Lignocellulosic wastes have emerged as a potential feedstock in the last decades. There are multiple reasons for its abundance, easy availability, economic, and abundant sources. It can be used to produce several value-added products. Among them, fuel is considered one of the important requirements. Production of fuel from lignocellulosic biomass is a tricky business. The major reason for its failure is the low product yield. Therefore, high yield and low-cost are the two key parameters which need significant optimization. To achieve the target several newer technologies such as pyrolysis, hydrothermal liquefaction and gasification have emerged. These techniques are much more efficient than that of conventional acid or alkali. At the same time quality of the product is also improved. The focus of this review is to analyze the efficiency of chemical conversion of lignocellulosic residues into valuable fuels keeping in mind the cost-reduction strategies. 

The concept of biorefinery depends on the recuperation of higher-value chemicals with potential for a wide dissemination and an untapped marketability. To construct a clearer picture of rural waste treatment system, this work was conducted to critically review the foremost regularly utilized agricultural waste management technologies from their state of the art, challenges for setting up the biorefinery and system of circular economy with self-efficient business model. The drivers that can make the biorefinery concept appropriate to waste management and the conceivable outcomes for its improvement to full scale were examined. Technological, strategic and market imperatives influence the effective usage of these frameworks. This review discusses the state-of-the-art biorefinery opportunities beyond conventional strategies as an economically viable solution to overcome numerous current challenges such as waste minimization and the biosynthesis of different high-value bioproducts biorefinery strategies, integrated approach as well as economic and environmental impact were discussed.

Citrus wastes (CW) are normally toxic to anaerobic digestion (AD) because of flavors such as D-limonene. In this study, bacterial community was evaluated during volatile fatty acids (VFAs) production from CW inoculated by sludge in a membrane bioreactor (MBR) using semi-continuous AD with different organic loading rates (OLR). Four treatments including untreated CW filled with 4 and 8 g center dot VS center dot L(-1)d(-1) OLR (UOLR4 and UOLR8), pretreated Dlimonene-free CW filled with 4 and 8 g center dot VS center dot L(-1)d(-1) OLR (POLR4 and POLR8). The initial inoculum and the CW mixture (DAY0) was used as control for comparison. There was an obviously higher bacterial diversity in raw material (66848 sequences in DAY0), while decreased after AD and higher in POLR4 and POLR8 (65239 and 63916) than UOLR4 and UOLR8 (49158 and 51936). The key bacterial associated with VFAs production mainly affiliated to Firmicutes (37.35-84.73%), Bacteroidetes (0.48-36.87%), and Actinobacteria (0.35-29.38%), and the key genus composed of Lactobacillus, Prevotella, Bacillus, Bacteroides and Olsenella which contributed in VFA generation by degradable complex organic compounds. Noticeably, methanogen completely suppressed after MBR-AD and UOLR4 has greater acid utilizing bacteria (70.09%).

Aimed to evaluate the coexistence of bacterial and fungal diversity and their correlation with enzymatic activity in response to biochar. This study performed aerobic composting based on typical agricultural wastes of sheep manure with additive apple tree branch biochar at distinct concentration (0, 2.5, 5, 7.5, 10 and 12.5% corresponding from T1 to T6). The result demonstrated that appropriate amendment of biochar enriched bacterial diversity (1646-1686 OTUs) but interestingly decreased fungal diversity (542-630 OTUs) compared to control (1444 and 682 OTUs). Biochar addition enhanced all enzymatic activities and its correlation with bacterial was more complex than fungal community (786 and 359 connect edges). The dominant microbes comprised of Firmicutes (45.2-35.2%), Proteobacteria (14.0-17.5%), Basidiomycota (32.4-49.5%) and Ascomycota (11.3-37.5%) among all the treatments. Overall, biochar regulates the composting microenvironment by influencing the microbial diversity and associated enzymatic activities.

The generation of bioenergy and bioproducts from biowaste streams has piqued global interest in achieving a cutting-edge circular economy. The integration of biowaste into the cutting-edge circular economy has the potential to significantly increase the production of sustainable bioproducts and bioenergy. The potential for advanced forms and innovations to transform complicated, natural-rich biowastes into a variety of bioproducts and bioenergy with an advanced circular economy has been demonstrated in this article. It is described to emphasise the critical nature of research into improving biowaste conversion into circular economies and the impact that bioeconomy has on various societal sectors. The present study examined how microbial profiles have transformed treasured bioenergy and bioproducts aspirations into mechanical bioproducts marvels discovered through cutting-edge microbial analyses of biowaste. Additionally, the article discussed contemporary experiences with the developing circular economy of biowaste as a resource for numerous bioproducts and bioenergy businesses, as well as the emanant biowaste biorefinery methods that could be used to evaluate industrial-scale maintainable financial models for updated bioproducts and other generation-related issues.

