No abstract

Our study presents a low-cost method (no expensive hardware platforms required) of quantified biomonitoring based on computer image analysis. The negative influence of toxins on surface waters was analysed. The method was verified on widespread freshwater macrophyte Lemna minor to test populations treated with non-ionic detergents. We showed that the proposed automated bioassay has a broad applicability in assessing the negative impacts of aquatic toxicants. This approach enabled fast and precise evaluation of the morphometric parameters of the duckweed test population. We observed that growth rate of L. minor reacts to non-ionic detergents, which is reflected by the change in the surface area. The decrease in the growth of L. minor was revealed at high doses of detergents. This test proved to be highly useful, because it is well repeatable and fast in its implementation. Unlike classical bioassays, the proposed test allows the elimination of measurement errors, resulting from observers' subjectivity.

Abstract:The paper presents a study leading to a new acute toxicity test on embryonic and juvenile organisms of the great pond snail (Lymnaea stagnalis Linnaeus). Sulfuric acid, nitric acid, and ammonium hydroxide were used as waterborne toxicants in laboratory experiments. The exposure time was 24 h. Tests were conducted in 5-10 replications for each toxicant. The toxicity of the substances was classified according to different scales and the test's sensitivity was compared to that of the commonly used bioindicator Daphnia magna Straus. The assessment of toxicity impact was supported by microscopic observations. The probit method was used as a parametric statistical procedure to estimate LC 50 and the associated 95% confidence interval. Our study showed that the early developmental stages of Lymnaea stagnalis are very sensitive bioindicators, making it possible to detect even very low levels of the above-mentioned water toxicants. The highest toxicity is shown by ammonium hydroxide with LC 50/24h values, respectively, 24.27 for embryos and 24.72 for juvenile forms, and the lowest is shown by nitric acid ions with LC 50/24h values, respectively, 105.19 for embryos and 170.47 for juvenile forms. It is highly cost-effective due to simple and efficient breeding and the small size of the organisms in the bioassay population. Compared with Daphnia magna, relatively low concentrations of toxicants caused a lethal effect on embryonic and juvenile organisms of the great pond snail. Owing to their common occurrence and sensitivity, early developmental forms of Lymnaea stagnalis can be a valuable new tool in biomonitoring of the freshwater environment.

Nutrient removal is a very important criterion in household sewage treatment systems. The process of sewage treatment must ensure an adequate degree of nutrient reduction from raw sewage, both in municipal treatment plants and in small treatment plants, below 50 PE [1]. The use of membrane bioreactors (MBR) in the treatment of wastewater is limited to small objects with relatively small organic pollutant load.

No abstract