Sistemas naturales (alternativas) para el tratamiento de ......•reduce water use ... Economic...
Transcript of Sistemas naturales (alternativas) para el tratamiento de ......•reduce water use ... Economic...
Sistemas naturales (alternativas) para el tratamiento de aguas (residuales)
Version 3
SWITCH Taller de CapacitaciónSan José, Costa Rica, 23 de noviembre 2010
Diederik Rousseau & Tineke Hooijmanswith inputs from Peter van der Steen
Natural treatment systems: response to main pressures
NATURAL TREATMENT SYSTEMS
SPACE REQUIREMENT
Climate Change
More floods More droughts
Stormwater management
BUFFERING CAPACITY
TREATMENT and REUSE
LOW ENERGY INPUT
Energy Reduction Urban Planning
Alternative water sources
Population growth
NUTRIENT RECYCLING
Food production(fertiliser)(water)Wastewater
management
Nhapi and Gijzen (2005)
STEP 1
POLLUTION PREVENTION AND MINIMISATION
• reduce water use
• reuse grey water
• ban undesirable compounds (toxicants)
• apply rainwater harvesting
STEP 2
TREATMENT IN THE DIRECTION OF REUSE
• convert waste to useful products (biogas, protein)
• optimize effluent reuse
STEP 3
DISPOSAL WITH STIMULATION OF SELF-PURIFICATION
• buffer strips
• floating wetlands
Water resource
NATURAL TREATMENT
SYSTEMS
3-Step Strategic Approach
Constructed wetland on the isle of Texel (NL) for further polishing of tertiary treated wastewater and ecological upgrading (Water
Harmonica concept) (Toet, 2003)
Benefit 1: Water reuse
Culemborg (Utrecht)The Netherlands
Benefit 1: Water reuse
Nutrients
PlantsAlgae
Periphyton
FishDucks
• Ornamental value• Mulching and composting• Pulping fibers• Silaging fodder• Proteins, food supplements
Benefit 2 - Nutrient reuse
Table 2.4. Economic efficiencies described as monthly profit per 1000 m2of current waste-water based farming systems in HCMC compared to traditional paddy rice farming.
Type of (wastewater) farming system Monthly profit per 1000 m2 Traditional paddy rice farming D$215,300 Wastewater-based water morning-glory D$320,000 Wastewater-based lotus monoculture farming D$440,000 Wastewater-based integrated lotus and fish culture farming D$452,000 Wastewater-based integrated water-mimosa and duckweed farming D$680,000 Wastewater-based integrated water-mimosa and fish culture farming D$830,000 Wastewater-based fish fingerling production D$766,400 Wastewater-based tilapia fingerling production D$920,000
• Mammals, birds, invertebrates, …
• Ecologists versus engineers
• Ecological value depending on:
• Size
• Structural diversity
• Influent quality
• Western Treatment Plant,Melbourne ~ RAMSAR
Benefit 3 - Habitat function
WWTP Liedekerke (Belgium), Aquafin Ltd70,000 PE - 1.3 ha FWS wetland
Benefit 3 - Habitat function
712,834 birds spotted (2 yr)132 species, 39 families29 Red List species
• Education• Recreation (walking, fishing), travel cost method• Art (photography)
Benefit 4 - Human use
Granollers, Metropolitan Area Barcelona, Spain• 06/2006 – 01/2007: 18,000 visitors• Travel cost method 60,000 Euro• 72,000 Euro investment, 12,000 Euro py O&M
Reservoir
River
Dam Water
Trans.
Water
Consumer
WW
Collection
Primary Treatmentand/or CW & WSP
RBF
LBF
SAT/ARR
Distribution
IrrigationEH
EH
Natural treatment systems
• Wastewater not too toxic
• Sufficient incident light
• Temperature not too low
• Adequate quantities of nutrients
• Detention time long enough
• Organic loading not too high
• Need for enough space
Prerequisites for natural treatment systems
Part 1 – Waste Stabilization Ponds
O2
Organic matterBacteria
Oxygen depleted rivers
CO2
Introduction: what is stabilization?
