Paper evaluates hydrodynamic cavitation as a method for wastewater treatment. In collaboration with Faculty of Mechanical Engineering and Faculty for Civil and Geodetic Engineering, University of Ljubljana we evaluated the efficiency of hydrodynamic cavitation for removing micropollutants, e.g. pharmaceutical residues, from wastewaters. In this study, the removal of clofibric acid, ibuprofen, naproxen, ketoprofen, carbamazepine and diclofenac residues from wastewater, using a novel shearinduced cavitation generator has been systematically studied. The effects of temperature, cavitation time and H2O2 dose on removal efficiency were investigated. Optimisation (50 °C; 15 min; 340 mg L−1 of added H2O2) resulted in removal efficiencies of 47–86% in spiked deionised water samples. Treatment of actual wastewater effluents revealed that although matrix composition reduces removal efficiency, this effect can be compensated for by increasing H2O2 dose (3.4 g L−1) and prolonging cavitation time (30 min). Hydrodynamic cavitation has also been investigated as either a pre or a post treatment step to biological treatment. The results revealed a higher overall removal efficiency of recalcitrant diclofenac and carbamazepine, when hydrodynamic cavitation was used prior to as compared to post biological treatment i.e., 54% and 67% as compared to 39% and 56%, respectively. This is an important finding since diclofenac is considered as a priority substance to be included in the EU Water Framework Directive.
The aim of this paper is to present a survey on the current status of wastewater treatment systems in 11 central and eastern European (CEE) countries, with a focus on rural areas and on small treatment wetlands for settlements of below 2,000 people. The results indicate that CEE countries have insufficient sanitation systems with different performance efficiencies. These differences stem from the different historical, political and economic developments as well as legislation in the previous five to six decades. CEE settlements with less than 2,000 inhabitants represent almost 30.0 % of the overall number of persons living in CEE countries. These data show that CEE countries have a mainly rural character, but this is slowly decreasing. Over 42 million inhabitants are waiting for proper sanitation systems. This requirement will be evergrowing in the next future, and it is important to know and to prepare appropriate steps for progressive realisation.
This study assesses the total suspended solids (TSS) retention capacity of different organic filter media for two potential applications: (i) a polishing unit for package treatment plants and (ii) a pre-treatment for blackwater from low-flushing toilets. The experimental system reached a TSS reduction of 60–70% for blackwater and 80–90% for simulated effluent peaks from a package treatment plant. The main challenge of a full-scale application of an organic filter is the issue of clogging, especially when treating concentrated blackwater. However, this work indicates that a clogged filter media can be regenerated by mixing the uppermost filter layer without significant loss of filter performance regarding TSS. More research is needed to develop an appropriate mechanical unit for automatic filter media regeneration.