This article deals with using computer vision in the evaluation of the Lemna minor bioassay. According to the conventional method, the growth of Lemna minor mass is determined from the number of leaves grown. In this work, instead of counting individual leaves, we propose measuring the area occupied by the leaves using computer vision and compare the new approach with the conventional one. The bioassay is performed according to the ISO 20079 standard as a 168 h growth inhibition test; the aim of the experiment was to quantify the negative effects on the vegetative growth using two parameters—the number of leaves and the area occupied by the leaves. The method based on image processing was faster and also more precise since it enabled us to detect the negative effect of the tested substance on leave size, not only on their number. It can be concluded that the toxic effect has shown to be more significant when considering the leaves area rather than the number of leaves. Moreover, mistakes caused by human factor during leaves counting are eliminated using the computer vision based method.

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Natural or synthetic zeolites have unique physical, chemical and structural properties that predetermine their use in many processes, including wastewater treatment. This study presents the results of our preliminary research in the field of nitrogen and phosphorus removal using adsorption and adsorptive ozonation with natural and modified zeolites. Iron-modified zeolite was the most efficient for the removal of ammonium nitrogen by adsorption. Phosphorus removal efficiency using adsorption was relatively low and natural zeolite was not suitable for the phosphorus removal at all. Ozone had no significant impact on the removal efficiency. Regeneration of loaded zeolites with ozone has also been studied. This method was partly efficient but it needs be further examined.

Ozone (O 3) is a tri-atomic form of oxygen, that is, three atoms of oxygen bonded together. It is an unstable gas with distinctive sharp odor. Under normal conditions, ozone is unstable and rapidly decomposes to a more stable gaseous form of molecular oxygen, O 2. Behavior of ozone shows more "faces" according to the circumstances. The ozone layer protects the Earth from damaging ultraviolet (UV) light; therefore, it is an inevitable compound to save life on Earth. Its applications also present benefits for human welfare. Thanks to its strong oxidizing properties as well as bactericidal, virucidal, and fungicidal effects, it is widely used for water disinfection, wastewater treatment, in various industrial fields, for example, in the pulp and paper industry and the textile industry and progressively for medical purposes as well. Unfortunately, there are also circumstances, mainly due to the activities of humans, when ozone behaves contrary to the mentioned benefits, with negative and harmful influence on human health, and life in nature, as well as to material environment [1]. While stratospheric ozone protects biological life on Earth, ozone in the troposphere is toxic to human health, plants, and trees and it also damages various materials [2]. One may have noticed a smell in the air after thunders and lightning bolts. The pure odor was most likely to the actual ozone formed by flashing atmospheres. Because ozone is unstable and cannot be stored successfully, it must be generated at the application site. To produce ozone sufficiently in the water, wastewater, and sewage treatment plant, ozone generators are used. The simplest method can be ozone generated by the passage of oxygen or oxygencontaining air through the area of electric discharge or spark. Ozone is a subject of interest and research for a number of reasons. This chapter will deal briefly with related aspects of stratospheric and tropospheric ozone as well as with utilization of ozone in practice.