What is the potential for biogas digesters to improve soil fertility and crop production in Sub-Saharan Africa?

Acknowledgements We are very grateful to the UK Department for International Development (DFID) New and Emerging Technologies Research Call for funding this work. PS is a Royal Society-Wolfson Research Merit Award holder.Peer reviewedPostprin

Biomethanation and Alkaline Wet Air Oxidation of Water Hyacinth (\u3cem\u3ePontederia crassipes\u3c/em\u3e) from Ozama River, Dominican Republic

Obtaining valuable products from environmental remediation waste is a sustainable approach that contributes to the ecological well-being of developing countries. In the present work, the feasibility of the water hyacinth anaerobic digestion as a post-weed management practice in the Ozama River (Dominican Republic) was demonstrated. The estimated energy required for harvesting was lower than that produced during digestion. The biomethanation of water hyacinth was improved by Alkaline Wet Air Oxidation (AWAO), a thermochemical pretreatment process that almost doubled the methane production rate and increased the yield by 24% when conducted at high temperatures. At lower temperatures, the methane yield of the AWAO water hyacinth was more than 40% higher than the unpretreated biomass. After subjecting water hyacinth to high temperature and low alkali AWAO, the addition of poultry litter biochar, a residue from thermochemical processing, improved the biomethanation kinetics of the system. This dissertation not only contains valuable information for the scale-up of the water hyacinth’s biomethanation as a biorefinery process in developed countries but also contributes to the development of sustainable \u27from waste to product\u27 technologies in developing countries like the Dominican Republic

Effects of biochar parent material and microbial pre-loading in biochar-amended high-solids anaerobic digestion

This study characterises the effect of biochar (pyrolysed biomass) produced from wood pellets, wheat straw and sheep manure on high-solids anaerobic digestion (HSAD) of poultry litter. Also, pre-loading biochar with microorganisms before addition to HSADs was investigated. The addition of wood pellet biochar provides a 32% increase to the methane yield compared with control digesters. The addition of biochar produced from either wheat straw or sheep manure has detrimental effects on digester performance compared with controls. The addition of wood pellet biochar pre-loaded by placing it in a high-solids digester for 90 days provides a 69% increase in the total methane yield, 44% increase in the peak daily methane yield and a 33% reduction in the lag time compared with controls. This study highlighted a need for careful selection of parent material for biochar production and, for the first time, the opportunities to re-use wood pellet biochar for further improvements.Mathu Indren, Cristian H. Birzer, Stephen P. Kidd, Tony Hall, Paul R. Medwel

Management of poultry manure in Poland : current state and future perspectives

This review aimed to analyse the current state of management practices for poultry manure in Poland and present future perspectives in terms of technologies allowing closing the loops for circular economy, and thus recovery of nutrients and energy. The scope of the review focused primarily on: (1) the analysis of poultry production and generation of poultry manure with special references to quantities, properties (e.g. fertilizing properties), seasonality, etc.; (2) the overview of current practices and methods for managing poultry manure including advantages and limitations; (3) the analysis of potential and realistic threats and risk related to managing poultry manure, and also (4) the analysis of promising technologies for converting poultry manure into added value products and energy. The review addressed the following technologies: composting of poultry manure to obtain fertilizers and soil improvers, anaerobic digestion of poultry manure for energy recovery, and also pyrolysis of poultry manure into different types of biochar that can be applied in agriculture, horticulture and industry. Poultry manure is rich in macro- and micronutrients but also can contain various contaminants such as antibiotics or pesticides, and thus posing a realistic threat to soil and living organisms when applied to soil directly or after biological treatment. The main challenge in poultry manure processing is to assure sufficient closing of carbon, nitrogen and phosphorous loops and safe application to soil

Effect of total solids content on anaerobic digestion of poultry litter with biochar

