Nature-based Solutions for wastewater treatment in cities
Transcript of Nature-based Solutions for wastewater treatment in cities
Dialogues template | XX.2019 1
10 March 2020
Nature-based Solutions for wastewater treatment in cities
Dr. Antonina TorrensFSUB-University Barcelona
BRASÍLIA - DF – BRAZIL III International Seminar on Nature based Solutions (NbS)The water challenge and cities
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Index
1.NBS for water and wastewater management in cities
2.Nature-based technologies for sanitation
3.NBS experiences
4. Implementing NBS for sanitation in cities: challenges
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The NBS definition by the European Union states that these solutions
are "inspired and supported by nature, which are cost-effective,
simultaneously provide environmental, social and economic benefits
and help build resilience.
• With respect to water issues, NBS can achieve the following (according to the World
Water Development Report 2018 by UN-Water):
1. Use natural processes to enhance water availability (e.g., soil moisture retention,
groundwater recharge),
2. Improve water quality (e.g., natural wetlands and constructed wetlands to treat
wastewater, riparian buffer strips), and
3. Reduce risks associated with water‐related disasters and climate change (e.g.,
floodplain restoration, green roofs)
1. Nature-based solutions for water and sanitation management in cities
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Chemical and microbiological
contamination
Sanitary risk
Environmental risk
SANITATION PLANS
- centralised-decentralised?
- disposal-reuse?
- rainwater?
- sludge?
LEGISLATION
TECHNOLOGIES (WWTP)
WASTEWATER- MUNICIPAL- INDUSTRIAL- RUNOFF- AGRICULTURALetc..
WATER POLLUTION
1. Nature-based solutions for water and sanitation management in cities
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Integrating Nature into Urban Sanitation Services
Current centralised vs. future decentralised and NBS based concepts for urban sanitation. Source: F.Masi, A.Rizzo, M.Regelsberger (2018).
NBS includes:
- circular economy,
- resource-oriented,
- green
infrastructure,
- and ecosystem
services
approaches to
respond to sanitation
needs worldwide.
1. Nature-based solutions for water and sanitation management in cities
From centralized to decentralized sanitation
From grey towards green
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Natural technologies (“extensive technologies”, “soft technologies”, “non-conventional
technologies” or “sustainable technologies”) for wastewater treatment use natural, commonly
occurring self-treatment processes that take place in soil, water and wetland environments.
Soil and vegetation are directly involved in the processes, mainly through the formation of
favourable conditions for the development of microorganisms taking part in the treatment
process.
2. Nature-based technologies
Beside the particular treatment aimed at, NBS can provide a variety of
other vital ecosystem functions, some of which are wildlife habitat,
evapotranspiration and thus urban heat cooling, water storage and
management, recreation, landscaping, green in the built environment.
Social benefits.
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Comparison of conventional and
natural technologies
Conventional Natural
High energy expenditure:
electrical energy for oxidation
and mixing in reactors (higher
cost)
Little or no energy expenditure: Natural
energy (sunlight and occasionally wind
energy)
Advanced technological
equipment
Little or no advanced technological
equipment. Ground movements in
construction are vital
Proportionally lower surface area Require considerable surface area
Short hydraulic retention time Long hydraulic retention time
Processes may be rapidly
modified
Treatment mechanisms have
considerable inertia
Complex maintenance and
exploitation
Simple maintenance and exploitation
Specialized labour supply Management should know the
processes and be able to prevent
problems
Technological appearance Good integration in landscape
Artificial processes (very
accelerated systems)
Natural processes at “natural” speeds
2. Nature-based technologies
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Water based (algae/plants): ponds
- Naturals
• anaerobic, facultative, maturation, storage
• macrophyte pond
- Aerated pond
Wetland based: constructed wetlands
- Natural
• Free water surface flow
• Subsurface flow
o horizontal
o vertical (conventional, “French”)
o Hybrid
• Intensified Systems (eg. aerated)
Soil /soil-plant based
- Infiltration-percolation
- Soil-plant aquifer treatment
- Soil-plant-aquifer treatment
- Green walls and green roofs
Types
2. Nature-based technologies
Alone, combined or combined with conventional
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Legislation
Governance
Environmental
aspects
Economical
constraints
Technical
aspects
Climatic
constraints
Sociological
constraints
WWT technology:
choice
Availability
of land
Geological
constraints
Technology choice
2. Nature-based technologies
Type of
wastewater
Disposal/reuse
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Applications
2. Nature-based technologies
Domestic wastewater (black, grey)
Urban wastewater (small medium size communities):
secondary treatment of municipal wastewater
Urban wastewater: tertiary treatment as polishing stage
in conventional treatment plants or other natural
systems (eg. big cities)
Industrial wastewater
Agro industrial wastewater
Agriculture source wastewater
Runoff water
Sewage overflow
Sludge
Landfill
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Costs and energy requirements2. Nature-based technologies
Constructed Wetlands vS conventional technological
solutions - Investment and O&M costs
Comparison among
investment costs of
CW and activated
sludge WWPTs on the
basis of Italian
experience (IRIDRA's
analysis)
O&M cost
comparison
between CW and
activated sludge
WWTPs on the
basis of Italian
experience
(IRIDRA's analysis)
Comparison of energy consumption for
different conventional and nature-
based treatment technologies
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French Subsurface Flow Constructed Wetlands for raw wastewater treatment
(towns and neighborhoods <20.000 PE)
“French reed beds”
FRB is an attractive solution to minimize the operational andmaintenance (O&M) costs of wastewater treatment.
