Research Paper on Food Waste: A Major Contributor to Climate Change

Introduction

Food wastes are unrecycled end products produced by various industries that process food. The increase in demand for biofuel increased the shortage of crude oil, and rising issues of global warming have led to the establishment of substitute fuels from food waste that has little greenhouse gas effect. Food waste has a significant impact on climate change, as food production uses resources like labor, energy, pesticides, fertilizers, and water. Disposal of food waste in landfills leads to the emission of carbon dioxide and methane, which constitute significant to global warming. Researchers have not focused on the importance of food waste management on the environment. Food waste is regarded as a solid raw material that can be converted to biomaterials and bioenergy (Bardhan, Kuldeep, and Manabendra 208). Through fermentation processes, food wastes can be used as raw materials for biofuel production because they are rich in nutrients and organic content. Bioenergy studies focus on generating energy products like biogas, diesel, hydrogen, and ethanol. The research paper discusses the use of food waste on the production of bioenergy to determine if microbial factories can eliminate the shortage of raw materials.

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Food Waste Analysis

Globally, food waste is either pre- or post-consumed. It is estimated that the amount of food to be wasted by 2025 is 1.3 billion tons, which can feed a certain percent of hungry individuals internationally. More than one billion tons of food wastes are discarded to the environment through landfilling and incineration, which is relative to one-third of the total amount of food consumed by humans internationally (Salemdeeb et al. 871). In the industrialized nations, a lot of food waste is generated from the customers who buy excess food and discard most of it. Production of food waste in developing countries results from poor harvesting methods, inaccessibility of appropriate infrastructure, scarcity of processing and packaging services, and inefficient marketing information. Post-consumed food waste results from a lack of clear strategy to separate food waste from the primary waste path, there is no suitable plan of collecting and managing food waste, and failure to implement strict legislation and policy measures.

Treatment of food waste helps to address worldwide energy demand and reduce fossil fuel resources by offering energy and fuel, reducing diversion of food materials to animal and fuel feed, and aiding in the utilization of lands rich in nutrients and food resources for consumption. 80% of annual food waste is mainly comprised of rice, fruits, potatoes, vegetables, and cereals (Scheer, Roddy and Doug 2020). There are different ways used for food waste management through bioenergy generation, which include reducing, reusing, recycling, recovery, and refinery (Paritosh et al. 2017). The first method is reducing the quantity of food waste generated. Reducing minimizes the cost incurred due to food waste. Conversely, reusing is repeating the utilization of foods that still have good value. The food can be reused by storing it in a refrigerator or sharing with the homeless. Recycling involves using waste as a resource to produce biogas or bio-fertilizer. Consequently, recovery consists of the collection, sorting, processing, and conversion of food waste to more valuable products. Finally, the refinery is the production of bioenergy from waste food.

Biofuel Production from Food Wastes

Biodiesel Production

Biodiesel that is made from renewable resources like waste cooking oil and food waste is carbon neutral, biodegradable, non-toxic, and has low emission. The production methods of biodiesel include microalgae fermentation and direct trans-esterification using chemical enzymes or catalysts. Food wastes are an excellent source of catalysts used for direct trans-esterification. Examples of food waste that can be utilized as catalysts for direct trans-esterification include shells, ashes, and bones as they are a good source of calcium oxide. Eggshells are a suitable heterogeneous catalyst for the production of biodiesel; whereby, waste cooking oil is used as feedstock.

Eggshells have a better catalytic activity because they large surface area and are more porous. The process requires pre-treatment of the oil-linked acid esterification to lessen catalysts' inhibition and minimize the number of suitable reactants like saponification. Nevertheless, the pre-treatment ought to be improved because many feedstocks have distinctive arrangements. Additional methods, such as microwave and ultrasound, assist the trans-esterification process by improving product yield. Additionally, the process must be conducted in an area free of water to prevent saponification.

The first-generation production of biodiesel relies majorly on edible vegetable oil. For instance, Brazil and the United States use oil generated from soya beans as the dominant source of biodiesel production. In contrast, Europe heavily uses rapeseed and palm oil (Li and X. 620). Due to the increasing population, most countries have shifted to the use of microbial resources for biodiesel production. The advantages of using microbial-based lipids to produce biodiesel include high yield, easy scale-up, minimal labor, and lesser biomass doubling period in exponential growth. Nonetheless, a significant amount of lipids ought to be produced to cater to the high demand for fuel. The high demand for fuel requires oleaginous microorganisms, which can gather lipids because their reduced dry weight is regarded as an appropriate substitute for plant-based lipids. Various microbes such as bacteria, filamentous fungi, yeast, and microalgae can bring together a substantial quantity of lipids; hence, it can be a potential agent in the production of biodiesel.

