Ruminal content biochar supplementation for enhanced biomethanation of rice straw: Focusing on biochar characterization and dose optimization.

Anaerobic digestion (AD) of agricultural wastes is a promising approach for energy recovery and crop residue management. However, its recalcitrant chemical structure hinders microbial hydrolysis and reduces biomethane production under AD. Biochar supplementation has been proven to promote the digestibility and biomethanation of lignocellulosic substrates. Therefore, this study investigated the influence of different pyrolysis temperatures (450 °C, 550 °C, and 650 °C) on the physicochemical properties of biochar. Furthermore, the impact of ruminal content biochar supplementation (1 %, 2 %, and 3 %) on the AD of rice straw with rumen fluid as inoculum has been investigated. The ruminal content biochar (RUCB) supplemented reactors showed an increment in biomethane yield and the highest cumulative biomethane yield 243.11 mL/g volatile solids (VS)) was recorded at 2 % RUCB supplementation, followed by 227.12 mL/g VS at 1 % RUCB supplementation and 162.86 mL/g VS at 3 % RUCB supplementation (P > 0.05). Compared to the control reactors (128.68 mL/g VS), RUCB supplemented reactors exhibited 1.88-fold, 1.76-fold, and 1.26-fold increments in biomethane yield due to pH stabilization and facilitation of microbial biofilm formation on the biochar. The correlation analysis showed that biomethane production is positively correlated with VS reduction (R2 = 0.9852). This study proposed a potential strategy to utilize ruminal content waste as a feedstock for biochar production and its application in AD for accelerating the biomethanation of rice straw.

Anaerobic digestion as a sustainable technology for efficiently utilizing biomass in the context of carbon neutrality and circular economy.

Carbon emissions and associated global warming have become a threat to the world, the major contributor being the extensive use of fossil fuels and uncontrolled generation of solid wastes. Energy generation from renewable energy sources is considered an alternative to achieving carbon neutrality. Anaerobic digestion (AD) is a sustainable technology that has been endorsed as a low-carbon technology complimenting both waste management and renewable energy sectors. The AD technology recovers the volatile matter from waste biomass as much as possible to produce biogas, thus reducing carbon emission as compared to open dumping or burning. However, there is a need of compilation of information on how each subsystem in AD contributes to the overall carbon neutrality of the entire system and chances of achieving a circular economy along with it. Therefore, this article aims to clarify the associated internal and external factors that determine the low carbon characteristic of anaerobic digestion technology. From this review, the potential of AD system for energy-atmosphere-agriculture nexus has been explored. Carbon emission mapping of the potential entities involved in AD were identified and perspective to life cycle assessment and future research direction has been pointed out. Climate change impact and acidification potential are the two entities that can influence the overall environmental sustainability of an AD system. It was recognized that each stage of AD system starting from substrate supply chain, biogas production, upgradation, utilization, and digestate application had a remarkable effect on the overall carbon emission potential based on its design, operation, and maintenance. Selection of suitable substrates and co-digesting them together for improved biogas production rate with high methane content and proper digestate post-processing and storage can vastly reduce the carbon emission potential of the AD technology. Further, a case scenario of India was assessed considering the utilization of major surplus biomass available through AD. Re-routing the three major substrates such as agricultural crop residues, animal wastes and organic fraction of municipal solid wastes through AD can reduce at least 3.5-3.8 kg CO2-eq per capita of annual carbon emission load in India. Furthermore, the pathways in which the policy and legislations over establishment of AD technology and how to explore linkages between achieving circular economy and low carbon economy for Indian scenario has been highlighted.

Biomimicry of ruminant digestion strategies for accelerating lignocellulose bioconversion in anaerobic digestion.

Biomimicking ruminant digestion strategies (RDSs) into anaerobic digestion (AD) enables efficient bioconversion of lignocellulosic biomass. Understanding RDSs is essential to translate their features into designing and developing bioprocesses and bioreactors. Here, we discuss insights into recently developed bioinspired bioprocesses, bioreactors, and future AD systems based on RDSs.

Why India is struggling to feed their young children? A qualitative analysis for tribal communities.