Biosolids are the biological organic matter extracted from various treatment processes of wastewater which are considered as a rich source of energy and nutrients. The most commonly used method for the disposal of biosolids is landfilling. But this causes the loss of valuable nutrients and creates environmental issues. Circular economy approaches provide a better way for utilization these resources in a sustainable manner. This allows maximum utilization of resources and many natural resources can be preserved and utilized for future generations. The present review provides a comprehensive illustration of biotechnological approaches for the utilization of biosolids. Various process strategies for the utilization of biosolids for the production of energy, fuels and valueadded products are discussed. The utilization of this rich organic matter under circular economy has also been described in detail.

Based on the sustainable development practice-zero growth in chemical fertilizer application, this article used bagasse organic fertilizer and rice husk derived biochar to investigate the response of soil bacterial community in apple orchard. Aimed at realize the soil quality improvement and biomass resource recovery to contribute agricultural and environmental sustainability. The co-trophic Proteobacteria was predominant in all the treatments (29–36 %) and enriched in non-nitrifying Alphaproteobacteria (9–11 %) and ammonia oxidant Betaproteobacteria (8–10 %), especially richest in bagasse fertilizer combine biochar treated soil. In addition, bacterial community variation was assessed by alpha and beta diversity, four treatments dispersed distribution and richer abundance observed in combined apply bagasse fertilizer and biochar treatment (3909.22 observed-species) than single application (3729.88 and 3646.58 observed-species). Biochar as microbial carrier combined organic fertilizer were established synergistic interaction and favorable to organic matter availability during sustainable agriculture. Finally, integrated biochar-bagasse fertilizer was richer than single organic or biochar fertilization in improving soil bacterial diversity, notably by promoting the metabolism of copiotrophic bacteria, nutrient cycling, plant growth and disease inhibit-related bacteria.

Increases in population and urbanization leads to generation of a large amount of food waste (FW) and its effective waste management is a major concern. But putrescible nature and high moisture content is a major limiting factor for cost effective FW valorization. Bioconversion of FW for the production of value added products is an eco-friendly and economically viable strategy for addressing these issues. Targeting on production of multiple products will solve these issues to greater extent. This article provides an overview of bioconversion of FW to different value added products.

Apple is among the most consumed fruits in the world and the expansion of their processing is increasing the generation of waste such as apple pomace. It finds some applications in food and feed systems, anaerobic digestion, and composting; however it most ends in landfills or in informal disposal. Therefore, waste management strategies that address this waste accumulation need to be explored. This review provides a state-of-art of valorization strategies adopted for recovery of value added products from apple processing-derived waste and discusses on their development stage. The research community has laid most of its efforts on incorporation of apple pomace into feed and food systems and in the development of pectin- and phenolics-extraction methods. Incorporation of apple pomace in feed and food systems is still negligible due to its low protein and high fiber contents. Therefore, coupling apple pomace with microbial conversion for nutritional upgrade could change this scenario. Some environmentally-friendly techniques have been developed for extraction of pectin and phenolics, but major developments are needed on their integration to attain tailored extraction of several compounds. Recovery of value added routes of apple pomace towards production of bio-chemicals are characterized by lack of deep research studies and of a holistic approach. Integrated approach with techno-economic analysis, life-cycle assessment, and inter-sectorial initiatives will possibly reveal the most promising valorization routes. 

Huge quantities of apple orchard waste (AOW) generated could be regarded as a promising alternative energy source for fuel and material production. Conventional and traditional processes for disposal of these wastes are neither economical nor environment friendly. Hence, sustainable technologies are required to be developed to solve this long-term existence and continuous growing problem. In light of these issues, this review pays attention towards sustainable and renewable systems, various value-added products from an economic and environmental perspective. Refined bio-product derived from AOW contributes to resource and energy demand comprising of biomethane, bioethanol, biofuels, bio-fertilizers, biochar, and biochemicals, such as organic acid, and enzymes. However, the market implementation of biological recovery requires reliable process technology integrated with an eco-friendly and economic production chain, classified management.