The Operwas tool allows users to optimize wastewater system configurations and costs through geographic analysis and modeling. It calculates costs of collection, treatment, reuse networks and benefits. Users input location data, costs and reuse options. The tool then delineates catchments, models pipeline networks and treatment plants, estimates flows, costs and reuse. It compares centralized and decentralized scenarios based on coverage, costs, energy use and environmental impacts to support strategic wastewater planning. The open source tool is freely available and was created through collaboration between researchers to benefit wastewater planning.

1. Operwas
Optimization, exploration and research of wastewater strategies
Optimization tool for support of strategic planning of wastewater systems |
Calculation of preliminary costs of wastewater systems, including: investments
needed for construction of pipeline network for gravitational collection, treatment,
operation and maintenance, reclaimed water distribution network, and benefits as
tariffs and fees | Use of geoprocessing techniques and calculation based on local
costs | Assessment of treatment plants' locations with the lowest costs and highest
coverage for any number of wastewater treatment plants | Production of maps that
allow the user to compare different configurations | Provision of a framework-code
that can be tailored for each situation and region

2. Strategic planning of wastewater treatment systems
Possible uses
DECENTRALISED
+ coverage of isolated places
+ resilience
+ flexibility
+ possibilities of reuse and
resource recovery
+ ownership
+ complexity
+ higher investment costs
CENTRALISED
+ economies of scale
+ known performance
+ localized operation
+ eutrophication
+ eutrophication in water bodies
+ high energy costs in networks
+ overflows (if combined
sewers)
Discussions regarding the optimal scale of a
wastewater network are common in the scientific
community and in decision making. Frequently,
advantages and disadvantages of each approach
are mentioned, but they can vary significantly
according to local conditions, and an individual and
local analysis is needed for better understanding of
the available possibilities.
The Operwas tool analyses includes: treatment plants (WWTP) investment, operation and maintenance costs,
investment costs of pipeline for wastewater collection by gravity, reclaimed water distribution pipelines,
reclaimed water reservoirs, land purchase costs, reclaimed water pumping costs, tariffs and fees of wastewater
collection and selling of reclaimed water, energy savings, environmental savings and coverage of the study area.
With this information, it supports finding answers to the following strategic questions:
Cost/Benefits: How can one estimate different costs
and combine them to analyze configurations of one or
more WWTPs?
Energy use: How much energy is consumed in the
studied area for water supply, wastewater collection and
treatment?
Topography: How does the topography influence the
energy prices and consumption in water supply and
wastewater treatment?
Appropriate technology: Which types of
technologies would be recommended for each
wastewater treatment plant (WWTP) considering
its potential for effluent reuse?
Reuse: Which areas in a catchment are more
interesting for reuse of treated effluent, in terms of
urban use (not potable) and agricultural (non
edible plants)?
Tool combines n WWTPs
from list with n options
List with n
positions
List with one
combination’s costs,
benefits and coverage
List with n++
possible
positions
Tool checks many possible
combinations, optimizing the
search
Chosen n
WWTPs
Data set
Do I know where the WWTPs
should be?
InputdataProcessingthe
data
Outputs
YES NO
The tool can be applied in two ways: to evaluate
costs of one combination of a number of WWTPs
which positions are already known, or to analyze
different combinations of a number of WWTPs build
at locations selected from a long-list of possible
positions. For the latter option the tool will generate
an overview of costs and benefits for different levels
of coverage. Both analyses can be done with the
same input data set, changing on the dashboard only
the list of available WWTPs positions and the number
of evaluations.
Maps with WWTP’s
positions and
catchments
List with combinations’
costs, benefits and coverage
(optimization curve)

3. How does Operwas work?
User input information
One WWTP
is planned
to serve
each
catchment
A catchment
delineation takes place
through the analysis of
the digital elevation
model
The length of the
pipeline within each
catchment is
estimated as the sum
of the natural water
channels
Georeferenced information
of housing, land prices,
population density, water
prices and tariffs is
constructed for each
catchment
Possibilities for reuse of the wastewater
around the WWTP is analysed and based
on those possibilities (urban reuse or
agricultural reuse) , the most appropriate
technology is decided , considering the
effluent quality standards for each reuse
Reclaimed wastewater
flows are calculated
according to the treated
flows
At each run of the
tool, total costs and
benefits (tariffs) are
accounted for a time
horizon given by the
user
Operwas can be adjusted to fit any situation. The adjustment of parameters to be used in the calculations
requires the following input variables:
Geographically distributed data
Digital elevation model | Channel delineation | Population distribution| Possible positions of
WWTP| Agricultural and urban water use for irrigation | Land prices
Fixed local data
Successful use of the tool depends on the input data, reflecting a certain case study. Therefore a preliminary
analysis of local costs and possibilities or reuse of the wastewater should be developed together with
stakeholders in order to have an integrated assessment of wastewater and reclaimed wastewater use. User
information is crucial to make the estimation closer to the reality of the region.
Losses of water and collection efficiency | Water consumption per capita | Investment and O&M costs of
known treatment technologies | Prices for wastewater pipelines and reservoirs | Energy costs for water
distribution | Water and wastewater tariffs |Discount rate for investment and planning horizon

4. Download and installation
Operwas (version 0.2) is a free
and open source tool and is still
under development. Its code
can be assessed on the QR
code below, which also
contains an example data set.
It is open for further
improvements to benefit the
scientific community and its
use is free if the appropriate
reference and sources are
mentioned by the user.
The Operwas tool was
developed through the Kidron/
Nar project with funds from
DUPC/Ministry of Foreign
Affairs from the Kingdom of
Netherlands.
Operwas is a result of
collaborative work by Alessia
Matanó, Maria W. de
Alvarenga, Peter van der Steen,
Leonardo Alfonso (IHE Delft)
and Jawad Hasan (Al Quds
University).
For further information, please
contact:
p.vandersteen@un-ihe.org
User input information
The tool was applied to the region
which contains Abu Dis, Al Ezaryia, As
Sawahera and Al Ubeidyia, in the
West Bank/Palestine. The region
contains 7 natural catchments and,
for each catchment, different
numbers of WWTPs were considered
to build one scenario with a total of 7 WWTPs and another with 27 WWTPs.
Both scenarios had the same coverage and their benefits and costs were
put together to be compared. The input data was obtained during field
work (2 months) with stakeholders from the municipalities and project
partners. The investment period of 20 years was assumed and assumptions
for reclaimed water use were together decided.
The highest costs
in both scenarios
were attributed
to the
wastewater
pipelines and to
the wastewater
treatment costs
(both investment
and operational).
The higher treatment costs in the decentralized scenario were
compensated for the smaller energy costs for pumping of the reclaimed
water. When all costs and benefits were summed, there was no significant
difference between them.
Besides those scenarios, many others can be developed, in order to assess
the change of costs with more or less reuse or with different land prices, for
example.
7 WWTPs 27 WWTPs
7 WWTPs 27 WWTPs