Mineral residue accelerant-enhanced anaerobic digestion of cow manure: An evaluation system of comprehensive performance

CO2 agitation combined with magnetized biochar to alleviate "ammonia inhibited steady-state": Exploring the mechanism by combining metagenomics with macroscopic indicators

The "ammonia inhibited steady-state" phenomenon is frequently observed in the anaerobic digestion (AD) process of nitrogen-rich substrates. Reconfiguring microbial ecosystems has proven to be an effective strategy for mitigating ammonia inhibition. In the current study, biochars were screened and targeted for modification. CO2 agitation combined with magnetized biochar was used to aid the semi-continuous AD systems with "ammonia inhibited steady-state." The results indicated that coconut shell biochar had the best stimulating effect on AD performance. The content of oxygen-containing functional groups (OCFGs), which had a positive correlation with the electron donating capacity (EDC), was targeted to be regulated. This strategy significantly increased the CH4 yield by 31.7 % (from 344 to 278 mL/g VS) (p < 0.05). Isotope tracing and KEGG gene annotation indicated that this strategy stimulated the efficiency of the hydrogenotrophic pathway. Simultaneously, it accelerated the attachment of microorganisms, which made the DIET pathway between bacteria and archaea efficient. Under CO2 agitation, the attachment of functional microorganisms to the biochar accelerated. Biochar weakened the synthesis of bioelectronic carriers (Cyt-c and chemosensory pili), while the electroactivity of the AD system was enhanced. This means that biochar replaced bioelectronic carriers and improved the DIET efficiency. In addition, the strategy had a positive effect on the colonization of simultaneous nitrification-denitrifying bacteria (Georgenia), which led to a decrease in ammonia nitrogen concentrations. This study revealed the mechanism by which this strategy alleviates ammonia inhibition and provided a promising strategy for the efficient AD of nitrogen-rich substrates.

Enhancing biogas production from cattle manure: A circular economy approach with solar thermal pretreatment and soil conditioning

Biogas production from cattle manure, pivotal for sustainable waste and energy management, encounters challenges from its low digestibility linked to lignocellulosic structures. This study investigates biogas efficiency enhancement through anaerobic digestion coupled with solar thermal (ST) pretreatment and digestate application in Napier grass cultivation (STAD-G). ST pretreatment at 40-60 °C for 20 h markedly increases methane yield, validated by pilot-scale trials that exhibited a 3.9-fold surge in methane production, attributed to improved acidification. Untreated manure's structure, however, impedes acidification, slowing methanogenesis as shown by lower volatile fatty acid concentration in effluents. In addition, utilizing digestate as soil conditioner notably improves grass yield (19.3 ± 0.8 ton dry/ha/year) and protein content, akin to urea fertilizer. Furthermore, the STAD-G system incurs higher upfront costs, it yields superior biogas efficiency and enhanced long-term financial returns. This integrated approach, by boosting economic and environmental sustainability, advocates for ST pretreatment as a key strategy in advancing sustainable agriculture and energy solutions.

Data quantifying the behaviour of macro and trace elements along the feed - manure - treated waste continuum in pig production

Manure from animal production is commonly spread on agricultural soil as an organic fertiliser to provide macro and trace elements to crops. However, some trace elements can accumulate in the soil and become toxic to plants and microorganisms. These elements include copper (Cu) and zinc (Zn), which can be applied in large quantities when pig manure is spread. The feeding strategy and manure management (e.g. through treatment chains) are two mechanisms identified to better control the use of these elements, but their fate from the feed to the soil in pig production remains poorly documented. Better understanding the fate of Cu and Zn, as well as that of other trace and macro elements, along the feed - excreta - waste chain is required to develop alternative ways to reduce their environmental impacts. This dataset provides insight into the composition (Cu, Zn and other trace and macro elements) of organic products along two contrasting manure management chains: (1) only storage or (2) in-building separation, anaerobic digestion (AD) of solids, and digestate drying. Feed, raw slurry, liquid and solid phases after separation of the manure and AD products were sampled and then analysed to measure their total compound contents.

Enhanced methane production in microbial electrolysis cell coupled anaerobic digestion system with MXene accelerants

Accelerants can improve the anaerobic performance of a microbial electrolysis cell coupled anaerobic digestion (MEC-AD). MAX phase titanium aluminum carbide (MAX), multilayer Ti₃C₂T_X MXene (ML-MXene) and few-layer Ti₃C₂T_X MXene (FL-MXene) were utilized as accelerants for MEC-AD to promote CH₄ production and CO₂ reduction at a voltage of 0.6 V. The highest CH₄ yield (358.7 mL/g VS) and the lowest CO₂ yield (57.4 mL/g VS) relative to the control group (170.6 and 125.1 mL/g VS) were obtained in MEC-AD with ML-MXene (0.035 wt%). The digestates of MEC-AD with 0.035 wt% ML-MXene have superior thermal stability (40.9%) and total nutrient content (42.1 g/kg). The ML-MXene enhanced the abundances of Methanosarcina and Methanobacterium. This work highlights the possible role of MXene in promoting methanogenesis. These important findings provide a novel avenue for the development of MXene accelerants for MEC-AD systems.