1. Stavnsholt Wastewater Treatment Plant, Denmark
STAR Control®
Pre-study
Overview of the many possibilities
Find your own STAR Control® solution
Economies behind STAR Control®
⊲
⊲
⊲

2. STAR Control® – Pre-study
What is a pre-study?
A pre-study at the wastewater treatment plant is a thorough
review of the technical and financial possibilities for implemen-
tation of a STAR Control® system. The choice of online control can
be based on the specific conditions at this wastewater treatment
plant.
A pre-study will comprise:
Collection of relevant data
▹ Flow sheet, dimensions, physical installation, mechanical
description etc.
▹ Analysis results from samples taken at inlet/outlet
▹ Consumption data (power, chemicals, etc.)
Comparisons with STAR installations at more than 30 plants
A report containing:
▹ the proposed control system
▹ the extent of necessary physical modifications and
▹ a description of the financial aspects and pay-back period
Depending of the plant size, a pre-study will typically require 50-
100 man hours distributed over a period of 1-2 months.
STAR will supply a “sound” return on investment
Our more than 15 years of experience have given us a long list of
references, and Krüger’s STAR team is able to present the most
optimum STAR solution for every individual wastewater treat-
ment plant. Over the years, almost every STAR system has been
extended on the basis of new ideas developed between the ope-
rating managers and Krüger’s STAR team so that an even higher
capacity and a further reduction of the operating costs have been
achieved.
⊲
⊲
⊲
The pre-study gives an overview of the savings
and costs related to STAR Control®:
Savings
Reduced power consumption for aeration
Reduced consumption of precipitants
Reduced consumption of carbon sources
Reduced “wastewater fee”
Plant modifications can be postponed or minimized
Renovation can be postponed or minimized.
Costs
Installation of online meters and other mechanical
­equipment
Adjustment of SCADA and/or PLC
Installation of STAR system including a 6-month running-in
period and thorough training of staff
Operation of new online meters
Result
The pay-back period is calculated on the basis of savings and
costs.
The implementation of a STAR Control® system is a comprehen-
sive project comprising many activities.
The pre-study will provide the possibility of evaluating various
alternatives of plant optimization.
⊲
⊲
⊲
⊲
⊲
⊲
⊲
⊲
⊲
⊲
⊲
STAR2Professional® is a unique control system
developed by Krüger on the basis of many years
of experience and process understanding.
STAR2Professional® reduces the operating
costs and optimizes the process capa-
city on the basis of a combination
of special measurements and
experience.

3. Pay-back period
The expected pay-back period is illustrated in the pre-study
­report, as e.g. the figure to the left.
During the preparation of the pre-study, the client will participate
in the necessary decisions as to e.g. how many and which online
meters to be used, what can be adjusted (pumps and blowers)
and what are the limitations to be considered.
The calculation may also comprise savings in the building costs by
e.g. admitting more storm water to the plant by means of storm
water control.
In most cases there is a further “profit” in the form of an optimi-
zation of the daily operation just by the implementation of minor
changes on the basis of the very thorough investigations made in
the pre-study and installation phase.
Plant size
STAR has various pay-back periods for the above possibilities. The
list is more or less in order of priority.
Naturally, the savings will be proportional to the size of the plant.
The larger plant the larger savings.
As a rule of thumb, all plants down to a size of 30,000 p.e. will
benefit from online control as alternative to physical increase of
the plant capacity.
Plants down to 50,000 p.e. will benefit from the online control of
the effluent quality to comply with the standards.
Large plants of more than 100,000 p.e. will experience that the
price of a STAR system will account only for a fraction of the costs
related to an extension.
-400
-200
0
200
400
600
800
1.000
0 1 2 3 4 5 6 7 8 9
Payback period Exampleville (100.000 PE)
k€
years 10
When is online control an issue?
The right time to consider a more advanced online control system
is when the wastewater system:
needs an increased biological or hydraulic capacity
must comply with new and more stringent effluent demands
has troubles with complying with present effluent demands
needs a reduction of the operating costs
(better control “pays off”)
operates with very high or low loads
experiences load fluctuations, e.g. from the industry
needs higher safety margins and a more reliable operation
needs better tools for operating and process understanding
⊲
⊲
⊲
⊲
⊲
⊲
⊲
⊲
5 10 15 20
10
15
20
25
30
35
40
N-tot(NH4
+NO3
)[mg/l]
intermittent drift
full luftning
koordinerad förfällning
5 10 15 20
10
15
20
25
30
35
40
N-tot(NH4
+NO3
)[mg/l]
tid [dagar]
intermittent drift koordinerad förfällning
full luftning
Let model simulations show the possibilities
Include a model simulation in the pre-study to determine the
effect of various STAR and process solutions.
Krüger and VWS have integrated STAR operation in WEST
(standard simulation software). On the basis of a few basic
input and configuration, it is possible to test control ideas and
estimate the effect of the online control of the effluent quality.
Intermittent operation Coordinated operation
Intermittent operation Coordinated operation
Days
Traditional
operation
Traditional
operation

4. STAR Control® – References
Linköping, Sweden
(161.000 p.e.)
N-upgrade by control
Reductions in Carbon dosing
Effluent Nitrogen stabilized
Helsingør, Denmark
(72.000 p.e.)
Economies in operation costs.
Bio-P removal by control.
Storm water control in a.
recirculation plant.
Aalborg Vest, Denmark
(265.000 p.e.)
Economies in operation costs
50% reduction of the needed
extensions in volume of the
secondary clarifiers
Poznan, Poland
(900.000 p.e.)
15% increase in electricity
consumption when
STAR was stopped.
Bruxelles, Belgium
(1,1 mio. p.e.)
Start 2008
Lundtofte, Denmark
(115.000 p.e.)
Economies in operation costs.
Improved effluent quality.
Bio-P removal with control
instead of physical
extension.
Blois, France
(103.000 p.e.)
Savings in electricity 22%.
Bio-P with STAR.
Effluent Nitrogen
stabilised.
For more information,
please contact:
Tine Berenhard Ønnerth
tbq@kruger.dk
Bjergmarken,
Denmark (68.000 p.e.)
Improvements in
the effluent quality.
Expansion postponed
5 years.
Krüger A/S
Gladsaxevej 363
DK-2860 Søborg
Tlf: +45 39 69 02 22
E-mail: kruger@kruger.dk�www.kruger.dk
Klamsagervej 2-4
DK-8230 Åbyhøj
Tlf: +45 87 46 33 00
Sofiendalsvej 88
DK-9200 Aalborg SV
Tlf: +45 98 18 93 00
Marts2008