Biotesting and phytoindication of aquatic environment quality of urbanized territories

Currently, there is a necessity for regular quality control over natural water bodies within the territory of industrial cities. The aquatic environment quality monitoring and the toxicity assessment of the water pollutants, in addition to the hydrochemical analysis data, require integral, biological indicators. In recent times, methods of direct aquatic toxicity assessment, namely biotesting water quality using sensitive hydrobionts and phytoindication with macrophytes, have become increasingly important. In this regard, we have conducted a comparative quality assessment of the water from three different areas of the Saksagan river, influenced by the Ternovska mine in Kryvyi Rih using various test objects. Hydrobiological samples were collected in September 2019 above wastewater outfall (residual rainfall and snowmelt runoff), at wastewater outfall (residual rainfall and snowmelt runoff) and below rwastewater outfall (residual rainfall and snowmelt runoff). In water the basic hydrochemical indicators have been defined: hydrogen index (pH), dissolved gases, biogenic elements, hardness, temperature, electrical conductivity, total mineralization (salinity). The quality of the aquatic environment was assessed by biotesting with daphnid Daphnia magna Straus and phytoindication by modified Mayer`s index. The analysis of the hydrochemical regime has been carried out according to generally accepted methods. Biotesting of water samples was carried out according to CTDC 211.1.4.054-97. In the experiments daphnid Daphnia magna Straus were used as test organisms. For testing the samples toxicity Daphnia youth under the age of 24 hours has been used. The toxicity criterion was the mortality of test organisms in relation to control. The number of dead animals was calculated after 96 hours, then the mortality (or survival) of objects in the samples was calculated. The survey of vegetation has been carried out visually. A rake and a d-shaped net have been used to study the submerged species. The detected algae have been systematized into 3 groups according to the modified Mayer`s index. The average index for the entire monitoring area has reached 15 points, which corresponds to the third quality class (moderately polluted river, β-mesosaprobic zone). It has been revealed that the hydrochemical composition of the water of the Saksagan river is characterized by a sufficiently high mineralization (2.6–3.5 g / l), which is caused by the complex influence of several factors: physiographic conditions, river control (the influence of Makartivske, Krasovske, Saksaganske reservoirs). A naturally simplified structure of the species composition of macrophytes has been noted, which is typical for reservoirs under anthropogenic load. Endangered and listed in the Red book of Ukraine plant species in the study area were absent. The comparison of the results of bioindication methods with hydrochemical analysis has shown that phytoindication by the modified Mayer`s index was more sensitive method with respect to biotesting on daphnid Daphnia magna. However, we consider it impossible to compare these test objects, since each object may have a specific reaction to individual toxicants (Daphnia – to insecticides, macrophytes – to herbicides). Thus, in the future, it is recommended to use a set of methods for rapid assessment of the water quality in urban areas.

Design Optimisation of Marine Wastewater Outfalls

This work presents a method that optimises the manifold pipe of a marine wastewater outfall under various hydraulic principles and cost considerations. Costing data from 37 international pipe supply companies providing pipes of various diameters for HDPE, steel and concrete were used to develop hybrid design equations for these three main materials used for outfall construction. These equations optimise the trade-off between pumping head and pipe size as well as the compromise between cost of material and favourable hydraulic characteristics. Various grades for each material were considered if relevant to marine outfalls. The resulting equations are very useful for outfall design, as oversizing of a project can incur unnecessary cost and under-sizing will not fulfil an outfall’s intended hydraulic purpose and will increase the operational cost in terms of energy