Bioaerosols at wastewater treatment facilities: sources, composition, sanitary and epidemiological risks (a review)

Summary

Attention to the issue of bioaerosol emissions in the process of wastewater treatment has increased with reports about wastewater aerosolization as a potential source of SARS-CoV-2 virus exposure to the air during the recent COVID-19 pandemic; however, the impact of exposure to bioaerosols on the health of the people with compromised immunity, personnel of treatment facilities and population of adjacent territories has been reported earlier. Emission of bioaerosols occurs at various stages of the technological process (mechanical treatment, biological treatment, wastewater sludge treatment). The amount of bioaerosols formed depends on the hydrodynamic conditions of wastewater treatment, type of treatment plant (closed or open), wastewater composition, treatment technology used, technical characteristics of the equipment, capacity of the treatment facilities, operating conditions, aeration rate and mode, concentration of biomass and growth phase of microorganisms. Bioaerosols contain pathogenic bacteria including those resistant to antibiotics, fungi that are potential pathogens of mycetogenic diseases, as well as viruses that can survive for a long period of time in wastewater and are spread by airborne transmission. The applied methods of bioaerosol analysis provide data on the presence, size and viability of aerosol microorganisms; however, until now no standard methodology for sampling bioaerosols has been available. Thermal treatment and ultraviolet irradiation, the use of air filters and ventilation have become widespread among the means of preventing the formation and spread of bioaerosols. Various research in this area has focused on the use of granular activated carbon, floating plastic balls for water surface isolation, reactor surface vacuum treatment, wastewater sludge composting using membrane coating, the use of biofilters, and installation of wind barriers along the boundaries of wastewater treatment facilities and vertical gardening systems.

Key words

wastewater , viruses , bacteria , treatment facilities , bioaerosols , fungi

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UDC 628.31.504.3.054

Rublevskaya O. N.

Measures on preventing malodors release at the facilities
of SUE «Vodokanal of St. Petersburg»

Summary

SUE «Vodokanal of St. Petersburg» has been introducing and testing different equipment for gas purification with the aim of preventing malodors release at the wastewater facilities. The experience of applying gas purification technologies at these facilities is analyzed. It was determined that the specified features of STOPKR sorption-plasma-catalytic gas purification unit and OPVS biological air oxidizing unit are efficiently used at the sewage pumping stations. The economic inexpedience of using STOPKR method at input concentrations of toxic substances higher than 1 g/m3 is a disadvantage. Testing OPVS filter in sewers showed positive results. The disadvantages of OPVS filter are in clogging of filter elements during operation as well as difficulties in processing multicomponent gas mixtures and mixtures of variable composition because of the specificity of the resulting microbial strains. The results of pilot testing TSUF-2000-400-I gas purification system showed the absence of malodors around sewer wells and convenient operation of the unit. The use of different filters including GreenKomplekt carbon filter-based units did not give any meaningful results. To control odor at the wastewater sludge landfills fine spraying of deodorant solution along the periphery of the landfill was suggested. At the sludge incineration plants exhaust gases pass three-stage purification with the use of electrostatic precipitation. At the wastewater treatment facilities the construction of either entire process flow or partially closed system was suggested. The prospects if introducing various technical and technological methods at each of the wastewater facilities are determined.

Key words

reeking substances , sludge , pumping station , sludge incineration plant , treatment facilities , sorption-plasma-catalytic unit , biological air oxidizing unit , landfill

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UDC 628.336.411

Ivanov A. N., Ivanova M. G.

Wastewater sludge dewatering with the use of «Sibfloc^®» flocculant and special wells

Summary

The technology of high-efficient wastewater sludge dewatering on sludge beds with the use of brand new «Sibfloc^®» flocculant made on the basis of polyethylene oxide and special slotted wells for the collection and removal of sludge water is described. The technology has been tested under various climatic conditions – from the Krasnoyarsk Area to the Krasnodar Area and introduced at the wastewater treatment facilities in Russia and Kazakhstan. The suggested technology when used on sludge beds provides for wastewater sludge dewatering to 68–75% moisture content; under the effect of «Sibfloc^®» flocculant the sludge is structurized and readily dried to 40–45% moisture content after unloading from the sludge bed. The sludge generated during dewatering is suitable for any type of utilization – from direct use as soil conditioner for reclamation of dumps and solid waste landfills to processing into fertilizers and soil for forest plantation. Sludge not suitable for any utilization because of fast drying capability to any moisture content (from 60 to 8%) can be efficiently used in biogas generating plants or special furnaces either in its initial state or in the form of fuel bricks. Technical and economic performance and environmental effect of using the considered technology allow classifying it as a best available technology. Introducing the technology of wastewater sludge dewatering with the use of «Sibfloc^®» flocculant provides for 4–7 times reduction of the required number of sludge beds, and improvement of sanitary and environmental situation at the treatment facilities and adjacent territories, including efficient odor control and unloading filled up sludge beds and sludge tanks.

Key words

dehydration , flocculant , wastewater sludges , treatment facilities , sludge bed , slotted well , reclamation

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UDC 628.212.2

Ganbarov E. S., GULIEV F. S.

Municipal surface runoff treatment in Baku

Summary

A number of problems related to establishing a centralized system of surface runoff treatment from built-up areas by the example of Baku under the conditions of the regulated inflow with the restoration of the functions of the operating separate wastewater disposal system are considered. A process flow scheme of the centralized treatment of surface runoff with placing treatment facilities in two locations has been developed. The location of one of the treatment plants is planned near the Azerbaijan Bay; it is designed for chemical free treatment by sedimentation and filtration of surface runoff from a group of sewers in the central part of the city in case of using part of the effluent for the municipal landscape irrigation; in case of discharging the effluent into the sea chemical treatment is applied. The second plant is planned to build outside the city on the basis of the operating treatment facilities of Zykh community with subsequent tertiary effluent treatment at the municipal treatment facilities. The efficiency of the basic elements of the surface runoff treatment and tertiary treatment scheme at the first plant was studied on the basis of the experimental tests of sedimentation and tertiary treatment by filtration through floating foamed polystyrene bed. Upgrade and re-equipment of the wastewater disposal systems is one of the most complicated engineering tasks focused on improving the environmental situation and protecting the municipal coastland from pollution with surface runoff. Establishing the scheme of surface runoff removal and treatment from the built-up Baku area with installing trunk storm sewers, separation chambers and regulating tanks will provide at last for the solution of the most important environmental problem.

Key words

storm sewers , trunk sewer , surface runoff , filtration , treatment facilities

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