research & education :: Living Machine

The Living Machine provides excellent opportunities for Oberlin College students and the community to explore issues of wastewater, wetland ecology, microbiology and plant dynamics. It has served as a laboratory for students of Systems Ecology, Mathematics, Environmental Chemistry and Microbiology. It has been the focus of several independent student research projects. Area elementary through high school students visiting the Living Machine learn about the importance of wastewater treatment for maintenance of healthy rivers and lakes and how wetland ecosystems purify polluted water. See current and past research projects below:

 

  
 
LM Operations



Living Machine Operators, 2005-06
Front: Elyse Perruchon, Mary Notari
Middle: Stacey Litner, Ella Ornstein
Back: Gavin Platt, Ben Greene, Cheryl Wolfe-Cragin, Anna Brown, Apostol (Apo) Dyankov
Not Pictured: Andrew DeCoriolis, Kevin Kralik, Emma Nolan-Thomas

A team of student operators and lab assistants maintain and monitor the treatment performance of the Living Machine. This dedicated group's responsibilities include monitoring of water quality parameters, horticultural and pest management, general cleaning and organization, maintainence of data collection equipment, sample collection and assessment of water quality in the laboratory, and educating each other on the structure and mechanisms of the Living Machine. Operators also attend weekly planning and educational meetings. Contact Cheryl Wolfe-Cragin if you are interested in getting involved.

Bacterial Culturing for Potential Pathogens

Rachel Cohn '04 spent Winter Term of 2002 optimizing the membrane filter procedure to quantify the presence of bacterial pathogens in the Living Machine.   She surveyed all tanks of the Living Machine for fecal coliform, the indicator organism utilized in the wastewater industry as an index of water quality with respect to pathogenic bacteria. Generally speaking, the presence of fecal coliforms in water indicates recent fecal pollution. As well as being in feces, fecal coliforms are also found naturally in the gut of warm-blooded animals, and are essential for the human body to function correctly. Specifically, fecal coliforms are a segment of coliforms that ferment lactose at temperatures above 35 C. The incubation temperature required is 44.5 C +/- 0.2 C. Because fecal coliforms possess the ability to grow at relatively high temperatures, they can be easily singled out and counted by experiment. The specific microorganism that is found using the membrane filter procedure with an M-FC medium is Escherichia coli (E. coli), the most common fecal coliform. Student operators now use this technique three times per week to verify the living machine system is meeting effluent standards.

 

  
 
Blue colonies grown on agar are fecal coliform bacteria (left). A close-up, colorized view of fecal coliform (right).

Bioregulation of Water Flow Through a Constructed Gravel Marsh

James McConaghie '03, Joel Musee '04 and Mike Pennino '05 are three of several students that have worked with Professor John Petersen to investigate the regulation of water flow through the Living Machine marsh. These studies examine how the introduction of emergent macrophytes to a sub-surface flow constructed wastewater treatment wetland might alter water flow. Flow patterns have been quantified using fluorescent dye and bromide ion.  The effect of plant community development on nutrient removal and movement in the wetland have also been investigated through the use of tracers.

Biotic Regulation of Water Flow and Nutrient Dynamics in a Constructed Wastewater Treatment Wetland
Honors Thesis, James McConaghie '03
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James McConaghie '03 collects samples from the gravel marsh for his senior honors research.

Nutrient Processing and Dynamics

Caroline Turner '04 and Professor John Petersen investigated the efficiency and dynamics of nitrogen removal from wastewater by the AJLC Living Machine. The Living Machine is a recently developed greenhouse-wetland wastewater treatment system that relies on biological and physical processes to remove nutrients such as nitrogen and phosphorus from wastewater. They identified denitrification as the limiting factor for nitrogen removal in the AJLC living machine. Denitrification is limited in turn by carbon availability. The locus of denitrification intended by Living Machine designers was a subsurface flow gravel wetland. System operators added plants to the gravel wetland to provide carbon for denitrification. However, plant colonization remained sparse one year following introduction and no improvement in denitrification was yet observable. Turner and Petersen's data indicate that most denitrification instead occurs when water is recycled back to anaerobic tanks at the beginning of the system where carbon is abundant. The author's suggest this mechanism for nitrogen removal could be optimized in design of future greenhouse-wetland systems.