O2
Organic matterBacteria
Oxygen-rich rivers
degradation of organic matter in a confined
and engineered system rather than in
the environment.
• Ponds are simple man-made basins, often surrounded by an earthen embankment.
• In waste stabilisation ponds both aerobicand anaerobic bacteria contribute to waste stabilisation.
• The oxygen required for aerobic stabilisation is produced by photosynthesis, waste stabilisation ponds are therefore typical natural systems: not requiring any electricity for oxygen input.
Principles of ponds
• Very effective removal of pathogens, and therefore effluent suitable for reuse
• Effective BOD removal
• Simple and cheap construction, operation and maintenance
• Low energy requirements
• Simple sludge management
Advantages of WSP
• Large land area required
• Performance strongly affected by temperature
• Potential odour release
• Mosquito proliferation ~ malaria
• Low degree of operational control
Disadvantages of WSP
Anaerobic ponds Facultative pond (s)
and Maturation Ponds
A typical WSP system
Aerated lagoon
Intensification: aerated ponds
Urban WSP
Ho Chi Minh City - Vietnam
NIMBYArea: corruption & illegal housesAmenities
3-5 meter
sludge
Influent
Anaerobic ponds - Mechanisms
The two main mechanisms in Anaerobic ponds:• Sedimentation of particles• Degradation of organic material via anaerobic degradation process
HRT = 1-3 days
Removal efficiencies in APs BOD 40-60% TSS 50-70% Faecal coliforms 90% Helminth eggs 75-90%
Anaerobic ponds - Efficiency
Influent BOD
Sludge layer
Soluble intermediates
Bacteria
CO2, N, P
Algae
O2
Anaerobic degradation
Facultative ponds: Algae – bacteria symbiosis & anaerobic digestion
Typical facultative pond effluent quality:
BOD 20 - 60 mg/l
TSS 30 - 150 mg/l
Faecal coliforms 104-106 1/100ml
Helminth eggs 0-50 1/liter
In most cases additional treatment is required! pathogen removal & algae removal
Facultative ponds - efficiency
• Main objective: pathogen removal
• Entirely aerobic and 1-1.5 m deep
• Typical HRT 3-10 days
• BOD removal less than 25%
• Usually more ponds in series
Maturation ponds
Removal (log units)Bacteria H. eggs
Primary sedimentation 0-1 0-2Activated sludge 0-2 0-2Trickling filter 0-2 0-2Chlorination/ozonation 2-6 0-1WSPs 1-6 1-3
Typical maturation pond effluent quality:
BOD 10 - 50 mg/l
TSS 20 - 100 mg/l
Faecal coliforms 102-103 1/100ml
Helminth eggs 0 1/liter
Maturation pond effluent satisfies the strictest WHO criteria for effluent reuse in irrigation (< 1000 FC/100 mL).
Maturation ponds - efficiency
• WSP have low O&M requirements• Low does not mean no!
• Main O&M activities:• Cleaning inlet/outlet• Cleaning/maintaining embankments• Prevent scum layers in FP and MP• Desludging anaerobic ponds• Influent/effluent monitoring
Operation and maintenance
WSP costs – price of land
Part 2 – Constructed Treatment Wetlands
Based on water flow characteristics• (free water) surface flow (FWS or SF)• subsurface flow (SSF)
Based on plant species characteristics• floating plants (e.g. Lemna, Nymphaea)• submerged plants (e.g. Elodea)• emergent plants (e.g. Phragmites, Papyrus)
Classification
HelophytesPleustophytes
HydrophytesPleustophytes
Vymazal et al., 1998
Different groups of macrophytes
CONSTRUCTED WETLANDS
Free floating plants
Floating leaved plants
Emergent plants
Submerged plants
Surface flow (FWS)
Sub-surface flow (SSF)
Vertical flow (VF)
Horizontal flow (HF)
Upflow
Downflow
Any combination of the above systems is called a “hybrid” system
Advantages• Low-medium investment cost• Low O&M costs• Simple operation and maintenance – unskilled labour• Little or no energy inputs• Can be integrated into landscaping
Disadvantages• Mosquitoes (in Free Water Surface Systems• Start-up problems• Space requirement• Variable performance possible (~ climate)• Lack of good models for design and operation• LOW PRESTIGE
Advantages and disadvantages of CTW
Advantages and disadvantages of CTWFlorida Everglades Stormwater Treatment Area
Courtesy: Jim Bays
Water flows over soil media and < 50 cm deep. Mostly planted with sedges, reeds, rushes. This is a land intensive system (5-10 m2 per PE).
