Bio-Compost Behaviour as Soil Additive by Food Waste Pretreatment on the Growth of Abelmoschus esculentus L.: A Systematic Review

Managing food waste is key to tackling climate change

Food waste has been identified as one of the major factors that constitute numerous anthropogenic activities, especially in developing countries. There is a growing problem with food waste that affects every part of the waste management system, from collection to disposal; finding long-term solutions necessitates involving all participants in the food supply chain, from farmers and manufacturers to distributors and consumers. In addition to food waste management, maintaining food sustainability and security globally is crucial so that every individual, household, and nation can always get food. “End hunger, achieve food security and enhanced nutrition, and promote sustainable agriculture” are among the main challenges of global sustainable development (SDG) goal 2. Therefore, sustainable food waste management technology is needed. Recent attention has been focused on global food loss and waste. One-third of food produced for human use is wasted every year. Source reduction (i.e., limiting food losses and waste) and contemporary treatment technologies appear to be the most promising strategy for converting food waste into safe, nutritious, value-added feed products and achieving sustainability. Food waste is also employed in industrial processes for the production of biofuels or biopolymers. Biofuels mitigate the detrimental effects of fossil fuels. Identifying crop-producing zones, bioenergy cultivars, and management practices will enhance the natural environment and sustainable biochemical process. Traditional food waste reduction strategies are ineffective in lowering GHG emissions and food waste treatment. The main contribution of this study is an inventory of the theoretical and practical methods of prevention and minimization of food waste and losses. It identifies the trade-offs for food safety, sustainability, and security. Moreover, it investigates the impact of COVID-19 on food waste behavior.

Food waste (FW) increases with urbanization and population growth, which puts pressure on the treatment system, causing a variety of harmful impacts on the environment. Proper FW treatment is imperative for ecological integrity and public health. Even though FW treatment is an extensively studied topic, the sustainable FW treatment considering holistic-lifecycle-based environmental impacts has rarely been evaluated. This study addresses this gap through a comprehensive analysis of various FW treatment methods, including co-treatment with sewage, anaerobic digestion, incineration, and aerobic composting. The impacts of greenhouse gas (GHG) emission and energy use efficiency are assessed by analyzing diverse FW treatment methods in Shenzhen, China. The study indicates that FW addition to sewage does not adversely affect the current sewage treatment plant, but benefits GHG avoidance and energy recovery. Compared with the other FW treatment methods, FW anaerobic digestion avoids the most GHG emissions with −71.3 kg CO2 eq/FU and recovers the most energy with −223 kWh/FU, followed by FW co-treated with sewage. The energy conversion efficiency of the combined heat and power (CHP) unit greatly affects FW incineration, while energy consumption in incineration and anaerobic digestion (AD) process is relatively minor. Perturbation analysis pinpoints key parameters influencing outcomes, including CHP efficiency, GHG emission factor of local electricity, and chemical oxygen demand (COD) in FW with ratios of −13~−0.942, −0.518~0.22, and −13~1.01, respectively, that should be given special attention. This study sheds light on sustainable FW management strategies, not only in China but also transferrable to regions confronting similar challenges. Advocating ecologically balanced and resource-efficient approaches, the study aligns with broader aims of fostering sustainable development.

Reducing our waste size

Globally, approximately one-third of food produced for human consumption is lost or discarded, comprising 1. 3 billion tons annually. Factors contributing to food waste from the food manufacturer to the consumer level are numerous. Events that may result in food waste include, but are not limited to, manufacturing food by-products, improper handling within the supply chain (e.g., cold chain deviations), misunderstood food date labels, over-purchasing, and consumer-level temperature abuse. From the manufacturer to consumer, each node in the food supply requires concerted efforts to divert food waste from entering municipal landfills. Depending on the state of the food waste, it is diverted to various outlets, from food donation for consumption to composting for soil amendment. To better understand the opportunities in the United States to divert food waste from landfills, current and emerging federal policies as well as the causes of food waste generation must be understood. Unfortunately, information on both the composition of food waste in the U.S. and how it impacts critical factors in food waste treatment, especially in food waste composting, is limited. Specifically, this review aims to: (1) discuss and compare critical factors that impact the fate of food waste and (2) examine emerging opportunities to advance the processing and products of food waste.

