I. INTRODUCTION
Wastewater treatment plants exist
in different sizes and forms. Systems of water supply and water sewage/waste water
management are very complex influenced by various single factors (supply area,
climate …). Aiming at the longevity of waste water treatment plants, a very
important and crucial point is their sustainability. The development of long
lasting, sustainable wastewater infrastructures is very critical at the
initiating design stage in order to guarantee a long-term achievement of enhanced
service by the wastewater systems. It is a major challenge for the design of
e.g. the treatment capacity, energy efficiency, and recycling to address both customer's needs (i.e. quality of sewage) and environmental
protection requirements. Changes of the treatment plants often are very expensive
in a later stage. Thus the sustainable strategic planning and engineering
process including site planning is an important economic factor.
II. SUSTAINABILITY
In 1987, the concept of sustainable
development entered political and public scenes. Based on the Brundtland report,
the most common definition of Sustainability reads: "Development that meets
the needs of the present without compromising the ability of future generations
to meet their own needs". Sustainability is often seen as encompassing
three dimensions: environmental, the economic and social, called "triple
bottom line" [2].
Figure
1. Triple bottom line
As a result, the design of sustainable
wastewater treatment plants is supposed to meet future objectives of design capacity,
regulatory on water quality, control and monitoring of technical processes and
uncertainties of economical development. “The designed wastewater treatment plant
can respond to social, environmental and economic needs of present generations
and anticipates those of future generations in communities / municipalities and
countries” [3]. One example for inadequate planning is found in
III. PLANNING PROCESS
Planning is the anticipatory preparation of
decisions intending to influence strongly the planning subject towards certain
targets. There are different steps within the planning process:
·
Target
definition and concept
·
Analysis
of status quo
·
Development
of measures and alternatives
·
Evaluation
of impact / effects / assessment
·
Decision
For the preparation of decisions on the investment
in a wastewater treatment plant, the engineering/dimensioning of this plant,
cost effectiveness and the site planning have to be included. To achieve easier
access to this kind of planning procedure, different strategic methods may be
applied. Two assessment method groups exist: the numeric-quantitative methods
and the qualitative-argumentative methods
Figure 2. Strategic methods
IV. APPROACH EXAMPLE
SYSTEM ENGINEERING – BUILDING BLOCK STRATEGY
There are different approaches for
dimensioning waste water treatment plants (WWTP). One approach is to use the
building block strategy. The subject is divided into blocks, each block is described
by search terms/questions and the search terms are combined with operators.
This strategy enables to see what each component of the facility may effect in
order to meet current and future needs.
For the wastewater treatment plant the blocks can be described through
three main questions [3]:
1. Which capacity is needed for the plant, both at the present time and in
future?
2. Which effluent quality is needed for the environment, both currently
and in future?
3. Which kind of management/refinancing methods (biosolids methods) is
most cost-effective and environmentally desirable at the present time and might
be desirable in the future?
Additionally to the aforementioned topics, the
following options for a municipality have to be considered when planning a
wastewater treatment plant:
·
Protection
of the Environment: soil and site characteristics; groundwater and surface water
conditions
·
Wastewater:
quality, quantity, and fluctuation,
·
Wastewater
management technologies: collection, treatment, disposal/recycle/reuse,
·
Operation & maintenance Infrastructure:
public or private utility system, and
·
Investment
cost and cost of managing wastewater; recycling.
V. APPROACH FOR SITE
PLANNING – VALUE BENEFIT ANALYSIS, SWOT
Having calculated the dimension of the wastewater
treatment plant, the approach for site planning may be started.
A site analysis should be carried out in order to
determine the best possible location for the waste water system. The procedure
comprises mainly the comparison of site requirements with those of alternative
sites, so that decision criteria for preferred sites will be generated, through
analysis and evaluation.
The choice of one specific site depends on different
impact factors. Depending on the requirements, there are differences in the
assessment of the significance of separate sites factors by the client (e. g.
industrial branches).
Figure 3. Site analysis [6]
Site-related factors are facts describing the sites.
A distinction is drawn between “hard factors” and “soft factors” (Fig. 3). "Hard"
site factors such as costs, quality and availability of power, water, waste disposal,
transportation and land are part of the traditional site evaluation and are
reasonably quantifiable. “Soft factors” are non quantifiable facts such as
political and social conditions, acceptance on the part of the public, quality
of the environment [1].
