Replacement of Petroleum Based Products With Plant-Based Materials, Green and Sustainable Energy—A Review
The most critical challenges confronting humanity's future are climatic change, water scarcity, and the impending end of the petroleum era, primarily driven by the depletion of fossil fuel reserves, rising global temperatures, and the rapid growth of the global population. Bio-resources have emerged as a promising alternative for reducing dependence on petroleum-derived materials. Plants and microbes collectively account for approximately 99% of Earth's total living biomass. The scientific interest in environmentally friendly and sustainable materials is based on their compatibility, biodegradability, recyclability, and benign behavior. Airborne nano-plastic pollution has become a significant environmental concern, adding to the existing challenges posed by water pollution, micro-plastics, and other harmful contaminants that endanger both living organisms and ecosystems. This work explores the replacement of petroleum-derived chemicals and fuels with naturally derived biomass products, emphasizing a future free from petroleum and fossil fuels. It discusses recent developments in plant-derived polymers, resins, and composites, showcasing their potential as functional and eco-friendly substitutes for conventional petroleum-based materials. It highlights various advancements, including green energy solutions, the development of renewable resource-based materials, bio-plastics, plant-based alternatives, and innovative water treatment technologies.
1 Introduction
The world of human activity lies in its commitment to green sustainability, where progress and environmental responsibility go hand in hand. As societies evolve, the need to balance economic growth with ecological preservation becomes more crucial than ever. Sustainable practices, such as renewable energy, waste reduction, and eco-friendly urban development, showcase humanity's ability to innovate while protecting the planet. The survival of the human race now depends on energy and environmental conservation. Efficiency in sustainability is one of the current most pressing needs. In terms of ecological, energy, and environmental sustainability, science and technology are at a crossroads. In recent years, the vigor and intricacy of science have been swallowed by the demands of human society—fuel, power, and water [1]. Materials scientists are looking for novel materials that fit the circular economy as well as sustainable concepts in response to the negative effects of using high volumes of fossil fuel-based materials, such as rising greenhouse gas emissions, expanding landfills, pollution of the environment, and issues with human health [2]. Green engineering covers a wide range of topics, from increasing the energy efficiency of manufacturing processes to creating plastic materials from renewable resources. Technology and green energy came to the fore as people all over the world began to take a real interest in maintaining the natural order [3].
Large amounts and a wide variety of waste from industry have been produced by business, mining, agriculture, and residential activities as a result of urbanization and technological advancements in a variety of industries [4]. For example, using recycled waste materials in construction may enhance cement concrete's physical and mechanical properties, durability performance, and microstructure, which are challenging to produce using only raw materials [1]. Recycling non-biodegradable materials is quite difficult. Natural resource depletion, widespread industrial waste production, and industrial pollution force the development of new and practical solutions for sustainable development [5]. Numerous studies have suggested creating biodegradable green composites from renewable sources such as fibers from nature, agro-feedstock, and biodegradable polymers/recyclable polymers to make them economical, sustainable, and environmentally benign. These environmentally friendly composites, which mostly consist of natural fibers and biological polymers, are also well suited for industrial usage since they offer excellent mechanical qualities, noteworthy manufacturing advantages, a low density, and are biodegradable [6, 7]. Green polymers have already been used in industries like packaging, horticultural products, vehicle panels, and furniture, though they can replace synthetic polymer components shortly [8].
For more than a decade, scientists have been increasingly interested in creating biodegradable materials. Many biopolymers have been created and are frequently employed in a variety of industries. Composites, as adaptable materials with exceptional properties, have many uses in industries like transportation, aircraft, and shipping [9, 10]. The primary drawback of current biodegradable polymers is their expensive price. Bio-plastics based on renewable resources are now being produced, and further research should remove any performance restrictions [11]. In many applications, bio-composites can complement and eventually replace petroleum-based composite materials, providing significant advantages for industries, agriculture, the environment, and consumers [1]. Recent improvements in the creation of biodegradable greener composite materials, including those based on soy protein, bamboo fibers, and starch, have demonstrated comparable properties [12, 13].
