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AGRICULTURE WASTE MANAGEMENT AND BIORESOURCE
Comprehensive resource detailing the generation of agricultural waste and providing insight into waste management
Agriculture Waste Management and Bioresource provides thorough coverage of the generation of agricultural waste with essential thought leadership about various options in managing the waste, including composting, vermicomposting to form manure, and biogas generation. Readers take a crucial step toward more sustainable development and creating a greener planet.
The text includes a wide range of information regarding resource recovery from the waste of the agriculture sector, energy generation, biofuels, reduction in the amount and volume of waste through circular economies, and much more. The authors place particular importance on understanding and managing agricultural waste concerning the sustainability of the environment in the era of global climate change.
Topics covered in Agriculture Waste Management and Bioresource include:
- Categories and amounts of agricultural wastes seen in a worldwide perspective and current challenges and perspectives in handling agricultural wastes
- State-of-the-art processing technologies relevant for agricultural wastes categories and sustainable methods used for management of agricultural??biomass
- Bioethanol production from lignocellulose waste of agricultural waste biomass and biogas production through anaerobic digestion of agricultural wastes
- Mechanical and chemical processing, aerobic and anaerobic treatment, other biological processing methods, and thermal processing
Academics, students, and industry professionals in environmental science and engineering, waste management, and agriculture can use the valuable insights in Agriculture Waste Management and Bioresource to understand the latest in the field and the advancements that can propel us towards a better and more sustainable future.
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Veröffentlichungsjahr: 2022
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Table of Contents
Cover
Title Page
Copyright Page
List of Contributors
1 Agricultural Waste as a Resource: The Lesser Travelled Road to Sustainability
1.1 Introduction
1.2 Sources of Agricultural Waste Generation
1.3 Agricultural Waste Characterization
1.4 Waste to Wealth: Agricultural Waste Management Approaches
1.5 Challenges in Agricultural Waste Management
1.6 Conclusion
References
2 Sustainable Physical Methods Used for the Management of Agricultural Waste Biomass
2.1 Introduction
2.2 Major Crops for Agricultural Waste Generation
2.3 Predominant Agriculture Residue of Agricultural Crops
2.4 Forest Biomass
2.5 The Application of Biomass Waste
2.6 Challenges in Biomass Residues Utilization
2.7 The Waste Management Concept
2.8 Waste Management Systems
2.9 The Choice of Technology
2.10 Sustainable Physical Methods for Agricultural Biomass Management
2.11 Biomass Waste Management: Adverse Effect of Biomass Waste
2.12 Sustainable Use of Biomass Resources
2.13 A Case Study of Southeast Spain: Managing Agriculture Waste Biomass
2.14 Conclusion
References
3 An Overview of Biomass Conversion from Agricultural Waste: Address on Environmental Sustainability
3.1 Introduction
3.2 Environmental Concerns of Renewable and Fossil Energy
3.3 Agriculture and Biofuels
3.4 Agricultural Residue Composition and Properties
3.5 Agricultural Residue Pre‐treatment Methods
3.6 Biomass Conversion Technologies
3.7 Production of Biofuels from Agricultural Biomass
3.8 Factors Influencing Biofuel Production
3.9 Biofuel Energy Potentials in India
3.10 Environmental and Economic Concern of Agriculture‐Based Biofuel Production
3.11 Future Perspectives
3.12 Conclusions
Acknowledgements
References
4 Agriculture Wastes: Generation and Sustainable Management
4.1 Introduction
4.2 Agrowastes and Its Composition
4.3 Agricultural Wastes as Source of Pollution
4.4 Realization of Sustainable Development from Agrowaste
4.5 Conclusion and Future Prospects
References
5 Microbiological Digestion of Agricultural Biomass: Prospects and Challenges in Generating Clean and Green Energy
5.1 Introduction
5.2 Agricultural Waste: Generation to Proper Utilization of Agricultural Waste
5.3 Anaerobic Digestion
5.4 Way Forward
5.5 Conclusion
References
6 Nothing is ‘Waste’ in Agriculture: From Nanotechnology and Bioprocesses Perspectives
6.1 Introduction
6.2 Relevance and Opportunities to Use Nanotechnology
6.3 Increase Productivity of Soil
6.4 Precision Farming
6.5 Restoration of Environmental Health
6.6 Agricultural Application of Nanotechnology
6.7 Nanofertilizers and Nanopesticides
6.8 Nanotechnology for Food Industry
6.9 Microbial Techniques for Bio‐Transforming Food and Agricultural Waste into Resources
6.10 Bioconversion of Food Waste to Wealth
6.11 Biowaste and its Products for Agricultural Sustainability
6.12 Post‐Harvest Agriculture Waste Management Using NPs
6.13 Sustainable Agriculture in India: Some Policy Recommendation
6.14 Risk and Safety Aspects of Nanotechnology in Agriculture
6.15 Conclusion and Future Implications
Acknowledgement
Conflict of Interest
References
7 Agro‐Wastes as Low‐Cost Biosorbent for Dyes Removal from Wastewater
7.1 Introduction
7.2 Dyes Classification and Their Toxicity
7.3 Conventional Dye Removal Technologies from Wastewaters
7.4 Agricultural Wastes and Characterization
7.5 Agricultural Wastes: An Excellent Dye Adsorbent
7.6 Adsorption Kinetics and Isotherm
7.7 Factors Influencing Dye Removal Using Agro‐Wastes
7.8 Economic and Environmental Concern of Agricultural Wastes‐Based Dye Removal
7.9 Conclusions and Recommendations
References
8 Agricultural Waste as Source of Organic Fertilizer and Energy
8.1 Introduction
8.2 Agricultural Waste
8.3 The Potential Risk of Agriculture Waste on Human and Environment
8.4 Traditional Technologies Used for Recycling of Agricultural Waste
8.5 Advanced Technology of Agricultural Waste for the Energy Production
8.6 Sustainable Use of Agriculture Waste for Biofuel Production
8.7 Conclusion
References
9 Production of Bioethanol Using Agricultural Waste: An Overview
9.1 Introduction
9.2 Origin of Bioethanol
9.3 Production Policy of Bioethanol in some Countries with Focus on India
9.4 Distribution of Bioethanol Worldwide
9.5 Comparison of Ethanol and Gasoline
9.6 First‐Generation Bioethanol
9.7 Prospects
9.8 Challenges
9.9 Conclusion
References
10 Bioethanol Production from Lignocellulose Agricultural Waste Biomass
10.1 Introduction
10.2 Discussion
10.3 Conclusion
References
11 Hydrothermal Liquefaction of Waste Agricultural Biomass for Biofuel and Biochar
11.1 Introduction
11.2 Composition of Waste Obtained from Agriculture
11.3 Hydrothermal Liquefaction
11.4 Recent Development in HTL Technology
11.5 Process for Degradation of Cellulose
11.6 Products of HTL
11.7 Factors Affecting the Productivity of Bio‐Crude Oil
11.8 HTL: Future Prospects and Practical Limitations
References
12 Biogas Production through Anaerobic Digestion of Agricultural Wastes: State of Benefits and its Future Trend
12.1 Introduction
12.2 Anaerobic versus Aerobic Digestion
12.3 Biochemical and Microbiological Aspect of Anaerobic Digestion
12.4 Parameters Involved in the Process
12.5 Anaerobic Digestion Process
12.6 By‐Products of Anaerobic Digestion
12.7 Types of Digesters
12.8 Mesophilic and Thermophilic Process
12.9 Suitable Wastes for Anaerobic Digestion
12.10 Perspective of Anaerobic Digestion
12.11 Policies and Application of Anaerobic Digestion Technology
12.12 Concluding Remarks
References
13 Expansion of Agricultural Residues to Biofuel Processing and Production
13.1 Introduction
13.2 Agricultural Residues and Importance in Biofuel Production
13.3 Process of Conversion of Biomass Residue to Biofuels
13.4 Agricultural Residue Sources for Biofuel Production
13.5 Conclusion
References
14 Creating Wealth from Agrowaste: Success Stories from India
14.1 Global Scenario of Agriculture
14.2 National Scenario
14.3 Types of Organic Inputs for Farms
14.4 Production by Self‐Help Groups (SHGs): A Microunit of Circular Economy
14.5 Linkages to United Nations Sustainable Development Goals (UNSDGs) and Government Schemes
14.6 Statistics of Stubble Burning in India
14.7 The Adverse Impacts of Stubble Burning on the Environment
14.8 Alternative Strategies to Stubble Burning in India
14.9 Riches from Rags’ Studies from Rural India: Case Studies of Recycling Farm Wastes into Valuable Products
References
Web Links
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 Chemical composition of residues.
