Can range from three-cell systems to a 20-cell system
Avg. HRT: 4.5 days applies when tanks with translus- cent light transmitting sides are used for waste treatment The first treatment room consists of four rows of six translucent tanks plumbed in series. The tanks are rich with microbial and algal communities, and water hyacinths, Eichornia crassipes, provide the dominant surface cover. The first five tanks in each line are mixed and aerated with fine bubble diffusers. The sixth tank is without aeration and functions to settle the solids. Solids are recycled to the first tanks in the series and periodically returned to the adjacent main sewage facility. The supernatant from these tanks flows into a set of engineered "tidal" marshes in the second room. Each treatment line flows into two gravel bed marsh trays. These marshes are planted with wetland species The flow is controlled to fill one marsh for 12 h and then switched to the other marsh, allowing the first to drain and dry. This simulates the wet/dry cycles of a tidal marsh. From the marshes the flow is pumped back up into another series of six translucent tanks. These tanks are stocked with a diverse community of racked and floating tropical and temperate plants. The biofilter is filled with a recycled plastic floating media installed in translucent cylindrical tank. The final marsh is a galvanized steel stock trough filled with gravel and planted to a variety of tropical and temperate wetland species
Living machine: The Ecological Wastewater Treatment
ECOLOGICAL WASTEWATER TREATMENT
• Living machine® is a
trademark and brand name
for a patented form of
ecological sewage treatment
designed to mimic the
cleansing functions of
• The technology is based on
fixed-film ecology and the
ecological processes of a
natural tidal wetland, one of
nature’s most productive
Dr. John Todd
• The initial development of the technology in the United States is
credited to Dr. John Todd, the internationally renowned ecological
designer, developed at the now-defunct New Alchemy Institute.
• The Living Machine system falls within the emerging discipline of
The world's most beautiful wastewater treatment
plant :Omega Center for Sustainable Living
1. Mineral diversity
2. Nutrient reservoirs
3. Steep gradients
4. High exchange rates
5. Periodic and random pulses
6. Cellular design and mesocosm structure
8. Microbial communities
9. Photosynthetic bases
10. Animal diversity
11. Biological exchanges beyond the mesocosm
12. Mesocosm/macrocosm relationships
Twelve Precepts of Ecological Design
• Biological richness of the earth is a result of the complexity and
diversity of its mineral foundations.
• In mineral-rich zones, life can be extraordinarily abundant.
• In designing living machines, mineral diversity should include
igneous, sedimentary and metamorphic rocks.
• In living machines they use finely ground rock powders which are
quickly incorporated into biological systems.
• In one experiment they have digested 19000 m3 of bottom
sediments in a polluted 4 ha pond with the application of 7200 kg of
rock powders from glacial materials.
• They were used in combination with a floating living machine
through which 750 m3 of pond water circulated daily.
1. Mineral diversity
2. Nutrient reservoirs
•Mineral diversity provides the long-term foundation for nutrient
•Microorganisms and plants require nutrients in an available form if
carbon is recalcitrant, or phosphorus in an insoluble state, or the
NPK ratios are out of balance, or trace elements are missing, the
ecosystems can become impoverished.
•Ex. If an appropriate inorganic carbon source is not available to the
nitrifying bacteria, the degradation of nitrogenous waste products is
reduced and toxic levels of ammonia can increase.
•The flora of waste purification systems can be completely altered by
trace mineral imbalances.
3. Steep Gradients
•It increase the diversity of internal processes and the multiplicity of
pathways within a living machine.
•Abrupt or rapid change, as measured in time or space, in the basic
underlying attributes or properties of the subsystems.
•For ex. a waste stream can benefit from passing through a series of
stages that have different oxygen regimes, redox potentials, pH,
temperature, humic and ligand or metal-related state.
•When the redox is low enough to cause hydrogen sulfide to form,
treats polluted lakes with forced aeration, or with the addition of
•The ecological designer should consider using diverse humic materials
in various subsystems to produce gradients.