This research aims to investigate the potential of replacing petroleum-based products with plant-derived materials, with a focus on the development and implementation of green and sustainable energy solutions. By evaluating the feasibility and advantages of bio-based alternatives, such as bio-plastics and renewable energy sources, the study seeks to uncover strategies for decreasing reliance on fossil fuels and fostering a more sustainable, circular economy. Additionally, the research explores innovative technologies for water treatment and material development that could contribute to advancing the transition to a more environmentally friendly future. This research is significant in addressing the growing environmental concerns associated with petroleum-derived products and the depletion of fossil fuel reserves. By shifting towards plant-based materials and green energy solutions, we can reduce greenhouse gas emissions, mitigate climate change, and conserve natural resources. Additionally, the development of renewable resources and sustainable technologies offers new opportunities for economic growth and energy security. The findings of this study could contribute to the global efforts towards a cleaner, more sustainable future, while promoting eco-friendly alternatives in industries such as energy, manufacturing, and waste management.
2 Sustainable Chemical Engineering
Chemical engineering plays a significant role in the material foundation of a sustainable society since it has a long history of producing a variety of crucial goods and commodities, everything from transportation and agricultural manufacturing to healthcare. Chemical engineering outcomes are necessary for the survival of humans but contribute to the deterioration of the services and goods ecosystem needed to support all human activities. It must resolve this dilemma by creating chemical goods and procedures that satisfy the requirements of the present and the future to contribute to sustainability [14, 15]. Chemical engineering's unintended consequences have typically manifested outside the field's conventional system boundary because of affects shifting across space, fluxes, time, or disciplines, as well as beyond nature's capacity to provide resources [16]. Chemical engineering has undoubtedly improved human well-being, and there is no denying it is beyond dispute. For example, without artificial fertilizers made using the Haber-Bosch process, it may not have been possible to maintain over 7.5 billion people in the world. The use of resources to produce consumer products and fuels for transportation, the development of novel materials for computing, tissue engineering, and packaging and the advancement of pharmaceuticals and medical technology, among numerous other things, are further significant contributions. Unfortunately, many of these innovations have negative direct and indirect effects on ecosystems, reducing their capacity to offer necessary commodities and services for maintaining human well-being [17]. This paradox makes one wonder how chemical engineering fits into sustainable development. A key driver of the build-up of ensuing global climate change and greenhouse gases in the atmosphere is the mobilization of billions of tonnes of fossil fuels, particularly by the chemical industry. Because of the emissions of nitrous oxide following the nitrogen fertilizers application and carbon dioxide following the usage of hydrogen from methane to produce ammonia, artificial fertilizers also involves in the greenhouse gases emission. Because toxic algal blooms consume the runoff of the fertilizer, fertilizers like nitrogen and phosphorus are also thought to be responsible for the establishment of aquatic dead zones all over the world [18]. Plastics are currently prohibited in many regions of the world due to their role in the accumulation of solid trash on land and the oceans, even though they possess many distinctive and irreplaceable qualities. Among many others, the following represent chemical engineering unsustainability. Even if chemical engineering methods and products satisfy the requirements of the present, many of them put future generations' ability to satisfy their own needs at risk. As a result, many chemical products and procedures have adverse effects that go against the traditional idea of sustainable development [19].
Bio-plastics have emerged as a key alternative to petroleum-based plastics, offering a more sustainable option derived from renewable resources such as corn starch, sugarcane, and algae. However, their environmental impact remains a topic of debate, particularly regarding their biodegradability and overall life cycle analysis. While some bio-plastics decompose faster than conventional plastics, others require specific industrial conditions to break down properly, limiting their real-world effectiveness in reducing plastic waste. Additionally, the production of bio-plastics involves energy use, land consumption, and water resources, which can offset some of their environmental benefits. A thorough assessment of their entire life cycle—from raw material sourcing to disposal—is essential to determine whether bio-plastics truly offer a greener alternative or if improvements are needed to enhance their sustainability.