Chapter 2
Table 2.1 Cumulative generation potential of agricultural residues in selec...
Table 2.2 Major global producers of forest residues.
Table 2.3 Potential of energy generation from biomass residues in the field...
Chapter 3
Table 3.1 Characteristics of different pyrolysis techniques.
Table 3.2 Biofuel potential from agricultural residues.
Chapter 4
Table 4.1 Composition and sources of different agricultural wastes.
Table 4.2 Biofuels obtained from agrowastes.
Table 4.3 Criteria for selection of energy extraction technology (CPHEEO 20...
Table 4.4 Methods used to convert agricultural wastes to economically usefu...
Chapter 5
Table 5.1 Primary energy consumption in various regions across the globe....
Table 5.2 Major agricultural crop wastes and processing residues.
Table 5.3 Generation of solid wastes in various areas.
Table 5.4 Generation of liquid wastes in various sectors.
Table 5.5 Environmental requirements: optimal conditions for biogas product...
Table 5.6 Optimum and inhibitory concentrations of inorganic salts and meta...
Table 5.7 Inhibitory and toxic concentrations of heavy metals.
Table 5.8 Summary of challenges of biogas plants in Asian countries.
Chapter 6
Table 6.1 Different types of NMs for environmental remediations.
Table 6.2 Some applications of nanomaterials in food industry.
Chapter 7
Table 7.1 Characterization technique used in dye removal process.
Table 7.2 Different agricultural wastes sorbents for removing dyes from was...
Chapter 8
Table 8.1 In comparison with other countries in the area, India generates a...
Table 8.2 Some study of the energy production from agricultural waste.
Chapter 10
Table 10.1 Cellulase production test for different yeast strains.
Table 10.2 Amylase production test for different strains of yeast.
Table 10.3 Optical density of the pretreated and untreated substrate.
Table 10.4 The reducing sugar yield from rice straw after pretreatment was ...
Table 10.5 Optical density of pretreated rice straw for carbohydrate estima...
Chapter 11
Table 11.1 Yield of HTL bio‐oil with different biomass.
Chapter 14
Table 14.1 Some welfare schemes for Indian farmers as proposed by Ministry ...
Table 14.2 Estimated production of major Indian crops.
Table 14.3 Stubble straw based 2G ethanol commercial projects in India (up ...
Table 14.4 Some innovative technologies undertaken by the agricultural scie...
List of Illustrations
Chapter 1
Figure 1.1 Agro‐industrial waste materials.
Chapter 2
Figure 2.1 Different types of wastes and their generation from various secto...
Figure 2.2 Global waste generation will nearly double by 2050. Most of the g...
Figure 2.3 Amount of food waste generated at various Asian countries.
Figure 2.4 Projected global demand for cereal crops.
Figure 2.5 Applications of waste derived from agro‐food and the generated as...
Figure 2.6 In the ashes of agro‐food waste, various oxides are found. These ...
Figure 2.7 Production of biogas components with time in landfill decompositi...
Figure 2.8 Burning of residue generated from paddy crop field.
Figure 2.9 Application of agricultural waste biomass in terms of environment...
Chapter 3
Figure 3.1 Different types of biofuel production with particular emphasis on...
Figure 3.2 Biofuel types and replacement of traditional fuels by second‐gene...
Figure 3.3 Different biomass conversion technologies for biofuel production....
Figure 3.4 Different stages of biofuel production from agricultural biomass:...
Figure 3.5 Different stages of biodiesel production.
Chapter 4
Figure 4.1 Sources of air pollutants from agriculture fields (Venkataraman e...
Figure 4.2 Flow of water pollutants from agricultural field (Wick et al. 201...
Figure 4.3 Agrowastes and technologies used to obtain valuable products from...
Figure 4.4 Classification of biofuel generations based on feedstock (Alalwan...
Figure 4.5 Technologies used to convert agrowaste biomass to energy.
Figure 4.6 Flowchart showing various steps of biomethanation process (Benich...
Figure 4.7 Various ways microbial interactions support sustainable agricultu...
Chapter 5
Figure 5.1 Agroindustrial waste materials.
Figure 5.2 Value‐added applications of agro‐industrial wastes.
Figure 5.3 Biofuel generation from organic wastes.
Figure 5.4 Biochemical reactions in anaerobic digestion.
Figure 5.5 Factors involved in anaerobic digestion process.
Figure 5.6 Major micro‐organisms involved in anaerobic digestion process.
Chapter 7
Figure 7.1 Conventional processes for dye removal from wastewaters.
Figure 7.2 Different agro‐waste used during dye removal process from wastewa...
Chapter 8
Figure 8.1 Different types of agriculture wastes and their sources.
Figure 8.2 Recycling of agricultural waste using vermicomposting method. A....
Figure 8.3 Anaerobic digestion of agricultural waste recycling.
Figure 8.4 Transesterification process for the production of biofuel.
Chapter 9
Figure 9.1 Bioethanol production globally by country or region from 2007 to ...
