The Living Machine is different from most wastewater treatment systems, so we get a lot of questions about how it works and in what ways it differs. Many of these questions originated on a bulletin board in the AJLC lobby. These questions and their answers are compiled below, along with others frequently asked to the center’s staff.

What happens to the toilet paper?

Toilet paper flows with wastes and water into the underground anaerobic tank, the first step in the Living Machine treatment process. In this tank, solid wastes and bulky toilet paper sink to the bottom of the tank, and the leftover brown water continues on through the Living Machine system.

Back in the anaerobic tank, bacteria begin to digest the solid wastes. Human wastes are primarily composed of organic carbon and nitrogen, two of the essential nutrients bacteria and other life forms require to grow and reproduce. Toilet paper (and other paper products) contain carbon, so in the anaerobic tanks, it becomes another carbon source that sustains bacterial populations.

Anaerobic bacteria transform organic carbon into smaller organic compounds and also into methane (CH4), releasing this gas into the atmosphere. The anaerobic tanks have off-gassing pipes to prevent methane buildup. The other byproduct of anaerobic metabolism is ammonium (NH4), and this inorganic nutrient is carried in dissolved form to other tanks in the system, where different bacteria transform it into other inorganic forms and eventually reduce it to nitrogen gas which is released to the atmosphere (N2).

What happens to the Living Machine in the summer? How does it get its poop?

The Living Machine receives wastes in the summer in the same manner as in other seasons, when people use the center’s toilets. The only difference is that in the summer, when classes aren’t in session, fewer people use the building. The Living Machine adjusts to these times of low flow by changes in ecological dynamics. Certain bacterial populations decline until autumn brings more poopers (students). Almost all natural ecosystems also experience variability in material and energy inputs over the course of a year. The effects of changes in input are reflected by changes in the concentrations of nutrients and organic matter in the different tanks in the system. Change is OK.

What happens to the methane released from the anaerobic tank? Could we capture it and use it as a fuel source?

Methane (CH4) is a byproduct of the anaerobic metabolism of organic material. Methane is an odorless gas that is vented to the atmosphere through the white PVC pipe extending up from the anaerobic tank. Methane is both a valuable fuel source and a powerful “greenhouse” gas that is potentially damaging to the environment. However, because of the particular composition of the waste that is processed in the Living Machine (particularly its low carbon/nitrogen ratio), only a relatively small amount of methane is produced; it would not be easily feasible to capture the methane as a fuel source, and its contribution to the greenhouse effect is negligible.

What is the “Poop Campaign”? Is there a problem with the Living Machine?

Student operators often conduct “Poop Campaigns” to encourage the campus to use toilets in the AJLC. In some instances, we have even given students a quarter, or edible treats for using the toilets. These campaigns are primarily intended as a fun way to raise awareness, educate the community, and challenge people’s preconceptions about the nature of waste and resource in our society. The Living Machine was designed to treat a larger waste flow, so we encourage people to make contributions! However, large flow is not necessary for the proper functioning of the Living Machine; it is capable of handling the variable input that characterizes building use.

Are the water fountains connected to the Living Machine and is the water from the Living Machine drinkable?

Creating drinkable water has never been the goal of the Living Machine wastewater treatment system. Living Machines are designed to clean water so that it can be released into natural ecosystems without damaging them or humans. Specifically they are designed to do three things:

  • Remove nutrients (nitrogen and phosphorus) that can cause unwanted plant growth,
  • Remove organic matter that can deprive aquatic ecosystems of oxygen, and
  • Remove human pathogens.

In addition to being permitted to reuse Living Machine effluent in the building’s toilets, we recently received permission to use the treated effluent water for irrigation in the orchard and gardens on the north side of the center. So no, the water fountains do not contain water that has been recently treated by the Living Machine, but the placement of the fountains immediately in front of the Living Machine greenhouse serves as an excellent reminder that the hydrological cycle is ultimately a closed loop – all of the water we drink leaves our body in a form that is no longer potable, and all of the potable water we drink was once dirty.

Are there any composting toilets on campus?