Enhanced anaerobic digestion of food waste by thermal and ozonation pretreatment methods

Cutting edge technologies to end food waste

The incorporation of organic amendments, such as food waste (FW) and biochar, into soil is an established agronomic practice known for enhancing soil fertility and improving overall soil health. However, the individual and combined effects of FW and biochar on soil properties in microplastic (MP)-contaminated soil–plant systems remain poorly understood. To address this knowledge gap, we conducted a field experiment to investigate the individual and combined effects of polystyrene MPs, FW, and FW-derived biochar on soil properties and lettuce growth. Soil chemical properties were unaffected by the addition of MPs. However, the application of FW and biochar increased the soil pH, with the highest pH (8.2) observed in the combined treatment of biochar and MPs. Despite the presence of MPs, FW application resulted in notable increases in soil electrical conductivity (EC; 2.04 dS m−1), available nitrogen (NO3−–N: 325.5 mg kg−1, NH4+–N: 105.2 mg kg−1), available phosphorus (88.4 mg kg−1), and total exchangeable cations (18.6 cmol(+) kg−1). However, these values decreased after lettuce cultivation. In soil cultivated with lettuce, the coexistence of MPs and biochar reduced soil Fluorescein diacetate hydrolase enzyme activity by 46.2% and urease activity by 94.0%. FW addition doubled acid phosphatase activity, whereas FW and its coexistence with MPs decreased alpha diversity. The relative abundance of Actinobacteria decreased with MP application, whereas that of Acidobacteria and Actinobacteria decreased with FW treatment. Gemmatimonadetes and Nitrospirae decreased in soil treated with FW and biochar. The highest relative abundances of Firmicutes and Proteobacteria were observed in the FW-added soils, and Planctomycetes were the highest in the biochar-added soils. FW application negatively affected lettuce growth. Overall, the coexistence of MPs with FW or biochar had limited effects on soil properties and lettuce growth, with FW and biochar serving as the primary factors in modifying soil–plant systems. Future studies should investigate the effects of different MPs and their interactions with organic soil amendments on soil properties and crop growth under different management practices.Graphical

In this study, we demonstrate that the addition of earthworm castings (EC) in kitchen waste composting reduces ammonia and greenhouse gas (GHG) emissions and improves compost maturity. Kitchen waste (KW) was mixed with sawdust at a ratio of 7:3 as the compost stock. Four treatments with different proportions of EC added (0%, 2.5%, 5.0%, and 7.5% on the basis of the initial kitchen waste mass) were designed and utilized in a composting process lasting 85 days. The results showed that the GHG and ammonia emissions were considerably reduced in the treatments with EC added. In addition, EC amendment prolonged the thermophilic stage and shortened the composting period. The addition of EC reduced ammonia, methane, and nitrous oxide emissions by 61%, 48%, and 94%, respectively, also indicating that nitrogen in the compost was conserved. Nitrogen and major nutrients were best preserved in the EC 7.5% treatment, which produced a compost product with a better nutrient profile. Furthermore, the total global warming potential of the KW composting process was reduced by 74% by using the mixture with EC. An effective reduction in GHG emissions was observed already with the addition of 2.5% EC, but a significant reduction in ammonia emissions was observed for the EC 7.5% treatment. Therefore, the results of this study suggest that EC is an effective additive in KW composting. More specifically, addition of EC at 7.5% of the initial KW mass was most recommendable for mitigating potential global warming effects and improving compost quality.

