household food waste. The results showed that, on average, 1.67% of food is wasted per household each day in rural China. Food waste is greater in economically developed areas, such as East China. Empirical analysis showed that cooking utensils, preparing the right amount of food, religious beliefs, number of family members, average weight of family members, percentage of purchased grain in the total food consumption in 1 year, and total grain output are significantly related to rural household food waste.

Anaerobic digestion is an emerging technology producing energy from renewable resources or food waste. Exposure screenings, comprising hazardous substances and biological agents, at different workplaces are necessary for a comprehensive overview of potential hazards in order to assess the risk of employees in biogas plants. In order to analyse these parameters, workplace measurements were conducted in seven full-scale anaerobic digesters. Personal and stationary sampling was performed for inhalable and respirable particles, volatile organic compounds, ammonia, hydrogen sulphide, carbon monoxide, and carbon dioxide. Furthermore, concentrations of the total cell count, endotoxins, and fungi—down to species level—were determined in comparison to windward air. Sequencing of the 16S rRNA genes was utilized for the determination of the bacterial composition inside the biogas plants. Measurements of hazardous substances show hardly values reaching the specific occupational exposure limit value, except ammonia. An approximate 5-fold increase in the median of the total cell count, 15-fold in endotoxins, and 4-fold in fungi was monitored in the biogas plants compared with windward air. Specifying the comparison to selected workplaces showed the highest concentrations of these parameters for workplaces related to delivery and cleaning. Strikingly, the fungal composition drastically changed between windward air and burdened workplaces with an increase of Aspergillus species up to 250-fold and Penicillium species up to 400-fold. Sequence analyses of 16S rRNA genes revealed that many workplaces are dominated by the order of Bacillales or Lactobacillales, but many sequences were not assignable to known bacteria. Although significant changes inside the biogas plant compared with windward air were identified, that increase does not suggest stricter occupational safety measures at least when applying German policies. However, exposure to biological agents revealed wide ranges and specific workplace measurements should be conducted for risk assessment.

PurposeThe study analysed the amount of plate waste in a university refectory in Izmir, Turkey to find ways of minimizing plate waste in the university, providing sustainability and contributing to the development of circular economy and raising awareness about the plate waste problem.Design/methodology/approachObservation and semi-structured interviews were used to determine the volume of plate waste and level of awareness of academicians, students and administrative staff and suggest sustainable solutions for food waste in university refectories. The data gained from the semi-structured interviews were analysed with qualitative analysis software (MAXQDA®).FindingsPlate waste in the university's refectories is increasing due to the lack of precautionary measures. Academicians, students and administrative staff all showed low awareness rates.Originality/valueThis study is original in investigating theoretically and empirically one of the main reasons for food waste, namely plate waste in mass consumption sites, and evaluating the effect of food waste from an economic, social and environmental perspective.

Bioconversion of food waste oil (FWO) into biodegradable plastic is a promising method for converting waste into high-value products. In this study, a strain (Pseudomonas sp. H3) was isolated for polyhydroxyalkanoate (PHA) synthesis from FWO. After 72 h of cultivation with 20 g/L of FWO, the high cell dry weight (CDW) of 3.6 g/L, PHA yield of 2.4 g/L, and PHA content of 65 wt% were obtained under the optimal temperature (25 °C) and inoculum amount (6% (v/v)). Fed-batch fermentation was conducted in a 5 L bioreactor with a maximum CDW of 16 g/L, PHA content of 54 wt%, and PHA productivity of 0.23 g/(L·h) after 36 h. The PHA had a molecular weight of 54 782 Da and a low polydispersity index of 1.41 with glass transition, melting, and degradation temperatures of −20 °C, 34 °C, and 210 °C, respectively. To further utilize the wastewater after PHA production, anaerobic digestion was employed for CH4 production, and the CH4 yield was 284 mL/g volatile solids. Microbial community analysis showed that the abundance of acetate-oxidizing bacteria and Methanobacterium significantly increased during anaerobic digestion. This study describes a new strain for the economical synthesis of biodegradable plastics and presents a novel framework for fully utilizing FWO with the production of PHA and CH4.

Management of Municipal solid waste in low-income countries with high population densities such as India has always been a strenuous task. With perpetual advancements, there are many available technologies dealing with waste management such as incineration, pyrolysis and landfill operations. But such technologies are often accompanied with some limitations (operational and maintenance problems) and have negative environmental impacts. In this regard, continuous efforts are currently spent to develop the sustainable technologies for coping with the problems of waste management. Confronted with such problems, BSF larval composting has emerged as a green approach for waste management which outshines the various current technologies. However, it is not widely explored and therefore in the present study, BSF larval treatment efficiency has been tested against different types of food waste treatments viz., mix food waste (T1), restaurant waste (T2), fruit waste (T3), and vegetable waste (T4). We have also evaluated the Biomass Conversion Ratio (BCR) of BSF larvae. The waste reduction efficiency was found to be 72% for T1 followed by T3 and T2 whereas the efficiency was least for T4 corresponding to lower BCR comparatively. BCR obtained for T1 treatment was almost 25% which was exceptionally high in comparison to other published studies. The highest waste reduction efficiency and the BCR values for T1 may be attributed to appropriately balanced food nutrition and C/N ratio Therefore, it may be concluded that substrate type and its nutritional value strongly determines the growth and development of larva influencing the waste ingestion rate.

