Biogas Production from Anaerobic Co-Digestion of Spent Mushroom Substrate with Different Livestock Manure

Replacing traditional nursery soil with spent mushroom substrate improves rice seedling quality and soil substrate properties

Currently, large quantities of spent mushroom substrate (SMS) are produced annually. Because SMS has high water retention and nutrients, it has great potential to replace traditional topsoil for raising seedlings in agricultural production. However, few studies have examined the effects of substituting SMS for paddy soil on rice seedling growth and soil nutrients. SMS was mixed with rice soil in different proportions (20%, 50%, and 80%), and chemical fertilizer, organic fertilizer, and peat substrate were added in addition to equivalent nitrogen as a traditional seedling nursery method for comparison. Compared to traditional paddy soil (CK), the seedling qualities of the three SMS ratio treatments were all higher. Adding SMS at different ratios promoted rice seedling root growth, elevated the soluble protein concentration, and amplified the superoxide dismutase (SOD) enzymatic action in rice seedlings. Total porosity and aeration porosity of the soil increased by 17.40% and 32.90%, respectively. Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) increased by 21.26-118.48%, 50.44-71.68%, and 23.08-80.17%, respectively. Besides, the relative abundance of Bacillus, Bacteroidetes, and other bacteria as well as the abundance of Ascomycota were all significantly increased. Adding 50% SMS increased the abundance of Pseudomonas by 8.42 times. The seedling quality of the 50% SMS treatment was even higher than chemical fertilizer and organic fertilizer treatments, only second to the peat substrate treatment. In summary, partial substitution of paddy soil with SMS can ameliorate substrate properties, improve seedling quality, and increase microbial diversity, indicating the suitability of SMS as a replacement for rice soil in seedling substrates. The 50% SMS ratio is the best. This study provides a basis for SMS to replace traditional rice soil in seedling cultivation.

Hydrogen and methane production through two stage anaerobic digestion of straw residues

Anaerobic digestion of agricultural waste can contribute to the European renewable energy needs. The 71% of the 20,000 anaerobic digestion plants in operation already uses these agro-waste as feedstock; part of these plants can be converted into two stage processes to produce hydrogen and methane in the same plant. Biomethane enriched in hydrogen can replace natural gas in grids while contributing to the sector decarbonisation. Straw is the most abundant agricultural residue (156 Mt/y) and its conventional final fate is uncontrolled soil disposal, landfilling, incineration or, in the best cases, composting. The present research work focuses on the fermentation of spent mushroom bed, an agricultural lignocellulosic byproduct, composed mainly from wheat straw. The substrate has been characterized and semi-continuous tests were performed evaluating the effect of the hydraulic retention time on hydrogen and volatile fatty acids production. It was found that all the tests confirmed the feasibility of the process even on this lignocellulosic substrate, and also, it was identified HRT 4.0 d as the best option to optimize the productivity of volatile fatty acids (17.09 gCODVFAs/(KgVS*d)), and HRT 6.0 d for hydrogen (7.98 LH2/(KgVS*d)). The fermentation effluent was used in biomethanation potential tests to evaluate how this process affects a subsequent digestion phase, reporting an increase in the energetical feedstock exploitation up to 30%.

Effects of Flammulina velutipes mushroom residues on growth performance, apparent digestibility, serum biochemical indicators, rumen fermentation and microbial of Guizhou black goat

Introduction

The primary objective of the current study was to evaluate the effects of Flammulina velutipes mushroom residue (FVMR) in a fermented total mixed ration (FTMR) diet on the fattening effect and rumen microorganisms in Guizhou black male goats.

Methods

A total of 22 Guizhou black male goats were allocated into two groups using the Randomized Complete Block Design (RCBD) experimental design. The average initial weight was 22.41 ± 0.90 kg and with 11 goats in each group. The control group (group I) was fed the traditional fermentation total mixed ration (FTMR) diet without FVMR. Group II was fed the 30% FVMR in the FTMR diet.