Nitrogen Dynamics and Metabolism In a Greenhouse-Wetland Wastewater Treatment System
Honors Thesis, Caroline Turner '04
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Automated Measuring of System Metabolism

In the Fall of 2000, an automated data collection system was installed in the Living Machine. Designed and implemented by Professor of Environmental Studies John Petersen and Alexander Maly ('02), the system consists of a series of dissolved oxygen probes in each aerated tank connected to a data collection and control system. The probes relay information to a Campbell datalogging computer which records real-time measurements of dissolved oxygen and water temperature every minute, 24 hours a day.

To measure rates of metabolism in the Living Machine, the air pumps to the tanks are turned off every 6 hours. The probes then measure how dissolved oxygen levels change as bacteria in the water use it up, and based on the time it takes for levels to drop by 1 mg/L, the computer calculates Total System Metabolism (TSM), an index of carbon content.


    

Surface Water Discharge Regulations

Background

The Center's Living Machine was designed to process wastewater into reusable grey water. Living Technologies, Inc., designers of the Living Machine, submitted a proposal in April of 1996 to both the City of Oberlin and the Ohio EPA suggesting that the treated grey water be recycled through the Center's toilets and used for landscape irrigation and recharging the wetland pond.

Recycling is Allowed, Irrigation is Not

Oberlin City officials focused on the proposed re-circulation system, concerned that the Living Machine's grey water might contaminate the city's fresh water supply. To alleviate these concerns, an "air gap" was installed into the Center's plumbing system to separate the re-circulation system from city water flow. This precaution satisfied the City of Oberlin, allowing work on the Living Machine to proceed.

The Ohio EPA, on the other hand, worried about the proposal to use treated effluent in the Center's landscape. For simplicity's sake, an effluent discharge permit was not pursued.

Federal and State Regulations

The Ohio EPA is responsible for, among other things, regulating the discharge of pollutants into Ohio's surface waters by authority of amendments made in 1973 to the Federal Water Pollution Control Act (more commonly known as the Clean Water Act). Among these amendments was the outline for a permit program known as the National Pollutant Discharge Elimination System (NPDES), which was instituted to control water pollution by regulating point source dischargers. Under this system dischargers seeking permits are required to meet Ohio Water Quality Standards which apply to the effluent itself and the quality of the water body into which the effluent will be introduced.

On a case-by-case basis, the EPA determines the effluent guidelines for fecal coliform, temperature, suspended solids, pH, total nitrogen, phosphorus, dissolved oxygen, biological oxygen demand, ammonia and other metals and toxins. The discharging facility is then granted a permit based on their specific situation.

The EPA and the Living Machine

The EPA maintains that the Living Machine cannot discharge into the Center's pond because the Center has sewer access, considered a more "attractive" discharging alternative to using effluent into the landscape. In addition, the extra nutrients (primarily phosphorus and nitrogen) in the effluent could potentially disturb the balance of the wetland pond area. For these reasons, the Center's staff will not consider this type of discharge permit.

Local Regulations and Irrigation

Another option for treated water reuse is to use excess water to irrigate the orchard. Irrigation is different from discharging because effluent isn't introduced into surface waters and therefore requires only an EPA permit to install an outdoor faucet from the effluent stream. Approval from the Lorain County Board of Health isn't mandatory, but the board has requested involvement so that they can respond to any inquiries they may receive about the project. A Permit to Install (PIT) has been placed to the EPA and the process of granting that permit is in motion. When the faucet installation has been implemented, the Lorain County Board of Health has asked for fecal coliform data from effluent both before and after it has undergone UV filtration.

Since this study was published, a permit has been granted for irrigating the landscape with treated effluent from the Living Machine.



    

Start-up and Development of the Living Machine Ecosystem

As the Center was opening in January of 2000, David Austin from Living Technologies (designers of the Living Machine), Oberlin faculty and twelve Oberlin students prepared the Living Machine for use.

They began by filling the newly installed tanks with city water, checking equipment for proper connections, and familarizing themselves with the layout of the system and its processes. Students attended several training sessions during which the workings and underlying principles of the Living Machine were reviewed and discussed. Standard wastewater analysis methods were also perfected in order to monitor the health of the future LM ecosystem.

