Delft University of Technology
Faculty of Civil Engineering and Geosciences
Section of Sanitary Engineering
CT5520 – Drinking water treatment 2
Design project
Harderbroek (Vitens) – Improving iron removal
prof.ir. J.C. van Dijk / K. Teunissen / Dr.ir. B. Heijman / Dr.ir. L.C.Rietveld
April 2007
,1. Problem description
Raw ground water from location Harderbroek can be characterised as soft, iron containing and
anaerobic. To remove iron the minimal requirement is to increase the oxygen concentration.
However, with the present treatment set-up iron is not sufficiently removed.
Develop practical alternatives to be realised in the present set-up of the treatment plant. Detailed
information about the situation at PS Harderbroek can be found in annex.
2. Actual situation
The treatment plant consists of cascade aeration (4 cascades divided into 2 lanes) to increase the
oxygen concentration, rapid sand filtration to remove iron and tower aeration to increase pH.
Raw water quality
The groundwater water quality is given in table 1.
Table 1. Raw water quality PS. Harderbroek
parameter unit value
0
Temperature C 14
Acidity pH 7.45
Saturation index - 0.79
Agressive carbon dioxide mg/l 4.3
Carbon dioxide mg/l 5.7
Oxygen (dissolved) mg/l 0.0
Methane µg/l < 10
Ammonium mg/l 0.05
Bicarbonate mg/l 86
Chloride mg/l 7
Sulphate mg/l 11
Sodium mg/l 5,9
Calcium mg/l 26
Magnesium mg/l 1,7
Total hardness mmol/l 0.72
Iron mg/l 1.6
Manganese mg/l 0.11
,Design capacity
The design capacity of the treatment can be determined with the following data:
year capacity: 9 mln m3
maximum day factor (peak factor): 1.8
minimum day factor: 0.7
Abstraction
The well field consists of 10 wells, with a capacity of 200 m3/h each.
Cascade aeration
The purpose of the cascade aeration is to remove CO2 and ad O2.
Number of cascades 4
Steps per cascade 6
Maximum capacity per cascade 450 m3/h
Rapid sand filtration
The purpose of rapid sand filtration is to remove iron and manganese from the ground water.
Number of filters: 8
Surface per filter: 25 m2
Sand bed, grain size: 1.0 – 1.6 mm
Height of sand bed: 1.8 m
Supernatant water level: 1.0 m
Flow per filter: 225 m3/h
Filtration velocity: 9 m/h
Tower aeration
Number of towers 3
Packing material pall 25 PE
Packing height 2m
Maximum capacity 320 m3/h
Surface 6.06 m2
Clear water storage
The clear water storage is necessary for levelling off the fluctuations in transport and for differences
in pumping flows (switches). The necessary water is storage is determined on 5.000 m3:
, Volume of clear water storage (nett): 5.000 m3
Number of reservoirs: 2 à 1.500 m3+ 1 à 2.000 m3
Clear water pumps
Transport capacity: 1.800 m3/h
Number of pumps: 4 to 500 m3/h
Faculty of Civil Engineering and Geosciences
Section of Sanitary Engineering
CT5520 – Drinking water treatment 2
Design project
Harderbroek (Vitens) – Improving iron removal
prof.ir. J.C. van Dijk / K. Teunissen / Dr.ir. B. Heijman / Dr.ir. L.C.Rietveld
April 2007
,1. Problem description
Raw ground water from location Harderbroek can be characterised as soft, iron containing and
anaerobic. To remove iron the minimal requirement is to increase the oxygen concentration.
However, with the present treatment set-up iron is not sufficiently removed.
Develop practical alternatives to be realised in the present set-up of the treatment plant. Detailed
information about the situation at PS Harderbroek can be found in annex.
2. Actual situation
The treatment plant consists of cascade aeration (4 cascades divided into 2 lanes) to increase the
oxygen concentration, rapid sand filtration to remove iron and tower aeration to increase pH.
Raw water quality
The groundwater water quality is given in table 1.
Table 1. Raw water quality PS. Harderbroek
parameter unit value
0
Temperature C 14
Acidity pH 7.45
Saturation index - 0.79
Agressive carbon dioxide mg/l 4.3
Carbon dioxide mg/l 5.7
Oxygen (dissolved) mg/l 0.0
Methane µg/l < 10
Ammonium mg/l 0.05
Bicarbonate mg/l 86
Chloride mg/l 7
Sulphate mg/l 11
Sodium mg/l 5,9
Calcium mg/l 26
Magnesium mg/l 1,7
Total hardness mmol/l 0.72
Iron mg/l 1.6
Manganese mg/l 0.11
,Design capacity
The design capacity of the treatment can be determined with the following data:
year capacity: 9 mln m3
maximum day factor (peak factor): 1.8
minimum day factor: 0.7
Abstraction
The well field consists of 10 wells, with a capacity of 200 m3/h each.
Cascade aeration
The purpose of the cascade aeration is to remove CO2 and ad O2.
Number of cascades 4
Steps per cascade 6
Maximum capacity per cascade 450 m3/h
Rapid sand filtration
The purpose of rapid sand filtration is to remove iron and manganese from the ground water.
Number of filters: 8
Surface per filter: 25 m2
Sand bed, grain size: 1.0 – 1.6 mm
Height of sand bed: 1.8 m
Supernatant water level: 1.0 m
Flow per filter: 225 m3/h
Filtration velocity: 9 m/h
Tower aeration
Number of towers 3
Packing material pall 25 PE
Packing height 2m
Maximum capacity 320 m3/h
Surface 6.06 m2
Clear water storage
The clear water storage is necessary for levelling off the fluctuations in transport and for differences
in pumping flows (switches). The necessary water is storage is determined on 5.000 m3:
, Volume of clear water storage (nett): 5.000 m3
Number of reservoirs: 2 à 1.500 m3+ 1 à 2.000 m3
Clear water pumps
Transport capacity: 1.800 m3/h
Number of pumps: 4 to 500 m3/h
