The investigation of solid slag obtained by neutralization of sewage sludge

Abstract

The purpose of this research is to investigate the feasibility of utilizing the slag collected after gasification of organic fuel combined with sewage sludge. The residue left after gasification process is likely usable as raw material for production of supercondensers. The sewage sludge neutralization system consists of a dosing system (fuel tank), gasifier, plasma reactor, electrostatic filter, and heat exchangers. For the gasification process, dried solid sewage is supplied in proportion of 70% to biomass 30% by weight. The slag is collected in a specially designed chamber beneath the gasifier. A scanning electron microscope (SEM) was used to evaluate surface morphology of the samples. Elemental analysis of the sewage sludge slag was performed using the energy-dispersive spectroscopy (EDS) method, which showed different solid-state elements contained in the porous structure of the solid phase: carbon 29%, aluminum 26%, potassium 20%, chlorine 1%, and others. The specific surface area of the sewage sludge slag is 6.15 m 2 /g as the BET analysis shows. In order to use the slag as a secondary raw material, detailed analysis of the structure and properties is necessary for a decision on whether the slag left after gasification of sewage sludge is suitable for any further usages. Initial results indicate that the slag may be used for production of electrodes for supercapacitors.Implications: Every year thousands of tons of sewage sludge are formed in Lithuania. Sewage sludge consists of organic and inorganic compounds. Partial combustion, plasma decomposition, and other methods are used to neutralize the sewage sludge. The incineration of sewage sludge results in generation of solid-phase slag. In this paper the material structure and composition of a solid slag (formed during neutralization of sewage sludge) is considered. Also, the impact the ambient temperature on structure and composition of solid slag is analyzed.

Removal of lithium and uranium from seawater using fly ash and slag generated in the CFBC technology

“…Similar results for the slag composition analysis were found in the literature. 41,42 The thermogravimetric analyses of both materials showed weight loss (TGA) with an increase in temperature from 29 C to 600 C (Fig. SM7 and SM8, ESI †).…”

“…Similar results for the FT-IR analysis of y ash and slag have been presented in the literature. 42,[52][53][54][55] The zeta potentials were determined in our previous studies. This parameter is important in many industrial applications, such as wastewater treatment and others related to environmental protection.…”

Biomasės ir atliekų dujinimo tyrimai Lietuvoje: esama būklė ir ateities perspektyvos

“…Tęsiant dujinimo procesų tyrimų kryptį, vykdyti dar trys dideli projektai, kurie sprendė atskiras dujinimo proceso problemas: šilumos rekuperavimo ir deginimo įrenginių sukūrimą siekiant pakeisti gamtines dujas žemo kaloringumo dujomis [3], biomasės dujinimo proceso optimizavimą kaloringoms dujoms gaminti [4] bei sausinto nuotėkų dumblo terminio skaidymo technologijos sukūrimą [5,6].…”

Investigation of the biofuel flue and producer gases cleaning efficiency using ESP

“…After passing the ESP, cleaned gas was transported by a fan to the gas boiler, and prepared flammable gas-air mixture was combusted. A more detailed description of the experimental setup is presented in [6].…”

“…The producer gas (flow rate ~ 62 m 3 /h) with a temperature of about 550°C entered the air plasma unit, which is needed for the neutralization of hazardous chemicals (dioxins, furans, etc. [6]), and existed as generated producer gas. The processed hot producer gas of about 1100°C from the plasma unit was supplied to the water-cooled gas cooler, where the temperature of the gas was decreased, and the gas with a temperature of ~160°C entered the electrostatic precipitator.…”