Results

The results showed that compared with group I, the addition of FVMR in the goat diet could reduce the feed cost and feed conversion ratio (FCR) of group II (p < 0.01). Notably, the apparent digestibility of crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and dry matter (DM) were higher in group II (p < 0.01). The levels of growth hormone (GH), immunoglobulin A (IgA), and immunoglobulin M (IgM) in group II were higher than that of group I (p < 0.01), which the level of glutamic oxalacetic transaminase (ALT) and interleukin-6 (IL-6) was noticeably lower than that of group I (p < 0.01). 30% FVMR in FTMR diets had no effect on rumen fermentation parameters and microbial composition at the phylum level of Guizhou black male goats (p > 0.05). However, at the genus level, the relative abundance of bacteroidal_bs11_gut_group, Christensenellaceae_R-7_group and Desulfovibrio in group II was lower than in group I (p < 0.05), and the relative abundance of Lachnospiraceae_ND3007_group was higher than in group I (p < 0.01).

Discussion

In conclusion, the results of the current study indicated that 30% FVMR in the FTMR diet improves rumen fermentation and rumen microbial composition in Guizhou black male goats, which improves growth performance, apparent digestibility, and immunity.

Unlocking the Potential of Spent Mushroom Substrate (SMS) for Enhanced Agricultural Sustainability: From Environmental Benefits to Poultry Nutrition

In this comprehensive review, we delve into the myriad applications of spent mushroom substrate (SMS) in agricultural contexts, with a particular emphasis on its role in fostering sustainable poultry production. Our examination spans three key domains: the use of SMS in fertilizers, its impact on environmental factors and gas emissions, and its contribution to poultry nutrition. This review synthesizes findings from multiple studies that underscore the potential of composted SMS as a viable alternative to conventional inorganic fertilizers, effectively meeting crop nutrient needs while mitigating groundwater contamination risks. Moreover, we highlight the substantial environmental advantages associated with the utilization of SMS and poultry waste, including reductions in greenhouse gas emissions and the promotion of sustainable waste management practices. Additionally, we explore the promising outcomes of integrating SMS into animal feed formulations, which have demonstrated significant enhancements in livestock growth performance and overall health. In sum, this review underscores the versatility and untapped potential of SMS as a valuable agricultural resource, with a particular focus on its role in advancing sustainable practices, optimizing nutrient management, and harnessing the value of organic waste materials, especially in the context of poultry production.

Utilization of agricultural residues for energy and resource recovery towards a sustainable environment

Fungal pre-treatment using Pleurotus ostreatus (PO) was carried out on individual and combinations of agro-waste wheat straw (WS), rice straw (RS), and pearl millet straw (PMS) with the addition of biochar (5%,7.5% and 10%) to reduce the pre-treatment duration. Further remaining substrate known as spent mushroom substrate (SMS) was used in anaerobic digestor (AD) for estimation enhanced biomethane yield. Equal ratios of RS + WS, WS + PMS, PMS + RS, and RS + PMS + WS and biochar addition were taken for enhancing pre-treatment, PO growth and AD process. The extent of pre-treatment was recorded with the maximum lignin removal of 40.4% for RS + PMS + WS as compared to untreated counterparts and 0.5%, 2.2%, and 3.3% times more lignin removal from individual PMS, RS, and WS respectively. Addition of biochar to the substrates reduced the total pre-treatment duration by days as compared to the non-biochar substrates. Biological efficiency (BE) used for the analysis of mushroom growth varied from 51-92%. Further, the average bio-methane yield was 187 ml/gVS for SMS of PMS + WS + RS with 10% biochar indicating an increment of 83.33% from untreated SMS of PMS + WS + RS. This, higher biomethane yield was 9.35%, 22.22% and 57.14% times higher than individual SMS of PMS, RS, and WS respectively. The current study shows that biochar not only enhances the bio-methane yield but also reduces the biological pre-treatment duration and removes the dependency on one lignocellulosic biomass for energy (bio-methane) and food (mushroom) production.