By means of source-segregation, organic waste streams are deterred from mass-burning and more sustainable treatment paths may be enabled. This study analyzed the environmental and economic performance of custom treatment paths for organic waste streams in Germany towards energy generation. The reference quantity was the production and export of 1 kWh of exergy, while treating a certain amount of waste. The methodologies of environmental life cycle assessment (eLCA) and levelized costs of exergy (LCOE) were applied. The considered treatment systems were (i) anaerobic digestion, (ii) hydrothermal carbonization (HTC) and (iii) incineration. The technologies were considered individually or in a cascade. The analyzed waste streams were the organic fraction of municipal solid waste (OFMSW), food waste and waste wood. For food waste and OFMSW, anaerobic digestion followed by the spreading of the digestate was characterized by overall beneficial environmental and economic properties. As the preferable treatment system was the same for both substrates, a separate collection of food waste was not considered worthwhile. For waste wood, the most environmentally friendly and economic option was direct incineration - either in a waste incinerator or in a lignite power plant. The implementation of an HTC process appeared viable for the treatment of OFMSW and food waste, both from an environmental and economic point of view. However, the energy intensive system must be outlined towards an environmentally friendly heat source. In this context, a cascading of anaerobic digestion with the HTC-process proofed to be an acceptable alternative.

The increasing rate of food waste (FW) generation globally, makes it an attractive resource for renewable energy through anaerobic digestion (AD). The biogas recovered from AD can be upgraded by the methanation of internally produced carbon dioxide, CO2 with externally sourced hydrogen gas, H2 (biomethanation). In this work, H2 was added to AD reactors processing FW in three successive phases, with digestate from preceding phases recycled in succession with the addition of fresh inoculum to enhance acclimation. The concentration of H2 was increased for succeeding phases: 5%, 10% and 15% of the reactor headspace in Phase 1 (EH1), Phase 2 (EH2) and Phase 3 (EH3), respectively. The H2 utilisation rate and biomethane yields increased as acclimation progressed from EH1 through EH3. Biomethane yield from the controls: EH1_Control, EH2_Control and EH3_Control were 417.6, 435.4 and 453.3 NmL-CH4/gVSadded accounting for 64.8, 73.9 and 77.8% of the biogas respectively. And the biomethane yield from the test reactors EH1_Test, EH2_Test and EH3_Test were 468.3, 483.6, and 499.0 NmL-CH4/gVSadded, accounting for 77.2, 78.1 and 81.0% of the biogas respectively. A progressive in-situ biomethanation could lead to biomethane production that meets higher fuel standards for gas-to-grid (GtG) injections and vehicle fuel – i.e. >95% CH4. This would increase the energy yield and carbon savings compared to conventional biogas upgrade methods. For example, biogas upgrade for GtG by in-situ biomethanation could yield 7.3 MWh/tFW energy and 1343 kg-CO2e carbon savings, which is better than physicochemical upgrade options (i.e., 4.6–4.8 MWh/tFW energy yield and 846–883 kg-CO2e carbon savings).

The circular economy is one of the leading sustainable development strategies that can help utilize waste to produce new products. Cereal food waste and residues represent a significant resource of million tonnes globally and a feasible feedstock for enzyme production via environmentally-friendly solid-state fermentation (SSF). This study presents a targeted review of 487 examples of quantified enzyme production from 209 studies reported on Science Direct. The collection of data enabled the identification of the key substrates and enzymes for potential production pathways. The main substrates were wheat (53 experiments), rice (22 experiments), and corn (22 experiments), while the most common enzymes reported were xylanase, CMCase, FPase with 92, 83, and 61 examples, respectively. Their activities showed a wide range with xylanase activities 7-10 000 U/gds, CMCase activities 1.4-950 U/gds, and FPase activities 1.7-438 U/gds. Other enzymes reported were β-glucosidase, Laccase, β-xylosidase. Both single substrates and mixed substrates were included, and several mixtures showed a synergistic effect for higher enzyme activities. Xylanase from wheat bran, rice straw, and their combination showed great potential for reaching high activity and promising revenues. Scale-up experiments were reported and demonstrated increased production of enzymes as a crucial step towards industrial application. Identified improvements in transparency and knowledge sharing for cross-disciplinary research are: i) harmonized enzyme names ii) expression of enzyme activity per mass unit specifying moisture content as found in 52% of studies. Only the results using the same unit (or enabling unit conversion) can be compared and used to identify the most promising production.