Methane production via anaerobic digestion of poultry litter provides a pathway for energy production from an abundant waste product. Recent studies have shown the use of biochar (pyrolysed biomass) can decrease methane production lag times and increase peak daily yields from ammonia-stressed low-solids anaerobic digesters. Due to the variety of feedstocks and digester configurations used, research to date has not yet determined the effect of biochar addition as a function of the digester total solids content. This study shows the addition of biochar reduces the lag time by a greater percentage in the digesters with a higher total solids content. There was a 17%, 27% and 41% reduction lag time due to biochar addition at total solids contents of 5%, 10% and 20%, respectively. The peak daily methane yield increased by 136% at 10% total solids. There was no significant increase in the peak yield at 5% total solids, while there was a 46% increase at 20% total solids. Real-time PCR analysis confirms the Methanosaetaceae family, which is a key methanogen due to its ability to facilitate direct interspecies electron transfer while attached to biochar, preferentially attaches to biochar. Furthermore, this research shows the attachment of the Methanosaetaceae family, does not decrease with increasing total solids content. A potential negative effect of biochar addition, a reduced volumetric efficiency, can be negated by using a shorter retention time. This new understanding will help to improve predictions of the impact of biochar addition for new digester designs operating in semi-solids and high-solids conditions.Mathu Indren, Cristian H.Birzer, Stephen P.Kidd, Paul R.Medwel

INCREASING EFFICIENCY AND SUSTAINABILITY OF WASTE-TO-ENERGY SYSTEMS USING BIOCHAR FOR HYDROGEN SULFIDE CONTROL AND LIFE CYCLE ASSESSMENT

The research aim was to increase energy production efficiency and reduce the environmental impacts of waste-to-energy technologies, specifically anaerobic digestion (AD) of dairy manure (DM) and combustion of poultry litter (PL). The first objective was co-digestion of DM with gummy vitamin waste (GVW) to increase methane (CH4) yield. The GVW co-digestion treatments significantly increased CH4 yield by 126% - 151% compared to DM-only treatment and significantly decreased the H2S concentration in the biogas by 66% - 83% compared to DM-only. The second objective was understanding the effect of hydrogen sulfide (H2S) scrubber management, operation, and maintenance parameters on H2S removal efficiency. Even though the capital and operating costs for the two H2S scrubbing systems in this study were low (< $1500/year), they showed ineffective performance due to insufficient air injection, substitution of proprietary iron oxide-based H2S adsorbents for cheaper alternatives, and the lack of dedicated operators. The third objective was adsorption of H2S using Fe-impregnated biochar as a substitute for activated carbon (AC). Fe-impregnation of biochar led to a 4.3-fold increase in the H2S adsorption capacity compared to AC. When compared to unimpregnated biochars, Fe-impregnation led to an average 3.2-fold increase in the H2S adsorption capacity. The fourth objective was in-situ use of biochar in AD to remove H2S. In-situ biochar addition at the highest dose (1.82 g biochar/g manure total solids (TS)) resulted in an average H2S removal efficiency of 91.2%. Biochar particle size had no significant effect on H2S reduction. In-situ addition of Fe-impregnated biochar resulted in an average H2S removal efficiency of 98.5%. The fifth objective was a life cycle assessment (LCA) of a PL fluidized bed combustion (FBC) system. The LCA assessment showed that heating poultry houses using heat obtained from the combustion of PL in the FBC system had 32% lower climate change potential (CCP) compared to use of propane for heating poultry houses. However, analyzing the FBC system under a net positive electrical output scenario resulted in 66% less impact on CCP and a 48 – 98% reduction in environmental impacts compared to the previous scenario with net electricity input

The influence of biochar position in a leach bed system anaerobically digesting chicken litter

As a consequence of the rapidly growing poultry industry, chicken litter is becoming an abundant and problematic waste. Anaerobic digestion of chicken litter can mitigate environmental issues while producing valuable by-products. Recent studies have shown that leach bed reactor (LBR) systems are suitable for processing chicken litter and that anaerobic digestion can be enhanced using biochar. This study investigates the influence of biochar position within an LBR system on anaerobic digestion of chicken litter. Compared to a system without biochar, application of biochar in both the LBR (mixed in with the feedstock or as a layer below the feedstock) and coupled leachate tank (LT) increased methane yield by 6 to 8% at 51 days and accelerated VFA degradation and methane production. More significant differences in methane yield were observed at shorter solid retention times. Biochar mixed in feedstock in addition to a filter in the LT performed best in terms of both methane and hydrogen sulfide production, with a 77% reduction in hydrogen sulfide yield and hydrogen sulfide contents maintained below 500 ppm. The enhanced rates of VFA degradation and methane production when applying biochar in both reactors corresponds with observed differences in the methanogen population. Biochar application in both reactors increased the abundance of Methanobacteriales in digestate and Methanosarcinaceae in leachate compared to the control. Microbial attachment and activity on biochar also increased when mixed in feedstock. Increased diversity of the methanogen population throughout the system, as well as increased activity on biochar, may have facilitated the syntrophic relationship between acetogenic bacteria and methanogens, thus accelerating VFA degradation and methane production. These results suggest mixing biochar in feedstock, in addition to a biochar filter in the LT, to enhance anaerobic digestion of chicken litter in this system.Ben A. Collins, Cristian H. Birzer, Stephen P. Kidd, Tony Hall, Paul R. Medwel

