Effective microorganism water treatment method for rapid eutrophic reservoir restoration.

Since reservoirs perform many important functions, they are exposed to various types of unfavorable phenomena, e.g., eutrophication which leads to a rapid growth of algae (blooms) that degrade water quality. One of the solutions to combat phytoplankton blooms are effective microorganisms (EM). The study aims to evaluate the potential of EM in improving the water quality of the Turawa reservoir on the Mala Panew River in Poland. It is one of the first studies providing insights into the effectiveness of using EM in the bioremediation of water in a eutrophic reservoir. Samples for the study were collected in 2019-2021. The analysis showed that EM could be one of the most effective methods for cleaning water from unfavorable microorganisms (HBN22, HBN36, CBN, FCBN, FEN) - after the application of EM, a reduction in their concentration was observed (from 46.44 to 58.38% on average). The duration of their effect ranged from 17.6 to 34.1 days. The application of EM improved the trophic status of the Turawa reservoir, expressed by the Carlson index, by 7.78%. As shown in the literature review, the use of other methods of water purification (e.g., constructed wetlands, floating beds, or intermittent aeration) leads to an increase in the effectiveness and a prolongation of the duration of the EM action. The findings of the study might serve as a guide for the restoration of eutrophic reservoirs by supporting sustainable management of water resources. Nevertheless, further research should be conducted on the effectiveness of EM and their application in the remediation of eutrophic water reservoirs.

Spatio-temporal evolution of eutrophication and water quality in the Turawa dam reservoir, Poland.

The objectives of the article are: to assess spatio-temporal evolution of eutrophication and water quality of the Turawa dam reservoir, located in south-western Poland on the Mala Panew River; to identify location and relationship between potential sources of physicochemical pollution related to the progressing process of eutrophication; and to determine trophic status and water quality indices of the selected research object. The analysis (Mann-Whitney U test, PCA, HCA, Spearman correlation matrix) showed a high susceptibility of the reservoir to eutrophication processes, especially due to the influence of dangerous loads of compounds emerging from areas with high tourist intensity and pollutants flowing from the Mala Panew River. The parameters deteriorating the ecological status were TP, DO, BOD5, and COD. Considering the cumulative results of water quality indices for the period 1998-2020, the average water quality was in classes II or III. A noticeable deterioration appeared in water quality for the years 2016-2020, which proves the progressing eutrophication in the Turawa reservoir. In 1998-2020, the reservoir was classified as eutrophic or mesoeutrophic based on the calculated three trophic status indices. This article would help in developing a strategy for dealing with water blooms, a reliable system for monitoring pressures causing eutrophication, and optimal technologies for the reconstruction of multifunctional reservoirs.

Impact of a small hydropower plant on water quality dynamics in a diversion and natural river channel.

This study innovatively evaluates the impact of hydropower plants located in a diversion channel on water quality dynamics. The spatial characteristics of water in the diversion channel above and below a hydropower plant were assessed; specifically, the investigation was conducted in the watercourse undeveloped by the hydropower plant and at reference points. Among the five analyzed points, the strongest statistically significant changes were observed in electrical conductivity, pH, and dissolved oxygen. Statistical analyses showed a similar, statistically significant relationship for most months. The water quality indicators proposed in this study help assess hydropower plants' impact on water quality dynamics because they enable water comparison at different locations. The best water quality, as calculated using designated indices, was recorded below the hydropower plant. Among the physicochemical parameter values, the most noticeable change occurred in dissolved oxygen below the hydropower plant and below the fixed weir; its value was 8.10 and 5.32% higher in the two locations at the reference point below the hydropower facility. Moreover, the NH4 -N content was higher by 7.06% below the weir than the point below the hydropower plant. In the long term, this research may help plant operators manage water resources on watercourses with hydropower development more efficiently, according to sustainable development principles. This research will contribute to the rational management of such facilities on diversion channels considering sustainable water management principles.