A key problem, which requires solution in today’s situation, is treatment of food waste. Nowadays food waste is mainly buried and it does harm to the environment and people’s heals, pollutes air because of dump gases (including greenhouse gases), soil and water and causes irreversible climatic changes. It is necessary to pass over to such level of production and consumption, which could minimize and even eliminate waste formation. The authors of the article substantiate the need to take steps aimed at waste involvement in economic turn-over by its recycling, which requires the development of the effective mechanism of food waste control in the Russian Federation. The economic mechanism shall include the system of normative, legal and other documents in the field of treating food waste, a set of technological and infrastructure decisions aimed at utilization of food products with expiring BB dates, methodological recommendations on cutting food waste formed in business activity and its utilization.

The disposal of food waste has attracted worldwide attention. Each year, the amount of wasted food accounts for an estimated one third of annual food production globally. This large amount of food waste has caused serious land, water, and air pollution. In the past, most research on food waste was focused solely on food waste disposal processing. Only a few studies analysed the flow of materials in food waste treatment processes. Therefore, this paper focused on the process of food waste anaerobic treatment in Beijing and investigated the treatment. According to a life cycle theory, the food waste treatment process is divided into three processes: "collection and transportation, disposal, and resource utilization." This paper analysed the input and output of food waste treatment in different processes and evaluated the economic and environmental costs and benefits of food waste treatment. The study found that 200t of food waste anaerobic treatment can obtain benefits 66,888 Chinese yuan, generate electricity energy 43,350kW⋅h, and reduce carbon dioxide emissions 16,087kg. Generally, the economic and environmental benefits of the food waste anaerobic treatment project are considerable. However, the economic benefits are mainly from government subsidies. There are many impurities in food waste, which indicates some problems in food waste treatment. Thus, the proposals to strengthen waste classification, optimize the layout of garbage collection and transportation, and accelerate the development of waste treatment plants have been put forward.

Solid waste management of temple floral offerings by vermicomposting using Eisenia fetida

Energy from food waste

Objectives : Black soldier fly larvae (BSFL) are organisms that effectively decompose various types of organic waste including food waste, and food waste treatment using BSFL is attracting attention as a sustainable waste treatment method. However, food waste discharged from Korea has a wide variety of properties, and its high salt concentration limits its treatment by BSFL. Therefore, to increase the efficiency of food waste treatment using BSFL, it is necessary to increase the quality of food waste as a production medium for BSFL. In this study, the ratio of protein and fat was adjusted by adding bean sprouts and wheat brans to food wastes treated at high temperature under vacuum, and whether such medium is suitable for rearing BSFL was investigated.Methods : To improve the medium, the ratio of protein and fat was adjusted to approximately 2:1 by adding bean sprouts and bran residue to food waste. Subsequently, the growth and development rate of BSFL reared on chicken feed, food waste, food waste + bean sprouts, food waste + wheat bran were measured. Also, the decomposition rate of each medium was analyzed.Results and Discussion : The growth rate of BSFL grown on food waste + wheat bran medium was similar to that of BSFL reared on chicken feed. The speed of development at day 7 was also the fastest for BSFL reared with food waste + wheat bran medium and chicken feed. These results suggest that the mixed medium to which wheat bran has been added to food waste has the potential to be used as a commercial medium for BSFL production. The survival rate of BSFL was 89% or higher in all media.Conclusions : When food waste was used alone, BSFL development was poor compared to that in media combined with agricultural by-products such as bean sprouts and wheat bran. Therefore, to use food waste as a rearing medium of BSFL, it is necessary to adjust the ratio of protein and fat by adding various agricultural by-products and reduce salinity. For the improvement of food waste treatment technology using BSFL, mass rearing of useful insects such as BSFL, and promotion of the use of agricultural by-products, additional research is needed to optimize the composition of rearing medium based on food waste.

