Fluidized Bed Incineration of Sewage Sludge in O₂/N₂ and O₂/CO₂ Atmospheres

Abstract

Sewage sludge incineration in a fluidized bed is considered to be one of the most suitable ways of sewage sludge disposal. This process reduces the volume of the waste and causes the destruction of organic contaminants such as POPs, pharmaceuticals, and other compounds with endocrine-disrupting potential. Oxygen-enriched air combustion and oxy–fuel combustion can increase the combustion efficiency, reduce the amount of flue gas, and make possible CO2 capture more effective. However, the influence of incineration medium composition has not yet been thoroughly investigated in the case of sewage sludge incineration. In this paper, the incineration of sewage sludge in a bubbling fluidized bed reactor was studied at oxygen-enriched air conditions, oxy–fuel conditions, and oxy–fuel conditions with zero and nonzero concentrations of steam, CO, NO, N2O, and SO2 in the inlet combustion medium. Consequently, the effects of various operating parameters on pollutants formation were comprehensively described with emphasis on aforementioned sewage sludge incineration processes. An increase in combustion temperature resulted in an increase in NO x and SO2 emissions and in a decrease in N2O emissions. Increase in inlet oxygen concentration led to a decrease in NO x and N2O emissions. N2O and SO2 emissions were higher in CO2-rich atmosphere (oxy–fuel combustion conditions). The presence of water vapor in the inlet combustion medium resulted mainly in the reduction of NO x emissions. The presence of CO, NO, N2O, and SO2 in the dry inlet combustion medium reduced mainly overall nitrogen-to-NO x conversion, while the effect on SO2 removal efficiency was only marginal.

Detailed Analysis of Sewage Sludge Pyrolysis Gas: Effect of Pyrolysis Temperature

“…Most of the impurities from wastewater are concentrated in the sludge, which makes it a potentially hazardous material; therefore, safe and reasonable disposal must be applied. Sewage sludge is typically disposed of using incineration [2], agriculture application (as soil fertilizer or part of the compost) and landfilling [3]; however, economic and rigorous environmental requirements limit these methods considerably. Alternatively, pyrolysis of sewage sludge has been proposed to be able to overcome the burdens of conventional sludge disposal management [4][5][6][7].…”

Sewage Sludge Thermal Treatment Technologies with a Focus on Phosphorus Recovery: A Review

“…For combustion of SS, both circulating fluidized bed (CFB) and bubbling fluidized bed (BFB) based technologies can be applied. BFB furnaces are used for mono-combustion of SS, while CFB technology is mainly considered for cocombustion of the sludge with coal, biomass, or other fuels [56]. Li et al [57] reported that after fluidized bed combustion of SS, 89.3% of the P was enriched in SS bottom ash and 5.6% was distributed in fly ash.…”

Effect of the Dried and Hydrothermal Sludge Combustion on Calcium Carbonate Decomposition in a Simulated Regeneration Reactor of Calcium Looping

“…NO x in the flue gas mainly comes from the conversion of fuel-nitrogen in HTS samples in the regeneration reactor. The NO x emission characteristics of the coal or dried sludge combustion under the O 2 /CO 2 atmosphere have been reported in many literature. , However, reports focused on the effect of the hydrothermal temperature on the NO x emissions of HTS samples under the O 2 /CO 2 atmosphere are few.…”