Living Technologies Ltd: Technical Background

Technical Background to the Eco-Restorer System

Dr. John Todd, an eminent Canadian biologist, undertook the research behind this technology through the non-profit research organisation Ocean Arks International of Falmouth, Massachusetts. For his work in pioneering the development of Restorer systems, Dr. Todd has received a number of honours including the Teddy Roosevelt Conservation Award from the White House in 1990, and the Chrysler Award for Industrial Design in 1994.

Performance

This will vary according to circumstances. The following table provides information on the influent and effluent of the Restorer system/Living Machine at Findhorn, which treats sewage to advanced wastewater treatment (tertiary) standards.

1	BOD before treatment 250 mg/l	after treatment less than 10 mg/l
2	TSS before treatment 160 mg/l	after treatment less than 10 mg/l
3	TKN before treatment 40 mg/l	after treatment less than 10 mg/l
4	NH4 before treatment 50 mg/l	after treatment less than 2 mg/l
5	NO3 before treatment 0 mg/l	after treatment less than 5 mg/l
6	TP before treatment 7 mg/l	after treatment less than 5 mg/l

1. BOD = Biological Oxygen Demand, (the oxygen being consumed by the wastewater)
2. TSS = Total Suspended Solids (the level of solids suspended in the water)
3. TKN = A measure of the nitrogen level in the water
4. NH4 = Ammonia levels in the water
5. NO3 = Levels of nitrate in the water. The system converts ammonia into nitrates and then to nitrogen gas
6. TP = Total phosphorous levels

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Design

Using the Findhorn example, the system is housed in a single-span greenhouse, approximately 10 Metres (M) wide by 30 M long. The flow from the Park at Findhorn has a loading of approximately 300 people equivalents. In other words about 60m3 waste water per day.

Anaerobic Septic Tanks

The first component of the treatment process is 3 anaerobic bioreactors buried outside the greenhouse. The function of this component is to reduce significantly the organic material and inorganic solids in the wastewater. During operation, no oxygen will be present in the wastewater, promoting the growth of anaerobic and facultative bacterial populations.

Closed Aerobic Reactor

Effluent from the anaerobic tanks flows into a closed aerobic tank in the greenhouse. Air is introduced through fine bubble diffusers to convert the waste water from an anaerobic to an aerobic state. Gases from the closed aerobic tank pass through an filter system to eliminate odours.

Open Aerobic Reactors

The four aerobic tanks have diaphragm aerators and are planted with plant species with large root masses on floating plant racks. The BOD and TSS is reduced at this stage and ammonia nitrified.

The primary function of the plants is to provide favourable environments for enhanced microbial activity. Bacteria and other micro-organisms attach themselves to the large surface area of submerged plant roots. These attached biofilms contribute significantly to the treatment process.

Secondary plant functions include nutrient removal, metal sequestering, pathogen destruction and some control of gas exchanges. The main objective is to have a healthy and diverse sequence of ecosystems present. The wide variety of plant species filling ecological niches in the system is a key to the robust nature of natural treatment systems. The ecological network of species creates internal biological redundancies compared with a purely microbial system, or a monoculture duckweed system. This gives the potential for improved efficiency and greater resilience.

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The Clarifiers

The solids kept in suspension in the aerobic tanks are removed in the Clarifier. They settle to the cone-shaped bottom of the tank and are returned to the anaerobic primary. In the Clarifier tanks you may see tiny water creatures such as Cyclops living in the water. They perform an important part in both treatment and in creating a complex food chain.

The Ecological Fluidized Beds

The three Ecological Fluidized Beds in each train are filled with light rock media. For aerobic operation, air lift pumps raise the water from the bottom of the fluidized bed to the surface, where the water flows down through the bed. Recycle rates can be varied up to 100 times the flow rate through the component.

The aerobic operation provides reductions in BOD and TSS and nitrification. For the anaerobic operation of the fluidized beds for denitrification, mechanical pumps circulate water up through the bed. The fluidized beds are planted and benthic animals graze the surface.

The first fluidized bed is usually run aerobically to nitrify any remaining ammonia in the waste stream. The second fluidized bed can be run anaerobically to denitrify. The third and final fluidized bed is run for final denitrification and polishing.

The underlying concept behind the design involves rapid flows of water by recycling through the media filled zones. The key attributes of an Ecological Fluidized Bed are:

•	Stable high surface area micro-environment sites for bacteria.
•	Ultra rapid exchanges across biological surfaces.
•	Direct NH4/NO3 uptake.
•	Nitrification and denitrification cycles.
•	The support of higher plant life and root systems within the media and in the aquatic environments.
•	Self-cleaning.

The biology is managed as a balanced ecosystem. The levels of dissolved oxygen, and carbon to nitrogen ratios, as well as recycle rates and bioaugmentation, are adjusted with the overall objective of reducing levels of BOD, ammonia, total nitrogen, faecal coliform and solids.

The Greenhouse

The greenhouse is built from a galvanised steel frame, clad in a high performance glazing system. The walls are 10 mm polycarbonate. The roof is composed of high light transmission panels, with good thermal efficiency normally used for solar panels.