Abstract
Due to the more and more serious cyanobacteria bloom problem, it is particularly urgent to find a technology suitable for large-scale disposal and the efficient recovery of abundant nitrogen and phosphorus resources in cyanobacteria. The combination of chemical looping combustion (CLC) and biomass densification technology is thought to be a promising utilization selection. Based on the experimental results, the mechanical strength and energy density of briquette cyanobacteria are evidently increased with the compressive load; whereas, 10% is the optimal moisture content in the densification process. A higher heating rate in TGA would result in the damage of the internal structure of the briquette cyanobacteria, which are conducive to the carbon conversion efficiency. The presence of a hematite oxygen carrier would enhance the carbon conversion and catalyzed crack liquid products. CO2 yield is increased 25 percent and CH4 yield is decreased 50 percent at 900 °C in the CLC process. In addition, the lower temperature and reduction atmosphere in CLC would result in a lower NO emission concentration. The reactivity and porous property of hematite OC in CLC also increased during 10 redox cycle experiments. The CLC process accelerates the generation of CaH2P2O7 and CaHPO4 in cyanobacteria ash, which is more conducive to phosphorus recovery.
Highlights
With the development of industry and agriculture, a large number of industrial sewage and domestic wastewater carrying nitrogen and phosphorus nutrients are continuously imported into the surrounding rivers, contributing to serious eutrophication [1,2]
The performances of briquette cyanobacteria during raw material preparation and in the chemical looping combustion (CLC) process are analyzed in three reactors (Table 3): single briquetting unit and pressure crushing detector to study the densification process, especially for the binding effect under different densification conditions; thermogravimetric reactor to study the mechanisms of mechanical strength evolution and thermochemical transformation of briquette cyanobacteria, including the drying, devolatilization and char burnout processes; single fluidized bed to study the thermochemical transformation of briquette cyanobacteria and the cyclical performance of hematite in the CLC of briquette cyanobacteria
Following the drying process or first break, the devolatilization process would take first break, the devolatilization process would take place Following and result the in adrying secondprocess break oforthe briquette cyanobacteria, which are conducted in place and result in a second break of the briquette cyanobacteria, which are conducted in thermogravimetric analyzer (TGA) under N2 atmosphere (1 L/min)
Summary
With the development of industry and agriculture, a large number of industrial sewage and domestic wastewater carrying nitrogen and phosphorus nutrients are continuously imported into the surrounding rivers, contributing to serious eutrophication [1,2]. Through the biomass densification technology, the cost of handling and conveyance is decreased and particle size distribution could be controlled and more uniform Another problem, a large amount of tar produced in the combustion process, is tricky. The combination of CLC utilization and biomass densification thought be a cyanobacteria is increased, and tarwhere cracking, andcyaphospromising cyanobacteria utilization selection, the NO energy densityreduction of briquette x emission phorus recovery may be realized. The present work aims to investigate the characteristics of briquette cyanobacteria as a tar can be catalyzed cracking to small-molecular-weight gases by iron oxide [34]. The NOx release rule in CLC is compared to that in the conventional reactivity stability, the morphological feature of hematite OC and phosphorus recovery combustion process. Reactivity stability, the morphological feature of hematite OC and phosphorus recovery possibility in the of briquette cyanobacteria
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