Schematic of french VFCW
3. Nature-based solutions experiences
WWTP of Orhei municipality (20000 PE)Moldavia, among the biggest CW systemworldwide.
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Residential area in
Preganziol (Italy)
Nature based solutions for the treatment and reuse of grey water
(decentralized sanitation in buildings or condominiums)
Constructed wetlands
3. Nature-based solutions experiences
Telaviv (Israel) Grey water for toilet flushing;
rain water harvesting and reuse
for irrigation
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Green walls (vertical gardens)
3. Nature-based solutions experiences
Greywater green wall by Vivers Ter-Asepma.
2.500 m2 vertical garden at the Tabacalera
Space in Tarragona (Spain).
Nature based solutions for the treatment and reuse of grey water
(decentralized sanitation in buildings or condominiums)
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Ponds for wastewater treatment and reuse of small-medium-large cities
3. Nature-based solutions experiences
Pond systems: Ouagadougou WWTP (Burkina Faso)Treating 96 m3/h of domestic and industrial wastewater
Reuse in periurban gardens
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Infiltration-percolation for wastewater reclamation
3. Nature-based solutions experiences
Infiltration-
percolation for
tertiary treatment,
Palamós, Spain
Infiltration-percolation
for secondary
treatment, Hostalets
de Pierola, Spain
Drip irrigation
Infiltration-
percolation pilot
for car-washing
wastewater
recycling
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Aerated constructed wetlands for urban, industrial wastewater and combined sewer overflow
treatment
Aerated CW for WWTP of Merone (CO-120.000 PE). The
centralised WWTP of Merone treats the wastewater from
the combined sewer serving 38 towns.
3. Nature-based solutions experiences
Combined sewer overflow upstream the WWTP of Merone (Italy)
Aerated wetland of 360 m², treating the sanitary waste
water from an elementary school, Bretch (Belgium)
The school has 700 students and 300 personnel
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Environmental problems of the final
stretch of the Besòs river.
▪ Very degraded and high
marginality
▪ Problems with the hydraulic
capacity
▪ Water pollution. High concentration
of nutrients in the river water.
▪ Polluted soils, the river use as a
brown field.
▪ No biota
▪ Citizens saw the river as a problem,
no connectivity between river sides
▪ No big green areas in this part of
the metropolitan area
Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
3. Nature-based solutions experiences
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The general objectives of this recovery project
were:
Improve the environmental and landscape
quality of the watercourse.
Improve the flow from the Montcada i
Reixac wastewater treatment plant through
the introduction, in the watercourse, of a
tertiary treatment based on the generation
of wetlands.
Guarantee the hydraulic capacity of the
river.
Recover and naturalize the final section of
the mouth.
Use certain spaces of the river for leisure.
Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
3. Nature-based solutions experiences
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Key features Project implemented in three phases:
Withdrawal of 69 high tension towers and its bases (2002-
2006)
Restoration of 9.2 km (5mi 1261.2yd) from the river.
Total budget: 40.5 million € 85% funded by the EU
(Cohesion Funds)
Social Success. More than one million visitors/year
Improved environmental conditions: more than 160 bird
species. aprox. 10 ha of wetlands / 3,8 Km with water
tertiary treatment
60 treatment beds (plots) grouped into 15 groups
1.000 m3/h of water treated / 30% of the effluent from
the Montcada waste water treatment plant
Treatment flow rate for the beds as a whole be between
0,3-0,4 m3/s (depending on natural conditions)
In operation since: Dec 2007
Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
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Constructed wetlands in Besòs river
Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
3. Nature-based solutions experiences
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Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
3. Nature-based solutions experiences
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Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
3. Nature-based solutions experiences
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Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
3. Nature-based solutions experiences
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Environmental Recovery of the final stretch of the River Besòs, Barcelona, Spain
3. Nature-based solutions experiences
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How to integrate NBS for WASTEWATER treatment IN the City?
Challenges
Space needed per PE
Legislation
Governance
Risk
Public acceptance (e.g. odours)
Incorporate into urban planning
4. Implementing NBS for sanitation in cities: challenges