Spent Mushroom Substrate Hydrolysis and Utilization as Potential Alternative Feedstock for Anaerobic Co-Digestion

Valorization of lignocellulosic biomass, such as Spent Mushroom Substrate (SMS), as an alternative substrate for biogas production could meet the increasing demand for energy. In view of this, the present study aimed at the biotechnological valorization of SMS for biogas production. In the first part of the study, two SMS chemical pretreatment processes were investigated and subsequently combined with thermal treatment of the mentioned waste streams. The acidic chemical hydrolysate derived from the hydrothermal treatment, which yielded in the highest concentration of free sugars (≈36 g/100 g dry SMS, hydrolysis yield ≈75% w/w of holocellulose), was used as a potential feedstock for biomethane production in a laboratory bench-scale improvised digester, and 52 L biogas/kg of volatile solids (VS) containing 65% methane were produced in a 15-day trial of anaerobic digestion. As regards the alkaline hydrolysate, it was like a pulp due to the lignocellulosic matrix disruption, without releasing additional sugars, and the biogas production was delayed for several days. The biogas yield value was 37 L/kg VS, and the methane content was 62%. Based on these results, it can be concluded that SMS can be valorized as an alternative medium employed for anaerobic digestion when pretreated with both chemical and hydrothermal hydrolysis.

Applications of artificial intelligence in anaerobic co-digestion: Recent advances and prospects

Anaerobic co-digestion (AcoD) offers several merits such as better digestibility and process stability while enhancing methane yield due to synergistic effects. Operation of an efficient AcoD system, however, requires full comprehension of important operational parameters, such as co-substrates ratio, their composition, volatile fatty acids/alkalinity ratio, organic loading rate, and solids/hydraulic retention time. AcoD process optimization, prediction and control, and early detection of system instability are often difficult to achieve through tedious manual monitoring processes. Recently, artificial intelligence (AI) has emerged as an innovative approach to computational modeling and optimization of the AcoD process. This review discusses AI applications in AcoD process optimization, control, prediction of unknown input/output parameters, and real-time monitoring. Furthermore, the review also compares standalone and hybrid AI algorithms as applied to AcoD. The review highlights future research directions for data preprocessing, model interpretation and validation, and grey-box modeling in AcoD process.

Valorization of spent mushroom substrate for low-carbon biofuel production: Recent advances and developments

Due to the nutritional values and functional bioactivities of mushrooms, the global market value of the edible mushroom industry has been growing steadily. However, the production of 1 kg of fresh mushroom generates about 5 kg of wet byproducts (known as spent mushroom substrate; SMS). This necessitates proper waste management to mitigate potential environmental threats. Embracing the "waste-to-fuel" concept, SMS as lignocellulosic waste can serve as cheap and abundant feedstock for the production of a variety of biofuels, including biogas, biohydrogen, bioethanol, bio-oil, and solid-biofuels. Mushroom cultivation serves as efficient biological pretreatment for biofuel production, promoting biofuel yield and improving the overall economy. Therefore, integrated mushroom cultivation and biofuel production can simultaneously satisfy the rapidly rising food and energy demand. The article systematically reviewed the recycling and re-utilization of SMS in sustainable biofuel production, discussing the possible challenges and proposing future directions for the green development of the mushroom industry.

A new type of calcium-rich biochars derived from spent mushroom substrates and their efficient adsorption properties for cationic dyes

Adsorption is commonly accepted as a most promising strategy in dye wastewater treatment, and the widespread use of adsorption emphasizes the need to explore low-cost but excellent adsorbents. Herein, a low-cost adsorbent (calcium-rich biochar) was developed, which was directly pyrolyzed from spent mushroom substate without any modification. This study evaluated the potential application of two calcium-rich biochars (GSBC and LSBC) derived from spent substrates of Ganoderma lucidum and Lentinus edodes, respectively. The effects of pyrolysis temperature on the calcium-rich biochars characteristics and their adsorption mechanism for cationic dyes (Malachite Green oxalate (MG) and Safranine T (ST)) were studied systematically. The increase in pyrolysis temperature from 350 to 750 °C led to an increase in both biochar ash, Ca content, and specific surface area, which made high-temperature biochars (GS750 and LS750) the superior adsorbents for cationic dyes. Batch adsorption results showed LS750 was more efficient to adsorb dyes than GS750 attributed to its higher Ca content and larger specific surface area. According to the Langmuir model, LS750 had high adsorption capacities of 9,388.04 and 3,871.48 mg g⁻¹ for Malachite green and ST, respectively. The adsorption mechanism of dye MG could be attributed to pore filling, hydrogen bonding, electrostatic interaction, ion exchange, and π-π stacking, while ST adsorption mainly involved pore filling, electrostatic interaction, ion exchange, and π-π stacking. Attributed to their excellent adsorption performance, cheap source, and good reusability, biochars obtained from SMSs were very promising in dyeing wastewater treatment.