OBJECTIVE: This interdisciplinary qualitative study aims to explore the health, education, engineering and environment factors impacting on feeding practices in rural India. The ultimate goal of the Participatory Approach for Nutrition in Children: Strengthening Health Education Engineering and Environment Linkages project is to identify challenges and opportunities for improvement to subsequently develop socioculturally appropriate, tailored, innovative interventions for the successful implementation of appropriate infant and young child feeding (IYCF) practices locally. DESIGN: Qualitative research method, involving five phases: (1) identification of local feeding practices; (2) identification of the local needs and opportunities for children aged 6-24 months; and (3-5) analysis of the gathered qualitative data, intervention design, review and distribution. SETTING: Nine villages in two community development blocks, that is, Ghatol and Kushalgarh, located in the Banswara district in Rajasthan, India. PARTICIPANTS: 68 participants completed semistructured interviews or focus group discussions including: mothers, grandmothers, auxiliary nurse midwife, Anganwadi worker, ASHA Sahyogini, school teachers and local elected representative. PHENOMENON OF INTEREST: IYCF practices and the factors associated with it. ANALYSIS: Thematic analysis. RESULTS: Our results could be broadly categorised into two domains: (1) the current practices of IYCF and (2) the key drivers and challenges of IYCF. We explicate the complex phenomena and emergent model focusing on: mother's role and autonomy, knowledge and attitude towards feeding of young children, availability of services and resources that shape these practices set against the context of agriculture and livelihood patterns and its contribution to availability of food as well as on migration cycles thereby affecting the lives of 'left behind', and access to basic health, education and infrastructure services. CONCLUSIONS: This interdisciplinary and participatory study explored determinants impacting feeding practices across political, village and household environments. These results shaped the process for cocreation of our context-specific intervention package.

Role of schools in community mobilisation to improve IYCF practices in 6-24-month-old tribal children in the Banswara district, India: findings from the qualitative PANChSHEEEL study.

OBJECTIVE: India has been struggling with infant malnutrition for decades. There is a need to identify suitable platforms for community engagement to promote locally feasible, resource efficient Infant and Young Child Feeding (IYCF) interventions. This study aims to explore if and how schools could represent a site for community engagement in rural India, acting as innovation hubs to foster positive change in partnership with the Angawadi centres. DESIGN: Five-phase formative study; A parallel mixed methods approach structured by a socioecological framework was used for data collection at individual, household and community levels. This paper focuses on the qualitative findings. SETTING: This study was undertaken in nine villages within two blocks, 'Ghatol' and 'Kushalgarh', in the Banswara district of Rajasthan, India. PARTICIPANTS: 17 schools were identified. Interviews were conducted with local opinion leaders and representatives in the education sector, including principals, schoolteachers, block and district education officers. Across the nine study villages, information was gathered from 67 mothers, 58 paternal grandmothers using Focus Discussion Groups (FDGs) and 49 key respondents in Key Informant Interviews. RESULTS: Schools were considered an important community resource. Challenges included limited parental participation and student absenteeism; however, several drivers and opportunities were identified, which may render schools a suitable intervention delivery site. Enrolment rates were high, with schools and associated staff encouraging parental involvement and student attendance. Existing initiatives, including the mid-day meal, play opportunities and education on health and hygiene, further highlight the potential reliability of schools as a platform for community mobilisation. CONCLUSIONS: Schools have been shown to be functional platforms frequently visited and trusted by community members. With teachers and children as change agents, schools could represent a suitable setting for community mobilisation in future wider scale intervention studies. Expanding the supportive environment around schools will be essential to reinforce healthy IYCF practices in the long term.

Anaerobic digestion of sugarcane bagasse for biogas production and digestate valorization.

Sugarcane bagasse is an abundantly available agricultural waste having high potential that is still underutilized and mostly burnt as fuel. There are various processes available for bagasse utilization in improved ways and one such process is anaerobic digestion (AD) of bagasse for biogas production. The complex structure of biomass is recalcitrant to degradation and is a major hindrance for the anaerobic digestion, so different pretreatment methods are applied to deconstruct the bagasse for microbial digestion. In this review, different processes developed for the pretreatment of bagasse and their effect on biogas production have been extensively covered. Moreover, combination of pretreatment methods, co-digestion of bagasse with other waste (nitrogen rich or easily digestible) for enhanced biogas production and biomethane generation along with other value-added products has also been reviewed. The digestate contains a significant amount of organics with partial recovery of energy and products and is generated in huge amount that further creates disposal problem. Therefore, integration of digestate valorization with AD through gasification, pyrolysis, hydrothermal carbonization and use of microalgae for maximum recovery of energy and value-added products have also been evaluated. Thus, this review highlights major emerging area of research for improvement in bagasse based processes for enhanced biogas production along with digestate valorization to make the overall process economical and sustainable.

