Thermal conversion behavior and nitrogen‐containing gas products evolution during co‐pyrolysis of cow manure and coal: A thermal gravimetric analyzer/differential scanning calorimetry–mass spectrometer investigation

Optimization of semi-continuous dry anaerobic digestion process and biogas yield of dry yellow corn straw: Based on "gradient anaerobic digestion reactor"

In China, the problem of low biogas yield of traditional biogas projects has become increasingly prominent. This study investigated the effects of different hydraulic retention times (HRTs) on the biogas production efficiency and microbial community under pilot conditions. The results show that the "Gradient anaerobic digestion reactor" can stably carry out semi-continuous dry anaerobic digestion and improve biogas yield. The highest volatile solids (VS) biogas yield (413.73 L/kg VS and 221.61 L CH4/kg VS) and VS degradation rate (48.41%) were observed at an HRT of 25 days. When the HRT was 15 days, the volumetric biogas yield was the highest (2.73 L/L/d, 1.43 L CH4/L/d), but the VS biogas yield and degradation rate were significantly decreased. Microbial analysis showed that HRT significantly affected microbial community. It provides basic data support for the development of a new anaerobic digestion process and the practical application of the straw biogas project in China.

Algae Pyrolysis in Molten NaOH-Na2CO3 for Hydrogen Production

Biomass pyrolysis within the alkaline molten salt is attractive due to its ability to achieve high hydrogen yield under relatively mild conditions. However, poor contact between biomass, especially the biomass pellet, and hydroxide during the slow heating process, as well as low reaction temperatures, become key factors limiting the hydrogen production. To address these challenges, fast pyrolysis of the algae pellet in molten NaOH-Na₂CO₃ was conducted at 550, 650, and 750 °C. Algae were chosen as feedstock for their high photosynthetic efficiency and growth rate, and the concept of coupling molten salt with concentrated solar energy was proposed to address the issue of high energy consumption at high temperatures. At 750 °C, the pollutant gases containing Cl and S were completely removed, and the HCN removal rate reached 44.92%. During the continuous pyrolysis process, after a slight increase, the hydrogen yield remained stable at 71.48 mmol/g-algae and constituted 86.10% of the gas products, and a minimum theoretical hydrogen production efficiency of algae can reach 84.86%. Most importantly, the evolution of physicochemical properties of molten NaOH-Na₂CO₃ was revealed for the first time. Combined with the conversion characteristics of feedstock and gas products, this study provides practical guidance for large-scale application of molten salt including feedstock, operation parameters, and post-treatment process.

Improving production of lactic acid and volatile fatty acids from dairy cattle manure and corn straw silage: Effects of mixing ratios and temperature

Anaerobic co-fermentation (AcoF) of dairy cattle manure (DCM) and corn straw silage (CSS) for producing lactic acid (LA) and volatile fatty acids (VFAs) was investigated. Batch experiments were conducted at seven different DCM/CSS ratios and at mesophilic and thermophilic temperatures. Results indicated that the highest concentration of LA was 17.50 ± 0.70 g/L at DCM:CSS ratio of 1:3 and thermophilic temperature, while VFAs was 18.23 ± 2.45 g/L at mono-CSS fermentation and mesophilic temperature. High solubilization of thermophilic conditions contributed to LA accumulation in AcoF process. Presence of the CSS increased the relative abundance of Lactobacillus for LA production at thermophilic. Meanwhile, the abundance of Bifidobacterium was increased when CSS was added at mesophilic, which could conduce to VFAs production. This study provides a new route for enhancing the biotransformation of DCM and CSS into short-chain fatty acids, potentially bringing economic benefits to agricultural waste treatment.

On-Line Thermally Induced Evolved Gas Analysis: An Update-Part 1: EGA-MS

Advances in on-line thermally induced evolved gas analysis (OLTI-EGA) have been systematically reported by our group to update their applications in several different fields and to provide useful starting references. The importance of an accurate interpretation of the thermally-induced reaction mechanism which involves the formation of gaseous species is necessary to obtain the characterization of the evolved products. In this review, applications of Evolved Gas Analysis (EGA) performed by on-line coupling heating devices to mass spectrometry (EGA-MS), are reported. Reported references clearly demonstrate that the characterization of the nature of volatile products released by a substance subjected to a controlled temperature program allows us to prove a supposed reaction or composition, either under isothermal or under heating conditions. Selected 2019, 2020, and 2021 references are collected and briefly described in this review.