Figure 9.2 Representative diagrams of sugar‐containing plant crops (a) sugar...
Figure 9.3 Representative diagrams of starch‐containing plant crops (a) whea...
Figure 9.4 Structure of (a) cellulose, (b) hemicellulose, and (c) lignin as ...
Chapter 10
Figure 10.1 Bioconversion of lignocellulosic biomass (rice straw) to ferment...
Figure 10.2 Estimation of ethanol from pretreated and untreated rice straw a...
Figure 10.3 Glucose standard curve at 535 nm.
Figure 10.4 The standard curve of glucose at 490 nm.
Chapter 11
Figure 11.1 Hydrothermal liquefaction process and products.
Figure 11.2 Degradation of macromolecules into useful products.
Chapter 12
Figure 12.1 Chemical reactions that are involved in anaerobic digestion proc...
Figure 12.2 Diagrammatic representation of anaerobic digestion process, by‐p...
Chapter 13
Figure 13.1 Different ways of utilization of crop residues.
Figure 13.2 Feedstocks belonging to different generation for biofuel product...
Chapter 14
Figure 14.1 UN SDG goal on responsible consumption and production.
Figure 14.2 Sustainable stubble management strategies.
Figure 14.3 Ramlakhan selling his manure to another farmer (left) and Puran ...
Figure 14.4 Manure made by Ramlakhan.
Figure 14.5 The sustainable development goals.
Guide
Cover Page
Title Page
Copyright Page
List of Contributors
Table of Contents
Begin Reading
Index
Wiley End User License Agreement
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Agriculture Waste Management and Bioresource
The Circular Economy Perspective
Edited by
Suruchi Singh
Sunbeam College for Women, Varanasi, India
Pardeep Singh
Department of Environmental Studies, PGDAV College,
University of Delhi, New Delhi, India
Anu Sharma
Department of Environmental Sciences,
University of Jammu, India
Moharana Choudhury
Environmental Research and Management Division,
Voice of Environment (VoE) Guwahati,
Assam, India
This edition first published 2023© 2023 John Wiley & Sons Ltd
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Limit of Liability/Disclaimer of WarrantyWhile the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.
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List of Contributors
Sangita AgarwalDepartment of Applied ScienceRCC Institute of Information TechnologyKolkata, West Bengal, India
Md. Abdullah AzizAgricultural Statistics DivisionBangladesh Rice Research Institute (BRRI)Gazipur, Bangladesh
Hangma BoroDepartment of BotanyRangapara CollegeRangapara, Assam, India
Ratan ChowdhuryDepartment of BotanyRangapara CollegeRangapara, Assam, India
Papori DahutiaDepartment of PhysicsDibrugarh UniversityDibrugarh, Assam, India
Soumendra DarbarFaculty Council of ScienceJadavpur UniversityKolkata, West BengalIndia; Research and Development DivisionDey’s Medical Stores (Mfg.) Ltd., KolkataWest Bengal, India
Tathagata DebDepartment of Applied ScienceRCC Institute of Information TechnologyKolkata, West Bengal, India
Sukhendu DeyDepartment of Environmental ScienceThe University of BurdwanBurdwan, West Bengal, India
Joystu DuttaDepartment of Environmental Science University Teaching DepartmentSant Gahira Guru UniversityAmbikapur, Chhattisgarh, India
Joysurya DuttaSymbiosis Institute of Operations Management (SIOM), Nashik, Maharashtra
Apurba Ratan GhoshDepartment of Environmental ScienceThe University of BurdwanBurdwan, West Bengal, India
Navamallika GogoiDepartment of ChemistryArunachal University of StudiesNamsai, Arunachal Pradesh, India
Nirmali GogoiDepartment of Environmental ScienceTezpur UniversityTezpur, Assam, India
Anwesha GohainDepartment of BotanyArunachal University of StudiesNamsai, Arunachal Pradesh, India
Avinash Pratap GuptaDepartment of Environmental ScienceSant Gahira Guru UniversitySarguja, Chhattisgarh, India
Ravindra Pratap SinghCentral Public Works DepartmentNew Delhi, India
Sumi HandiqueDepartment of Environmental ScienceTezpur UniversityTezpur, Assam, India
R.Y. HiranmaiSchool of Environment and Sustainable DevelopmentCentral University of GujaratGandhinagar, Gujarat, India
Md. Shahadat HossainTraining DivisionBangladesh Rice Research Institute (BRRI)Gazipur, Bangladesh
Asha HumbalSchool of Environment and Sustainable DevelopmentCentral University of GujaratGandhinagar, Gujarat, India
Rani JhaDepartment of ChemistryArunachal University of StudiesNamsai, Arunachal Pradesh, India
Sanjib KalitaDepartment of BotanyGauhati UniversityGuwahati, Assam, India
Mohammad Ashik Iqbal KhanPlant Pathology DivisionBangladesh Rice Research Institute (BRRI)Gazipur, Bangladesh
Vinod KumarAlgal Research and Bioenergy LabDepartment of ChemistryUttaranchal UniversityDehradun, Uttarakhand, India; Department of Environmental Monitoring and ForecastingEcological FacultyRUDN UniversityMoscow, Russia
A.K. MallDivision of Crop ImprovementICAR‐Indian Institute of Sugarcane ResearchLucknow, Utter Pradesh, India
Varucha MisraDivision of Crop ImprovementICAR‐Indian Institute of Sugarcane ResearchLucknow, Utter Pradesh, India
Manisha NandaDepartment of BiotechnologyDolphin (P.G.) Institute of Biomedical and Natural SciencesDehradun, Uttarakhand, India
Ajay NeearajSchool of Environment and Sustainable DevelopmentCentral University of GujaratGandhinagar, Gujarat, India
Amrita Kumari PandaDepartment of BiotechnologySant Gahira Guru VishwavidyalayaSarguja, Ambikapur, Chhattisgarh, India
A.D. PathakDivision of Crop ImprovementICAR‐Indian Institute of Sugarcane ResearchLucknow, Utter Pradesh, India
Bhawana PathakSchool of Environment and Sustainable DevelopmentCentral University of GujaratGandhinagar, Gujarat, India
Md. Khairul QuaisRice Farming Systems DivisionBangladesh Rice Research Institute (BRRI)Gazipur, Bangladesh
Farhana RahmanUniversity of Technology Sydney (UTS)Sydney, NSW, Australia
Vishal RajputHimalayan School of Bio‐sciencesSwami Rama Himalayan UniversityDehradun, Uttarakhand, India
Priyabrata RoyDepartment of Molecular Biology and BiotechnologyUniversity of KalyaniKalyani, West BengalIndia
Subham RoyDepartment of BotanyRangapara CollegeRangapara, Assam, India
Ankita SahaDepartment of Environmental ScienceTezpur UniversityTezpur, Assam, India
Srimoyee SahaDepartment of Life Science and BiotechnologyJadavpur UniversityKolkata, West Bengal, India
Kundil Kumar SaikiaDepartment of Environmental ScienceTezpur UniversityTezpur, Assam, India
Palas SamantaDepartment of Environmental ScienceSukanta MahavidyalayaUniversity of North BengalDhupguri, West Bengal, India
Santeshwari SrivastavaDivision of Crop ImprovementICAR‐Indian Institute of Sugarcane ResearchLucknow, Utter Pradesh, India
Biman Kumar SarmaDepartment of Zoology, Rangapara CollegeRangapara, Assam, India
Payal SenIndependent ResearcherChembur EastMumbai, Maharashtra, India
Tirthankar SenDepartment of Biosciences and BioengineeringIndian Institute of Technology GuwahatiGuwahati, Assam, India
