Regulation of the physicochemical and biotechnological process parameters of the liquid-phase aerobic degradation of nitrocellulose-containing wastewater sludge

Abstract

The physicochemical process parameters of the liquid-phase aerobic degradation of nitrocellulose- containing sludge from the Aleksin Chemical Industrial Complex was studied by laboratory simulation with the use of activated indigenous microflora. The intensification of the aeration process and the saturation of sediments with atmospheric oxygen in a concentration of no lower than 7.7 (mg O₂)/L, the maintenance of the pH values of a bioreactor medium in an alkaline range (7.8–8.0), and the moistening of bottom sediments to 90% led to a nitrocellulose removal efficiency of no lower than 55.1% after 31 days. The kinetic characteristics of the fermentation process were determined: the rate constant of nitrocellulose degradation was 0.032 day^–1 and the half-life time was 22 days. Upon the annealing of sediment after fermentations, it was found that the residual combustible component was most likely pure cellulose, which was formed as a result of the degradation (elimination of nitro groups) of parent nitrocellulose. An activated sludge concentrate (10% on a total sediment weight basis) with a 99% moisture content and a 18.7% ash content from the Aleksin Aeration Station was added to the test sediment mass in order to enrich indigenous microflora and to increase the efficiency of nitrocellulose biodegradation. The stimulating influence of activated sludge microorganisms on the biodegradation of nitrocellulose was not detected because of their low cellulolytic activity.