Such unplanned and unexpected adverse effects are common. However, as the effects of processes and unsustainable products go against engineering's mission of “solving problems for people and society”, preventing processes and unsustainable products from occurring is one of the most significant difficulties the field is now facing. To solve such issues, engineering has frequently created new and improved technologies. Figure 1 serves as an example of the transition from unsustainable to the sustainable development of chemical engineering disciplines. For example, (i) Precision farming and decentralized ammonia manufacturing are being explored as solutions to the issues with ammonia-based fertilizers; (ii) Degradable plastics of newer varieties are less prone to build up in the environment; (iii) Techniques for carbon collection, utilization, and storage are being constructed as a response to greenhouse gas emissions. Many initiatives have focused on renewable energy systems, intelligent power networks, and energy storage, are also seen as sustainable. Unintended harm always manifests outside the engineering system boundary, according to a close examination of engineering consequences that are socially and environmentally unacceptable [20].
FIGURE 1
Development of chemical engineering in unsustainable to sustainable disciplines.
The product, its supply chain, its raw materials, and its manufacturing have traditionally been considered within the scope of chemical engineering. The engineering that created these products did not include stratosphere environmental systems, where the ozone hole appeared first, global climate, which is impacted by the ocean gyres, greenhouse gases build-up where plastic islands form in oceans and lakes, where algal blooms occur. Engineering also aims to increase technological productivity per unit (like energy consumption of desalinated water per liter), fuel combustion productivity, and the yield of the desired outcome, energy utilization per unit (L) of desalinated water [14, 15]. Engineers frequently believe that when the products are employed on a large scale, the advantages to society will accrue because such advancements result in less resource consumption and lower emissions per unit of product. Unfortunately, this in-depth analysis of technological growth and scientific innovation ignores the impact of widespread technology adoption when unintended consequences can vary across fields. Therefore, chemical engineering must broaden its system boundary to decrease the potential of such shifts if it is to produce sustainable solutions. The influence of engineering operations on these entities and their ability to absorb the damage must also be taken into account because effects manifest in environmental systems [16, 21].
The three pillars of economic sustainability, ecological, and societal—also known as the three Ps: profit, planet, and people—are widely recognized in the context of engineering decisions. A Venn diagram has demonstrated the overlapping of three circles where each variety stands for one of the sustainability three pillars. Each circle also has its metrics, which are often referred to as indicators but are, by their very nature, 1-D (one-dimensional). When all three facets of sustainability are met, as determined by 3-D sustainability indicators in the region where three circles overlap (Figure 2), technology is fully sustainable. The three types of 2-D metrics, which are socio-ecological, socio-economic, and eco-efficiency, are obtained at the two varieties intersections [17].
FIGURE 2
Venn diagram represents sustainability metrics
(Reprinted with permission from [17]).
Processes and products must be socially and commercially sustainable as well as ecologically sustainable. Sustainable development is one of the “wicked” problems because of the intricate relationships between the environmental, economic, and social systems [22]. Since it is impossible to even describe these problems in an unambiguous way that captures all the requirements, they are challenging to address. Due to their complexity, many issues may not have a single “correct” solution, only better or worse decisions that can be made. This paper is driven by the difficulties in assuring chemical engineering contributes beneficially to sustainable development and focuses on the role of the engineering system process in doing so. Building on earlier analyses and viewpoints, it offers a critical assessment of how process engineering has been pursuing this objective.
3 Chemical Engineering Relates to the Environment, Sustainability, and Energy
Designing and using chemistry-based separation techniques for which chemists and mechanical engineers lacked the necessary understanding led to the development of chemical engineering. The global demand for chemical engineers increased due to the success of gas and oil exploration and the subsequent need for refining crude oil and flavoring natural gas to produce various fuels, mainly petrol for the automobile sector. Chemical engineers should maintain leadership in r&d concerning global energy systems. In addition, field experts can construct more bridges between scales to ongoing improvements in the design of instruments with precise and quick response measurements at the cellular or molecular, reactor scales, and particle, along with improvements in processing power for enabling the sustainable development associated with energy and the environment [23].