Tarakeshwar SenapatiDepartment of Environmental ScienceDirectorate of Distance EducationVidyasagar UniversityMidnapore, West Bengal, India
Anu SharmaGovt. SPMR College of CommerceConstituent College of Cluster University of JammuJammu, Jammu and Kashmir (UT), India
Pradeep Kumar TiwariIndependent ResearcherNew Housing Board ColonyShahdol, Madhya Pradesh, India
Prachi UpadhyayIndependent Researcher Forest Research Institute (Deemed‐to‐be) UniversityDehradun, Uttarakhand, India
Monu VermaDepartment of Environmental EngineeringThe University of SeoulSeoul, Republic of Korea
M.S. VlaskinLaboratory for Energy Accumulating MaterialsJoint Institute for High Temperatures of the Russian Academy of SciencesMoscow, Russia
1Agricultural Waste as a Resource: The Lesser Travelled Road to Sustainability
Avinash Pratap Gupta1, Prachi Upadhyay2, Tirthankar Sen3, and Joystu Dutta1
1 Department of Environmental Science, Sant Gahira Guru University, Sarguja, Chhattisgarh, India
2 Forest Ecology and Environment Management Division, Forest Research Institute (Deemed-to-be) University, Dehradun, Uttarakhand, India
3 Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
CHAPTER OUTLINE
1.1 Introduction
1.2 Sources of Agricultural Waste Generation
1.2.1 Lignocellulosic Waste
1.2.2 Proteinaceous Waste
1.3 Agricultural Waste Characterization
1.3.1 Food Processing
1.3.2 Meat and Poultry Processing Industry
1.3.3 Livestock Waste
1.4 Waste to Wealth: Agricultural Waste Management Approaches
1.4.1 Natural Fibres
1.4.2 Agriculture
1.4.3 Bioenergy Production
1.4.4 Biofertilizer Production
1.4.5 Value‐Added Products
1.4.6 As Adsorbents for the Removal of Heavy Metals
1.4.7 Animal Feed
1.5 Challenges in Agricultural Waste Management
1.6 Conclusion
References
1.1 Introduction
With the expansion of agricultural activities, the amount and type of wastes being produced from them have increased. As per the Organization for Economic Cooperation and Development and the Food and Agriculture Organization (OECD‐FAO), 39.35 million tons of natural fibres are annually being obtained from plants by the farmers, which also contribute to waste production. China reportedly produces 56.2 million tons of agricultural wastes. The types of wastes and their amount are dependent on the country and their management (Nagalakshmaiah et al. 2016; Letcher and Vallero 2019; Kamel et al. 2020). Agricultural wastes are basically the outputs that are not utilized in products or residues produced from the harvest/rearing and processing of raw agricultural products. Although many agricultural wastes contain substances of human value or benefit, it is mostly the case that the economic value of these processed substances is lower than the cost of collection, transportation, and processing of the feedstock. Therefore, wastes are generated due to the economic infeasibility of processing or reusing discarded agricultural by‐products.
Agricultural wastes may be in the many forms like solids, slurries, or liquids and can have both plant and animal origins. For example, agricultural wastes encompass
animal wastes such as manure, carcasses and bones;
food processing wastes such as corn stalks, fruit peels cores pits pulp stems and seeds, twigs, spoiled fruits, sugarcane bagasse, and molasses;
crop discards such as corn stalks, fruit/vegetable drops, culls, and pruning;
toxic agricultural wastes such as pesticides, herbicides, herbicides, and antifungals.
The composition of agricultural wastes can be different from location to location and is dependent on the particulars of the point of origin like the agricultural activities carried out and the regional specialization. Interestingly, the challenges in waste management as well as the opportunities faced by a region because of the primary residues generated are also related to the regional specialization. For example, in locations specifically used for animal husbandry, vast quantities of organic matter rich in nitrogen and nutrient‐rich waste materials are generated alongside repugnant odours, microbial contamination, and greenhouse gas (methane) emissions. Manure production is therefore among the most feasible waste management routes for these regions in comparison with the regions devoted to crop production where nutrients and the organic matter deplete because of the nutritional demands exerted by the growing crops on the soil (Gontard et al. 2018).
During the past several decades, significant scientific and technological advancements have resulted in a gradual increase of agricultural yield and productivity throughout the world. This, however, has also resulted in a steady increase in the quantity of waste from livestock, agricultural crop residues, and by‐products of agro‐industries. Although highly accurate estimates of agricultural waste production are rare, it is believed that agricultural waste contributes significantly to the global total waste production. Over a decade ago, the world was estimated to produce nearly 1000 million tons of waste from agriculture (Agamuthu 2009). Organic wastes have been documented to account for up to 80% of the total solid waste being produced in a farm (Brown and Root Environmental Consultancy Group 1997). In 2012, organic wastes accounted for more than half of the fresh waste of the harvested crops representing a potential of 90 Million Tons Oil Equivalent (MTOE) which was far higher than the energy potential of other wastes such as round wood, municipal wastes, and tertiary forest residues (Elbersen et al. 2012). This scenario is likely to worsen if proper interventions are not put in place.
In this modern age of industrialization and globalization, economic progress is heavily intertwined with non‐renewable resource utilization which adversely impacts environmental balance and biodiversity, jeopardizes global food security, and depletes our planet’s non‐renewable energy reserves (UNEP 2011). Agricultural waste can be transformed into economically valuable products, such as fertilizers, energy, and chemicals, by using specialized conversion processes. This is of critical importance so as to promote a sustainable bioeconomy and consequently decouple non‐renewable resource utilization and economic progress from human well‐being and environmental sustainability.
As per Indian Ministry of New and Renewable Energy (MNRE), on average, India generates half a billion metric tons (Mt) of crop residue every year. Although a significant fraction of this crop residue is used as fodder, fuel and for other domestic and industrial purposes, there still is an unutilized surplus of 140 Mt each year and 92 Mt of that are incinerated (NPMCR 2019). More agricultural wastes are generated in India than Bangladesh, Indonesia, and Myanmar combined. In fact, the agricultural waste volume that is incinerated in India is more than the net volume of agricultural waste produced by other countries in the region (Bhuvaneshwari et al. 2019).