•Iron compounds are key redox elements in regulating paddy soils and
4. High exchange rates
• Maximize the surface area of living material to which a waste stream
• The challenge is to create surfaces and associated communities that
are not disrupted by strong currents and turbulence yet do not
• One approach is to grow floating aquatic plants on the water surface
and, with aeration, to create up wellings that pass large volumes
through the root mass and associated biological communities.
• Surface area of roots available to microorganisms is several order of
magnitude greater than that of manufactured substitute surfaces.
Ecological fluidized beds
• It is a technological development a step beyond
trickling filters or conventional biofilters used in
intensive closed system aquaculture.
• The medium, whether plastic or of mineral origin,
must have a specific gravity approaching 1 so that
the medium will be buoyant or capable of being
• Medium should have rough-surfaced or porous.
• Ecological fluidized beds have rapid internal
recycling rates and still provide habitat for diverse
benthic animal communities. Such communities
can include snails and clams, attached algae,
aquatic plants, and higher plants.
• Nitrification as well as some denitrification can
occur within the same internal recycle loop due to
the abrupt oxygen gradients and the presence of
endogenous organic carbon in the beds
• "Direct reaction of organisms to environmental change is most useful
if the environment is being altered in an unpredictable way... One can
say that the ecosystem has "learned" the changes in the
environment, so that before it takes place, the ecosystem is prepared
for it, as it happens with yearly rhythms. Thus the impact of the
change, and the new information are much less".
• "By creating a pulse, perhaps by controlling the water table or by
covering plants with black plastic an introducing new plantings to
accelerate the self design, a simpler system with a large net yield may
replace the complex one with many low yields".
• living technologies become robust enough in ecological terms to
survive the inevitable failure of some of the system's external
hardware and software.
multiple rows of "cells" connected together like beads on a string.
7. Minimumnumberof subecosystems
• All the ecologically engineered systems they describe
have at least two subecosystems.
• One is an algae growth chamber or algal scrubber that
operates under intense light and acts as a control
• Three major components or subsystems.
• It consists of photosynthetically driven system that is
connected to an animal consumer component, which in
turn, is connected to a detritus/bacterial system
8. Microbial Communities
• That microbial communities are the foundation of
• bacteria species have highly specific nutritional and
• Many important reactions are catalyzed only by
• In their work with the degradation of coal tar
derivatives (PAHs) they inoculated the treatment
systems with microbial communities from such
diverse locations as salt marshes, sewage plants and
rotting railroad ties
• Nucleated algae, water molds,slime molds, slime nets and protozoa are organisms with
exceptionally diverse life histories and nutritional habits.
• Protozoan's are important in removing coliform bacteria and pathogens from sewage. They
also serve to remove moribund bacteria and improve system efficiencies.
• Fungi are key decomposers in ecological systems. It is estimated that there are about
1,00,000 species, many capable of excreting powerful enzymes.
• They can be as efficient as heterotrophic bacteria in the removal of organic matter from
• Fungi tend to be more dominant in low ph and terrestrial soils than in aquatic environments.
• It may be that living technologies should incorporate soil-based acid sites linked to the main
process cycles into their design.
9. Photosynthetic foundations are essential
• Employing plant diversity can produce living technologies that
require less energy, aeration and chemical management.
• Root zones are superb micro-sites for bacterial communities.
• Enhanced nitrification in treatment cells covered with pennywort,
hydrocotyle umbellata, and water hyacinth, eichhornia crassipes, as
cornpared with comparable cells devoid of higher plants.
Pennywort, hydrocotyle umbellata Water hyacinth, eichhornia crassipes
•One species of mustard, Brassica juncea, has been found to remove metals from flowing
waste streams, accumulating up to 60% of its dry weight as lead.
•Metals can be recovered from harvested, dried and burned plants.
