Though no significant changes in the technological processes were made, specialists implemented new process solutions in the Plant, new process equipment was installed which made it possible to considerably improve the sewage treatment and sludge processing quality.

Namely:

1. 1988 saw the introduction of the aerobic stabilization and thickening of surplus activated sludge, the only one such process implemented in Ukraine. Its main advantages are a high degree of sludge disinfection, design simplicity, process explosive safety (unlike the case with thermophilic treatment of sludge in digestion tanks), absence of smell and better dewatering of sludge.

Photo: Aerobic stabilization tanks and thickeners of stabilized sludge of the aerobic sludge stabilization section.

2. In 2006-2010 the overall technical rehabilitation of the screen section as part of treatment facilities of Blocks 2 and 3 was done. That included the introduction of an up-to-date system of the fine treatment of sewage with the replacement of 11 fully worn old-fashioned screens of the rake type МГ-5Т with the 16 mm pitch with the Swedish mechanized screens of the stepped type with the 6 mm pitch, including the transportation system, pressing and collecting of screened grit. The installed new screens much improved the process of removing litter and suspended solids. It also decreased the amount of pollutants emitted into the atmosphere.

Photo: The mechanized screens of the stepped type Spirac located in the screen section of Blocks 2 and 3, Bortnychi Sewage Treatment Plant.

3. In 2004-2008 a joint Ukrainian-Danish project was implemented. There was the renovation of 4 aeration tanks of Block 3 of Novo-Bortnytska Station of Aeration (No.No. 15-18). It included the introduction of the nitrification-denitrification technology and biological phosphorus removal (technology of Danish company Per Aarsleff A/S). Its main advantages were a decrease in the number of biogenic elements in treated sewage to the level permitted under the regulations, lower consumption of electric power by the biological treatment process, less pollutants emitted into the atmosphere and improvement of the ecology of the Dnipro river.

Photo: The process diagram of the renovation of aeration tanks of Block 3, with arranging nitrification-denitrification zones and biological removal of phosphorus.

Photo: Renovated aeration tanks No. 15-18, Block 3 of Bortnychi Sewage Treatment Plant.

4. In 1995 there was the full replacement of the worn-out sucking filter slab-based system with the up-to-date system that included filtering pipes produced by LLP "Ecopolymer” in all aeration tanks and aerobic stabilizers in Plant. Tube aerators tend to be more reliable in operation, make it possible to evenly distribute air in the aeration tank, increase oxygen mass transfer in sludge mixture and improve the treatment quality. What is valuable in the process is that electric power consumption decreases by 10-20%.

Photo: The aeration system based on filtering pipes in aeration tanks of Block 2, Bortnychi Sewage Treatment Plant.

5. Toothed overflow weirs were installed in all secondary settling tanks of Blocks 2 and 3. It allowedto level trough edges, secure the even overflow of treated sewage, and additional aeration

Photo: A secondary settling tank with the toothed overflow weir.

6. Since 2009 a reconstruction project of embankments of sludge fields No.1 and No.2 has been implemented. The embankments will be made higher thus securing further dumping of sludge from process facilities of the Plant till the new treatment and disposal technology is introduced.

7. In 1997 the existing process of feeding sludge into digestion tanks was replaced with a new process which included the construction of new reservoirs for raw sludge (capacity of 600 m3each), the pump facility with up-to-date pumps manufactured by Netzsh, equipped with macerators, which made it possible to escape the continuous clogging of digestion tanks, provide a backup buffer tank and uninterruptedly feed sludge for processing.

8. In 1996 the process of the treatment of return sludge water from sludge fields in aerobic stabilizers was implemented. Thus the pollution load on sewage treatment facilities was decreased by 40-50 %, biological treatment improved, electric power consumption lowered thanks to getting additional blowers out of operation.

9. In 1999 a process was implemented which helped intensify the thickening of aerobically stabilized sludge by means of flocculants. The use of chemicals made it possible to significantly decrease sludge moisture, its volume and amount of pollutants which arrived with sludge supernatant water at wastewater treatment facilities. Thus the treatment effect was seen better in primary settling tanks, raw sludge and surplus activated sludge decreased twice in volume. And because the amount of secondary pollutants also decreased, the needed quantity of air fed into aeration tanks and electrical power consumption lowered.

Photo: A plant for preparing and dosing flocculants for the intensification of the thickening of aerobically stabilized sludge “Autofloc.”

While in recent years, using mainly investment program funds, specialists have managed to buy the following up-to-date process equipment:

1. 3 new affluent quality control units at the discharge points of treatment facilities of each block, which are set up for the timely measurement of major water treatment quality indicators, namely: ammonia nitrogen, phosphates, nitrites, nitrates, pH and oxidation-reduction potential. Besides, 5 automated samplers were installed at main affluent quality control points (sewage which arrives at facilities of Block 1, Blocks 2 and 3)

Photo: An automated sampler with cooling of samples ISCO 5800.

Photo: The Systea analyzer of chemical content of treated return water.

2. 3 flow meters are installed in the sludge transfer and 5 more are planned in the main sludge transportation pipelines of the Plant.

3. The heating plant of the Right Bank Pumping Station was reconstructed in order to decrease heating costs and improve the control quality of heat supply and hot water supply systems of the pumping station by means of the installation of a high-performance heat pump which has the weather dependent control system. This step made it possible to disconnect the Right Bank Pumping Station from the centralized heating system of Kyiv and significantly save on heat energy consumption.

Photo: The heat pump in the heating plant of the Right Bank Pumping Station.

4. Specialists also replaced 10 pumps in a different department of Bortnychi Sewage Treatment Plant, which were completely worn. The new up-to-date pump equipment manufactured by Flygt was installed instead. There was also a change of pumps needed to transport sludge from primary settling tanks, surplus and return activated sludge, transport sludge to sludge fields, etc. It allowed to secure the more even removal of sludge with lower moisture, decrease overall scopes of sludge, the time of pumping and electric power consumption at the expense of the lower capacity of pump engines.

Photo: A new up-to-date pump which is manufactured by Flygt and installed in the raw sludge pumping facility.