Large wastewater treatment plants Aquatec VFL

AT1000 - AT5000 wastewater treatment plants are intended to treat sewage arising from small villages with 5 000 population equivalent (PE), which combining the biological reactors, can be increased up to about 20 000 PE. After mechanical or hysic-chemical treatment of industrial wastewater with organic pollution, the plants serve as biological treatment for meat processing factories, dairy factories and slaughterhouses, wineries, etc. 
Biological waste water is treated and purified to the required level allowing discharging in sensitive areas with the removal of nitrogen and phosphorus.

veľké čistiarne odpadových vôdBasic description

Larger biological wastewater treatment, series AT1000 - AT5000, consist of two or more parallel-connected treatment lines with the bio-logical reactors and sludge tank in one compact unit and having additional building structures and machinery (pump station, mechanical pretreatment, sludge management, tertiary treatment, instrumentation and control, etc.). 

Vertical Flow Labyrinth – VFL® - Treatment process

veľké čistiarne odpadových vôd

The technology uses a continuous-flow activated sludge process with biological nitrogen and phosphorus removal, which combines the following processes in a single tank:  mechanical pre-treatment, excess sludge collection, biological treatment using a low-loaded activated sludge process, separation of the treated water from activated sludge in the final clarification chamber, flow balancing of fluctuating inflow of wastewater in the retention chamber. The treatment process consists of several technological processes. Raw wastewater flows into the non-aerated activated sludge chamber with anaerobic and anoxic zones creating and admixture with the recirculated activated sludge, the mechanical pre-treatment of inflowing raw wastewater and the decomposition of coarse impurities, denitrification and accumulation of readily degradable organic contamination is taking place in the non-aerated activated sludge chamber, which is divided by inner partition walls to create a vertical flow labyrinth, where internal circulation is established. 
Furthermore, allowing the admixture flow gravitationally into the aerated activated sludge chamber with includes fine-bubble diffusors. In oxic conditions the biological degradation of organic contamination, nitrification and phosphorus uptake is taking place.  The activated sludge flows into the final clarification chamber, where the activated sludge is separated from the treated wastewater. The treated wastewater is discharged into a water flow, infiltrated or recycled and the separated activated sludge is recirculated by air-lifts.
A flow regulator is installed at the water level in the final clarification chamber which controls the outflow in order to maintain the water level between the normal and maximum level in the tank (integrated retention chamber).
The pressurized air is supplied by blowers for aeration of the activated sludge chamber and for recirculation via air-lift pumps. The recirculation and aeration is controlled by a microprocessor control unit which also enables the wastewater treatment plant to work in various modes depending on the loading. 
 

Technological parameters
The quality of purified water corresponds with the Directive No. 269/2010 requirements in the Collections of Laws for discharging the water into the ground or on the surface.

The guaranteed and commonly achieved parameters from the outpour of the wastewater treatment plants without tertiary treatment:

Parameter

Commonly achieved values

Guaranteed value

CODCr

50 mg/l

75 mg/l

BOD5

10 mg/l

15 mg/l

SS

10 mg/l

20 mg/l

N-NH4

2 mg/l

5 mg/l

Ntot

15 mg/l

25 mg/l

Ptot

3 mg/l

7 mg/l

without chemical precipitation  

The guaranteed and commonly achieved parameters from the outpour of the wastewater treatment plants with tertiary treatment:

Parameter

Commonly achieved values

Guaranteed value

CODCr

35 mg/l

50 mg/l

BOD5

5 mg/l

10 mg/l

SS

5 mg/l

10 mg/l

N-NH4

2 mg/l

5 mg/l

Ntot

15 mg/l

25 mg/l

Ptot

0,3 mg/l

1 mg/l

Technical parameters:

  TYPE

Maximum design
flow rate
 [m3/d]

Design load
[kg BSK5/d]

Reactor sizes
length x width x height
[m]

Nr. of lines

Sludge production
[kg/d]

Average electricity
consumption

[kWh/d]

AT 1000

150

60

11,4 x 10,6 x 4,0

2

45

72

AT 1500

225

90

13,9 x 12,5 x 4,0

2

68

155

AT 2000

300

120

16,8 x 13,4 x 4,0

2

91

213

AT 2500

375

150

16,8 x 14,9 x 4,5

2

113

249

AT 3000

450

180

17,7 x 16,8 x 4,5

2

136

323

AT 3500

525

210

20,5 x 16,8 x 4,5

2

159

391

AT 4000

600

240

23,0 x 16,8 x 4,5

2

181

453

AT 4500

675

270

21,1 x 20,2 x 4,5

3

204

494

AT 5000

750

300

22,7 x 20,2 x 4,5

3

227

525

Technical and construction design of the Larger wastewater treatment plant

  • the  designed device as a compact unit with the variety of shapes and modularity with a combination of watertight concrete and lightweight thermoplastic wall or structural elements allow one functional unit to perform the task of balancing variable flow and achieving the highest possible efficiency of biological treatment of nitrogen and phosphorus removal at low servicing requirements and maintenance
  • Simple modular construction, can adapt to the waste water gradual increase in production
  • concrete tanks that are monolithic or prefabricated  are made of watertight concrete with a circular, quadrangular or polygonal ground plan including the bottom, outer shell and dividing wall separating non-aerated activation space and aeration activation space and deflector composed ​​of watertight concrete. The inner dividing walls and sedimentation room sheath are built with polypropylene thermoplastic construction elements.