The objective of the current work is to study the impact of the operational parameters' variation (HRT, OLR and T) on biomethane productivity in a periodic anaerobic baffled reactor (PABR). The feedstock used was a biomass product named food residue biomass (FORBI), which is dried and shredded source-separated household food waste. The PABR is an innovative, high-rate bioreactor. Apart from the hydraulic retention time (HRT) and the organic loading rate (OLR), an important operational parameter is the switching period (T) of the feeding compartment: when T is high, the bioreactor operation is similar to an anaerobic baffled reactor (ABR), while when it is low, the operation approaches that of an upflow anaerobic sludge blanket reactor (UASBR). Nine distinct experimental phases were conducted, during which the operational parameters of the PABR were consecutively modified: the HRT varied from 9 to 2.5 days, T between 2 days and 1 and finally the OLR from 1.24 gCOD/Lbioreactor*d to 8.08 gCOD/Lbioreactor*d. The maximum biomethane yield was 384 LCH4/kgFORBI corresponding to the operation at HRT = 5 d, OLR = 2.14 gCOD/Lbioreactor*d and T = 2 days. Similar efficiency (333 LCH4/kg­FORBI) was achieved at higher OLR (4.53 gCOD/Lbioreactor*d). Highlights The feedstock used was a biomass product food residue biomass (FORBI), which is dried and shredded food waste.; Periodic anaerobic baffled reactor (PABR), a high-rate bioreactor.; The switching period (T) of the feeding compartment gives the bioreactor the element of operational flexibility.; The PABR can efficiently operate at HRTs as low as 2.5 days, however, the highest biomethane yield was achieved under HRT of 5 d.

Food waste remains a high priority greenhouse gas (GHG) emission problem and household curbside collection - green bin1 - with mass treatment is often adopted as a viable solution for GHG reduction. The aim of this study is to explore attitudinal and situational predictors of support for residential curbside green bin programs. Using responses to 517 household surveys from the mid-sized Canadian cities of London, Ontario (proposed green bin program) and Kitchener-Waterloo (KW), Ontario (operating green bin program for 10+ years) comparison of means t-tests, correlations and linear regression are used to test five hypotheses derived from the food waste and waste diversion literatures that predict green bin support: situational factors, current food wasting, theory of planned behaviour attitudes, concern that green bin encourages food wasting, and concern that food waste ends up in the garbage regardless of green bin. There is some support for all five hypotheses. Residents in Kitchener-Waterloo were significantly more supportive (83%) than those in London (65%). While residents in both communities are supportive because of the perceived convenience and environmental benefits of the green bin, the number of regression model predictors is greater in London (16 compared to 9 for Kitchener-Waterloo). The findings overall suggest sustained municipal education at the implementation stage may lead to positive resident habituation to green bin and thus, durable public buy-in.

Biorefining of Chinese food waste (FW) into transport fuels was assessed in terms of amount of fuel produced and over all Global Warming Potential (GWP) for six different scenarios including biogas, biomethane, bioethanol and biodiesel in different combinations. The life-cycle perspective used included GWP aspects of material and energy use, emissions during biorefining and management of residues, as well as substitution of fossil fuels according to the energy content of biofuels. All of the six FW biorefineries revealed savings in GWP ranging from −19 to −138 kg CO2 eqv. per ton of wet FW. Compared to the reference scenario with only anaerobic digestion (S0), introducing biogas upgrading to biomethane (S1) improved the GWP by 37%; while producing bioethanol prior to anaerobic digestion (S2) decreased the savings in GWP. Introducing biodiesel prior to anaerobic digestion (S3) revealed around 60% improvement in GWP, while combining biodiesel and biomethane gave the largest improvement in GWP, 84% compared to the reference scenario, and the most fuels (around 2400 MJ in terms of 30 kg biodiesel and 35 kg biomethane per ton of wet FW). A sensitivity analysis revealed that the electricity production based on the biogas was an important parameter and appears in all refineries, while the results was less sensitive to the production of biodiesel and biomethane. The residue management contributed also to the GWP, but did not vary much among the biorefinery scenarios.

Black soldier fly (BSF) larval bioconversion can recycle nutrients in organic wastes into larval biomass and frass. While the frass has been commonly marketed as a soil amendment, its usefulness in soilless cultivation remains largely unexplored. Growth experiments were conducted to investigate the effectiveness of surplus food-derived and okara-derived BSF larval frass as an incorporated compost, side-dress fertilizer and frass-tea drench for the cultivation of pak choi and lettuce in waste-wood derived biochar growing media. Pak choi yields from treatments with surplus food-derived frass and biochar at a 10:90 (v/v) ratio and inorganic fertilizer were comparable to those of the control which consisted of soil, peat-based compost and inorganic fertilizer. However, yields decreased with increasing frass incorporation rates owing to high salinity and potentially low oxygen conditions in the growing media. When used as a fertilizer on biochar-coir growing media, the direct application of frass as a side-dress fertilizer was 1.6-6.8 times more effective in promoting lettuce growth than the application as a frass-tea drench. Frass fertilizers derived from surplus food outperformed those derived from okara by 1.3-5.3 times. Lettuce yields were not significantly different between the treatment with surplus food-derived frass applied as a side-dress fertilizer and the control of liquid inorganic fertilizer. Variations in fertilizing potential were attributed to nutrient availability and the presence of plant growth promoting microbes in the growing media. BSF larval frass derived from food waste shows promise in partially replacing unsustainable agricultural inputs for leafy vegetable cultivation, including soil and inorganic fertilizers.