The assessment of the sites is based on site-related
criteria. Criteria are requirements specified by e. g. legal, financial
and technical requirements and clients’ demands (e. g. minimum site size, distance
to sewer). Site criteria describe the minimum requirements for the site (high
priority); additionally there are many further criteria on the part of the
client.
After the description of different sites via
site-related factors, the site-related factors will be evaluated against the
criteria and a first rough selection of site alternatives will be made.
Site planning is always based on a multi-dimensional
system of targets. Objectives often compete and will have to be balanced
against each other if dealing with planning proposals. Balancing means looking
into the single case and weighting its advantages against disadvantages in
order to make a decision.
There are different methods how to assess and weight
data/items. One method is the Value Benefit Analysis (VBA). It is a method
which describes the benefit of different decision alternatives in correlation
to each other. For each alternative there is a value describing the benefit.
This method applies particularly to “soft criteria”.
The value-benefit analysis is composed of following
steps:
1.
Target
definition
2.
Definition
of targets criteria (soft and hard criteria), “must-have” criteria and “nice to
have” criteria
3. Definition of alternatives
4. Target analysis: Definition of weighting factors for
each target in accordance to the different impact
5. Identification of the target of each alternative
regarding each sub-goal.
6. Weighting of the target level
7. Calculation of the total benefit through summing up
the weight levels of each sub-goal.
8. Sorting of the numbers, the site with the highest
number suits best.
Before applying VBA, another strategic method may be
used to make a first pre selection of sites: the SWOT Analysis
(verbal-argumentative method). SWOT Analysis, is a strategic planning tool used to evaluate the
strengths, weaknesses, opportunities, and threats identifying the internal and
external factors.
Figure 4. SWOT analysis [4]
This tool is mainly used during the ex ante evaluation of programs/geographic
regions. A SWOT analysis describes positive and negative aspects and identifies
the factors in the environment which may positively or negatively affect the project/planning
targets.
VI. APPROACH FOR OVERALL SYSTEM -
SCENARIOS
A further method to consider the entire waste water
treatment system is the visualization via scenarios. Scenarios are tools, which
provide an insight into the remote future including uncertainties. Scenarios
are stories about the world of tomorrow. A central characteristic is the
thinking in systems. The scenario technique enhances the entirety/ integrative approach
instead of the investigation of details concentrating on interactions/ interdependencies.
The effort for scenario preparation varies; mostly it is a combination of both
method blocks. The scenario steps are as follows [5]:
1.
Definition
of the central problem
2.
Identification
and list of important influence factors (including factors for engineering of
plants, site planning, cost effectiveness).
3.
Identification
of influence factors of the wider environment (political, …)
4.
Ranking
of influence factors
5.
Selection
of a number of key factors with the highest uncertainties. These factors are
the scenario driver and the basis of the scenario structure.
6.
Completion
of the scenario structure with the other influence factors and describing of
scenarios
7.
Development of activities and options on the
basis of the different scenarios (point 6)
8.
Selection of indicators for early warning about
certain development trends and selective application of prepared activities
(point 7) for adjusting planning to the realistic development.
VII. RESULTS & CONCLUSIONS
There are many possibilities how to execute
planning. In this article only a few approaches are presented. Planning processes
are always processes in which many stakeholders have to be involved to
guarantee an agreement on sustainable and accepted products. Today, it is very
important to anticipate future demands regarding economy, social responsibility
and environmental compatibility already in the planning process of wastewater
treatment plants. Particularly the impact on the environment has to be as low
as possible. For building up new waste water treatment plants, the sustainability
should always be a key factor. To guarantee the sustainability of waste water
treatment plants strategic planning methods including “soft” criteria are
necessary and essential tools.
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REFERENCES |
1. Bathelt H. and
Glückler J., 2003: Wirtschaftsgeographie. 2. Auflage. Ulmer, Stuttgart
2. Brundtland G., 1987. Our
Common Future: The World Commission on Environment and Development.
3. Daigger G., and
4. European Commission: Evaluation Tools; http://ec.europa.eu/europeaid/evaluation/methodology/tools/too_swo_def_en.htm
5. Hiessl,
H. et al., 2003: Alternativen der kommunalen Wasserversorgung und
Abwasserentsorgung. Physica-Verlag, Heidelberg
6. Muncke
G., Walther M., Schwarte M., 2000: Standort- und Marktanalyse –
Das Buch mit sieben Siegeln wird geöffnet. In: Immobilienzeitung. IZ
– Tutorial, Standort- und Marktanalyse. Nr. 17