Analysis of the Theoretical Performance of the Wind-Driven Pulverizing Aerator in the Conditions of Góreckie Lake—Maximum Wind Speed Method

Abstract

The eutrophication of surface waters is a natural process; however, anthropogenic activities significantly accelerate degradation processes. Most lakes in Poland and in the world belong to the poor and unsatisfactory water quality class. It is therefore necessary to limit negative anthropogenic impacts and introduce restoration methods, in particular those that are safe for the aquatic ecosystem. One of these is a pulverizing aeration Podsiadłowski method that uses only wind energy. The method allows for the moderate oxygenation of hypolimnion water, which maintains the oxygen conditions in the overlying water zone in the range of 0–1 mg O2·dm-1. The purpose of the work was to develop a new method of determining the efficiency of the aerator pulverization unit in the windy conditions of the lake. The method consists in determining the volumetric flow rates of water in the aerator pulverization unit, based on maximum hourly wind speeds. The pulverization efficiency in the conditions of Góreckie Lake was determined based on 6600 maximum hourly wind speeds in 2018. Based on the determined model, the theoretical performance of the machine was calculated, which in the conditions of Góreckie Lake in 2018 amounted to less than 79,000 m3 per year (nine months of the effective aerator operation).

Analysis of Performance of the Wind-Driven Pulverizing Aerator Based on Average Wind Speeds in the Conditions of Góreckie Lake

“…In 1995, the Institute of Agricultural Engineering at the Agricultural University in Poznan (currently, the Institute of Biosystems Engineering at the University of Life Sciences in Poznan) began research on the integrated technology of lake restoration. The core of the proposed method was a wind-driven pulverizing aerator (Figure 1), allowing degassing and simultaneous oxygenation of hypolimnion waters, and a mobile aerator to perform precise phosphorus inactivation in the water column [20]. The pulverizing aerator, for discharging harmful gases of anaerobic decomposition of organic matter contained in bottom sediments, such as hydrogen sulfide, methane and ammonia, and for the simultaneous oxygenation of hypolimnion waters, uses only wind energy [10,20].…”

“…Many recent publications indicate there is a deterioration of water quality in Poland [15][16][17] and around the world [18,19]. In order to improve water quality, many protective measures are necessary [20]. The most important include cutting off the biogens inflow and creating buffer zones separating arable fields [3].…”

“…We can distinguish biological, chemical and mechanical restoration methods [24,25]. However, the best results are achieved by combining several methods, preferably non-invasive ones [20][21][22]. One of the mechanical methods supporting chemical restoration of surface water reservoirs is pulverization aeration with the use of wind-driven aerators (Podsiadłowski's method) [13,26].…”

“…Osuch et al [20] presented the possibility of determining the volumetric flow rate through the pulverizing aerator unit in the windy conditions of a particular lake. They based findings on the author's method of maximum wind speeds.…”

Were there any changes in zooplankton communities due to the limitation of restoration treatments?

“…Sustainable restoration based on three methods (aeration, phosphorus inactivation and biomanipulation) started in autumn 2011 and was conducted until 2014. The deepwater oxygenation was conducted with the use of a wind-driven aerator (in the deepest part of the lake), without disturbing the thermal stratification (Podsiadłowski et al 2018;Osuch et al 2020). The second method was phosphorus inactivation in the water column with iron sulphate (Fe 2 (SO 4 ) 3 ) and magnesium chloride (MgCl 2 ).…”