Performance Assessment of Solid State Anaerobic Digestion of Poultry Litter

The disposal of poultry litter can exert an economic and environmental burden to the agriculture community. As a result, it is desirable to reduce the amount of waste and recover resources from the waste. This study focuses on the construction and preliminary testing of a laboratory scale (20 L) solid state anaerobic digester (AD) fed with dry poultry litter. Glucose was added in addition to the poultry litter to achieve the appropriate C:N ratio to support the growth of anaerobic microorganisms. The AD was first fed every 4 days at 4 g VS/L/feeding for 24 days, rested (no feeding) for 32 days, and then at 8 g VS/L/feeding every 4 days for 24 days, followed with 33 days of no feeding. During the experiment the following parameters were measured: total solids (TS), volatile solids (VS), total nitrogen (TN), total carbon (TC), chemical oxygen demand (COD), pH, and biogas yield and composition. Throughout the experiment, as the litter accumulated in the AD, TS, VS, TC, TN, and COD all increased gradually. pH however showed a dramatic decrease to 5.2, which is likely the main reason for the low biogas yield and near zero CH4 production. It is recommended to closely monitor pH and buffer it to a near neutral range to sustain the growth of methanogens

Proceedings...

PRESENTATION AND EDITORIAL COMMENTS : Sustainable alternatives that promote economic circularity through the use of agroindustrial residues is a strategic challenge for companies to remain competitive and to generate new business models. The Brazilian Society of Agricultural and Agro-industrial Waste Management (Sbera) is the result of reflection, pioneering spirit and citizen commitment of professionals who intend to contribute to the evolution of the environmental condition of two large complexes of extreme social, economic and cultural importance for Brazilian agriculture and the agro-industrial sector. Found in 2008, Sbera promotes the International Symposium on Agricultural and Agro-industrial Waste Management (SIGERA) with the objective of fostering scientific debate and presenting technological alternatives to waste from the agro-industrial chain. The VII SIGERA, held online from 3 to 5 November 2021, was addressed the developments resulting from the Climate Conference (COP26) as the agreements made by 130 countries to cut methane emissions by 30% by the year 2030, demonstrating opportunities for biotechnology based industries for waste-to-energy use combined with the mitigation of greenhouse gas emissions. During the debates, the importance of technological alternatives based on bioprocesses to amplify aspects related to economic circularity and enable environmental, social and corporate governance were also established. The VII edition of symposium athered 460 subscriptions, including 372 paper authors and 150 attendant, including academic professors, researchers, undergraduate and graduate students from several Brazilian universities and research centers, as well as specialist professionals from Argentina, Chlie, Colombia, Germany, Mozambique, Spain, USA and Uruguay. In this edition, 120 abstracts were received. Of these, 114 are presented in this proceedings, grouped by 7 topics: - Technologies for waste transformation, reuse and disposal - By-products application for agricultural, forestry and livestock use - Environmental impacts to the air, soil, water and plant system - Waste to energy - Refractory and persistent substances - One health and food safety - CasesComissão organizadora: Ricardo L. R. Steinmetz, Helen Treichel, Vinicius Benites , Francisco Salazar Sperberg, María Cristina Diez, Fabiane Goldschmidt Antes, Vanessa Theodoro Rezende, Julio Cesar Pascale Palhares, Heidi Schalchli, Aline Frumi Camargo, Thamarys Scapini, Camila Michels, Gabriela Bonassa