RESUMEN
The paper presents the results of investigations on the effectiveness and reaction rate constants of the oxidation of sulfide ions and organic sulfides in real industrial effluents from the production of bitumens (2000â¯mgâ¯S2-â¯L-1) using hydrodynamic and acoustic cavitation. The content of the effluents was analysed in terms carbon disulfide, dimethyl sulfide, and di-tert-butyl disulfide concentration. A possibility of complete oxidation of sulfides by cavitation alone as well as by its combination with external oxidants such as hydrogen peroxide, ozone or peroxone was demonstrated. The oxidation time for the most effective processes is as little as 15â¯min. Due to the presence of sulfide ions, the effluents from the production of bitumens were oxidized at a strongly alkaline pH. The results of this study reveal the advantage of performing advanced oxidation processes (AOPs) at a basic pH. The effective degradation of sulfide ions enables performance of further degradation of organic contaminants at an acidic pH, ensuring high efficiency of treatment based, for example, on the Fenton reaction without the risk of release of hydrogen sulfide to the atmosphere. The results of this research are applicable to all kinds of caustic effluents for which the lack of possibility of pH adjustment limits their efficient treatment.
RESUMEN
Cavitation has become on the most often applied methods in a number of industrial technologies. In the case of oxidation of organic pollutants occurring in the aqueous medium, cavitation forms the basis of numerous advanced oxidation processes (AOPs). This paper presents the results of investigations on the efficiency of oxidation of the following groups of organic compounds: organosulfur, nitro derivatives of benzene, BTEX, and phenol and its derivatives in a basic model effluent using hydrodynamic and acoustic cavitation combined with external oxidants, i.e., hydrogen peroxide, ozone and peroxone. The studies revealed that the combination of cavitation with additional oxidants allows 100% oxidation of the investigated model compounds. However, individual treatments differed with respect to the rate of degradation. Hydrodynamic cavitation aided by peroxone was found to be the most effective treatment (100% oxidation of all the investigated compounds in 60â¯min). When using hydrodynamic and acoustic cavitation alone, the effectiveness of oxidation was diversified. Under these conditions, nitro derivatives of benzene and phenol and its derivatives were found to be resistant to oxidation. In addition, hydrodynamic cavitation was found to be more effective in degradation of model compounds than acoustic cavitation. The results of investigations presented in this paper compare favorably with the investigations on degradation of organic contaminants using AOPs under conditions of basic pH published thus far.
RESUMEN
Utilization of cavitation in advanced oxidation processes (AOPs) is a promising trend in research on treatment of industrial effluents. The paper presents the results of investigations on the use of hydrodynamic cavitation aided by additional oxidation processes (O3/H2O2/Peroxone) to reduce the total pollution load in the effluent from the production of bitumens. A detailed analysis of changes in content of volatile organic compounds (VOCs) for all processes studied was also performed. The studies revealed that the most effective treatment process involves hydrodynamic cavitation aided by ozonation (40% COD reduction and 50% BOD reduction). The other processes investigated (hydrodynamic cavitation+H2O2, hydrodynamic cavitation+Peroxone and hydrodynamic cavitation alone) ensure reduction of COD by 20, 25 and 13% and reduction of BOD by 49, 32 and 18%, respectively. The results of this research revealed that most of the VOCs studied are effectively degraded. The formation of byproducts is one of the aspects that must be considered in evaluation of the AOPs studied. This work confirmed that furfural is one of the byproducts whose concentration increased during treatment by hydrodynamic cavitation alone as well as hydrodynamic cavitation aided by H2O2 as an external oxidant and it should be controlled during treatment processes.