Valorization of crop residues and animal wastes: Anaerobic co-digestion technology

To switch the over-reliance on fossil-based resources, curb environmental quality deterioration, and promote the use of renewable fuels, much attention has recently been directed toward the implementation of sustainable and environmentally benign 'waste-to-energy' technology exploiting a clean, inexhaustible, carbon-neutral, and renewable energy source, namely agricultural biomass. From this perspective, anaerobic co-digestion (AcoD) technology emerges as a potent and plausible approach to attain sustainable energy development, foster environmental sustainability, and, most importantly, circumvent the key challenges associated with mono-digestion. This review article provides a comprehensive overview of AcoD as a biochemical valorization pathway of crop residues and livestock manure for biogas production. Furthermore, this manuscript aims to assess the different biotic and abiotic parameters affecting co-digestion efficiency and present recent advancements in pretreatment technologies designed to enhance feedstock biodegradability and conversion rate. It can be concluded that the substantial quantities of crop residues and animal waste generated annually from agricultural practices represent valuable bioenergy resources that can contribute to meeting global targets for affordable renewable energy. Nevertheless, extensive and multidisciplinary research is needed to evolve the industrial-scale implementation of AcoD technology of livestock waste and crop residues, particularly when a pretreatment phase is included, and bridge the gap between small-scale studies and real-world applications.

Sustainable crop production: Highlights on economic, environmental and social life cycle thinking

Seeking multi-dimensional inclusion is one of the most global concerns of the crop production sector worldwide. Socio-eco-effectiveness or socio-eco-efficiency optimization plays a crucial role in future strategy establishment. Life cycle is a widely used approach examining economic, environmental, and social impacts. Recently, life cycle thinking approaches have been increasingly utilized to bring to light useful perceptions of the crop production processes. This study aims to apply a systematic review and prescriptive analytics to critically investigate the life cycle thinking approaches application according to sustainability pyramid aspects, life cycle thinking unicity, goal and scope variability, functional units' causality, system boundary' diversity, involved aspect' concentration, indicators, impacts categories and influencing variables distribution, as well as to define a first datasheet model and directive axis to apply per aspect and family for socio-eco-effectiveness or socio-eco-efficiency evaluation. Over 295 peer-reviewed studies from 2019 to the middle of 2023, 52 reviews and articles gathered from Web of Science and Scopus meet the criteria to be analyzed. Our inspection revealed that related reviews are few, approximately 2 %. Moving from the traditional life cycle perspective to the sustainability pyramid approach, the indicators applied by researchers were classified per aspect and family belonging. A deductive analysis was carried out to narrow the impact categories, and the influencing factors to the population's main interests: four economic (input status, resources consumption, waste, and Costs of Life Cycle), eight environmental (Climate Change, Global Warming, Ozone, Acidification, Eutrophication, Photochemical Oxidation, Abiotic Depletion, and Toxicity), and three social families (Human Toxicity, employment, and Ionizing Radiation). The results combination highlights the construction need for a directive datasheet model to address the optimizing problem under the identified families and aspects constraints, as well as to envisage the units and methods worldwide standardization's necessity for spatial-temporal studies comparison in the present, the past, and the future.

Economic, environmental and social efficiency and effectiveness development in the sustainable crop agricultural sector: A systematic in-depth analysis review

Multi-dimensional inclusion of economic, environmental, and social sustainability spheres together are the most global concerns of the agricultural crop sector. Therefore, optimizing waste and natural resources guides researchers and policymakers to structure actions and strategies to attain sustainability. Several studies have been published around the world to choose between focusing on eco-efficiency or eco-effectiveness in different aspects. This work aims to systematically apply an updated review to critically assess the agricultural research articles' contributions among the assessment of those methods, models or tools, as well as a quantitative and qualitative in-depth analysis review to classify them, according to their mapping, functions, strengths, weaknesses, and logical relationships for the evaluation in the crop agricultural sector, which is expected to be needed in future to better understand the research gaps and select the appropriate methods for sustainability evaluation from different spheres (ecology, economy, and sociology). Of 242 peer-reviewed records from 2018 to the beginning of 2023, 135 reviews and articles gathered from Web of Science and Scopus meet the criteria to be examined. Our analysis revealed that the number of reviews is limited to approximately 4.5 %; most of the case studies were carried out in countries, such as China (36 %) and Brazil (6 %), and continents such as Europe (16 %). Depending on considered aspects, most studies evaluate the efficiency, effectiveness and derivatives using a set of tools, varying between the managerial tools applied for the macro-level structuration (DPSIR, EMA, and LCA) and mathematical tools applied for the micro-level quantification, subdivided into the visualization methods (GIS), and the optimization methods (DEA, SFA, MILP, FO). Thanks to their multifunctionality in considering different aspects of input, output and influence factors variables, the in-depth analysis study suggests the application of data envelopment and stochastic analysis to carry out a multidisciplinary evaluation for the socio-eco-efficiency or the socio-eco-effectiveness.