1

Waste Water Treatment Plant Case Study

Aartselaar Aquafin

MAIS AL JUBORI HANNES DECADT MOHAMMED HERZALLAH

April 2015

2Outline

Introduction

General Scheme of the WWTP

Description of the WWTP

Calculations

Problems and Possible Solutions

Conclusion

3Introduction Aquafin is a regional wastewater treatment company in

Flanders. Mission: expanding, operating and financing the sewage

treatment infrastructure in Flanders. responsible for the operation of 287 sewage treatment

plants distributed over the 5 provinces of Flanders. Each plant recives household wastewater collected from

the municipal sewers and treats it according to the European and Flemish standards.

Aquafin Aartselaar is one of these plants, located in province of Antwerp and serves the population of the zone Aartselaar and part of Wilrijk using the biological treatment.

4

GENERAL SCHEME OF THE WWTP

Aartselaar

5Description of the WWTP

A. Collectors and screw system

B. Sand traps

C. Selector, anaerobic and anoxic tank

D. Aeration tanks

E. Sedimentation tanks

F. Sludge handling

screw system

Sand traps

Selector tankAnaerobic tankAeration tank with surface aeratorSedimentation tank

F

A B C D E

6CalculationsNitrification-denitrification

Nitrification: NH4

+ O2 NO3-

Denitrification: NO3

- N2

Unaerated tanks Aeration tanks

Recycling

Selector

Anaerobic

Anoxic

Facultative aerated

Aerobic

7Calculations Phosphate removal

Growth P-uptake

Selector

Anaerobic

Anoxic

Facultative aerated

Aerobic

PHB formingP-release

Unaerated tanks Aeration tanks

Recycling

8Calculations Removal efficiencies

Qinf = 28875 m³/d

= 5962 m³/d

G

= 444 m³/d

TT

= 28818 m³/d=51788 m³/d

Xt = 70 kg/m³

= 28488 m³/d

= 22526 m³/d

= 22970 m³/d

Qtot = 57750 m³/d

Unaerated tanks 2500 m³

Aeration tanks 5600 m³

Settle tanks4242 m³

Xeff = 14.6 g/m³ X = 4 kg/m³

= 387 m³/d = 57 m³/d

Xw = 9 kg/m³

Qsi

Qr’

Qr

Qr+Qr’

Qreflow G+TT

Qt

Qso

Qw

Qeff

ΔX=4000 kg sludge/d

Calculations Flow scheme

10CalculationsSludge-related parameters

11CalculationsOxygen demand & aeration costs

30%

€0.15/kWh

12Problems and Possible Solutions

The high concentration of the suspended solids in the effluent

Poor nitrogen removal

- Improving NH4+-removal: longer sludge residence time

- Improving NO3--removal: recycling more or making the anoxic zone

larger

- Turn-off the paddlers of the aeration tanks to let the sludge settle down calmly

- Use of membranes

13Conclusion

Typical conventional activated sludge system with recycling for biological treatment of COD, nitrogen and phosphate

Removal efficiencies reach the actual quota, but can be bettered: The COD is removed properly Concentration of suspended solids has to be carefully followed

up Removal of nitrogen could be improved by more recycling Biological phosphate removal works satisfied