In this review, we aim at constructing a picture of the state of agricultural waste and its generation. Agricultural wastes, their different types, and their characteristics have also been discussed. Apart from that, the key challenges and most promising opportunities in developing smart, sustainable, and efficient agricultural waste conversion mechanisms and residue management strategies are described.
1.2 Sources of Agricultural Waste Generation
Waste produced from agriculture can be broadly divided into two groups based on their composition namely:
Lignocellulosic waste
Proteinaceous waste
1.2.1 Lignocellulosic Waste
Lignocellulosic biomass is about 50% of the world’s total biomass. Its annual production is around 10–50 billion tons (Mood et al. 2013; Kumar et al. 2018). It is the main constituent of the cell walls in plants and contains cellulose (40–60%), hemicellulose (20–40%), and lignin (10–25%) (Dionisi et al. 2015). The plant residues produced in agricultural field also come under this and are known as agricultural residues.
They can be grouped into two categories: field residues and process residues. Agricultural wastes which remain in the field after the process of crop harvesting has been concluded are referred to as field residues. Field residues function as feedstock for a number of processes designed to transform agricultural waste into economically valuable products such as animal feed, organic manure, raw materials for different manufacturing industries, and even various biochemicals of clinical and industrial significance. However, these processes also produce by‐products which are known as process residues. Field residues and process residues can include a variety of waste products like molasses, husks, bagasse, seeds and seed pods, leaves, stems, straws, stalks, shells, and pulp. India being an agrarian nation produces nearly 686 million tons of lignocellulosic waste and 234 million tons of that are agricultural residues (Kapoor et al. 2020). But because of the current inefficiencies in plaguing agricultural waste management processes, a significant portion of the agricultural residues produced in India is underutilized. This also presents an opportunity for future initiatives aimed at processing agricultural waste and turning waste into wealth.
1.2.2 Proteinaceous Waste
Proteins are known part of our daily nutrition and biochemical function. They also are promising sources of raw material for polymers. The protein obtained from agricultural waste has a huge potential for various utilities. The waste produced from aquaculture and livestock are abundant in protein and can be utilized to derive novel ways to produce value‐added products (Barone Justin and Schmidt Walter 2006). So, the proteinaceous waste can be from two major sources: (i) aquaculture and (ii) livestock.
1.2.2.1 Waste Produced from Aquaculture
The expansion of aquaculture has resulted in an increased feeding of feed for improved aquaculture productivity. In a proper aquaculture installation, approximately 30% of the feed fed is converted into solid waste. In aquaculture, the most prominent wastes generated are the metabolic wastes. It could be in soluble or suspended form. Since feeding rates are ambient temperature‐dependent, rise in temperature leads to increased feeding. This consequently results in increase in volume of waste being generated. Optimized patterns of water flow in the production units are critical considerations for waste management as proper water flow minimizes fish faecal matter fragmentation and enables the rapid sedimentation of insoluble solid waste. Furthermore, if the non‐fragmented waste like faeces is higher in amount, it becomes easier to capture them, and this greatly reduces the concentration of dissolved organic waste in the system (Mathieu and Timmons 1995; Obi et al. 2016).
1.2.2.2 Waste Produced from Livestock
Waste generated by livestock activities is produced from different sources. Slaughterhouses produce organic materials and solid wastes like manure, whereas animal’s farms produce high amount of animal faeces and fodder waste. Urine, water produced during cage washing, water from bathing animals, and water from cleaning of slaughterhouses are part of the wastewater produced from livestock activities. Also, air pollutants like H2S and CH4 and odour are produced here. These wastes if not managed well contribute to greenhouse gas production and affect the soil and water quality. These also act as a source of bad odour and site for parasites and germs making them a threat for human health and environment (Obi et al. 2016). Poultry industry is also expanding with increase in consumption of poultry products. The feather left out from the birds are contributing significantly to the waste. This waste is mainly composed of protein (90%), specifically keratin which is insoluble and is hard to degrade naturally. Hence, better management is needed to utilize these wastes (Jana et al. 2020).
Figure 1.1 Agro‐industrial waste materials.
Source: Sadh et al., 2018 / Public Domain / CC BY 4.0.
Figure 1.1 shows the different types of Agro‐industrial waste of their potential sources.
Table 1.1 Chemical composition of residues.
Source: Thadikamala and Reddy Shetty (2013) / Springer Nature.
Name
Carbon (%)
Nitrogen (%)
Hydrogen (%)
Wheat bran
49.81
0.7
6.11
Rice bran
48.39
0.89
5.43
Oat bran
40.62
0.31
4.31
Corn cob
53.61
1.91
8.97
Sugar cane bagasse
48.32
0.2
7.84
Redgram husk
42.23
ND
5.52
Green gram husk
43.17
1.86
ND
Bengal gram husk
42.45
0.75
5.82
Black gram husk
39.61
2.34
5.87
Ground nut oil cake
40.34
2.31
4.21
Spent coffee
34.51
0.36
3.95
Spent tea
32.61
0.31
ND
Pineapple waste
45.68
0.61
3.97
Palmoil fiber
41.4
1.67
5.44
Coconut oil cake
48.16
1.69
5.15
ND not detectable.
1.3 Agricultural Waste Characterization
Knowing the characteristics of agricultural waste is important for formulating an effective waste management system. Wastes produced from agriculture vary in both their quality and quantity. Wastes produced by the processing of crops and from livestock need both solid and liquid waste management. Knowing the characteristics of waste helps in reusing the waste, recovery of useful components, production of useful products like biofuels, biofertilizers, and overall management (Loehr 2012). Table 1.1 shows the chemical composition of waste having different resources. The wastes can be categorized on the basis of their sources as given in the following sections:
1.3.1 Food Processing
The variation in wastes produced during food processing is due to the type of product, methods used to harvest the raw materials, and the processing methods used. For example, wastes generated from fruit and vegetables are often acidic and contain good amount of organic matter. Also, wastes from fruit and vegetable processing from operations like peeling and blanching have high percentage of total dissolved organic solids. The analysis of edible part of vegetables has shown the presence of water (74–94% of total weight), carbohydrate (3.2–19.1% of total weight), protein (1.1–6.7% of total weight), and fat (0.1–0.5%). Also processes like washing contribute to production of wastewater (Loehr 2012). Apart from this, crop residues left after harvest are also the major waste produced and are of high concern, especially in countries like India. They comprise cellulose, hemicellulose, lignin, nitrogenous material, chlorophyll, and other inorganic material (Bhuvaneshwari et al. 2019). Food wastes also consist of natural as well as anthropogenic toxins such as solanine and dioxin which needs to be excluded to make the quality control systems more efficient. Also, the less use of potentially hazardous products in food processing will lead to the generation of less toxic waste making its management easy (Pandey and Dwivedi 2020).
