Ekotoxicita kalů z ústředí ČOV Ostrava.

Abstract

This thesis is focused on verification of possible causes of high ecotoxicity values of hazard characteristics H14 - ecotoxicity in the Central Waste Water Treatment Plant in Ostrava Přívoz. Because of requirement to reduce the amount of waste going to landfill it is desirable to maximize recovery of waste - sewage sludge. The thesis presents the results of laboratory analyses of sewage sludge, including comparative samples of sludge. The comparative sample of sewage sludge was chosen from WWTP where ecotoxicity was negligible. Qualitative composition of purified waste water was also established. The regular sampling of sewerage network profiles for verification of possibility of affecting the quality of water flowing to the Waste Water Treatment Plant in Ostrava was incorporated into the dissertation for the wider scope of this research. The point sources of pollution were also identified in individual network profiles. The influence of the profiles closer to the waste water treatment plant in Ostrava which accumulate water from the previous sampling positions was found too. This situation is depicted graphically. For a complete opportunity to check possible causes of the high ecotoxicity values were took into account the hydrological (weather) conditions which affects water quality in the sewer network. For the purposes of this work following materials were regularly sampled: sewage sludge before and after hygienization, water outflow from the Waste Water Treatment Plant, comparison sample of sludge and also water from the sewerage network (monthly), all by accredited sampler. The obtained samples were processed in laboratories OVaK, VSB-TU Ostrava and Health Institute in Ostrava (Ostrava laboratories and Frydek-Mistek). It was found that hygienized and unhygienized sludge are different in composition and ecotoxicity values which is given by hygienization neccesary for elimination of undesirable microorganisms. The sludge from the Waste Water Treatment Plant Ostrava is used as raw materials for production of substrate which in accordance with the method of production used either as a basis for technical land reclamation or as a basis for landscaping. After "dilution" of the sewage sludge we can eliminate undesirable properties, and also it leads to the use of nutrients what is very desirable. It also leads to the use of generated sludge and decreases the load on the environment due to the elimination sludge storage in landfills.