The purpose of the work was to determine the relationship between the of the water quality parameters in an artificial reservoir used as cooling ponds. Multivariate methods, cluster analysis and factor analysis were applied to analyze eighteen physico-chemical parameters such as air and water temperature, dissolved oxygen concentration, visibility of the Secchi disk, concentrations of total nitrogen, ammonium, nitrate, nitrite, total phosphorus, phosphate, concentrations of calcium, magnesium, chlorides, sulfates and total dissolved salts, pH, chemical oxygen demand and electric conductivity from 2002-2017 to investigated cooling water discharge. Hierarchical cluster analysis (CA) allowed identified five different clusters that reflect the different water quality characteristics of the water system. Similar results were obtained in exploratory factor analysis, five factors were obtained with 65.96% total variance. However, confirmatory factor analysis showed that four latent variables: salinity, temperature, eutrophication, and ammonia provide better fit to the data than a five-factor structure. Correlations between latent variables temperature, eutrophication and ammonia show a significant effect of temperature on the transformation of nitrogen and phosphorus compounds.

The results of investigation on the amount and chemical composition of biogas emitted from bottom sediments of polluted Dzierżno Duże dam reservoir have been presented. The bottom sediments could be a resource of considerable quantity of biogas, e.g. methane. The dilution of methane in water is similar to that of oxygen. The presence of methane dissolved in the water deteriorates environmental conditions. The quantity of biogas depending on temperature ranged from 2 to 12 dm3/m2*d. The biggest singular grow exist in the water temperature 10-15°C. Chemical composition for biogas is dependent on the temperature. Along with the water temperature growth from 7 to 24°C, participation of methane in the biogas increased from 73% to 85%, and the participation of nitrogen from 3.9% to 22.47%. The participation of carbon dioxide decreased from 22% to 4.5%. The heterogeneous process of biogas emission arc running in the kinetic and diffusion area is dependent on temperature. In the low temperature the progress of the process is controlled by the speed of biochemical reaction. The progress of the diffusion process grows in a high temperature, and in the range of 15-24° C the processes is controlled by diffusion of substrates and products of reaction.

Improving the effects of hydrolysis on waste activated sludge (WAS) prior to anaerobic digestion is of primary importance. Several technologies have been developed and partially implemented in practice. In this paper, perhaps the simplest of these methods, alkaline solubilization, has been investigated and the results of hydrolysis are presented. An increase to only pH 8 can distinctively increase the soluble chemical oxygen demand (SCOD), and produce an anaerobic condition effect favorable to volatile fatty acids (VFA) production. Further increases of pH, up to pH 10, leads to further improvements in hydrolysis effects. It is suggested that an increase to pH 9 is sufficient and feasible for technical operations, given the use of moderate anti-corrosive construction material. This recommendation is also made having taken in consideration the option of using hydrodynamic disintegration after the initial WAS hydrolysis process. This paper presents the effects of following alkaline solubilization with hydrodynamic disintegration on SCOD