The multifaceted and intricate sustainability idea calls for addressing present-day needs without compromising the capability to fulfill the future generations [24]. Social, economic, and environmental (three pillars of the sustainability concept) are identified nine processes and established nine quantitative planetary boundaries, which are Climate change, the destruction of the ozone layer (depletion of the ozone layer), the extinction of species (loss of biodiversity), the nitrogen and phosphorus cycles, the use of freshwater worldwide (global freshwater usage), the loading of the atmosphere with aerosols, ocean acidification, chemical pollution, and changes in land use that would allow humanity to develop and flourish for future generations [25, 26].
Renewable energy is the fastest-growing energy source in the world, with consumption rising per year between 2015 and 2040 by an average of 2.3%. The global energy consumption from every kind of fuel source, except coal, will increase through the period of 2040. Renewable energies will still make up most of the energy use in 2040, even though non-fossil fuel consumption is anticipated to expand more quickly than fossil fuel consumption. The forecasts show that natural gas will increase the quickest among all fossil fuels, with other fossil fuel percentages falling by 2040 [Report from the Energy Information Administration, 2017] [23]. Chemical engineers must intensify their collaboration with computer science researchers to develop more effective computer codes for computational transport phenomena (CTP) that can shorten the time needed for computation for design and simulation, chemical looping processes, and scale-up of CO2 capture, taking into account the ongoing advancements in computational capability and measurements [27].
Future research in chemical engineering has a lot of potential attributed to the carbon dioxide catalytic conversion into fuels, which offers an appealing use for CO2. For example, one researcher demonstrated catalytic electrochemical carbon monoxide (CO to CO2) to carbon dioxide conversion in an ionic liquid [28]. Carbon dioxide must be sequestered in a way that prevents it from escaping from the rock formation into which it is introduced. This gives chemical engineers a chance to contribute significantly to interdisciplinary research studies on the time and stability range in the pores of trapped CO2 of underneath formations [29]. Figure 3 shows the Carbon dioxide closed loop cycle for bio-fuels.
FIGURE 3
Carbon dioxide closed loop cycle for bio-fuels
(Reprinted with permission from [30]].
Process intensification is the creation of a novel strategy that significantly improves chemical and biological processes by boosting productivity, lowering energy consumption, and producing less waste. This results in significant environmentally friendly processes and cost savings. Chemical engineers have an ongoing commitment to conducting research and development on process intensification regarding pharmaceutical processes, biological, and chemical to improve lower energy, water consumption, and process efficiency, gradually switching from fossil fuels to renewable sources of energy [31]. This work is based on the fundamental chemical engineering principles and their expertise in scale-up and process design. As tools for process intensification in biological and chemical processes, including the production of biodiesel, separation processes, solid handling, and solar energy, are a few examples of processes that showcase this potential. Another example is the use of rotating fluidized beds in the polymerization process to improve mass and heat transfer, reduce reactor size at higher rotating speeds, and gravitational forces [32, 33]. An illustration of the study on the advancement and benefits of chemical engineering domains is shown in Figure 4.
FIGURE 4
The objectives of sustainable development in chemical engineering.
By adopting recycled materials for various applications and carrying out the fundamental research necessary to produce long-lasting and financially viable biodegradable polymers, the field of chemical engineering can make a significant contribution to the development of material recycling novel processes. Additionally, these fields are well positioned to play a crucial part in multidisciplinary initiatives in the future studies and development in the water management field, which includes innovation in the new generation development of fertilizers that will reduce the release of phosphorus in the water cycle. These fields have significant expertise in biological and chemical method design and development, as well as biology and chemistry knowledge. This field creates an outstanding opportunity to lead research and instructional efforts in ongoing fields like membranes and connected problems like bio-fouling and microbial desalination cells, as well as to perform fundamental research to develop new, inventive, and more effective desalination methods [34, 35]. Geothermal energy is heat that is produced beneath the Earth's surface and can be used to provide green, renewable energy. Desalination is one example of a process that could utilize this energy as it only requires a few amounts of heat or energy [23]. Even if we recognize that these sustainability characteristics are intricately linked, it is helpful to discuss each one separately to gauge each method's potential. By using these specifications, we demonstrate the use and advantages of evaluating approaches in the sections that follow.