Increasing waste generation in developing countries has alarmed authorities on waste disposal issues. Therefore, various alternatives have been looked into to reduce waste disposed into landfill. Among others are the bioremediation options which may allow the conversion of putrescible wastes into value added products such as compost, biogas and others. This study was aimed to find optimal experimental set-up to conduct small scale vermicomposting suitable for households, since approximately 40-50% (wt) of the waste is putrescible component. The wastes were weighed and exposed to worms namely Eisenia foetida. Results indicated that household putrescible waste can easily undergo vermicomposting. However, factors such as high acidity and presence of certain materials in the waste can be detrimental to this process. Worms are very sensitive to pH changes and the vermicomposting process will reduce drastically when pH is lower than 5.0. Experimental set-up with the layering system proved to be the best method of conducting small scale vermicomposting. The layering set-up prevents worms from escaping the vermicomposting system and allows the gathering of the offspring in a safe environment. Different combinations of organic mixture resulted with different rate of vermicomposting completion. The fastest to degrade was the combination of kitchen waste with vermicompost, which come to completion within three weeks. Vermicompost provides the most suitable environment for the worms to flourish in addition to the availability of less complex components in kitchen waste. The average water holding capacity of the vermicompost was 25% (wt) while the total organic content was 12%. In conclusion, vermicomposting of organic components found in the MSW stream can be accomplished by taking into consideration crucial factors such as acidity and presence of hindering components. The identification of the most suitable conditions for vermicomposting will allow the implementation of this alternative biological remedy to reduce waste and tackle the problem in waste management, particularly in developing countries.Pertambahan penghasilan sisa di negara-negara membangun membimbangkan pihak berkuasa. Maka, pelbagai alternatif telah dipertimbangkan untuk mengurangkan jumlah sisa ke tapak pelupusan. Antara pilihan yang ada ialah bioremediasi yang membolehkan pertukaran sisa yang mudah terurai kepada produk bernilai seperti kompos, biogas dan lain-lain. Kajian ini bertujuan untuk mengetahui penyediaan eksperimen terbaik bagi menjalankan proses vermi-pengkomposan skala kecil yang sesuai bagi isirumah memandangkan hampir 40-50% (berat) sisa yang dihasilkan terdiri daripada bahan mudah terurai. Sisa ditimbang dan didedahkan kepada cacing jenis Eisenia foetida. Keputusan menunjukkan bahawa sisa mudah terurai yang dihasilkan sesuai menjalani proses vermi-pengkomposan. Walau bagaimanapun, faktor- faktor seperti keasidan yang tinggi dan kehadiran elemen-elemen tertentu di dalam sisa boleh membantutkan proses ini. Cacing-cacing ini sensitif kepada perubahan pH dan proses vermi-pengkomposan akan menurun dengan drastik apabila pH kurang dari 5.0. Persediaan eksperimen dengan sistem lapisan terbukti sebagai teknik terbaik bagi menjalankan vermi-pengkomposan skala kecil. Sistem lapisan menghalang cacing keluar dari sistem vermi-pengkomposan dan membolehkan penggumpulan anak-anak cacing dalam persekitaran yang selamat. Kombinasi-kombinasi yang berbeza dalam campuran organik lengkap diproses pada kadar yang berbeza. Campuran sisa dapur dan vermi-kompos paling cepat terurai iaitu selepas tiga minggu. Ini adalah kerana ia menyediakan persekitaran yang paling sesuai bagi cacing untuk membiak di samping terdapatnya komponen-komponen yang kurang kompleks. Secara purata kapasiti air tanah bagi vermi-kompos ialah 25% sementara kandungan organik total ialah 12%. Sebagai kesimpulan, vermi-pengkomposan komponen organik dalam sisa munisipal boleh dijalankan dengan mengambil kira beberapa faktor penting seperti asiditi dan kehadiran komponen penghalang tertentu. Pengenalpastian keadaan yang paling sesuai bagi vermi- pengkomposan membolehkan perlaksanaan rawatan biologi alternatif ini untuk mengurangkan sisa dan menyelesaikan masalah pengurusan sisa terutama di negara-negara membangun.