This paper describes the experimental study of a behavioural barrier consisting of a bubble curtain placed near an ecological river water intake, aiming to assess the bubble curtain’s influence on the velocity field of water flowing in the water intake proximity. The scientific novelty is given by the water intake solution operating in tandem with the dedicated bubble curtain generator used for avoiding fish entrapment. The water intake solution used in the present research is based on a run-of-river intake without a dam in the riverbed, maintaining the mountain rivers longitudinal connectivity. An experimental setup was designed and built to study the behavioural barrier for ecological water intakes in different operating conditions. Thus, tests were performed for two water velocities (0.33 m/s and 0.535 m/s) in the experimental setup, two water depths (92 mm and 119 mm) and two air flow rates (10.5 LPM and 15 LPM). The results were compared with the case when no air is injected through the bubble curtain generator. The assessment of the bubble curtain influence on the water flow inside the channel was made by measuring and analysing the velocity variation in vertical and horizontal direction. The results showed a significant velocity gradient in the bubble curtain proximity, which can contribute to influencing the behaviour of the fish by deterring them from the water intake area.

The results of a pilot-scale study on the influence of electric field use for stimulating the active sludge in the biological purification tank of a small capacity wastewater treatment plant (up to 600 m³/day) are presented. Through specific comparative chemical tests (DO, COD, N-NH₄, and Pt) it was found that, by applying a sinusoidal electric field of 5 Vrms/m at 49.9 Hz on the active sludge suspension, the overall pollutant denitrification process speed is doubled compared with the reference case when no stimulation is used. Also, under identical operating conditions, the residual pollutant content of the biological treatment tank outlet water is reduced approximately three times for COD and approximately two times for N-NH₄ and P_t compared to the reference tank. These findings lead to the conclusion that, by stimulating the active sludge microbial activity of the wastewater treatment plants by a sinusoidal electric field of 5 Vrms/m at 49.9 Hz, the time of the biological purification treatment can be reduced by approx. 50%. This leads to a corresponding decrease in energy consumption, which usually represents more than 30% of a wastewater treatment plant’s specific electricity consumption.

The protection of fish habitat near water diversion or hydrotechnical facilities is of particular interest for researchers working in various fields. The chapter is focused on an experimental study of a fish behavioral barrier consisting of a bubble curtain operating along a river water intake scale model. It approaches elements of fish hydrodynamics, river water intakes, as well as physical and non-physical barriers for fish diversion from hydrotechnical facilities. The design, development, and testing of the fish behavioral barrier as well as the results of the experimental analysis are discussed. The proposed experimental setup was based on a barrier placed in the proximity of a river water intake scale model fitted and tested in a closed-circuit hydraulic stand. The intake chamber is provided with perforated orifices which communicate through an inlet with a lower tank for discharging the water into another tank located beneath. A certain water velocity within the hydraulic stand was set to assess the tandem operation of the bubble curtain and water intake. A sharp velocity gradient was found in most cases, indicating local velocity changes and creating the premises for impacting the fish behavior. Conclusions and future research development are also envisaged in the chapter.

Materiale Plastice - a peer-reviewed scientific journal,specialised in the field of chemistry, polymers, elastomers and plastics research

An assessment of the tectonic activity in Vâlcea-Fâgâraş-Câmpulung seismic area is presented, with a direct impact on the power facilities operational safety - especially of the numerous hydropower plants in this area. The analysis of the acquired data revealed that the seismic activity in this mountainous area (with a high hydropower potential) shows an intensifying trend. As the seismic hazard is significant, in order to increase the operational safety of energy equipment and installations, to reduce the damage caused by crustal earthquakes specific to the area, it is strongly recommended that energy equipment and installations to be provided with complex adequate protection systems as warning systems based on local assessment of seismic events.