Biotechnological potential of rumen microbiota for sustainable bioconversion of lignocellulosic waste to biofuels and value-added products.

Lignocellulosic biomass is an abundant resource with untapped potential for biofuel, enzymes, and chemical production. Its complex recalcitrant structure obstructs its bioconversion into biofuels and other value-added products. For improving its bioconversion efficiency, it is important to deconstruct its complex structure. In natural systems like rumen, diverse microbial communities carry out hydrolysis, acidogenesis, acetogenesis, and methanogenesis of lignocellulosic biomass through physical penetration, synergistic and enzymatic actions enhancing lignocellulose degradation activity. This review article aims to discuss comprehensively the rumen microbial ecosystem, their interactions, enzyme production, and applications for efficient bioconversion of lignocellulosic waste to biofuels. Furthermore, meta 'omics' approaches to elucidate the structure and functions of rumen microorganisms, fermentation mechanisms, microbe-microbe interactions, and host-microbe interactions have been discussed thoroughly. Additionally, feed additives' role in improving ruminal fermentation efficiency and reducing environmental nitrogen losses has been discussed. Finally, the current status of rumen microbiota applications and future perspectives for the development of rumen mimic bioreactors for efficient bioconversion of lignocellulosic wastes to biofuels and chemicals have been highlighted.

Influence of gender and parental migration on IYCF practices in 6-23-month-old tribal children in Banswara district, India: findings from the cross-sectional PANChSHEEEL study.

BACKGROUND: The interdisciplinary Participatory Approach for Nutrition in Children: Strengthening Health, Education, Engineering and Environment Linkages (PANChSHEEEL) study used a participatory approach to develop locally-feasible and tailored solutions to optimise Infant and Young Child Feeding (IYCF) practices at an individual, household, community, and environmental level. This paper aims to evaluate the influence of gender; migration; and Health, Education, Engineering and Environmental (HEEE) factors on IYCF practices, with the primary outcomes being three key complementary-feeding practices of Minimum Dietary Diversity (MDD), Minimum Meal Frequency (MMF) and Minimum Acceptable Diet (MAD). METHODS: A cross-sectional survey of 325 households with children aged 6-23 months was conducted in nine purposively selected villages in two blocks of Banswara district, Rajasthan, India. A survey tool was developed, translated into the local language, pre-tested, and administered in a gender-sensitive manner. Data-collection processes were standardized to ensure quality measures. Association of the primary outcome with 27 variables was tested using a Chi-square test (Mantel-Haenszel method); backward stepwise regression analysis was conducted to assess the impact of effect modifiers (gender, parental migration). RESULTS: Half of the surveyed children were of each gender, and fathers from half of the households were found to have migrated within the previous year to search for additional income. Parental literacy ranged from 60 to 70%. More than half of the households had access to milk-producing animals. Consumption of each of the seven food groups, eggs (4.7% vs 0.7%; p < 0.02), MDD (10.5% vs 3.2%; p < 0.02) and MAD (9.4% vs 2.6%; p < 0.02) were higher for boys than for girls. After controlling for contextual factors, a male child was 4.1 times more likely to get a diet with MDD and 3.8 times more likely to get a diet with MAD. A child from a non-migrant household was 2.0-2.1 times more likely to get a diet with MDD and MAD as compared to a child from a migrant household. However, this association was not found to be statistically significant after regression. Presence of milk-producing animals in households and consumption of milk/milk products by children in the previous 24 h were the other two strong predictors of MDD and MAD, although access to animal milk in the house did not translate to an increase in consumption of milk/milk products by a child. CONCLUSION: Gender discrimination in diet diversity and complementary-feeding practices starts early in childhood with boys having a distinct advantage over girls. In the case of parental migration, further research is required to establish if it has an adverse impact on feeding practices. Emphasis needs to be given to gender issues and other contextual factors when developing strategies to optimise complementary feeding practices. TRIAL REGISTRATION: With UCL ethics [Ethics ID 4032/002] in United Kingdom and with Sigma IRB [10,025/IRB/D/17-18] in India.

Stabilization of anaerobic digestion of kitchen wastes using protein-rich additives: Study of process performance, kinetic modelling and energy balance.