Excessive food waste (nearly 1.3 billion tons per annum) has exacerbated the world hunger crisis. This comprehensive review focuses on the food waste scenario, adverse effects, food waste management, existing waste management policies, and regulations in Bangladesh. Municipalities and urban centers generate 3.78 million tons of waste each year (15.96% of total food waste). This study utilized the national database to analyze food waste generation and projected growth by the year 2050. Yearly an estimated 17215.2 thousand acres of land and a significant amount of natural resources (water, energy) are being used to produce 23691.15 thousand tons of wasted food (45% of total food production). This study critically analyzed the waste management policy gap of Bangladesh and clearly identified each stage of the food loss production supply chain. The study assessed that yearly 481.6 MW energy could be generated from food waste. Focusing on effective policy and sustainability, a national food waste management model has been proposed for Bangladesh in compliance with sustainable development goals 12.3.1 global food loss. Food accumulates 16.7% to 20% of the world economy; therefore, any measures taken to reduce the food waste will be economically beneficial and environmentally sustainable.

The COVID-19 pandemic has drawn attention to food insecurity in developed countries. Despite adequate levels of agricultural production, consumers experienced demand-induced scarcity. Understanding the effects on nutrition and the environment is limited, yet critical to informing ecologically embedded mitigation strategies. To identify mitigation strategies, we investigated wheat flour and egg retail shortages in the United Kingdom (UK), focusing on consumer behavior during the COVID-19 lockdown. The 6 Steps for Quality Intervention Development (6SQuID) framework informed the methodology. Mixed qualitative and quantitative methods were used to pinpoint the causes of the shortages, and ecological impacts of consumer behavior were related using survey results (n = 243) and environmental and nutritional databases. This research confirmed consumers’ narrowed consideration set, willingness to pay, and significant reliance on processed foods which indicates agronomic biofortification, breeding strategies, selective imports and improved processed food quality are important mitigation strategies. We identified positive and negative synergies in consumer, producer and retailer behavior and related these to mitigation strategies in support of a circular bio-economy for food production. We found that the substitutes or alternative foods consumed during the COVID-19 lockdown were nutritionally inadequate. We identified the most ecological substitute for wheat flour to be corn flour; and for eggs, yogurt. Our findings also indicate that selenium deficiency is a risk for the UK population, especially to the increasing fifth of the population that is vegetarian. Due to the need to implement short-, medium-, and long-term mitigation strategies, a coordinated effort is required by all stakeholders.

Food waste has attracted wide attention around the world. A better understanding of food waste generation and consumers’ willingness to pay (WTP) for effective food waste management is important for addressing growing food waste challenges, but this is still largely missing in the literature, especially for developing countries and cities in Asia. In this study, we conducted field interviews and questionnaire surveys, with effective samples of 463 residents and 18 restaurants in Macau. Our results show that over 80% of respondents think food waste in Macau is serious. “Food exceeded expiration date (28.2%)” and “Ordering too much food (39.5%)” are the two main reasons for throwing away food at home and when eating out, respectively. Vegetables and fruits (22.4%) are the most common type of food wasted at home, followed by snacks (17.3%), in Macau. About 70% of respondents agreed to pay for separate food waste collection and treatment facilities, and the WTP value per household in Macau is 42.5 MOP (Macau Pataca)/month. Respondents’ income level was positively and significantly correlated with their WTP, while age and educational level had negative effects on the WTP, under the 5% significance level. Some respondents’ perceptions and attitudes on food waste also significantly affected their WTP, according to our analysis. Because of the lack of effective management measures and collection facilities, about 72% of surveyed restaurants mixed their food waste into municipal solid waste (MSW). More information sharing, education and promotion should be done to raise environmental protection awareness and improve the food waste treatment system.

Trends show that strategies for effective utilization of food wastes will emerge as a key field of research and markets shortly. In this study, for the first time, 3D printing technology, an emerging approach for food customization, was used to prepare nutrient-rich noodles from peel wastes obtained from potato processing industries. The study involves the characterization of material properties for 3D printing. Based on the analysis, the fine fractions of potato peel were found to exhibit better printability than the coarse fractions. Whole wheat flour and potato peel powder were used to formulate the material supply (60:40), and extrusion printing conditions for the in-house developed CARK printer were optimized at 600-mm/min printing speed, 600-rpm extrusion motor speed, and 6-bar pressure for a 1.28-mm-diameter nozzle. Consumer acceptance of the 3D printed and post-processed instant noodles were on par with the market product; with an energy value of 414.39 kcal/100 g, the formulated noodles can be a good choice for breakfast. Importantly, the concept provides new insights to improved utilization of food waste streams; 3D printed foods can be nutrient-rich as well as customized to any shape or layering for enhanced product acceptability. Further, the technology can be conveniently scaled up and the approach is sustainable.

