Wastewater Treatment Plant - Sofia

1.Design Parameters
Mean volumetric flow (m3/day) - 500 000
Qmax - Maximum dry weather flow (m3/s) - 7.7
Qmax - Maximum wet weather flow (m3/s) - 15.4
Suspended Solids load, SS (mg/l) (t/daily) - 316 - 76.8
Population equivalent - 1 600 000
2. Effluent Standards
SS (mg/l) (t/daily) - 35
BOD5 (mg/l) - 15
3. Treatment Process and Technological Scheme
I.Mechanical Treatment
Fine Screens
Grit and Grease Chambers
Primary Settling Tanks
Primary Sludge Pumping Station
II.Biological Treatment
Aeration Tanks
Secondary Settling Tanks
Activated Sludge Pumping Station
Blower Building
Contact Tank with Disinfection Building
III.Anaerobic Sludge Stabilizing
Surplus Activated Sludge Thickeners
Pumping Station
Anaerobic Digesters
IV.Mechanical Sludge Dewatering
Flushed Digested Sludge Thickeners
Dewatering Plant with Chemical Plant
V.Natural Sludge Dewatering
Emergency reserve from the Sludge Drying Beds for  two months
4.The WWTP was put into operation in 1984. Currently the water line is under reconstruction and modernization. The project is financed by the European Bank for Reconstruction and Development. The WWTP equipment was delivered by German companies
5.Treated Wastewater Recipient – Iskar River

Wastewater Treatment Plant - Plovdiv

1. Design Parameters
Mean volumetric flow (m3/day) - 294 600
Qmax  - Maximum dry weather flow (m3/s) - 4.5 м3/с
Qmax - Maximum wet weather flow (m3/s) - 9 м3/с
Suspended Solids load, SS (mg/l)  (t/daily) - 143 - 42.264
BOD5 load (mg/l) (t/daily) - 160 - 47.136
Total nitrogen load (mg/l) (t/d) - 23.8 - 7.026
Total phosphorus load (mg/l) (t/d) - 3.5 - 1.792
Population equivalent - 873 000
Industrial enterprises - 207
2.Effluent Standards
SS     (mg/l) - 35
BOD5  (mg/l) - 25
Total nitrogen (mg/l) - 12
Total phosphorus (mg/l) - 2
3. Treatment Process and Technological Scheme
Screens
Grit and Grease Chambers
Primary Settling Tanks
Primary Sludge Pumping Station
Aeration Tanks in nitrification-denitrification regime
Secondary Settling Tanks
Activated Sludge Pumping Station and Blower Chamber
Contact Tank
Disinfection Building
Surplus Activated Sludge Thickeners
Heated anaerobic digesters
Pumping Station at the Digester
Digested Sludge Thickeners
Mechanical Sludge Dewatering Chamber
4.The WWTP is put into operation in 1984.
The current reconstruction, enlargement and modernization of the Plant include both design and construction of:

• 4 Secondary Settling Tanks with dia.=40m,
• Activated Sludge Pumping Station with Blower Building,
• Reconstruction of the Aeration Tanks aeration system

The WWTP equipment was delivered by Swiss companies.
5.Treated Wastewater Recipient – Maritza River

Wastewater Treatment Plant - Burgas

1.Design Parameters
Mean volumetric flow (m3/day) - 139 226
Qmax - Maximum dry weather flow (m3/s) - 2.3
Qmax - Maximum wet weather flow (m3/s) - 4.6
BOD5 load (mg/l) (t/daily) - 199 - 27.706
Suspended Solids load, SS (mg/l) (t/daily) - 259 - 36.059
Population equivalent - 510 703
Industrial Enterprises - 35
2. Effluent Standards
SS (mg/l) (t/daily) - 25
BOD5 (mg/l) - 15
3. Treatment Process and Technological Scheme
I.Water Line
Fine Screens
Grit and Grease Chambers
Primary Settling Tanks
Primary Sludge Pumping Station
Aeration Tanks with bubble aeration
Secondary Settling Tanks
Activated Sludge Pumping Station and Blower Chamber
Chlorine Mixer
Contact Tanks
Disinfection Building
II.Sludge Line
Activated Sludge Pumping Station
Primary and Surplus Activated Sludge Pumping Station
Pumping Stations at the Digesters
Activated Sludge Thickeners
Flushed Sludge Thickeners
Dewatering Plant
Drying Beds
III.Internal Flows and Ancillary Facilities
Effluent Water, Sewer Water and Drainage Water Pumping Station
Flushing Water Pumping Station
Gas Chamber
Steam Plant
Treated Water Pumping Station
4.The WWTP was put into operation in 1989. Currently new Secondary Settling Tank is designed, constructed and put into operation. The Activated Sludge Pumping Station is under reconstruction and upgrading. There is a preparation for construction of forth corridor of the Aeration Tank, preliminary phosphorus elimination, laboratory modernization, reconstruction of the Gas Chamber, commissioning of a pair for Aeration Tanks. The WWTP equipment was delivered by Italian companies.
5.Treated Wastewater Recipient -  Vay Dam, Black Sea

Wastewater Treatment Plant - Pomorie

1.Design Parameters
Mean volumetric flow (m3/day) -18 000
SS, (mg/l) - 186
BOD5, (mg/l) - 226
Population equivalent 21 000
2. Effluent Standards
SS (mg/l) (t/daily) - 50
BOD5 (mg/l) - 15
3. Treatment Process and Technological Scheme
I.Mechanical Treatment
Screens
Grit chambers
Primary Settling Tanks
II.Biological Treatment
Mechanical aeration tanks
Secondary Settling Tanks
III.Disinfection
Mixer
Contact tank (serpentine)
IV.Sludge treatment
Open (cold anaerobic) digesters
Drying beds
V.Additional buildings
Combined pumping station
Electrical substation
Disinfection building
Laboratory building
Farm building
4.The WWTP is put into operation in 1998. The WWTP equipment was delivered by Bulgaria, Czech and Swiss companies
5.Treated Wastewater Recipient – Black sea

Wastewater Treatment Plant - Tzarevo

1.Design Parameters
Daily waterflow in dry weather, (m3/day) -4 200
SS, (mg/l) - 265
BOD5, (mg/l) - 220
Population equivalent 16 650
2. Effluent Standards
SS (mg/l) (t/daily) - 50
BOD5 (mg/l) - 15
3. Treatment Process and Technological Scheme
I.Mechanical Treatment
Ballansing tank
Pumping station
Screens
Pista Grit Chambers
II.Biological Treatment
Pneumatical aeration tanks
Secondary Settling Tanks
III.Disinfection
Mixer
Contact tank (serpentine)
IV.Sludge treatment
Activated sludge pumping station
Sludge silo
Workshop for mechanical dewatering of sludge
5.Treated Wastewater Recipient – Popska River