Microalgae generated from food waste can store intracellular triacylglycerol in case there is the presence of stress conditions. Carbon is integrated into intracellular triacylglycerol that is present in the microalgae cells. Microalgae have various advantages in biodiesel production because they have a rapid growth rate, and they are rich in oil. They usually double their biomass in twenty-four hours. Additionally, their photosynthetic nature prevents competition with starting plants for the production of biofuel. Microalgae contribute to the prevention of global warming by minimizing the emission of carbon dioxide to the atmosphere.

Currently, researchers are experimenting with the use of heterotrophic algae in the production of biodiesel through the use of sugars as the substrates (Thi et al. 36). Compared to phototrophic algae, heterotrophic algae is better because it has a high growth rate, thereby increasing the biodiesel quantities. Additionally, algae can be grown to produce biodiesel in manmade ponds, although there is the uncertainty of the economic procedure. The challenge of using ponds for biodiesel production is the costs of collecting and harvesting the algae. Growth of algae in natural oceans and lakes pose environmental threats to the ecosystem.

Bioethanol Production

Bioethanol can be applied in transportation instead of gasoline, co-generation processes, fueling power generation through thermal combustion, fueling cells using thermochemical reaction, and as feedstock in the chemical industries. The traditional production of bioethanol involves crops rich in starch, such as sugarcane, rice, potato, and corn (Li and X. 622). The vegetable and fruit wastes can be used in industries for the production of butanol and ethanol to manufacture liquid fuel supplements and solvents. The conversion of vegetable and fruit waste to biofuel involves biomass pre-treatment, saccharification, and fermentation. Saccharification is the total degradation of starch to simple sugars like maltotriose, maltose, and glucose.

Commercial bioethanol production requires the establishment of a pre-treatment technique that substantially eliminates lignin without modifying the cellulose. Also, the production requires creation of an effective saccharification procedure and establishment of viable industrial strains that provide effective fermentation of sugars, which are unaffected by the inhabitation of compounds formed during delignification. The 1st generation biofuels utilize agricultural crops to generate simple sugars that are then converted to bioethanol. The 2nd generation biofuels apply individual natural and continually growing plants that do not need any cultivation to produce bioethanol.

The production of ethanol involves direct fermentation and indirect fermentation. Direct fermentation relies on the conversion of various vegetable and fruit wastes to bioethanol. In direct fermentation, starting plants are identified, bacterial and fungal strains are isolated and developed, and suitable procedures are designed to ensure the effective conversion of vegetable and fruit wastes to sugar monomers. Then, the conversion of sugar monomers to bioethanol occurs using genetically engineered bacterial strains or yeasts. The starting plants used in direct fermentation include starch acquired from corn kernels, molasses from sugarcane, and lignin, hemicellulose, and cellulose acquired from plant tissues. Indirect fermentation is rarely applied and relies on burning the wastes and converting the gases produced during burning, which include carbon dioxide, hydrogen, and carbon monoxide to ethanol. Indirect fermentation occurs in the presence of acetogenic bacteria.

The challenges involved in the production of bioethanol include genetic lignin content decrease of vegetables and fruits waste biomass and improvement of advanced technology for effective pre-treatment of lignocellulosic biomass. Another challenge is the adjustment of a procedure to ensure the immediate application of hexose and pentose sugars from a single reactor vessel. Also, genetic alteration to create high ethanol-tolerant strains is a significant challenge in bioethanol production. Synchronized saccharification and fermentation procedures for bioethanol manufacture are being developed to ensure that both processes take place in one vessel. Also, simultaneous fermentation and saccharification procedures prevent microorganisms from inhibiting the final product.

Bio-methane Production

Bio-methane is a type of renewable energy produced by the microbial community through anaerobic digestion. Biogas is usually comprised of forty-five to seventy percent of methane. Also, the composition of a specific biofuel depends on the source and mixture of biodegradable biomass. The process of producing bio-methane is a single-stage strategy, which involves three steps, which include hydrolysis, acidogenesis, and methanogenesis attained through a chain of microbial interactions in a single reactor (Capson-Tojo et al. 542). Bacteria regulate all three stages; hence the end product formed is determined by the bacterial population. The single-stage anaerobic digestion is easy to operate, has minimum frequent technical failures, and low cost of investment.

Besides, the anaerobic digestion can be dry or wet, and the latter offers higher production of methane than reduction. Nevertheless, a significant challenge linked to single-phase digestion is the high loading rate, which impacts the activity and growth of methanogens. Also, using the three stages in a single-stage process leads to low production of biogas. For example, acidogenesis reduces pH that leads to methanogenesis inhabitation. Additionally, food wastes are perishable and have a high concentration of lactic acid bacteria that can have resilient acidogenesis, which leads to instability in the single-stage anaerobic digestion process. However, two-stage anaerobic digestion can be used as a modification for the single-stage anaerobic digestion....