Thesis for the degree of doctor of technical sciences in specialty 21.06.01 – Ecological safety. – National Aviation University. – Kyiv, 2019.
Thesis is dedicated to solving scientifically applied problem of increasing of ecological safety of sewage systems functioning by improvement of existing technological processes and creation of new ecologically safe technological processes. It is also dedicated to creation of equipment, which will provide rational use of present renewable resources and diminishing of harmful influences of sewage systems on natural environment. The different methods of organization of sewage systems are considered and their basic general drawbacks are described. It is shown that modern technologies of sewerage do not allow achieving the proper level of ecological safety mainly through the insufficient degree of sewage water treatment and ecological risks, related to utilization of their sludges.
A conclusion is drown, that at application of traditional mechanical and biological methods of treatment there is necessity for additional purification of sewage waters from biogenic elements and in improvement of methods of treatment and utilization of their sludges. Biogenic elements, such as nitrogen and phosphorus, are present in wastewater in the form of various compounds. While getting into the water bodies, they can cause eutrophication processes, which leads to the death of aquatic organisms and decrease in environmental safety. Ecological risks are especially high in the case of using the water body for recreational purposes or for water supply. Eutrophication results in cyanobacteria development, which leads to the appearance of cyanotoxins in the water. The last ones are regarded as pathogens, despite the fact that they do not develop in the human body. At the same time, it has been shown that cultivation of microalgae for biofuel production on an industrial scale faces a number of difficulties, primarily economic ones. Ensuring the metabolism of microorganisms requires large amounts of water, nutrient (biogenic elements), as well as electricity for mixing in order to ensure uniform illumination. In the cold period, heating and temperature stabilization are also necessary. As one of the most perspective methods of additional treatment is offered using of sewage waters as environments for cultivation of power microalgae in photobioreactors of the closed type with subsequent production of liquid biofuel of the third generation.
As one of the most perspective methods of treatment and utilization of sludges is offered intensive anaerobic digestion with organization of the process in accordance with kinetics of digestion and subsequent using of digested biomass as organic fertilizer. There is justified necessity of sewage water measuring and facilities are developer for measuring. There is justified reasonability of using screw pumps for sewage water and sludge pumping and the construction of a screw pump of high efficiency.
Based on the new strategy of sewerage, which allows promoting the degree of sewage water purification, getting renewable energy sources is possible for partial or complete providing of necessities of enterprise in thermal and electric energy. In the case of having surplus of renewable energy sources, it is possible to sell them. It allows obtaining safe organic fertilizer, carbon dioxide and it allows decreasing discharge of carbon dioxide in atmosphere.
Keywords: biogas, biofuel, ecological safety, sewage sludge, technological foundations, improvement of technological processes, sewerage.