Yes, there is a Phoenix Composting Toilet and a waterless urinal in the Environmental Studies AJLC Annex, an energy-efficient and ecologically remodeled residential-scale building next door (to the west) of the AJLC. The Annex opened as a classroom, environmental studies laboratory, and office space in Fall 2006. The Annex features both composting and dual-flush toilets, as well as a solar greenhouse, recycled laboratory cabinets and counters, ceiling fans, and an instant hot water heater. Look inside for the door with a “Composting Toilet Inside” sign. Composting toilets offer unique challenges and opportunities for the treatment of human waste, including:

  • Building plans and codes assume that bathrooms will be plumbed and connected to city lines. In many regions (including Oberlin) an exemption must be granted to use composting toilets, which do not fall under this description. Additionally, an alternative bathroom must be installed in a building with a composting toilet; the AJLC Annex has a dual flush toilet to meet this requirement.
  • With composting toilets, waste handling becomes the responsibility of the building owner. Composting toilets are ecological systems and do, indeed, require care and attention to function properly. Bulking materials, such as wood chips, need to be added regularly, and the compost must be mixed and kept moist. Current Living Machine operators have taken on this responsibility as part of their duties.
  • Many people assume that composting toilets will be smelly and attract insects. If operated properly this need not be so; we have never received odor complaints about our composting toilet.
  • It’s also arguable that people in this society are not psychologically prepared to take more direct responsibility for their wastes. We have been separated from our waste for so long that we’ve collectively forgotten that those wastes were once considered resources and could in fact be used again for nourishing our fields and gardens. Other societies such as in China still consider human manure to be a resource, sometimes called “night soil.” Farmers there put toilets along the road by their fields and vie for travelers’ wastes because they use them on their crops as fertilizer. At the AJLC, we have used the composted human waste to fertilize the fruit tree in our orchard.
Does the Living Machine evolve?

In biology, the term “evolution” is generally restricted to changes that occur in the genetic composition of populations. Change in ecological systems is often termed "development". The Living Machine was specifically designed to “self-organize” or to develop and change over time in response to varying conditions. When the system was first started, more plant species and bacteria were introduced into the system than could realistically survive. The populations were allowed to naturally sort themselves based on the environmental conditions. As the system has matured over the years, it has become more efficient at processing nutrients. The development of the system in ways that meet wastewater treatment objectives is dependent on a careful balance between human management and ecosystem self-organization.

How is the wetland in front of the AJLC connected with the Living Machine?

The wetland pond is NOT physically connected to the Living Machine. The pond is, however, connected with the larger goals of the AJLC in the sense that it demonstrates environmentally responsible approaches to water use. In addition to harboring a diverse community of native Ohio plant species, the wetland serves as a stormwater retention basin. Water falling on the roof of the building is channeled into the pond and then overflows into a storage cistern and finally overflows into the city storm sewers. Stored water can be used to replenish the wetland during dry periods of the summer. Treated water from the Living Machine currently goes to a separate underground storage tank. Living Machine effluent is reused in the toilets and can be used to water plants in the landscape. More information on water flow, storage and use in the landscape is available under the “Landscape” tab above

Can tampons be flushed in the AJLC’s toilets?

The Living Machine is a biological system and can not degrade plastics -- please do not flush any non-biodegradable material down the toilet. Biodegradable tampons are OK as long as they do not clog the toilet. Some women choose to use reusable “Keepers.”

How much water does the Living Machine treat and how much of this water is recycled in the building?

Living Machine-type treatment systems are scaled for large facilities or small communities. A Living Machine was incorporated in the AJLC principally because of its educational value. Since the AJLC is a college office building, its use varies seasonally and also with semester scheduling. Although our Living Machine is capable of treating about 2,500 gallons/day, it actually treats a very small percentage of this capacity. Depending on building use, the amount of water that is processed by the Living Machine typically ranges from 0-200 gallons/day. Because the center does not contain showers or dining facilities, toilet flush water comprises the majority of water use. This means that 60-80% of the water used in the AJLC is Living Machine treated, internally re-used wastewater!

In spring of 2004 students Jonathan Beckhardt, Ellen Kunz, and Trevor Walter investigated the possibility of treating wastewater from other campus buildings in the center’s Living Machine. Their report, presented to facilities planners in May 2004, has laid the groundwork for expansion of the system which would maximize both its research and educational value.

How can I learn about other Living Machines?

Visit these websites to learn more about ecological engineering and LMs:

How can I get involved?

The Living Machine is operated and monitored by student employees and volunteers who report to Environmental Studies staff and faculty. Student operators are responsible for daily evaluations and maintaining the ecosystem in top working order. Student lab technicians are responsible for analyzing key aspects of water quality including nutrient concentration, organic carbon metabolism, and pathogenic bacteria. You can volunteer with a current operator to get an inside perspective on the system. The Living Machine is also used extensively for classroom and independent research projects. Stop by the Environmental Studies Program Office, located in Room 212, for more information.