Oxidation of municipal sewage sludge, chicken and swine manure in the water-oxygen fluid flow under uniform heating

Abstract

The paper presents the research results of the oxidation of municipal sewage sludge (MSS), chicken (CM) and swine (SM) manure when pumping water-oxygen fluid through their bed at a uniform temperature increase (1.5 K/min) to 733 K. Temperature dependences were obtained for the yield of volatile and liquid products, as well as data on the content of mineral components in the ash residue and water, collected at the reactor outlet. From the time-dependent temperature of the reactor wall, the power of resistive heaters, and the degree of total organic carbon removal, it follows that most of the organic matter of biowastes is oxidized at T < 643 K. It is shown that the rate of organic carbon removal increases in the sequence: CM < MSS < SM, and is determined by the consumption of oxygen supplied to the reactor. According to IR spectroscopy and ultimate analysis data, an increase in the oxidation duration and temperature leads to a decrease in the content of functional groups, and to an increase in the proportion of aromatic compounds in liquid products. Liquid products, formed during the oxidation of CM are characterized by the highest N/C atomic ratio. It was revealed that during the oxidation of biowastes, from 50% to 75% of nitrogen passes into the aqueous phase in the form of NH4+ ions, while the main elements (Si, Ca, Mg, P, K, and Al) are concentrated in the ash residue. The results of XRD analysis show that CaCO3 and SiO2 predominate in the composition of ash residues of CM and SM, respectively.