1.3.2 Meat and Poultry Processing Industry
The main waste produced in this is from killing, dehairing, removal of hide, processing, and other clean‐up operations. It contains blood, inorganic and organic solids, salts, and chemical used during processing. Usually at a beef slaughterhouse, 50‐lb blood, 50‐lb paunch manure, and 40‐lb animal manure per animal can be produced. At poultry processing farms, waste is generated by killing, scalding, defeaturing, evisceration, washing, chilling, and clean‐up activities. Quantity and quality of waste generated totally depend on how processes are being handled. With the expansion of poultry industry, water usage, biological oxygen demand (BOD), and solid waste produced have also increased. Now, water used for each bird is about 12–15 gal, BOD produced is 60 lb/1000 birds, and solid waste produced is about 47 lb/1000 birds. These industries are not much affected by seasonal variations, and with expansion of these industries, the waste produced is also of high concern (Loehr 2012).
1.3.3 Livestock Waste
The characteristics of animal waste may be defined on the basis of changes in environment and overall productivity of the animals. The volatile matter present in the waste is found by summing up the percent of protein, fat, fibre, and non‐fibre found in feed after digestion. The fibre and non‐fibre extracts are measured by analysing the lignin, cellulose, and hemicellulose contents. Wastes generated from grass‐fed animals are found to be less biodegradable compared to concentrate‐fed animals. The characteristics of the waste depend on the digestibility of feed and feed composition. The faeces produced mainly have undigested food which was not broken down by the bacteria. Undigested proteins are the part of faeces, and undigested excess nitrogen is removed through urine. Livestock waste can be solid, liquid, or semi‐solid. So, depending on the waste type, the process to handle waste should be formulated with the traditionally used methods. It is necessary to device newer methods and proper training of individuals for waste handling (Loehr 2012).
1.4 Waste to Wealth: Agricultural Waste Management Approaches
Among the existing renewable resources, biomass is seen to be found abundantly. It can be used as an energy source or can be transformed into other usable forms. In the present global scenario, impending energy shortages are an area of immense concern. Using biomass as a source of energy is a probable solution for the energy shortage. Furthermore, biomass utility is not only limited for energy generation, but it can also be utilized in making a variety of commercial products. A lot of work has been carried out to make the utilization of biomass efficient, and the major ones are described in the further sections and subsections.
1.4.1 Natural Fibres
With increasing plastic pollution and poor recycling rate (only 9% of plastic waste is recycled), the need to develop bio‐based polymers has aroused. Two main strategies have been taken up for this: first by deriving biodegradable polymers from bio‐based products like agriculture waste and second by using non‐biodegradable polymers and modifying their properties accordingly. Both the strategies are effective, if the products can be successfully marketed and commercialized (Maraveas 2020).
In another study by Kuan et al. (2011), the physiochemical properties of the residues from alkali‐treated raw cereal materials like wheat straw and corn cob were studied. They produce good amount of fibrous wastes and contain high dietary fibres (49.87–68.65%) as well. In contrast to the soluble fibrous waste, the cereal materials and the left insoluble fibrous residues have essential minerals, the ability to scavenge 2,2‐diphenyl‐1‐picrylhydrazyl radical, good emulsification and the stability of emulsion, mineral binding capacity, and good water and oil holding capacity. Also, the production of nanofibres using silk fibroin (SF) by the process of electrospinning is successfully done. Zhang et al. (2012) studied various properties of fresh coir fibre and reported absorption coefficient to be 0.8 at 20 mm thickness and frequency more than 1360 Hz. They also found that an increase in thickness helps in improved low‐frequency sound absorption.
There have been a lot of studies analysing the scope of different agricultural wastes like grape and tomato pomace, green tea extracts, coconut shells, vegetable wastes, rice husks, fruit peels, grapefruit seed extract, and waste vegetables in the production of biopolymers. But the key issue faced is collecting the waste as the mechanism of collection and sorting of waste is not effective enough to acquire the waste completely. Also, the variability of the waste globally demands variation in the standard production protocols. But, bio‐based products from waste need to be made commercially for the overall global sustainability (Maraveas 2020).
1.4.2 Agriculture
In 2016, the agricultural waste was analysed as a stabilizer of soil, and it was seen that these wastes were not disposed off properly in India. So, ashes produced from these materials at different concentrations (3, 6, 9, 12, and 15%) were taken, and California bearing ratio (CBR) and standard proctor tests were carried out. The parameters studied were specific gravity (2.662), liquid limit (66), plastic limit (26.62), plasticity index (39.99), free well index (23.08), optimum moister content (26.11), and maximum dry density (1.445). It is seen that during milling paddy, 78% of the total weight is because of broken rice grains and bran and rest is contributed by husk. This husk is used as a source to generate steam in parboiling process in the mills. The husk is composed of organic volatile matter (75%) and rest contributes to ash production during firing process which is also known as rice husk (RHA). RHA has about 85–90% of amorphous silica (Maiz et al. 1997; Harshwardhan and Upadhyay 2017).
In another study by Jansirani et al. (2012), production of vermicast and its utilization using organic waste were analysed. Vermicasts produced by the decomposition of tea waste, coir of coconut, and sugarcane bagasse were the main parameters to be studied. So, there is scope for using the agricultural waste for betterment of agricultural produce only. It could be used for energy generation, as compost, as feed for livestock, and for many things (Duque‐Acevedo et al. 2020).
1.4.3 Bioenergy Production
Biofuels are fuels that are produced from biomass instead of being purified from the planet’s underground reserves of fossil fuels such as crude oil. Bioethanol is produced via the alcoholic fermentation of glucose derived from sustainable and renewable sources like agricultural wastes and food discards. They have a comparatively lesser negative impact on the environment than conventional routes of industrial‐scale ethanol production. Bioethanol is chemically undisguisable from ethanol except that they have different substrates and carbon footprints. Bioethanol is a type of biofuel. By the year 2023, ethanol is expected to be responsible for around 67% of the global growth in conventional biofuels, while the remaining 33% is expected to be attributed to biofuels such as biodiesel and hydrotreated vegetable (OECD‐FAO 2018). In 2011, bioethanol production increased by 85 billion litres all across the world (Avci et al. 2013; Saini et al. 2014). By the end of 2024, the global bioethanol production and consumption will increase to about 134.5 billion litres (Bušić et al. 2018). Several studies have explored agro‐industrial residues like rice straw, potato, sweet potato and beet discards, corn stalks, and sugarcane bagasse (Duhan et al. 2013; Kumar et al. 2014; Kumar et al. 2016) for the production of biofuel. Faraco and Hadar (2011) in their study found that residues obtained from cereal crops, olive tree, tomato, and grape were rich in waste with lignin and cellulose. They also have the potential to be utilized as raw material for producing ethanol at large scale.
