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Ecological Design in Urban Environments:
Recent JTED Projects
John Todd, Ph.D., Thayer School Lecture, Dartmouth College, April 28, 2015
Healing The Waters: A Tale of Ecology and Living Technologies
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Greening the Planet
Carbon Neutral Design
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Designs for Southern Africa
Towards an “Invisible” Technology at Langrug, Western Cape Province, South Africa
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Managing Greywater at Langrug
The citizens of Langrug are already piloting two innovative systems for the conveyance and disposal of greywater.
The first system, greywater gutters are simple troughs that allow Langrug citizens to easily dispose of washwater while minimizing the creation of fetid pools and eroded gullies. While the citizens of langrug see these gutters as “working” the greywater sewers are highly unsanitary, create a foul odor and deliver untreated wastewater to the bottom of the hill. Moreover contact with this water is a danger to human health, a condition which is exacerbated by the accumulation of trash within the gutter. Accumulated trash causes stagnation and is a breeding ground for pathogens.
The second system, an ad hoc greywater sewer is more promising. This system most notably makes use of centralized collection points and, through the use of screens, attempts the separation of food‐waste from wash‐water and, when unclogged, succeeds in eliminating the risk of children coming into contact with dangerously pathogen rich water. This ad hoc gutter system succeeds in separating the liquid waste from the ever present blowing trash and reduces the pathogen‐breeding stagnation found in of the rest of the settlement.
This promising system can be modified and improved through the addition of Living technologies and Ecological Treatment. Greywater Gutters
Strengths
• Easy to use
• Easily maintained with broom and shovel
• Limits possibility for human contact
• Low cost
• Easy installation
Current Ad Hoc Sewer
Weaknesses
• Solid and liquid waste are combined resulting in stagnation and breeding pathogenic organisms
• Combination of greywater and stormwater
• High risk of human contact
• Sewers empty into street, problems are simply moved down hill
Strengths
• Separation of trash and liquid wastes
• Separation of greywater and Stormwater
• Limits possibility for human contact
• Centralized collection points allow for some removal of solids
• Low cost
• Easy installation
• Reduction of odor
Weaknesses
• Some solid waste enters sewers
• Prone to clogging and difficult to clean
• Sewers are open to air • Sewers empty into street, problems are simply moved down hill
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Flexible Sewers for Informal Communities
A living sewer system will expand upon the example set by the ad hoc sewer found in the upper region of Mandela Park. The proposed system retains the flexibility of the ad hoc sewers while creating a system which is more robust, less prone to fouling, easier to maintain, effects treatment of the greywater, recharges the groundwater table, and contributes to the overall greening of Langrug.
The living sewer system combines collection, conveyance, treatment and disposal in a novel holistic system. Collection points are evenly spaced every 8‐10 meters throughout the community and provide pre‐filtration removing fines and food‐scraps that can cause the sewers to clog.
Along the path of conveyance Micro‐Wetlands provide biological filtration and maintain an aerobic condition. Above ground these wetlands are small well irrigated gardens that enhance the community.
Branching sewer lines converge upon Phototrophic Soil Makers (PSM) these are deep pit tree wells where greywater is purified through the processes of adsorption, decomposition and root associated micro‐organisms and fungal communities. The PSM removes nutrients and organic material converting them to humus and allowing purified effluent to infiltrate back into the ground.
As a disposal system the PSMs can be though of as creating a highly decentralized septic field. Compared to a conventional septic field this mechanism of discharge creates steeper gradients of soil moisture and a more dynamic subterranean condition.
This system can function both independent‐of and in‐concert‐with the eco‐machine designed for Bioremediation and treatment of greywater at Langrug. If constructed the Eco‐Machine™ will be an “end of the line” treatment cleaning pre‐filtered water to a higher level. Unlike a conventional foul sewer this living sewer is designed to grow and shift along with the community. Over time the system will leave behind a network of deep planted tree wells with rich high carbon soils. Healthy soil is the by far the most effective way to retain moisture in a landscape, and these tree wells will now serve a new role as locuses of stormwater retention, mitigating flooding and creating a landscape of abundance.
KEY
Collection and pre‐filtration
Micro‐Wetland
Phototrophic Soil Maker
Small diameter piping
Direction of Flow
Eco‐Machine™
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PRETREATMENT at COLLECTION points
The citizens of Langrug are already willing to carry their greywater from homes to evenly placed collection points throughout the community. These collection points can be reconfigured to provide increased pretreatment and separation of solids. The collection basins will be stacked for easy use and maintenance and can be simply constructed out of threaded plastic sleeves and 25 liter buckets, ideas for the construction and configuration of these collection basins and their pre‐filtration mechanisms will be explored in greater depth in the detailed design.
USE AND MAINTENANCE
Daily:
‐Pour the water in
‐remove collection basin ‐clean 1st screen
Some awareness and education campaign may be needed to train residents to clean the 1st screen after use. This action is similar to what is already being done where the ad hoc sewer has been installed
Periodically ‐remove collection basin and 1st screen
‐clean second screen
Annually or as needed
‐replace sand or media layer
Existing basin uses chicken wire to partially screen out some solids and trash.
These maintenance tasks would be carried out by trained personnel.
Collection Basin with Inset 1st screen a coarse filter. Filter can easily be removed for cleaning as solids accumulate. Basin is 50 litres.
Collection Basin
Sized to accommodate the full volume of a standard laundry basket ~25‐50l
A 2nd screen separates the collection basin from a chamber filled with compost and wood chips. A layer of rubble or large stone ensure even flow through this filtration chamber.