Living Machines are composed of a lot more than just a set of pumps, tanks and pipes, however. It is life that directly cleans and conditions the water for reuse. Therefore, a Living Machine's active components -- plants, bacteria, and other aquatic organisms -- had to be grown, rather than built in place. The life that started the Living Machine came from many places:

  • Activated sewage sludge that harbors abundant microbes
  • Sediments from area marshes and ponds provided bacteria, protozoa, and other aquatic microorganisms
  • Freeze-dried bacteria
  • Clippings from plants grown in the Living Machine in Burlington, VT
  • Transplants from local marshes and ponds

Like natural ecosystems, Living Machines are designed to be self-oranizing. That means that we simply put the bacteria and plants into the system, and they establish themselves in communities where survival is most favorable.

After initial plantings and bacterial inoculations in January and February of 2000, the biological systems of the Living Machine developed throughout the spring. The plant roots began forming a fine, dense mat, an excellent substrate for microbial populations.

Life began to emerge in all corners of the living machine: Snails thrived in every tank, filling up the rims at the water's edge then subsided after a few weeks; of a group of a dozen goldfish introduced to the Clarifier, four of the heartiest survived to grow to very large size; and a pair of Anoles, a species of Chameleon, was introduced.

The start-up period was also characterized by anaerobic events as microbiological communities stabilized. The living machine was helped through this period with sludge additions and dog food feeding during the first few months. The machine became fully operational -- that is, began operating within designed norms -- in the latter half of May 2000. Since the biological systems are now in place, such a long startup period will not be required again.


  
 
Varuni Tiruchelvam ('00, center) and Sarah Eastman ('00, right) studied plant growth and care strategies with David Austin (left).

Comparison of BOD5 and Total System Metabolism Techniques for Measuring Carbon in the System

One important indicator in an ecological system is the measure of its production and respiration over time. In an ecosystem, as in an organism, we can call this activity "metabolism". Measuring this metabolic activity gives us information on how the ecosystem functions. The Living Machine is specifically designed to maximize the removal of organic carbon from wastewater through the respiration from bacteria in the water. Because the water contains so much biological activity, the opportunity exists to compare two different methods for measuring system metabolism. Both methods assess metabolic activity by tracing changes in dissolved oxygen levels over time. By measuring the rate of decline in dissolved oxygen, we can gain an understanding of the amount of labile (easily broken down) y broken down) carbon available to the biology in the system. 

The major goal of this project is to discern whether a relationship exists between BOD5 and the technique we've developed for measuring system metabolism. A positive correlation between BOD5 and TSM results would suggest that BOD5 provides a good measure of existing conditions in the tanks. It would also indicate that the relatively rapid TSM technique is a useful substitute for the labor-intensive and ex-situ BOD5 technique. A negative correlation would raise questions about how useful BOD is as a tool for managing wastewater treatment ecosystems.

Comparing BOD and Metabolism 
James McConaghie '03, Alex Maly's '02 and Professor John Petersen
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A Comparison of Nitrification and Carbon Metabolism Using the BOD5 Method

Timothy Haineswood '03 and Naomi Morse '03 examined the factors that limit denitrification in the gravel marsh that serves as the final stage of wastewater processing in Oberlin College's Living Machine. Denitrifying bacteria, Pseudomonas denitrificans, are obligate anaerobes that use the reaction C6H12O6 + 4 NO3 ? 6 CO2 + 6H2O + 2N2 + energy, or variants with other sources of organic carbon, for respiration. Denitrification requires sufficient bacteria, nitrate, anoxic conditions and a source of organic carbon. They took samples from the marsh and added organic carbon in the form of sodium acetate to test the effect of carbon on denitrification. Tim and Naomi found that adding organic carbon significantly increases denitrification and that providing anoxic conditions without the addition of carbon does not. Furthermore, direct sampling of the marsh indicated that only a limited amount of denitrification occurred even though conditions were anoxic. They concluded that the only condition necessary for denitrification not being met in the Living Machine marsh is a lack of organic carbon, most likely because this marsh currently has few plants, while the marshes in comparable systems are densely planted with emergent vegetation.

Low Organic Carbon Limits Denitrification in the Marsh of an Ecologically Engineered Wastewater Treatment Facility at Oberlin College 
Timothy Haineswood '03 and Naomi Morse '03

 

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