Apart from ethanol, butanol is also produced from lignocellulosic biomass. Butanol is not only more energy rich than ethanol, but it can also be mixed with gasoline and can even be used instead of gasoline in car engines with minimal modifications. Lignocellulosic biomass obtained from agricultural wastes like corn stovers, fibres, and straw is generally subjected to complex pre‐treatment procedures that yield simple sugars which are subsequently treated with butanol‐producing microbial cultures (Ezeji and Blaschek 2010). Over the years, a variety of studies have reported biofuels production from agricultural residues like rice straw, potato and sugar beet discards, sawdust, corn stalks, and sugarcane bagasse (Duhan et al. 2013; Kumar et al. 2014; Kumar et al. 2016). They are supposed to present a viable substitute to fossil fuel‐based fuels. Moreover, biofuels made from agricultural wastes or other comparable feedstocks recycle carbon sequestered from the atmosphere thereby helping slow down the process of global warming. Since agricultural residues are cheaper, are easier to source, and have fast harvest times, they are a superior choice over woody forest biomass (Limayema and Ricke 2012). Therefore, biodiesel production using agricultural wastes disincentivizes deforestation and forest ecosystem destruction. Furthermore, agricultural waste‐based biofuel production also reduces the need to allocate precious farmland to dedicatedly grow suitable crops such as non‐edible oilseed crops (jatropha oil, castor oil, and tall oil) exclusively for biodiesel production (Koçar and Civaş 2013). Modern science and technological and even social progress are critically dependent on an easily available, stable, consistent, and low‐priced energy source resistant to natural, social, and economical perturbations. Agricultural residue‐based biofuels can be used to meet that demand. India, being an agrarian nation, holds the calibre to be among the global leaders in renewable, sustainable biofuel production from agricultural waste.
Methane gas generation by digesting agricultural wastes anaerobically is another promising technology that achieves that bioconversion of agricultural wastes high in organic material (Timbers and Downing 1977). During the digestion, methane is not formed in pure form, but as a mixture of gas which is called as biogas. This is a renewable source of energy with numerous advantages. Along with the gas, it produces hugely fertile manure which can be utilized in fields (Kapoor et al. 2020). This microbial fermentation‐based digestion of agricultural waste in the absence of oxygen helps to produce methane that involves two steps. Acid‐forming bacteria first digest volatile solids to produce organic acids which act as the substrate for a consortium of methane‐producing micro‐organisms and then methane is produced. Biogas constitutes methane (50–70%), carbon dioxide (25–45%), nitrogen (0.5–3%), and hydrogen gas (1–10%) with traces of H2S. The heating value of the gas ranges between 18 and 25 MJ/m3 (Timbers and Downing 1977). This gas can help in electricity generation and also for cooking purpose (Kapoor et al. 2020).
Over the past 50 years, the world’s meat production has more than tripled. To keep up with the world’s insatiable hunger for animal proteins, animal husbandry and livestock rearing activities have increased significantly in most countries including India (Ritchie and Max 2017). However, this has also significantly increased the waste being generated from livestock activities. Malodorous gases such as hydrogen sulphide, ammonia, and greenhouse gases like methane are also released into the atmosphere as a direct consequence of rearing livestock, particularly ruminant livestock. Anaerobic digestion simplifies the treatment and disposal of animal waste to a considerable extent by stabilizing the sludge and producing relatively odour‐free digestion sludge; hence, it offers an alternative energy source.
1.4.4 Biofertilizer Production
The tropical climate of India not only favours the growth of crops but also promotes the growth of pathogenic microorganisms, pests, and weeds. Therefore, farmers are highly reliant on chemical pesticides and herbicides to avoid the destruction of their valuable produce. Although the use of pesticides and herbicides in moderation can help increase agricultural productivity, farmers often end up overusing and even abusing these chemicals. Furthermore, the packaging and containers using which these chemicals are distributed at retail outlets are often discarded indiscriminately by farmers in open fields and waterbodies. The Plant Protection Department (PPD) estimates that standard packaging tends to retain approximately 1.8% of the chemicals in it (Dien and Vong 2006). Most farmers tend to vastly underestimate the environmentally detrimental effects concentrated doses of chemical pesticides and herbicides can have on the environment and its active ecosystems. Improper storage of unused pesticides and herbicides also can lead to serious environmental risks as the chemicals may leak or leach out of their primary containment thereby contaminating the surrounding environment. Chemical fertilizers play a pivotal role in modern agriculture. They are primarily composed of nitrogen, phosphorus, and potassium. Like pesticides and herbicides, fertilizers too are often abused by farmers in hopes of increasing their agricultural output by a substantial margin (Hai and Tuyet 2010). The absorption rate of such fertilizer compounds depends on a variety of parameters such as the physiochemical properties of the land, plant types, and fertilization technique used (Thao 2003). A fraction of the excess fertilizer is retained in the soil, whereas most of the remainder ends up in various waterbodies such as ponds, lakes, streams, and rivers via surface run‐off and irrigation canals. A small part of the excess fertilizer also evaporates or gets denitrated resulting in air pollution. Therefore, given the current situation, natural fertilizers derived from agricultural wastes of both plant and animal origin are advantageous over conventional chemical fertilizers. Organic fertilizers can be applied alongside chemical fertilizers or as a complete replacement for chemical fertilizers. The nutrients provided by chemical fertilizers can easily be supplemented by manure. Poultry manure has been reported to be rich in phosphorous and is said to positively impact the agricultural productivity (Mokwunye 2000). Adding manure in soil improves its fertility as it increases the nutrient retention capacity or cation exchange capacity, water holding capacity, and overall physical condition and stability.
One of the areas of focus in agricultural research is boosting the natural rate of soil carbon sequestration using soil amendment techniques, as it can enhance agricultural productivity. These techniques have the capability to mitigate Green house gas (GHG) emissions as well as to decrease the volume of agricultural waste being generated. This is because sequestration of carbon requires substantial residence time in the soil as well as chemical protection from oxidation into carbon dioxide or reduction to methane (Srinivasarao et al. 2013). Over the years, partially burnt products such as black carbon and biochar have been receiving increasing interest for soil amendment applications because of their ability to be a long‐term carbon sink with a very low rate of chemical transformation (Izaurralde et al. 2001; McHenry 2009). Biochar is a fine‐grained product, which is rich in carbon and porous in nature. It consists of varying proportions of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), sulphur (S), and ash, derived from the pyrolysis of biomass (Amonette and Joseph 2009; Masek 2009). In pyrolysis systems, biomass such as agricultural waste is heated and the temperature ranges between 400 and 600 °C, in anaerobic conditions. This prevents oxidation of the material thereby avoiding release of carbon dioxide. Instead, a part of the biomass is vaporized, and a carbon‐rich char is left behind, which is referred to as biochar.