•Certain species of higher plants such as Mentha aquatica produce compounds or antibiotics
that can kill certain human pathogens.
•There is economic potential in plants from living machines.
• Flowers, medical herbs and trees used in rhizofiltration in a waste treatment facility can
subsequently be sold as byproducts.
mustard, Brassica juncea Mentha aquatica
10. Animal Diversity
• Find control species, meaning those organisms capable of
directing living processes towards such useful end points
including foods, fuels, waste recovery, and environmental
• The potential contributions of animals to living
technologies is remarkable.
•Snails are central to the functioning of living technologies.
•Pulmonate snails, including members of the physidae, lymnaeidae and planorbidae
families feed on the slime and sludge communities.
•They thrive in zones where predators are lacking.
•Snails play a dominant role in sludge reduction, tank maintenance and ecological
fluidized bed and marsh cleaning.
•Snails of the family planorbidae graze and control filamentous algae mats that
would otherwise clog and reduce the effectiveness of the diverse fluidized bed
communities. Some snails digest recalcitrant compounds.
planorbidae familyPhysidae family
•The salt marsh periwinkle, littorina irrorata,
produces enzymes that attack cellulose, pectin,
xylan, bean gum, major polysaccharide classes,
algae, fungi and animal tissues as well
•As 19 other enzymes interactive with
carbohydrates, lipids and peptides.
•Snails can function as alarms in the living machines
•When a toxic load enters the providence sewage
treatment system for example the snails quickly
leave the water column and move onto the moist
lower leaves of the floating plants above the water.
•Observing this behavior the operator then
increases the rate of recycling clean water back
upstream into the first cells.
•Virtually all phyla of animals in aquatic environments feed through some filtration
•Bivalves, algivorous fish, zooplankton, protists, rotifers, insect larvae, sponges and
others are in this functional category.
•They remove particles of roughly 0.1 µm to 50 µm from the water column.
Freshwater sponges, SpongillaRotifers
•Bivalves are significant filterers.
•Mussels can retain suspended bacteria smaller than 1 µm.
•Efficiencies reach 100% for particles larger than 4 µm.
•Individual freshwater clams of the genera Unio and Anodonta filter up to 40 l/day of
water, extracting colloidal materials and other suspended organic and inorganic
•Removal rates are 99.5%.
•In one experiment clams were used in a Russian river to reduce total suspended
solid levels of 50 mg/1 to 0.2 mg/l
Duck mussel, Anodonta anatina
• Zooplankton can be employed to good effect in applied mesocosms.
• They feed upon particles 25 μm and smaller.
• Their nauplii or juvenile stages graze sub μm sized particles.
• Since they can exchange the volume of a natural body of water several times
per day it is difficult to overstate their importance in ecological engineering.
• We have found zooplankton throughout 3m deep ecological fluidized beds
comprised of 2 cm sized pumice rock in a prototype living technology that
upgrades secondary sewage effluent to reusable quality water in San
• Insects play pivotal roles in living
• Removed from predators in ecologi-cally
engineered systems, they proliferate and
impact significantly on the water.
• In their sewage treatment facilities
chironomid larvae attach themselves to
the walls of the aerated tanks, often in
great numbers. They developed mass
culture methods for chironomids fed on
• Their objective was to culture live foods
• Chironomid production levels were as
high as 400 g /𝑚2/day.
• Water quality improvement was an
chironomid life cycle
facilities chironomid larvae Chironomid adult
• Vertebrates play key roles in the functioning of living technologies.
• fishes are the most numerous and diverse of the vertebrates.
• In diet, behavior, habitat and function fish are extraordinarily diverse.
• Filter and detritus feeding fish are common to all the continents.
• The filtration rate of algivorous fish may be five orders of magnitude greater than their
volume every day.
• In theory it is possible for the total volume of a fish pond to pass through algae-filtering fish
on a daily basis.
• There are edible fish species like the Central American Characin, Brycon guaternalensis, that
are capable of shred- ding and ingesting tough and woody materials.
