Abstract
The study presents the results of the research which aimed to estimate the opportunities for increasing the efficiency of humic substances (HS) adsorption on active carbon (AC). The modification was carried out through exposure of HS solution to 20 kHz ultrasonic field (amplitude 114 µm, time 1 min.). The processes of sonication of the solution caused disintegration of high-molecular compounds into compounds of lower mass (more easily adsorbed and biodegraded), and creation of highly-oxidizing radicals. The research was conducted in four systems: sorption, sono-sorption, biosorption and sono-biosorption. A solution of the humic substances was provided by a commercial formulation of humic acid salt concentration of 20 mg/L. The substrate was sonicated partially, each time by 0,25 L. The research was conducted in filtration columns (diameter 25 x 10-2 m), packed with AC (ROW 08 Supra), up to the level of 0.5 m. The process of HS biodegradation, which was conducted on biological filters with AC layer inoculated with suspension of microorganisms and left for 60 days in order to be colonized (oxygen conditions and access to nutrients was ensured). The biological filter was created based on microorganisms from biopreparation and activated sludge. Analysis of efficiency of these processes was verified by parameters such as: DOC, absorption at UV254, oxygen consumption, colour, pH. The bacterial count on three levels of the bed and in the eluate from columns was also measured. In the solutions where biodegradation occurred the amount of the dissolved oxygen was measured in order to evaluate the EMS index (which defines intensity of sorption and biosorption processes). The results obtained in the study demonstrated that carbon filters colonized by microflora operated 100 % longer. Furthermore, no significant improvement in the process was observed after using the method of sorption combined with exposure to ultrasounds. DOC analysis revealed that after the same flow time, through the column, depletion of HS is higher in beds sorbing HS solution modified with ultrasounds. Advantageous influence of ultrasound modification was confirmed in the effects of work of the column with biopreparation.