4 Replacement of Petroleum-Based Products (Plastics) With Plant-Based Materials
Since the discovery of fire, plant-based chemistry has likely been utilized. Processes based on plant biomass were abandoned as a result of the phenomenal rise of petroleum-based ones. Based on studies from the 20th century, we now know that practically all petroleum-based products and chemicals might be replaced by their plant-based equivalents from a scientific standpoint. However, in many instances, bio-based production costs are higher than the costs of petrochemical production. The transformation of plant biomass into ingredients, goods, and reagents for global businesses at levels that are acceptable for society, the environment, and economics is the issue. Innovations that depart from the past are needed to find solutions rather than just maintaining “Plant-Based” green chemistry [36].
The initial goal is to describe the many forms of plastics, as well as biodegradable, biomass, and bio-plastics. Plastics are technically known as “thermoplastic resin,” and depending on how biodegradable they are and how much biomass they contain, they fall into one of four categories. (1) Non-biodegradable polymers/plastic made from substances derived from petroleum have been used for over a century and are the main source of plastic pollution.
FIGURE 5
Automobile bio-plastic components disposal at end-of-life [37].
Some plastic parts can be recycled, enabling the manufacturer to reuse materials cost-effectively. A plastic disposal program should include one branch of recycling and one of disposing of biodegradable plastics [38]. The term “general plastics” refers to the common examples of this type of plastic, which include polyethylene, polypropylene, polyethylene terephthalate, polystyrene, and polyvinyl chloride. (2) Petroleum-derived materials are used to create biodegradable polymers and plastic (polyvinyl alcohol, polybutylene succinate, and poly (butylene adipate-co-terephthalate)), which have recently been used in industries including agriculture and film production. (3) Non-biodegradable plastics made from biomass are made from biomass but do not degrade naturally. Because they are formed of biomass rather than petroleum, this type of plastic can be seen as being more environmentally friendly in terms of lowering CO2 emissions. (4) The best plastic is one that is made from biomass and is also biodegradable. These polymers are classified as biomass biodegradable plastics and include polylactic acid (PLA), biodegradable plastic based on starch, biodegradable plastic based on cellulose, and polyhydroxyalkanoate (PHA) [39].
The release of CO2 into the atmosphere, which has considerably grown because of human use and the burning of fossil fuels like petroleum to create chemicals and fuels for modern society, is one of the causes of global warming. This is because plants absorb CO2 throughout their growth, making natural biomass or derived from plant's chemical compounds and fuels carbon neutral. Additionally, using biomass-based biodegradable chemical products like biodegradable plastic can help reduce the issue of plastic pollution [39]. Another issue is plastic waste, which is damaging the natural world, including the marine ecosystem. Plastics have been produced from petroleum and used extensively over the last century, which has resulted in significant CO2 emissions from both their manufacturing and consumption. Even though certain bioplastics have been produced and are in use, most plastics still include petroleum since it makes them more affordable and durable than bioplastics. However, these polymers made from petroleum pollute the environment with plastic [40- 42].
Due to the nonbiodegradable nature of the polymer matrix and petroleum-based supply and natural fiber–polyester composites or natural fiber–polypropylene are not sufficiently environmentally harmful. Solving many environmental problems will be made possible by combining natural fibers with polymers made from renewable resources [43, 44].
A portfolio of environmentally friendly, sustainable products that can compete in and seize markets currently dominated by goods made solely from petroleum feedstock can be built on the foundation of bio-based polymer goods and biodegradable plastics based on yearly biomass feedstock and renewable agricultural. Bioplastic alterations to make it the right matrix for composite application, surface treatment to make it more reactive, and development of suitable processing techniques, based on the fiber type composed such as fabrics, chopped, (woven/nonwoven), silver, yarn, etc., are a few crucial issues related to bio-fiber that must be addressed. Natural fibers are biodegradable. However, bio plastics made from renewable resources can be either biologically degradable or not depending on the demands of a particular application. To create composite elements that are competitive with synthetic composites, bio fiber-matrix interface and novel processing must receive special attention. Examples of such bio-fibers include hemp, kenaf, jute, flax, sisal, and pineapple leaf [45].