Biochar being porous in nature helps to improve soil water retention capacity and surface area, when amended to soil. It also actively influences and interacts with the soil matrix, soil microbiome, and plant roots, thus promoting retention of nutrients and triggering a number of biogeochemical reactions which help to enrich the soil (Lehmann and Joseph 2009). In fact, there are several reports describing soil quality improvements such as improved soil pH stability, increased earthworm population, and decreased fertilizer requirement, on amendment with biochar (Tryon 1948; Gaunt and Cowie 2009). The applications of biochar are not limited to agriculture. Biochar finds varied uses in a number of domains, including water treatment, construction, food technology, cosmetic manufacturing, metallurgy, chemical engineering, and many more.
Natural fertilizers made from organic remains such as agricultural waste are known as compost. They are formed by the process of composting (Tuomela et al. 2000; Misra et al. 2003). Composting is considered as a safe method for managing waste. It is an aerobic process where microbes act on complex degradable matter and turn them into organic and inorganic by‐products (Toledo et al. 2018; Ayilara et al. 2020). These transformed by‐products can be utilized as biofertilizers and for enhancing soil quality. It is also known to boost the overall agricultural yield and productivity (Ayilara et al. 2020). They are also known to be more resistant to drought, disease, and toxicity (Misra et al. 2003; Lei et al. 2010). Furthermore, compost promotes the nutrient uptake, cycling, and microbial activity of soil and hence is a viable substitute to harmful chemical fertilizers and pesticides. Large‐scale compost using agricultural waste is an ambitious undertaking which, if implemented appropriately, will be of significant social and economic benefit. However, the production of organic fertilizers from agricultural waste at scale is a challenging undertaking requiring significant upfront technical, economical, and time investment. There are reports discussing the technical and economical common challenges plaguing organic waste composting projects (Hettiarachchi et al. 2018). One of the prominent issues is the lack of a steady, stable, and secure market for the product. This is, however, not an issue for small‐scale, on‐site fertilizer production plants as farmers can make compost from their own agricultural waste and feed in back into their own land, thus creating a self‐sufficient circular supply chain. Small‐scale production of biofertilizers in a domestic set‐up, i.e. composting, is also a viable alternative which has attractive economic incentives especially for economically downtrodden farmers who have easy access to agricultural waste. Furthermore, crop residue, animal manure, and food discards are rich in organic content which make them ideal raw materials for composting purposes.
A bio‐composting study carried out by Pratap Singh and Prabha (2017) in Uttar Pradesh, India, reported notable increases in the agronomic properties of rice and wheat when the soil was supplemented with bio‐compost (Pratap Singh and Prabha 2017). The compost preparation was mostly composed of agricultural waste materials such as wheat straw, rice straw, and leaves. Wheat and rice straw, vegetable crop, leaves contributed to the biomass used, and compost was prepared. It constituted of total solids (45%), organic matter (26.7%), carbon (15.3%), and total nitrogen (1.36%). The compost produced was rich in organic matter and carbon and provided sufficient nitrogen and phosphorus to the crops (Brady and Weil 1966). This also helped to enhance the soil health by supporting micro‐organism and necessary native flora and fauna (Nielsen and Angelidaki 2008; Wall et al. 2015). This study also showed the contribution by compost layer of 1 in. thickness. The total nitrogen added to the soil was about 1 ton/ha, carbon was 13.3 ton/ha, and organic carbon was 24 ton/ha. And also, it helped in the availability of other important nutrients like phosphorus, potassium, magnesium, and iron. (Pratap Singh and Prabha 2017).
Composting has shown to be advantageous in terms of enhancing productivity, providing disease resistance, and many other things. Its use should be spread across by utilizing the biodegradable waste which is combusted (Ayilara et al. 2020).
1.4.5 Value‐Added Products
Agricultural residues such as wheat and rice bran, corn cobs, gram husks, coffee bean discards, oil cakes, and inedible fruit wastes are rich in nutrients and can therefore be utilized by a variety of different industries as value‐added products.
In a study by Igor and Ruta (2015), the possibility to use potato peel which is produced in the food production unit was studied. Also, the use of potato peel powder was seen as a partial flour replacement, and it did not affect the fermentation and other properties.
Another study done in 2016 showed the potential usage of coffee waste to produce bricks. The study analysed two main parameters, namely CW (coffee waste) ratio and temperature. Also, compressive strength and shrinking density were the properties considered in the study. A control brick and three bricks made of coffee waste with different percentages were exposed to high temperature (1050 °C). Apart from that, the manufactured brick was tested for any possible heavy metal leaching. It was seen that with the addition of CW there was a linear increase in shrinkage, but it was complying with the minimum standard of 8% and overall, a good quality brick was produced. Therefore, it can be concluded that CW could be used to produce fire clay bricks, and different proportions of CW can be used. Also, it also becomes an alternative way of coffee waste disposal and a low‐cost waste additive for brick production (Loeppert and Suarez 1966).
The leftover parts of different fruits and vegetables are commonly thrown away as wastes and are considered to be of no use. But several research works have shown their utility (Parashar et al. 2014). For example, pomegranate peels are documented to have a number of bioactive compounds like phenolic acids, flavonoids, and hydrolysable tannins which have promising applications in food preservation using natural compounds (Chia‐Hui et al. 2020). In a recent report by Kumar and colleagues, the authors explored a variety of novel applications of fruit and vegetable peels, ranging from the production of microbiological media and fortified probiotics to reducing agents in metal nanoparticle synthesis and biosorbents (Kumar et al. 2020).
Solid state fermentation (SSF) can help to increase the antioxidant activity of various substrates with the help of substrates. Pineapple waste can also be used as a substrate in SSF, and it also produced anticancer agents along with antioxidants. The skin and the central part of the fruit were used, and it was concluded that using fermented pineapple waste increased protein content, fibre content, phenols, and antioxidants. Hence, it can be used as a source for antioxidants (Rashad et al. 2015).
1.4.6 As Adsorbents for the Removal of Heavy Metals
Industrialization and urbanizations have led to numerous environmental issues including release of heavy metals in excess. The main problem associated with heavy metals is that unlike organic pollutants which degrade to non‐toxic components, heavy metals do not break into harmless form (Gupta et al. 2001). It is also a matter of concern as heavy metals pose a threat to different life forms. Different studies have been carried out to resolve this matter, and it has been determined that adsorption is a highly effective technique for heavy metal removal in effluent treatment plants. Activated carbon has also been found effective (Chand et al. 1994). But lately, agricultural waste has aroused as an effective, low‐cost alternative to treat effluents with heavy metal using adsorption. The low‐cost agricultural waste can be many by‐products like sugarcane bagasse (Mohan and Singh 2002), rice husk (Ayub et al. 2002), sawdust (Ajmal et al. 1996), coconut husk (Tan et al. 1993), and oil palm shell (Khan et al. 2003), and many of them are researched by scientists for heavy metal removal.