As we eat, we transform social, natural, and economic systems. Here we briefly explore these transformations.

Excess reactive nitrogen (Nr) in the global system has led to a wide variety of environmental and human health problems. To minimize the negative impacts of nitrogen loss from agriculture, we need to develop more sustainable farming systems that can efficiently produce food for humans while balancing ecological functioning and reducing Nr losses. This paper looks at recent research examining Nr losses in organic systems, using conventional Nr losses in the United States (U.S.) as a baseline to identify leverage points for reducing Nr loss. The paper discusses the sources of Nr used in organic versus conventional farming and highlights the importance of increasing the use of recycled Nr to prevent additional Nr loss to the environment. Specifically, we note that organic production is advantageous when it comes to the creation of new Nr because of its reliance on recycled sources of Nr, improved ability to access nutrients in the soil, and higher residue recycling rates. We also highlight areas where additional research, policies, and protocols are needed to improve Nr efficiency, including increasing organic yields, increased recycling of processing waste, matching nutrient flows, reducing and recycling edible food waste, and examining potential benefits and risks of land application of sewage sludge in organic systems.

A novel approach of using two stage anaerobic digestion coupled with electrodialysis technology has been investigated. This approach was used to improving bio hydrogen and methane yields from food waste while simultaneously producing a green chemical feedstock. The first digester was used for hydrogen production and the second digester was used for methane production. The first digester was combined with continuous separation of volatile fatty acids using electrodialysis. The concentrations of carbohydrates, proteins and fats in the prepared food waste were 22.7%, 5.7% and 5.2% respectively. Continuous removal of volatile fatty acids during fermentation in the hydrogen digester not only increased hydrogen yields but also increased the production rate of volatile fatty acids. As a result of continuous VFA separation, hydrogen yields increased from 17.3 mL H2/g VS fermenter to 33.68 mL H2/g VS fermenter. Methane yields also increased from 28.94 mL CH4/g VS fermenter to 43.94 mL CH4/g VS fermenter. This represents a total increase in bio-energy yields of 77.1%. COD reduced by 73% after using two stage anaerobic digestion, however, this reduction increased to 86.7% after using electrodialysis technology for separation of volatile fatty acids. Electrodialysis technology coupled with anaerobic digestion improved substrate utilization, increased bioenergy yields and looks to be promising for treating complex wastes such as food waste.

Hydrothermal liquefaction (HTL) is a promising route to convert food waste (FW) to value-added biocrude. Real FW collected from a university campus dining hall and three principal FW components, na...

International audience; Background: The impact of the cold chain breaks on food products is widely documented with multiple stakes: health, environmental and economic. The emergence of Internet of Things (IoTs) will enable more rigorous temperature monitoring in real time but raises new questions about the processing of the generated data. Scope and approach: Different definitions and challenges associated with the detection of cold chain breaks are presented and discussed. Machine learning methods applied to cold chains are described in order to highlight the issues related to these data. In addition, these studies allow us to bring out the different data sources that can be used to train the learning models. Key findings and conclusions: The field of cold chain generates experimental and numerical data that have a great potential to train machine learning models. To our knowledge, although machine learning methods have been used to predict temperature, these methods have not been used to detect breaks in the cold chain. However, several methods already exist to detect anomalies in time series data. Learning from these data would be a step forward: on one hand, to get a better knowledge of cold chain breaks, and on the other hand to alert operators at the right time.

Bio-hydrogen production is of significant interest as it is capable of consuming waste material and synthesizing hydrogen which is a green gas. In this study, we examined the dose-dependent effect of iron shaving on bio-hydrogen production from an integrated dark and photo fermentation system from an artificial food waste. Overall, introduction of iron shaving enhanced the bio-gas production. Statistical analysis was performed on the extracted parameters obtained from fitting the experimental data to Gompertz function, revealing that the bio-gas production can be significantly enhanced by addition of iron shaving at concentrations up to 500 mg/L, with a maximum enhancement at 200 mg/mL. GC analysis showed that introduction of iron shaving at 200 mg/L also maximized the hydrogen percentage in the produced bio-gas. Based on the HPLC results, it was postulated that the dark-fermentation step was probably the step that was more affected by the introduction of iron shaving. Investigation of the pH showed that the acidification of the solution approximately coincided with the termination of the process. Our finding suggests that a more efficient buffer-assisted setup can significantly enhance the bio-hydrogen efficiency.

Pursuance of the strong motivation in combating climate change and energy security as well as the desired shift toward biofuels from food waste as a renewable energy sources offers opportunities fo...