Anaerobic digestion (AD) of acidic kitchen waste (KW) streams is found to be unstable and leads to poor overall efficiency. This study assessed the effect of pongamia de-oiled cake addition on KW-AD. High acidic KW (pH: 2.00-5.00), medium acidic KW (pH: 5.00-7.00) and low alkaline KW (pH: 7.00-8.00) fed into digesters I, II and III at 10% total solids (TS) achieved biogas yields of 177.82 ± 19.30, 216.57 ± 7.42 and 280.45 ± 2.55 L/kg VS. d, respectively. Maximum synergistic effect of pongamia de-oiled cake was observed in digester I with increased methane production of 46.04% and volatile solids reduction of 11.18%. The principal component analysis and kinetic evaluation revealed that pongamia de-oiled cake addition had a positive effect on the AD parameters in all digesters. With energy efficiencies exceeded 96% in all the digesters, the study proposes the addition of protein-rich additives for KW-AD stabilization.

Enhanced biogas production from municipal solid waste via co-digestion with sewage sludge and metabolic pathway analysis.

The present study intends to evaluate the potential of co-digestion for utilizing Organic fraction of Municipal Solid Waste (OFMSW) and sewage sludge (SS) for enhanced biogas production. Metagenomic analysis was performed to identify the dominant bacteria, archaea and fungi, changes in their communities with time and their functional roles during the course of anaerobic digestion (AD). The cumulative biogas yield of 586.2 mL biogas/gVS with the highest methane concentration of 69.5% was observed under an optimum ratio of OFMSW:SS (40:60 w/w). Bacteria and fungi were found to be majorly involved in hydrolysis and initial stages of AD. Probably, the most common archaea Methanosarsina sp. primarily followed the acetoclastic pathway. The hydrogenotrophic pathway was less followed as indicated by the reduction in abundance of syntrophic acetate oxidizers. An adequate understanding of microbial communities is important to manipulate and inoculate the specific microbial consortia to maximize CH4 production through AD.

Evaluation of biogas upgrading technologies and future perspectives: a review.

Biogas is acknowledged as one of the foremost bioenergy to address the current environmental and energy challenges being faced by the world. Commonly, biogas is used for applications like cooking, lighting, heat and power production. To widen the scope of biogas application, like transportation, natural gas grid injection and substrate for the production of chemicals and fuel cells, mainly CO2, H2S and other impurities need to be removed by various upgrading technologies. It is an important process to produce biomethane with above 90% methane. There are various physico-chemical (adsorption, absorption, cryogenic and membrane separations) and biological (in situ and ex situ) processes for biogas upgradation, and each process is site and case specific. The aim of the present paper is to thoroughly evaluate the existing and emerging biogas upgrading technologies. Analysis of each technology with respect to basis of operations, energy requirement, methane purity and recovery and cost economics has been carried out. A thorough analysis has been done on the major hurdles and the research gaps in this sector. For a wider and successful implementation of the biogas upgradation technology, the trends in research and development (R&D) such as development of efficient biogas upgrading technologies, adsorbents, reduction in cost and methane loss have been thoroughly evaluated.

Assessment of methane emissions and energy recovery potential from the municipal solid waste landfills of Delhi, India.

Rising rate of MSW generation and unscientific disposal in the open dumping sites are responsible for emission of high concentrations of methane in developing countries. IPCC Default method (DM), First-order decay (FOD) and LandGEM were used to estimate methane emissions from the unengineered landfill sites of Delhi-Okhla, Bhalswa and Ghazipur between 1984 and 2015. During the period, the total CH4 emissions was found to be 1288.99, 311.18, 779.32 Gg from the 3 landfill sites of Delhi as predicted by DM, FOD and LandGEM respectively. The energy generation potential from methane for the year 2015 was found to vary from 4.16 × 108 to 9.86 × 108 MJ for Ghazipur, 2.08 × 108 to 4.06 × 108 MJ for Okhla and 3.42 × 108 to 8.11 × 108 MJ for Bhalswa. Efficient utilization of methane from the landfills as an energy source can be a sustainable waste management option.

Characterization of leaf waste based biochar for cost effective hydrogen sulphide removal from biogas.

Installation of decentralized units for biogas production along with indigenous upgradation systems can be an effective approach to meet growing energy demands of the rural population. Therefore, readily available leaf waste was used to prepare biochar at different temperatures and employed for H2S removal from biogas produced via anaerobic digestion plant. It is found that biochar prepared via carbonization of leaf waste at 400 °C effectively removes 84.2% H2S (from 1254 ppm to 201 ppm) from raw biogas for 25 min in a continuous adsorption tower. Subsequently, leaf waste biochar compositional, textural and morphological properties before and after H2S adsorption have been analyzed using proximate analysis, CHNS, BET surface area, FTIR, XRD, and SEM-EDX. It is found that BET surface area, pore size, and textural properties of leaf waste biochar plays a crucial role in H2S removal from the biogas.