Slotted pipe forwastewaterdistribution
Slope 1%
Rhizome network Watertight membrane
Effluent outlet
Emergent plants
Soil, sandor gravel
Type 1: Free-water-surface or surface-flow CTW
Reed ditches, serpentine shape promotes plug flow and avoids dead zones
Type 1: Free-water-surface or surface-flow CTW
pre-settlement
diversion weir
Water flows below a medium of sand, gravel, soil and/or rock. Grasses and trees are commonly used. Amount of land reduced (3-5 m2 per PE).
Slotted pipe for wastewater distribution
Slope 1%Rhizome network
Watertight membrane
Effluent outlet
Emergent plants
Soil, sand or gravel
Slotted pipe for wastewater distribution
Slope 1%Rhizome network
Watertight membrane
Effluent outlet
Emergent plants
Soil, sand or gravel
Type 2: Horizontal-subsurface flow or rootzone CTW
Water is pumped on the surface and then drains down through the filter layer. Amount of land minimal (2-3 m2 per PE).
Type 3: Vertical-flow or infiltration CTW
Several vertical riser pipes ensure good distribution.
Filter material coarse sand or fine gravel.
Two-step constructed wetland consisting of a HSSF and VSSF flow bed.
Different conditions in both wetlands trigger different removal pathways hybrid systems are usually more efficient.
Type 4: Hybrid CTW
1. Normal CW Physical transfer Plant root oxygen release
HSSF-CW: 1 – 6 g O2/(m2.day)≅ 10 - 60% of daily cBOD
2. Intensified CW Intermittent feeding Passive aeration Tidal flow Active aeration
SSF-CW: <0.1 kW.h/m3
Intens-CW: 0.17 kW.h/m3
Act. Sludge: 0.76 kW.h/m3
O2
O2
Type 5: Intensified wetlands
IW: up to 100 g O2/(m2.day)
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Forced Bed AerationTM
(picture Scott Wallace, NAWE)
Tidal flow CW
Type 5: Intensified wetlands
landfill leachate (sludge stabilization)
sewage
domestic
municipal separate
combined
agricultural
dairycattle
swinepoultry
industrial
mine drainage coal, metal
food processingwinery, abattoir, fish, potato, vegetable, meat, cheese, sugar , milk productions
heavy industry oil refineries, fertilizers, explosives, polymers, chemicals, pulp and paper mills
runoff urban highway field crop nursery greenhouseairport
Sludge treatment
Rudkøbing
Sludge treatment
32
SLUDGE RESIDUE
1% DM 40% DM
‘natural’, low-tech systems require low but nevertheless adequate maintenance
Vymazal (1998) recommends checking larger systems (> 500 PE) on a daily basis, including:
• pretreatment units• inlet structures• outlet structures
If maintenance ignored:• uneven flow distribution• local overloading• deterioration of treatment efficiency in the long term
Basic maintenance
Lack of maintenance results in failure
Excessive sludge accumulation threatens to block the influent distribution pipes.