The sustainable management of household food waste (FW) and household blackwater (BW) is becoming more challenging. This research investigated three different semi-continuous stirred tank reactor (CSTR) performances for digestion of the mixture of BW and FW; for producing biogas. Through the application of the serial semi-CSTR digestion (35 °C), the produced biogas from the BW-FW (1:1 proportion) offered to be higher than the single semi-CSTR 55 °C (25%) and that of the single semi-CSTR 35 °C (31%). The serial semi-CSTR higher biogas volume production was attributed to the extra biogas generated from the residual organic matter and residual volatile fatty acids decomposition existing in the digestate of the first reactor and further utilized in the second-step methanogenic reactor chamber. The serial semi-CSTR physicochemical parameters showed stable performance with total chemical oxygen demand reduction efficiency of 97%, and without inhibition at the pH value of 8.5 ± 0.9. The serial semi-CSTR 35 °C digestion offered the advantages for improving the worth of resources recovered from FW and the BW to accomplishing a higher biogas percentage and enhanced sludge stabilization for water resources and waste management.

Chinese economic development has continuously increased national municipal solid waste (MSW) output. However, the existing MSW classification method is insufficient and exacerbates several urgent problems. There are many factors to consider in Chinese waste classification (population, MSW production, food waste content, water content, economy, environment, and waste disposal methods). Based on research and analysis, MSW classification should highlight and implement treatment methods that focus on incineration, the distinct treatment of kitchen waste, and landfills as a waste disposal supplement. MSW is divided into five categories: kitchen waste, incineration, recyclable, hazardous waste, and other waste. Using economic benefit analysis, life cycle assessment, and radar chart analysis, a quantitative study is conducted on the classification methods of MSW used in Germany, the US, the UK, Sweden, Japan, China, and this study. The results indicate that a more refined classification can effectively improve many aspects of MSW management, especially regarding economic and environmental benefits, which are significantly affected. Effective MSW management can reduce the cost of waste disposal by 69.4% and greenhouse gas and acidic substance emissions and increase the energy utilisation rate four fold. This research is of great significance to environmental protection and the development of a circular economy and provides a reference for the management of MSW.

Wide-scale implementations or industrial-scale productions of biofuels from food/fruit waste are insufficient. One of the major reasons of wider implementations is lack of confidence on potential outcomes and subsequent monetary benefit. A mathematical model can provide estimations of potential biofuel generation capability under different input conditions. This paper presents a mathematical modelling framework for the estimation of bioethanol production potential from waste/rotten banana. A simple mathematical formulation comprised of three contributing factors such as shaking hour, temperature and water content is proposed. The factors were derived based on an earlier experimental study on production of bioethanol from waste banana. Results from the proposed mathematical model were compared with the experimental measurements. It is found that the proposed model is capable to estimate potential bioethanol productions from waste banana with very good accuracy achieving a coefficient of correlation of 0.995. Standard errors of the model’s estimations are RMSE = 0.08, MAE = 0.06 and RAE = 0.01. Finally, to facilitate proper estimations of benefit–cost ratio, a mathematical framework is proposed. For industry-scale implementations of biofuel generation, such modelling framework is useful for the decision makers on deciding optimum input parameters through optimised energy consumption, which will ultimately render monetary benefits from such production. Similar mathematical framework can be adopted for such biofuel production from other fruit/food waste.

The potential for obtaining renewable energy from organic substrates such as food waste (FW) and biowaste has generated increasing interest in the anaerobic digestion process. Kinetic models are used to analyse the impact of different parameters on biological processes and thus, to optimize them to achieve and to increase the quality and quantity of biogas. This study presents an approximation of the pre-dimensioning of semi-continuous anaerobic reactors treating FW, based on: (i) biochemical methane potential (BMP) assays, in different conditions of substrate-inoculum ratio (S/I: 0.5 and 4.0 g volatile solid-VSsubstrate·g VSinoculum−1) and nutrients (with macro-nutrients (N and P) and micronutrients, only micronutrients (Ni, Co, Mo and Fe) and without nutrients), and (ii) the kinetic performance through three kinetic models (transfer function-TF, logistic function-LF and modified Gompertz-MG), using Pmax (maximum methane production) and Rmax (maximum rate of methane production) as kinetic parameters related to the hydraulic retention time. The best S/I ratios were below 1.0 gVSsubstrate·gVSinoculum−1 with nutrients. Although the three kinetic models obtained a good fit (R2 > 0.9 and RMSE

To minimise the food waste, this paper applied the antimicrobial plates produced from poly(butylene succinate) (PBS)/geraniol blend which was processed into two different microstructures. Experimen...

Food waste is a major issue in the context of pollution, climate change, and the future circular economy. Composting kitchen waste is a promising method to recycle elements, yet the efficiency of composting is limited, calling for new processes that degrade rapidly and thoroughly organic matter. Here, we built a rapid laboratory-scale aerobic composting system, equipped with a water bath fueled with either solar energy, or electricity under low sunlight. We tested compositing with and without energy. Results show that only three days are needed to raise the temperature to over 45 °C by energy composting in winter, leading to notable increases in pH, total nitrogen, and cation exchange capacity after 7 days. Composting materials were thoroughly decomposed and mature in 10 days, displaying pH of 7.5, ratio of total organic carbon to total nitrogen of 9.9, cation exchange capacity of 65.61 cmol kg−1, and germination index of 80.4%. Overall, energy composting starts biodegradation quickly in 2 days, reduces effectively the inhibition from some waste compounds, decomposes organic substances well, and yields mature compost.

