Hydrochemistry and Technology

Water treatment is a technological branch aimed at reaching such properties of water to meet the quality requirements with respect to its further use. It uses the knowledge of many scientific disciplines, e.g. hydrochemistry, biochemistry, physical chemistry of surfaces, hydrodynamics, civil and chemical engineering or mathematic modelling. Particularly, the treatment of water for drinking purpose is still a current issue due to the growing population. The drinking water treatment includes the following technological processes: pH adjustment, possibly pre-oxidation; formation of suspension (destabilisation/coagulation and aggregation/flocculation of undesirable impurities by the means of iron/aluminium reagents); separation of formed suspension (sedimentation, flotation, filtration); and disinfection. The processes of suspension formation and separation can be combined into one technological step with the use of clarification in specially constructed devices – clarifiers. For removal of dissolved substances in lower concentration, adsorption (onto activated carbon, organic resins, ion exchangers) or membrane processes (micro-, ultra-, nanofiltration, reverse osmosis) can be used.

The research at the Institute of Hydrodynamics is aimed at the study of mechanisms of removal of problematic substances from water. Firstly, it is the AOM (Algal Organic Matter) – organic matter originating from the metabolic activity and decay of algae and cyanobacteria, removed by the conventional treatment, i.e coagulation (suspension formation by the means of iron/aluminium coagulants and its subsequent separation), possibly also using pre-oxidation (by potassium permanganate, ozone, chlorine, UV radiation). Secondly, there are micropollutants (pesticides, pharmaceuticals) that are removed by adsorption onto activated carbon. Recently, an occurence and characterization of microplastics in drinking water has become our new research topic. Since microplastics are micropollutants with potential health risks, their presence in drinking water is undesirable. The research in this field is also aimed at the occurence of microplastics in raw water sources and at microplastic removal by individual water treatment pocesses. This is especially important, since no special technology has been designed for microplastics removal so far. Further, the research is aimed at the influence of physical-chemical parameters (type and dose of coagulant, pH, alkalinity, temperature) and hydrodynamic conditions (magnitude and distribution of shear rate) on the properties of flocs (size, structure, porosity and shape) formed during conventional water treatment. Floc (aggregate) properties fundamentally influence the efficiency of their subsequent separation. It is necessary to understand the mechanisms of aggregation and the evolution of aggregate properties in dependence on mentioned conditions to optimize the aggregate formation for particular separation processes.