Biotransforming the Spent Substrate of Shiitake Mushroom (Lentinula edodes Berk.): A Synergistic Approach to Biogas Production and Tomato (Solanum lycopersicum L.) Fertilization

Agro-wastes, such as crop residues, leaf litter, and sawdust, are major contributors to global greenhouse gas emissions, and consequently a major concern for climate change. Nowadays, mushroom cultivation has appeared as an emerging agribusiness that helps in the sustainable management of agro-wastes. However, partial utilization of agro-wastes by mushrooms results in the generation of a significant quantity of spent mushroom substrates (SMS) that have continued to become an environmental problem. In particular, Shiitake (Lentinula edodes Berk.) mushrooms can be grown on different types of agro-wastes and also generate a considerable amount of SMS. Therefore, this study investigates the biotransformation of SMS obtained after Shiitake mushroom cultivation into biogas and attendant utilization of slurry digestate (SD) in tomato (Solanum lycopersicum L.) crop fertilization. Biogas production experiments were conducted anaerobically using four treatments of SMS, i.e., 0% (control), 25, 50, and 75% inoculated with a proportional amount of cow dung (CD) as inoculum. The results on biogas production revealed that SMS 50% treatment yielded the highest biogas volume (8834 mL or 11.93 mL/g of organic carbon) and methane contents (61%) along with maximum reduction of physicochemical and proximate parameters of slurry. Furthermore, the biogas digestate from 50% treatment further helped to increase the seed germination (93.25%), seedling length (9.2 cm), seedling root length (4.19 cm), plant height (53.10 cm), chlorophyll content (3.38 mg/g), total yield (1.86 kg/plant), flavonoids (5.06 mg/g), phenolics (2.78 mg/g), and tannin (3.40 mg/g) contents of tomato significantly (p < 0.05) in the 10% loading rate. The findings of this study suggest sustainable upcycling of SMS inspired by a circular economy approach through synergistic production of bioenergy and secondary fruit crops, which could potentially contribute to minimize the carbon footprints of the mushroom production sector.

Exploring Farm Anaerobic Digester Economic Viability in a Time of Policy Change in the UK

The combination of a post-Brexit agricultural policy, the Global Methane Pledge announced during the last United Nations Climate Change Conference in Glasgow (COP26), and urgency of meeting climate goals means the UK has a unique opportunity to create an exemplar through recognition of the benefits of small-scale farm anaerobic digesters that valorise on-site wastes for renewable electricity and heat, cushioning agri-businesses against energy perturbations. To explore economic viability of farm-based biogas production, combinations of support levels, energy prices, capital cost, internal rate of return (IRR), and digestate value were analysed, employing a 550-cow dairy farm with access to other agricultural wastes. A 145 kWe system utilising 100% of CHP electricity (grid value: £0.1361 per kWh) and 70% of the heat (heating oil value: £0.055 per kWh) could achieve an IRR above 15.5% with a median electricity tariff of £0.1104 per kWh at a heat tariff from £0.0309 to £0.0873 per kWh thermal. Under a subsidy-free regime, the same system could achieve a 10% IRR with electricity prices in the range £0.149 to £0.261 per kWh. High fertiliser prices could increase digestate value, further improving viability. With late-2021 high energy prices, the technology approaches subsidy-free viability, but uptake is unlikely unless wider environmental and societal benefits of on-farm systems can be explicitly valued.