This work presents an integrated approach of anaerobic digestion (AD) at the urban scale, based on on-site collected wastes, experimentation in a pilot reactor, and model approach. To cope with urban waste limitations (season inflow, organic matter decrease, limited area), it was proposed a settlement of wastewater (WW), a drying of food waste (FW), and silage of green waste (GW). The results obtained highlight the performance of these pretreatments to concentrate and/or preserve the organic matter over time. Co-digestion in a 30-liter reactor was then successfully carried out, resulting in an 83% of volatile solids reduction and stable methane production of 321 ml CH4/g VSadd, in 35 days. Finally, we developed a standard neighbourhood model with AD based on these experimental results. It appears that 66% of the primary sludge (PS) and 28% of the FWs produced daily could be treated by the proposal process. 14% of the annual production of GW could thus be processed daily. From an energetic point of view, the process generates a surplus of respectively, 2500 MJ/year and 38,000 MJ/year in terms of electricity and heat. The generation of 15 times more heat energy than electricity, supports an installation of anaerobic digestion, close to homes. Moreover, if these results are encouraging, we suggest different scenarios of co-digestion ratios and operational parameters for their optimization.

This study aims to assess the transportability of food waste disposer particles within a sewer system. A series of laboratory studies has examined the physical characteristics of solid particles derived from domestic food waste disposers. Particle size distributions and maximum settling velocity characteristics were measured for 18 common food types, and stored in a publicly accessible database. Particle size distributions are shown to fit well with a 2-parameter Gamma distribution. Settling velocity is generally higher for larger particles, except when particle density and sphericity change. For most food types, particle specific gravity was close to unity. Egg shell particles had a significantly higher specific gravity. This information, combined with the particle size data have been used to show that there is a very low likelihood of food waste particle deposition in sewers during normal operational flows, other than temporary transient deposits of egg shell particles. HIGHLIGHTS Particles characterised for 18 common food types.; Sizes fit a Gamma distribution, mode of 0.59 to 4.76 mm.; Most particles had apparent densities close to water.; Most particles entrained at low boundary shear stress, unlikely to form deposits in sewer pipes.; Egg shell showed higher entrainment threshold, but still expected to transport during dry weather flows.

Gamma‐aminobutyric acid (GABA) is a pharmaceutical, bioactive amino acid that can produce by some species of Lactic Acid Bacteria (LAB). For the first time, we evaluated the production of GABA by Lactobacillus brevis PML1 in the medium that contain the contaminant food bio‐product like dairy sludge and soybean meal. GABA production was analyzed by chromatography (TLC, HPLC) and the features of fermented extract which contains this amino acid were evaluated. The results of Response Surface Methodology (RSM) of Central Composite Design (CCD) at p, The results of response surface methodology (RSM) of central composite design (CCD) at p

Biotechnological production of omega-3 polyunsaturated fatty acids (PUFAs) has become a commercial alternative to fish oil in the past twenty years. Compared to PUFA production by fatty fishes, that from microorganisms has increased due to its promising sustainability and high product safety and to increasing awareness in the expanding vegan market. Although autotrophic production by microalgae seems to be more sustainable in the long term, to date most of the microbial production of omega-3 is carried out under heterotrophic conditions using conventional fermentation technologies. The present review critically analyzes the main reasons for this discrepancy and reports on the recent advances and the most promising approaches for its future development in the context of sustainability and circular economy.

Polylactic acid (PLA) plastic is becoming a popular alternative to traditional petroleum-based plastics, but the biodegradability in engineered biological system is still a matter of concern. In this study, the biodegradability of PLA plastic at mesophilic and thermophilic AD were investigated, and a hydrothermal pretreatment was proposed to enhance the hydrolysis of PLA plastic and subsequent biomethanization. For raw PLA plastic, the biodegradation results indicated that PLA was hardly biodegraded at mesophilic conditions (only 50.5 ± 0.5 mL/g VS after 146 days). Although it was converted into biogas at thermophilic conditions after long incubation period (442.6 ± 1.1 mL/g VS), the long digestion time (T90 95.8 days) was destined to be infeasible for practical application. In contrast, hydrothermal pretreatment significantly enhanced the hydrolysis rates of PLA plastic in AD process from 0.001 day-1 for raw PLA plastic to 0.004–0.111 day−1. By balancing biogas production efficiency, energy and reagent cost, the conditions of 200 °C, 10 min and no alkali addition were recommended for hydrothermal pretreatment of waste PLA plastic in practice. At the optimized hydrothermal pretreatment conditions, 460.1 ± 25.0 mL/g VS was achieved in less than 30 days, which was comparable for AD of food waste (FW). Furthermore, LC-QEMS analysis proved that cleavages of ester bonds in PLA and its reaction with water molecule was the mechanism of triggering the hydrothermally decomposition of PLA. These results suggested the PLA-plastic waste co-mingled with OFMSW could be efficiently biomethanized into biogas by involving a mild hydrothermal pretreatment in practical application.

