Combustion of Sewage Sludge: Kinetics and Speciation of the Combustible

Abstract

Combustion of sewage sludge has become a viable route for sewage sludge management 9 especially as the agricultural use of sewage sludge has become increasingly difficult due to more stringent requirements on the quality of the sewage sludge. Combustion of digested sewage sludge in dedicated 11 mono-combustion facilities is advantageous, as it substantially reduces the volume of the sludge and still 12 allows for a recovery of phosphorus from the sewage sludge ash at a later stage. Despite increasing 13 amounts of sewage sludge being combusted, our knowledge on the respective combustion kinetics is still 14 fragmentary. The goal of this study was, therefore, to identify the major combustion reactions of sewage 15 sludge, assess their Arrhenius parameters (activation energy, pre-exponential factor) and assign suitable 16 reference compounds to the individual reactions. For that purpose, experiments were conducted using a 17 thermogravimetric analyzer (TGA). With matrix inversion, we identified 10 individual reactions. Despite 18 the apparent kinetic compensation most likely caused by insufficient precision of the TGA temperature 19 setting, we were able to relate the major reactions of sewage sludge combustion to the combustion of 20 individual reference compounds. In addition to cellulose and lignin which dominated the weight loss with 21 35% and 20% respectively, hemicellulose, xylan, alginate, and calcite were identified. The dominant 22 fraction of cellulose is consistent with recent studies identifying cellulose mainly originating from toilet 23 paper as a major constituent in wastewater. As the identified model compounds explain more than 80% of 24 the total weight loss observed, our approach allows a rough speciation of the combustible of sewage 25 sludge based on TGA experiments.

Evaporation of Metals during the Thermal Treatment of Oxide Nanomaterials in Cellulose-Based Matrices

“…An effect of a change in the ICP plasma conditions, which can be caused by the evaporated carbon compounds, is excluded. Indeed the maximum evaporation of carbon species (i.e., from cellulose) was about 330 °C, 30,31 at which no significant signal change of all measured elements was observed.…”

Release of gold (Au), silver (Ag) and cerium dioxide (CeO2) nanoparticles from sewage sludge incineration ash

“…The formation of Ca(OH) 2 in the ash column occurred through the initial contact of the electrolyte with CaO which forms during sewage sludge incineration and potentially induces pozzolanic activity. 31,[33][34][35][36] The Ca concentration in the fly ash was 24 000 mg kg −1 . The dissolution of Ca(OH) 2 released 2 mol of OH − per mol of Ca and thus buffered the pH at the measured value of 12.7 during the first 70 pv.…”

Combustion characteristics of biomass and bituminous coal co-firing in non-isothermal and isothermal conditions

“…The atmosphere in the furnace was 21% O2/79% N2 and the gas flow rate was 100 mL/min. Repeated thermogravimetric experiments were carried out (Wielinski et al 2018), and the number of repetitions for the same sample was 3 times.…”