1st screen
Separation of larger solids. This screen is easily accessible and is scraped clean on a regular basis
2nd screen
Provides artificial surface for an active biofilm this screen protects the sandfilter from clogging
Media filter
Modified slow sand filter. Sand or possibly woodchips/compost. The purpose of this layer is to provide additional filtration as well as to seal the lower sewer from the upper collection system.
MULTIPLE PROTOTYPES
For the purpose of arriving at an optimal system it will be desire able to test a range of solutions. Some collection points will use a sand filter, others woodchips, and others simply nylon shadecloth for screening.
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MICRO WETLANDS AND SIDESTREAM TREATMENT
Micro wetland are placed in between collection point these are at lower grade then the direct piping. When unclogged all water will flow through the micro wetlands. Root growth should keep the Micro Wetlands permeable to water but if flows increase or any clogging occurs the direct line will serve as a bypass routing excess flow directly along the sewer.
Collector
Side View
Collector
Micro‐Wetland
At the surface these wetlands will have the appearance of tufts of grasses or restios and wetland plants. Micro‐
Wetlands may be maintained as small gardens for water loving plants.
Collector
Micro‐Wetland
Top View
Collector
Direct Bypass Line
Micro Wetland Line
Arrows show direction of preferential flow
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Photrophic Soil Maker
Where the informal settlement allows us to use greater space we can locate deep sun powered soil generating treatment wells. These Phototropic Soil Makers mimic a submerged or high moisture forest floor. Charcoal limbs provides a high carbon base for the formation of soils as it serves simultaneously to adsorb nutrients and contaminants and to fuel the micro‐organismal processes of soil creation.
The mature PSM will be a deep tree well located below grade. This well will serve not only to enhance the community, providing shade, cleaning the air and greening Langrug, it will also serve to reduce flooding and erosion as the loose carbon rich soil absorbs and retains storm water running down the cities streets.
A sand and mulch layer ensure that no odors or volatile organic compounds will escape the deep well. Rubble provides lines the well and provides void space for improved infiltration.
As greywater treatment the PSM retains valuable nutrients and organics for the creation of soil. Purified effluent is used by the tree and respired into the air through evapotranspiration. Excess liquids may infiltrate into the ground where they will be further purified by Langrug’s sandy soils before entering the deeper groundwater. A steep soil moisture gradient surrounding the infiltration zone will ensure a biologically dynamic environment for micro‐organisms.
Monitoring wells can be located down slope of the PSM to ensure no contaminants leach into the groundwater.
Greywater Treatment Condition
Mature Condition
Shown as a tree well for the capture and infiltration
Of stormwater
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Thin Film Flow Eco‐Machine
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Algal Turf Screen
TYPICAL ORGANISMS
ALGAL TURF SCREEN
Periphytic algaes (monera &Protista)
Grazed by snails (Animalia)
REFERENCE
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FEEDING PEOPLE
New Food Webs from Neglected Resources
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Decontaminating Industrial Waters
The Blackstone River Canals, Grafton, MA
Heavy Oil Contaminated Canals Along an Industrial Corridor
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4 Symbiotic Technologies
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Canal Restorer
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Rebuilding an Industrial Waterfront
Peoria, Illinois
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Ecological Design Plan Overview
Downtown Wetland Water Park
River-fed Eco-Machine™ Swimming Pool
Pilot Project River-Restorer and Urban Wilds
Peoria_eco_park.png
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Drawing credit: ASLA
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Illinois River Restorer
Cross Section
River Restorer with central boardwalk
Stabilized bank and native plantings
Diffuser
Curtain
CSO Treatment
River Water Treatment
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Cape Cod Regional Transit Authority
ECO‐MACHINE FOR THE BUS WASHING FACILITY, INCLUDING REMOVAL OF ROAD SALTS
EXISTING PROCESS
Wash Station
Municipal Rinse Water
Floor Drain
Suspended Solids
Cyclone Filter
Low Pressure Wash (90 gpm)
Floor Drains
Sludge
Tank
High Pressure Wash (64 gpm)
Sump Pit
Hauling & Disposal
Reclaim Tank
Tight Tank
Oil Water separator
Sump Overflow Gravity Line
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PROPOSED PROCESS
Municipal Rinse Water
Wash Station
Floor Drain
Suspended Solids
Sludge
Tank
Cyclone Filter
Low Pressure Wash (90 gpm)
Floor Drains
High Pressure Wash (64 gpm)
Sump Pit
Treated Water Storage
Eco‐Machine
Hauling & Disposal
Reclaim Tank
Tight Tank
Oil Water separator
Sump Overflow Gravity Line
TREATMENT PROCESS CONCEPTUAL DEVELOPMENT
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TREATMENT PROCESS CONCEPTUAL DESIGN
Mixed media septic and anoxic
Aerobic mixed media reactor
Aerobic Botanic cell 1
Aerobic Botanic cell 2
Aerobic Botanic cell 3
Upflow
polishing wetland cell
Tight Tank
Algal Turfs
Pleated Cartridge Filter
Treated Water Storage
Halophytic Planter
Ultra Violet disinfection
MOSQUITO ISLAND, BRITISH VIRGIN ISLANDS
ECO‐MACHINE FOR TREATING AND RECYCLING OF WATER FOR THE ISLAND’S NEW COMMUNITY
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Moskito Island
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Moskito Island : Process Flow Diagram
30,000 gpd
Treated for Irrigation re‐use
Vertical wetland collection and inpection ports
Botanic Aeration Machine backfilled with gravel
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Construction
Construction Progress
Coir matt installed, plants are in shade tent awaiting planting
STRUCTURES THAT TREAT SEWAGE AT THE SOURCE
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