Petroleum-based plastics cause a variety of environmental issues, such as greenhouse gas emissions and pollution of the marine and terrestrial environments. As an alternative to customary petroleum-based plastics, bio-plastics and biodegradable plastics are put forward. However, bio-plastics can contribute to some environmental problems, including greenhouse gas emissions and adverse changes in land use; therefore, it is important to examine the true environmental impact of bio-plastics when determining their life cycle [39].
5 Microplastics and Managing Waste More Sustainably
Devastating environmental issues include climate change, global warming, the loss of natural resources, water pollution, deforestation, species extinction, and plastic pollution currently calling for quick mitigation efforts. These days, airborne nano-plastics as well as micro-plastics are a threat to living things and the environment [39, 46- 48]. The UN has pledged to lessen the plastic amount that leaks into the environment on a global scale [49].
Microplastics, which are particles of plastic that are 5 mm in size or smaller, are found in the environment either because of the growing usage of microbeads and microfibers, especially in cosmetic items and textiles, or as a result of the weathering of the plastics that are already there [50]. Microplastics eventually find their way into the ocean, much like larger plastics, mostly through water movements. Microplastics in the aquatic environment are more difficult to identify and remove than bigger plastics, which can usually be eliminated via natural or human-aided procedures. They can float or become trapped in sediments for a long time due to their microscopic size, which allows them to eventually infiltrate the food chain [51]. The plastics presence in lakes and rivers, water treatment facilities, as well as the plastics penetration into freshwater food chains render freshwater pollution by microplastics [52]. Additionally, unmanaged tipping sites, landfills, and other human activities may let microplastics infiltrate into the terrestrial environment, contaminating the terrestrial systems, especially the soil. 80% to 90% of the microbeads and microfibers in untreated home sewage would be retained in the sludge. Completing the treatment and use of the treated sludge as fertilizer, there may still be a lot of microplastics in the sludge, causing the microplastics to enter the agricultural land [53]. Because microplastics come in a variety of sizes, shapes, and additive kinds that make studying their ecotoxicological impacts challenging, our understanding of the consequences of microplastics on the environment is limited [54].
FIGURE 6
Replacement of petroleum-based products with plant-based materials.
The common term reported for sustainable is “Development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. Downstream and Upstream solutions for the environmental pollution caused by micro-plastics can be distinguished. While downstream solutions to remove micro-plastics or actively recover from the environment, upstream approaches to micro-plastic contamination focus on intervention and preventing micro-plastics from entering the ecosystem. The main anthropogenic variables contributing to the widespread prevalence of micro-plastics in the environment are population density and the effectiveness of waste management. Prioritizing waste management quality improvement is necessary, and this can be accomplished in part via stronger legislation and law enforcement. Recycling plastics should be the focus instead of depending on antiquated waste management techniques to enhance the overall quality of waste management [55]. Koistinen, et al. reported that maximum percentage of micro-plastics removed by the membrane bioreactor (MBR) during treatment at 99.9%, while the dissolved air flotation (95%) and quick sand filter (97%) which remove micro-plastics [56]. The use of membrane bioreactors (MBR) has drawn a lot of attention due to the improvements that are now possible to make them more cost-effective to operate after the original investment expenditures and more energy efficient and fouling resistant [57]. Micro-plastic formation schematic diagram is presented in below Figure 7.
FIGURE 7
Schematic diagram of Micro-plastic formation.
Upstream issues must be resolved before downstream issues may be sustained. Technically speaking, it is possible to recover or remove micro-plastics from the environment; however, given the volume of micro-plastics already in the environment, it would be logistically impossible to do so. Plastics can also be eliminated from the environment biologically or chemically in the meantime. Studies on bacteria that break down plastic have advanced; for example, Ideonellasakaiensis 201-F6 was demonstrated to break down and absorb polyethylene terephthalate in a lab-scale study [58]. Degrading polymers at the reactor scale can be accomplished using both biological and chemical processes. It is not logistically possible nor economically viable to remove micro-plastics from terrestrial ecosystems and freshwater on our own without finding upstream solutions. As a result, upstream solutions will generally be more sustainable [55]. This section makes a vital contribution to addressing the difficulties posed by environmental micro-plastics by thoroughly and methodically outlining the problems associated with micro-plastics occurrences, prospective remedies, and an understanding and conceptualization of sustainable solutions.