• We use members of the South American armored catfish family Plecostomidae
to control sludge build up in waste treatment and
food culture living technologies.
• Tilapia, Oreochromis spp., are used to harvest
small plants like duckweed and aquatic ferns.
• The grass carp, Ctenopharyngodon idellus,
recycles a variety of plant materials.
• In several living machines minnows, including
the golden shiner, Notemigonus crysoleucas,
and fathead minnow, Pimephales promelas,
feed on organic debris and rotting aquatic
• They breed among rafted higher plants grown
on the surface of the water. Excess minnows
are sold as bait fish.
Tilapia, Oreochromis spp
grass carp, Ctenopharyngodon idellus
Notemigonus crysoleucasfathead minnow, Pimephales promelas
11.Biological exchanges beyond
• To optimize their self-design and organization capacities a living technology may
require gaseous, nutrient, mineral and biological linkages with larger natural
• For aquatic mesocosms select organisms from stream, pond and lake
• Its is valuable to return each season to these same environments for samples.
• Doing so will provide organisms adapted to seasonal differences.
• An interesting experiment would entail linking a living machine to a natural
ecosystem and exchange biological materials between the two.
• A sewage treatment facility for could be connected with a nearby marsh or pond.
• A small percentage of the flow could be directed to the natural system which, in
turn, could be linked back to the living technology.
• natural system would provide, on a periodic or a continuous basis, an inflow of
chemical and biological materials.
• The linkage would allow the natural water body to act as a refugia for the living
technology, protecting it from toxic upsets or unnatural loadings.
12. Microcosm, mesocosms, macrocosm relationships
• The most complete living system of which we are
aware, the earth, should be the overriding basis for
• the planet having 70% of the interior space
occupied by water and the remainder terrestrial.
• Use renewable energy
• Ecological design will help create a symbiotic
partnership between humanity and nature.
Ocean Arks International has a Solar Aquatic TM living
machine for the treatment of sewage.
Water samples at the Ocean Arks International
research facility in Providence, Rhode Island
• Flow: 61- 34 m3/d
• HRT: 2.5-4.5d
• Influent COD : 800-100 mg/l
• Since Providence is a city with a large electroplating industry metal uptake was a
concern in performance evaluation.
• Cadmium, chromium, copper, silver and zinc were an order of magnitude below the
• The data suggests that living technologies may be a cost effective new way of
protecting and improving water supplies.
Heavy metals removal
• Water hyacinths played only a minor role in metals uptake.
• No more than 1% of the metals appeared in the plant tissue
• One of our design objectives was the removal of most of the coliform bacteria
without the need for chlorination or other sterilization procedures.
• Except for two occasions coliform counts in the effluent were below swimming
water standards of 200 counts per 100 ml. The effluent was below 15 coliforms per
100 ml, the standard for food contamination, over 60% of the time.
Raw, untreated sewage in the
Baima Canal before Restorer
bad odor & health problems.
The Baima Canal after
Restorer also functions as a
community walking bridge.
Urban Municipal Canal Restorer
Flowering plants now line the walkway
Produce beneficial byproducts, such as
• reuse-quality water,
• ornamental plants,
• plant products—for building material, energy biomass, animal feed.
Less energy and land requeriment w.r.t. conventional WWT.
No chemical are required.
It can handle flow variation & seasonal variation.
It is sustainable.
No production of sludge.
The living machine significantly decreased the COD of sewage
inputs, as compared to zero-treatment model outputs.
The living machine has the potential to effectively remove
phosphate, but optimum pH and redox conditions must be
Efficient nitrogen removal by nitrification and dinirtification.
• John Todd *, Beth Josephson, The design of living
technologies for waste treatment, Ecological
Engineering 6 (1996) 109-136.
• John Todda,b∗, Erica J.G. Browna,b, Erik Wellsb,
Ecological design applied, Ecological Engineering 20