E. Nowicka, K. Grübel, A. Machnicka
University of Bielsko-Biala, Faculty of Materials and Environmental Sciences, Institute of Environmental Protection and Engineering, Bielsko-Biala, PL
IMPACT OF CHEMICAL-THERMAL DISINTEGRATION OF ACTIVATED SLUDGE ON EFFICIENCY OF MESOPHILIC AND THERMOPHILIC DIGESTION PROCESS
The use of chemical-thermal disintegration of activated sludge against anaerobic stabilization of sludge contributes to the intensification of organic compound decomposition and increase the efficiency of the process compared to the fermentation of raw activated sludge. The paper presents the results of research on the effect of the hybrid disintegration process using alkalization (pH = 9) and freezing/thawing by dry ice (1: 1 dry ice), on the surplus activated sludge and on the mesophilic and thermophilic digestion. As a result of the studies, it was found that the chemical-thermal disintegration process of the surplus activated sludge results in the increase of the concentration of organic matter in the supernatant (expressed as a change in the COD value). The introduction of disintegrated sludge into the fermentation reactors causes, depending on its volume share in the reactors, the higher biogas production and the increase of biogas yield. The hybrid process is easy and simple to implementation at technical scale and does not affect on the pH value of the influent sludge to the fermentation chambers (dry ice neutralizes the previously alkalized sludge).
Keywords: activated sludge, alkalization, freezing/thawing, methane fermentation