This study presents an integration of acidogenesis (dark-fermentation) and methanogenesis for green hythane/biohythane production from food waste in two stages (S–I and S-II) and phases (P–I and P-II) of operational variations. The regulatory influence of biocatalyst and redox environment on anaerobic fermentation was evaluated through a rapid protocol in the context of biogas up-gradation with reference to bio-hydrogen (bio-H2), biomethane (CH4), bio-hythane (H2+CH4) and their composition (H2/(H2+CH4)) as major markers. Bioreactors with two different parent cultures (heat-shock pretreated and untreated) were operated at pH 6 and 7 in two phases to overcome the impediment of single-phase operation aiming for maximum energy recovery from the untreated substrate of P–I. Integration of S–I with S-II was beneficial to achieve 1.22 times higher cumulative bio-hythane production (4.25 L) compared to S–I (3.47 L) condition alone. The bio-hythane composition mimics the H2 enriched CNG (H-CNG) and showed the potential to be implemented for biogas up-gradation as a tool.

This study investigated the performance of anaerobic co-digestion (AcoD) of pig manure and food waste on the reduction of antibiotic resistomes under wet and dry AcoD conditions. High-throughput quantitative PCR technology was utilized for a comprehensive assessment of the performances of the two processes. The results show that dry AcoD with a total solids (TS) content of 20% effectively reduced total antibiotic resistance genes (ARGs) by 1.24 log copies/g wet sample, while only 0.54 log copies/g wet sample was reduced in wet AcoD with a TS content of 5%. Dry AcoD was more efficient in reduction of aminoglycosides, multidrug and sulfonamide resistance genes compared with the reduction of other classes of ARGs. Dry AcoD caused a significant reduction of ARGs with resistance mechanisms of efflux pump and antibiotic deactivation. In contrast, there was no obvious difference in reductions of ARGs with different resistance mechanisms in wet AcoD. Network analysis showed that ARGs were significantly correlated with mobile genetic elements (MGEs) (Spearman's r 0.8, P 0.05), as well as microbial communities. Enrichment of ARGs and MGEs was found at the early period of AcoD processes, indicating some ARGs and MGEs increased during the hydrolysis and acidogenesis stages. But after a long retention time, their abundances were effectively reduced by dry AcoD in the subsequent stages.

In this study, a mixed-level orthogonal array design was employed for the optimum conditions of breeding housefly larvae by food waste. The results showed that the effects of these factors on the weight of 50 larvae, larvae yield, and crude protein content were the culture substrate ratio > the breeding density > the feeding mode. The optimum conditions for the housefly larvae to convert food waste were as follows: culture substrates ratio 1:3, breeding density 10.0 g/kg, and all substance added on the first day. The optimum food waste mass reduction rate was 79.1-83.6%. The value of the essential amino acids (Eaa)/ the total amino acids (Taa) (45.1%) and E/the nonessential amino acid (Naa) values (0.83%) in the housefly larvae products met the Food and Agricultural Organization (FAO) requirements for feed protein. The crude fat content (30.1 ± 1.18%) was higher than of the housefly larvae after bioconversion of pig manure (22.0%) and the fish meal standard of China. The contents of total nutrients (N+P+K ≥ 5.5%) and heavy metals (Pb ≤ 0.40 mg/kg, Cr ≤ 1.50 mg/kg, Cd ≤ 0.40 mg/kg) in the residues of this study met the Chinese standard for organic fertilizer. Tilapia raised with the dried housefly larvae showed the best growth performance and nutrient concentrations in the experiment groups (p < 0.05). Moreover, the trace elements concentration in tilapia raised with the four kinds of feeds complied with the maximum levels of contaminants in foods in both China and WHO. These findings show that the housefly larvae products that converted food waste are suitable for use in the production of fish feed.

Anaerobic digestion of food waste appears promising to generate biogas in the context of the growing energy demand and the circular economy. In particular, anaerobic digestion causes less air and solid waste pollution compared to incineration, gasification and pyrolysis. Actual research on biogas production using food waste focuses on the performance of substrates such as manure and bacteria, yet few investigations evaluate the impact of anaerobic digestion on the environment. Here, we review the steps of anaerobic digestion, factors that influence the process, and food waste as main and co-substrate to increase biogas yield. High metabolic activity of anaerobes is optimized by controlling temperature, pH, retention time, carbon-to-nitrogen ratio, volatile fatty acid and organic loading rate. We discuss the effect of pre-treatments such as biological, thermal, chemical and mechanical treatments, on anaerobic digestion performance. The impacts of food waste treatments on the environment are compared by life cycle analysis.