Algae mediated treatment and bioenergy generation process for handling liquid and solid waste from dairy cattle farm.

In the present work four algae were tested for their biomass production potential in neat livestock wastewater. Chroococcus sp.1 was found to be the best for biomass production under controlled (2.13 g L(-1)) and outdoor conditions (4.44 g L(-1)) with >80% of nutrients removal. The produced biomass was then digested with cattle dung as cosubstrate. Interestingly, up to 291.83 ± 3.904 mL CH4 g(-1) VS fed was produced during codigestion studies (C/N ≈ 13.0/1). In contrast to this, only 202.49 ± 11.19 and 141.70 ± 2.57 mL CH4 g(-1) VS fed was recorded with algae (C/N ≈ 9.26/1) and cattle dung (C/N ≈ 31.56/1) alone, respectively. The estimated renewable power generation potential of the investigated coupled process was around 333.79-576.57 kW h d(-1) for a dairy farm with 100 adult cattle. However, further scale-up and testing is needed to make this process a reality.

Bioconversion of algae to methane and subsequent utilization of digestate for algae cultivation: a closed loop bioenergy generation process.

The present investigation was targeted on anaerobic digestion of Chroococcus sp. and utilization of resultant "Liquid Digestate" for its further biomass production. The algal biomass has biomethane potential of 317.31 ± 1.9 mL CH4 g(-1) VSfed. Regular process monitoring revealed that process was stable throughout the experiments. The "Liquid Digestate" was explored as nutrient supplement for further algal growth. Diluted "Liquid Digestate" (30% concentration) was found optimal for algal growth (0.79 ± 0.064 g L(-1)). Simultaneously, 69.99-89.31% removal in nutrient and sCOD was also recorded with algal growth. Interestingly, higher growth was observed when rural sector wastewater (1.29 ± 0.067 g L(-1)) and BG11 broth (1.42 ± 0.102 g L(-1)) was used for diluting the "Liquid Digestate". The current findings have practically proven the feasibility of hypothesized "closed loop process".

Phycoremediation coupled production of algal biomass, harvesting and anaerobic digestion: possibilities and challenges.

Biogas produced from anaerobic digestion is a versatile and environment friendly fuel which traditionally utilizes cattle dung as the substrate. In the recent years, owing to its high content of biodegradable compounds, algal biomass has emerged as a potential feedstock for biogas production. Moreover, the ability of algae to treat wastewater and fix CO2 from waste gas streams makes it an environmental friendly and economically feasible feedstock. The present review focuses on the possibility of utilizing wastewater as the nutrient and waste gases as the CO2 source for algal biomass production and subsequent biogas generation. Studies describing the various harvesting methods of algal biomass as well as its anaerobic digestion have been compiled and discussed. Studies targeting the most recent advancements on biogas enrichment by algae have been discussed. Apart from highlighting the various advantages of utilizing algal biomass for biogas production, limitations of the process such as cell wall resistivity towards digestion and inhibitions caused due to ammonia toxicity and the possible strategies for overcoming the same have been reviewed. The studies compiled in the present review indicate that if the challenges posed in translating the lab scale studies on phycoremediation and biogas production to pilot scale are overcome, algal biogas could become the sustainable and economically feasible source of renewable energy.

Phycoremediation and biogas potential of native algal isolates from soil and wastewater.

The present study is a novel attempt to integrate phycoremediation and biogas production from algal biomass. Algal isolates, sp. 1 and sp. 2, obtained from wastewater and soil were evaluated for phycoremediation potential and mass production. The estimated yield was 58.4 sp. 1 and 54.75 sp. 2 tons ha(-1) y(-1). The algal isolates reduced COD by >70% and NH3-N by 100% in unsterile drain wastewater. Higher productivities of sp. 1 (1.05 g L(-1)) and sp. 2 (0.95 g L(-1)) grown in wastewater compared to that grown in nutrient media (0.89 g L(-1) for sp. 1 and 0.85 g L(-1) for sp. 2) indicate the potential of algal isolates in biogas production through low cost mass cultivation. Biogas yield of 0.401-0.487 m(3) kg(-1) VS added with 52-54.9% (v/v) methane content was obtained for algal isolates. These results indicate the possibilities of developing an integrated process for phycoremediation and biogas production using algal isolates.