50
• autarctic houseboat• 2 vertical-flow CW floating alongside• closed water cycle by means of Reverse Osmosis and UV disinfection• 60,000 Euro (excl. VAT)
GEWOONBOOT, NL
Part 3 – Soil-based systems
• ARR = Aquifer Recharge and Recovery(injection well or infiltration basin recovery well) - ASR = Aquifer Storage and Recovery- ASTR = Aquifer Storage Transfer and Recovery
• BF = Bank Filtration- River bank filtration (RBF)- Lake bank filtration (LBF)
Natural drinking water treatment systems
Soil Aquifer Treatment (SAT)
SAT – Dan region project Israel – 140 .106 m3/year
• Natural and Sustainable Treatment• A Multi-Objective (≈Contaminant) Process• Removal of Turbidity and Suspended Solids• Removal of Biodegradable Organics
• Bulk Organic Matter• Trace Organic Compounds
• Removal of Microorganisms• Removal of Nitrogen (Ammonia + Nitrate)• Replaces or Supports Other Treatment Process
• A Robust Barrier within a Multi-Barrier System• Low Cost
Advantages of RBF/LBF and SAT/ARR
• Only Limited Barrier for Certain Contaminants• Same is true for Granular Activated Carbon, Advanced
Oxidation and Membranes• Proven Barrier for Microbes
• No Reliable Transfer of Experiences to Other Locations• Need for Pilot and/or Demonstration Scale Testing• Soil Column Experiments Scale-Up?
• Possible Release of Fe and/or Mn at Some Sites• Need for subsequent oxidation (post-treatment)• Also, Possible Release of Arsenic (As) and Fluoride (F-)
Limitations of RBF/LBF and SAT/ARR
Part 4 – Ecohydrology / Ecohydraulics
Onsite treatment and reuse
Off-site treatment, (storage) and reuse
In-stream and riparian technologies
Saturated zone
Unsaturated zone
Where does it fit in the water chain?
Quantitative scarcityQualitative scarcity
Vegetated buffers
watercourse & wetland
Buffer strip(natural or man-made)
Source: Jontos (2004)
Vegetated buffer functions
1. Sediment removal (filtration)
2. Nutrient removal (plant uptake & soil adsorption)
3. Stormwater runoff (filtration & infiltration)
4. Water temperature moderation
5. Habitat and wildlife diversity / corridor function
6. Biomass production
Source: Jontos (2004)
Buffer size
Width of VBS range between 2 - 500 meters
Majority fall within 4.6 – 15 meters
Slope of buffer >10%, increase in width
Area ratio range 15:1 to 5:1 or less
watercourseV.B.S
Drainage area
Source: Jontos (2004)
Effects of plants in buffer strips
Function Grass Shrubs Trees
Sediment Trapping High Medium Low
Filtration of Sediment Borne Nutrients, Microbes & Pesticides
High Low Low
Soluble Nutrients & Pesticides Removal Medium Low Medium
Flood Conveyance High Low LowReduce StreambankErosion Medium High High
Source: Jontos (2004)
In-stream remediation – floating wetlands
• Layers of recycled plastic “matrix” bonded together with adhesive foam
• Planted with sod, garden plants, or wetland plants • Plants grow naturally with roots growing through matrix
into the water• Natural eco-system evolves over time Source:
Biohaven
In-stream remediation – floating wetlands
Source: Biohaven
Functions of floating islands
Remove pollutants (nutrients) from water
Provide critical riparian edge, shelter & general wildlife habitat
Erosion control & wave mitigation
Structural alternatives for docks, walkways, bridges & more
Beautify a waterscape
Hyporheic zone treatment (1)
Hyporheic zone treatment (2)
SWITCH demo city - Lodz
SWITCH demo city - Lodz
Lodz – Project 1 – resurfacing Sokolowska river
• Stormwater management improved water quality• Increase water retentiveness less flooding• Improvement of quality of life housing prices
Lodz - Project 2 - Ner river sewage system management
• Green belt• Phytoremediation• Energy
Fish passage
Controlled flooding area – “Room for the river”
La Cienaga de la Virgen, Cartagena, Colombia
The End