The Effects of Using Pretreated Cotton Gin Trash on the Production of Biogas from Anaerobic Co-Digestion with Cow Manure and Sludge

Anaerobic co-digestion (AcoD) has been practiced for decades to convert waste into value-added energy products, especially biogas. This study aimed to assess the potential of biogenic methane (CH4) production from the co-digestion of pretreated cotton gin trash (CGT), cow manure, and sludge. CGT contains high cellulosic content, making it a reliable feedstock for biogenic methane production. To further improve the biogas quantity and quality, the CGT was subjected to physical pretreatments, i.e., hot water (HW), ultra-sonication (US), and a combination of both (HW+US). After 91 days of AcoD, 79–110 L of biogas was produced by the treatments. Among the treatments, HW+US-pretreated CGT presented maximum biogas production capacity, at 110 L. Besides, this treatment showed the high-quality biogenic CH4 content, 52.4% of the total biogas volume, with an improved conversion rate of 0.37 L/g of volatile suspended solids consumed. In addition, this study discussed the structural changes in feedstock due to pretreatments and correlated them with the corresponding biogenic methane production. The study reports the potential of pretreated CGT conversion to CH4. It will impact the circular economy by contributing to on-farm energy requirements and reducing the financial expenditures incurred in this regard.

Recent advances and future directions on the valorization of spent mushroom substrate (SMS): A review

Commercial mushrooms are cultivated on lignocellulose wastes, such as corncob, saw dust, straw and wood chips. Following the rapidly increasing global mushroom production, the efficient recycling and utilization of the by-product, known as spent mushroom substrate (SMS) has garnered much attention due to the serious pollution issues caused. Embracing the concept of 'circular economy', the SMSs have demonstrated immense potential in wide range of applications, including recycling as the substrate for new cultivation cycle of mushroom, biofertilizer and soil amendment, animal feed, renewable energy production and pollution bioremediation. The review provided an overview and recent advances focusing on these applications, analyzed the possible challenges and proposed future directions for sustainable development of global mushroom industry.

Anaerobic Co-Digestion of Sheep Manure and Waste from a Potato Processing Factory: Techno-Economic Analysis

Anaerobic co-digestion of sheep manure and potato waste was studied under batch and semi-continuous conditions. Biochemical methane potential tests were carried out for the different substrates before evaluating co-digestion at high-solid content. The reactors presented stable performance under mesophilic conditions, at an organic loading rate (OLR) of 3.5–4.0 kg VS/m3 and a hydraulic retention time (HRT) of approximately 20 days. Increasing the OLR of semi-continuous reactors decreased the methane yield and degradation efficiency of the digestion. Methane-specific production was in the range of 196 and 467 mL CH4/g vs. (sheep manure system and co-digestion, respectively). Based on the experimental data obtained, a techno-economic study was performed for wet and solid-state fermentation systems, with the first configuration presenting better results. The economic feasibility of the hypothetical plant was analyzed considering the variability in electricity and compost selling prices. The economic feasibility of the plant was determined with an electricity selling price of EUR 0.25/kWh, and assuming a centralized plant serving several farmers. Still, this price was considered excessive, given the current electricity market values.

Biogas Production from Coffee Pulp and Chicken Feathers Using Liquid- and Solid-State Anaerobic Digestions

Agricultural waste, particularly lignocellulose, has been used in the second generation of biogas. Coffee pulp and chicken feathers can be developed as biogas raw materials because of their suitability as a biogas substrate. This study investigates the effect of the percentage of total solids (TS), carbon to nitrogen ratio (C/N, g/g), and delignification pretreatment on biogas production from coffee pulp and chicken feathers, and aims to compose kinetics using the modified Gompertz model. The results show that adjusting the percentage of TS at low-level speeds up the degradation process, which increases chemical oxygen demand (COD) reduction and biogas production. COD reduction and biogas production increase optimally at the 25 (g/g) C/N ratio. Pretreatment delignification aids microorganisms in substrate decomposition, resulting in faster COD reduction and biogas conversion. The 25% TS and 25 (g/g) C/N ratio with the delignification process achieved the best biogas production, with biogas production of 10,438.04 mL. The Gompertz method shows that the difference in TS percentage can influence biogas production. Moreover, the method shows that biogas production is higher with the delignification process than without it.