**1. Introduction**

Current agricultural and agro-industrial systems apply the linear mode of production and, therefore, the majority of today agricultural and agro-industrial production and consumption systems are unsustainable. In other words, current agricultural and agro-industrial systems are economically, environmentally, and socially not sustainable. Precisely, the problems associated with nowadays agricultural, and agroindustries are (1) inefficient use of resources, (2) inefficient use of energy, (3) high production costs, (4) high environmental risks, and (5) massive wealth gap between the poor and the rich. Therefore, sustainability is a key issue in this context, where sustainable development encompasses the integration of social and environmental issues with economic development to convene the pressing needs of the population at present without undercutting the requirements of future generations. One key issue is to mimic the sustainable models provided by natural ecosystems. Precisely, turning the linear mode of production (linear economy) into the cyclic mode of production (circular economy). The current farming and agro-industrial processes have two main problems, which are the inefficient use of energy and wastes are not utilized within the production processes, which leads to the degradation of the surrounding environment. In contrast, natural ecosystem -which should be mimicked- allows the efficient use of energy, and all wastes are bioremediated and utilized by the system. Hence, the current farming and agro-industrial processes (linear) should be amended to mimic the natural ecosystem (circular), where this leads to the concept of industrial ecology, which fills the gap between the farming and agro-industrial processes on the one hand, and the ecologically sustainable natural system on the other hand.

### **2. Bioeconomy**

According to the EU, "the bioeconomy encompasses the production of renewable biological resources and the conversion of these resources and waste streams into value-added products, such as food, feed, bio-based products, and bioenergy" [1]. Furthermore, "the transition to a more circular economy, where the value of products, materials, and resources is maintained in the economy for as long as possible, and the generation of waste minimized, is an essential contribution to the EU's efforts to develop a sustainable, low carbon, resource-efficient, and competitive economy. Such transition is the opportunity to transform the economy and generate new and sustainable competitive advantages" [2]. Consequently, the bioeconomy is broader and deeper than a circular economy. On the other hand, biomass is defined as "the biodegradable fraction of products, waste, and residues from biological origin from agriculture (including vegetal and animal substances), forestry and related industries including fisheries and aquaculture, as well as the biodegradable fraction of industrial and municipal waste" [3]. In other words, biomass types are agricultural biomass (crops residues and animal wastes), fisheries biomass, algae biomass, and forest biomass.

Circular bio-based economy aims at reaching a net zero-carbon community by creating sustainable technologies and efficient resource use approaches to substitute the fossil-based economy. The circular bioeconomy primarily depends on biomass as a building block, while social, economic, and environmental are the principal factors. The technologies that are projected to be industrialized under circular bioeconomy must guarantee that the value of product carbon is preserved to decrease the wastewater production, greenhouse gas (GHG) emissions, and impairment to the ecosystems. In the context of circular bioeconomy growth, the biomass production, process advancements, and reuse approaches ought to be well defined to meet the global supply chain and demand. This urges conducting techno-economic assessment (TEA) and life cycle analysis (LCA) of every product and process.

*An Approach to Modify the Current Agricultural and Agro-Industrial Systems into Integrated… DOI: http://dx.doi.org/10.5772/intechopen.102360*

### **3. Bioprocesses and bioproducts**

Bioproducts or bio-based products are biomaterials, biochemicals, and bioenergy derived from renewable biological resources. The biological resources include agriculture, forestry, and biologically derived waste. One of the renewable bioresources is lignocellulose. Cellulose-based materials and lignocellulosic tissues are biologically derived natural resources.

Conventional bioproducts and emerging bioproducts are two broad categories used to categorize bioproducts. Examples of conventional bioproducts include building materials, pulp and paper, and forest products. Examples of emerging bioproducts include biofuels, bioenergy, starch-based, and cellulose-based ethanol or bioethanol, bio-based adhesives, biochemicals, bioplastics, etc. Bioproducts derived from bioresources can replace much of the fuels, chemicals, plastics, etc. that are currently derived from petroleum. As a result, the emerging bioproducts are environmentally friendly products and independent of fossil sources.

Bioprocessing and bioproducts production include the use of engineered microbiological systems for generating biofuels, bioelectricity, and new high-value bioproducts. Additionally, scientists are investigating the utilization of forestry products in untraditional applications, including industrial foams and flame-retardant materials. This needs to combine a conglomerate of mathematics, biology, and industrial design, and consists of numerous varieties of biotechnological processes, which pertain to the design, development, and implementation of processes, technologies for the sustainable manufacture of biomaterials, biochemicals, and bioenergy from renewable bioresources. Bioprocessing deals with the design and development of equipment and processes for making bioproducts such as food, feed, pharmaceuticals, nutraceuticals, biochemicals, biopolymers, and paper from biological materials (i.e., biomaterials). Practically, bioprocessing takes place in devices called bioreactors.

Bioreactors are categorized, based on the mode of operation, as a batch, semicontinuous or continuous bioreactors. Microorganisms growing in bioreactors may be submerged in a liquid medium or may be attached to the surface of a solid medium. The bioenvironmental conditions inside the bioreactor, such as temperature, nutrient concentrations, pH, and dissolved gases (especially oxygen for aerobic processes) affect the growth and productivity of the microorganisms.

### **4. Value-added bioprocessing of biowastes**

Biological wastes i.e., biowastes, generated from agriculture, wastewater treatment, or industry are a largely untapped source for the production of value-added bioproducts or bioenergy. Their recovery utilizes biological and chemical processes that provide alternative sources for chemical feedstocks to produce different products e.g., bioplastics or other biopolymers, high-value biochemicals, protein for animal feed, and enzymes. For example, nutrients, cellulose, volatile fatty acids, extracellular polymeric substances, or proteins can be recovered from biowastes. Similarly, many opportunities exist for alternative energy products, e.g., bioethanol, biobutanol, biogas, biohydrogen, or bioelectricity. Resource biorecovery thus supports sustainability goals by reinjecting products into the circular economy.

For instance, the value-added bioprocessing of fish waste produces numerous bioproducts, which are: (1) pharmaceuticals such as proteins, jadomycin, collagen, lactic acid, glycerol, proteases, lipases, and collagenases; (2) nutraceuticals such

as omega-3, amino acids, fish oil, fatty acids, carotenoids, isoflavones, and lutein; (3) chemicals such as 1,2-propanediol and 1,3-propanediol, dihydroxy-acetone, and methanol; (4) biofuels such as biodiesel, bioethanol, and biohydrogen; and (5) further products such as fish meal and fish silage. On the other hand, the value-added bioprocessing of slaughtering waste produces the same above-mentioned products except that the intermediate product, in this case, is the tallow compared to fish oil as an intermediate product in the bioprocessing of fish waste.

Furthermore, there are several potential uses of fish waste in the production of further pharmaceuticals such as chymotrypsin, pepsin, enzyme inhibitors, anticoagulants, insulin, nucleic acid, nucleotides, protamine, and proteolytic enzymes. Besides, several biochemicals can be produced such as bile salts, glue, gelatin, leather, and pearl essence.