6 Water Treatment Technologies
Due to the growing disparity between freshwater supply and usage, water resources have grown scarcer in the world, making access to clean, safe water one of the most significant challenges facing our contemporary society. The need for water is growing because of factors like population growth and migration to areas prone to drought, rapid industrialization, and rising water consumption per capita, and climate change-related changes in local weather patterns. Water is used for many different things, including drinking and irrigation, but to use it for these things, the water sources must typically be treated first. Wastewater discharges from industrial and municipal treatment facilities have been identified as one of the primary causes of aquatic contamination worldwide. The majority of domestic and industrial wastewater is typically released directly into water streams in many developing nations either after only primary treatment or without any further processing [59]. The dumping of wastewater that has not been treated into bodies of water without any kind of treatment will cause several environmental issues, which include untreated wastewater [60].
A Biofilm (microorganism communities or clusters that are affixed to a surface) also known as slime, is a polymeric conglomeration that is typically made up of extracellular biopolymers in a variety of structural forms and is a system that can be internally adapted to environmental conditions by its inhabitants. The dissolved oxygen (DO) content is at its highest at the interface between the hydrophobic and biofilm membrane, declines as the biofilm thickness increases from this interface, and may even be zero or very low at the biofilm and wastewater contact [61]. Single or many species of microorganisms with the capacity to develop on biotic and abiotic surfaces could produce biofilm. A more effective and secure alternative to bioremediation using planktonic bacteria is biofilm-mediated bioremediation. This is because the matrices that shield the cells in a biofilm give them a greater chance of surviving and adapting to the process. Additionally, a microbial consortia in the form of a biofilm can decolorize and metabolize colors since dyestuffs are subject to inherent biological mechanisms that cause their breakdown or biosorption [60]. Zhang et al. proposed MBBR (traditional moving bed biofilm reactor) method, which utilizes HN-ad (heterotrophic nitrification-aerobic denitrification) bacteria as the MBBR inoculum, significantly reduced startup time and enhanced TN removal efficiency [62]. Matheus et al. investigated the responses of high-loaded MBBRs with distinct effective specific surface areas and HRTs to nutrient limitation during P&P wastewater treatment [63]. Compared to bioremediation using planktonic microbes, biofilm offers a reliable and safe alternative since its cells have a high likelihood of adapting to their environment and surviving, especially under challenging conditions.
Desalination technologies have dominated the market for converting seawater into usable water when pure freshwater sources are unavailable. It has thus become one of the primary methods for supplying fresh water. Growing public awareness of the decreasing water supplies and the need for a sustainable strategy, as well as technology improvements that make water treatment and desalination competitive with conventional freshwater supply, are the causes of the expanding capacity. Through decreased energy use, superior building materials, and extended membrane lifespan (in the example of membrane processes), treatment costs have declined dramatically during the past few decades [64]. Lastly, makers of membranes are developing novel spiral-wound elements that can function at high hydraulic pressures in response to the growing interest in treating hypersaline waters with RO technology [65]. New approaches to natural water treatment may be made possible by improvements in desalination technology.
With millions of bacterial cells per gram of biomass, the granular sludge produced by bio granulation techniques has a higher microbial density and is more capable of retaining and recycling biomass. It also has a wider variety of bacterial strains for feasible bio augmentation. In a single sequencing batch reactor (SBR) system, bio granulation can produce two types of granular sludge: anaerobic granular sludge (AnGS) and aerobic granular sludge (AGS). Both types of sludge can be developed in a fixed arranging cycle of feeding, reacting, settling, and decanting. In comparison to the granular sludge, typical floc sludge had inferior settling properties, enabling high biomass stability and dense microbial structures to survive excessive-strength organic wastewater and its shock loading [60, 66]. Wang, Li, et al. suggested that the findings of their work offer a
