The Eco Machine

Solid settlement tanks are the first step in the Eco Machine™ process at the Omega Center for Sustainable Living. From various tanks located throughout campus, wastewater flows into multiple solid settlement tanks. All solids settle out in the tanks as sludge and are injected with microorganisms to accelerate decomposition. The remaining wastewater flows out of the solid settlement tanks to the equalization tanks, step 2 of the Eco Machine™.

All the wastewater from the solid settlement tanks flows into the equalization tanks, the next step in the Eco Machine™ process for natural wastewater reclamation at the OCSL. Two 6,000 gallon tanks equalize the flow of water over 24 hours. This helps balance out natural surges in water use on campus (typically in the morning and early evening), evenly releasing water to the anoxic tanks, step 3 in the Eco Machine™ process.

Without the equalization tanks, the Eco Machine™, and the Omega Center for Sustainable Living, would need to have been designed and built at a much larger scale. By using equalization tanks, we were able to build the smallest facility possible, greatly reducing the carbon footprint of the Omega Center for Sustainable Living.

Step 3 in the Eco Machine™ at the OCSL is the anoxic tanks. Two 5,000 gallon tanks are located underground, right next to the constructed wetlands at the OCSL. Here, naturally occurring microbial organisms use the wastewater stream as food. They begin to digest ammonia, phosphorus, nitrogen, potassium, and many other substances in the water. This process happens with very little oxygen (called either anaerobic or anoxic) and produces a modest amount of methane gas, though not enough to harvest and use as an energy source.

When it's time for the water to move to step 4 of the Eco Machine™ process at the Omega Center for Sustainable Living, the constructed wetlands, a splitter box evenly divides the water in half and distributes it between the upper two wetlands.

There are four constructed wetlands in the Eco Machine™ at the Omega Center for Sustainable Living, each the size of a basketball court. They are three feet deep, lined with rubber, and completely filled with gravel. About two inches beneath the gravel is wastewater, which flows from the anoxic tanks, to the splitter box, to the upper two constructed wetlands. The wetlands use microorganisms and native plants, including cattails and bulrushes, to reduce biochemical oxygen demand, remove odorous gases, continue the denitrification process, and harvest nutrients such as phosphorus. As the wastewater flows through the wetlands, the microorganisms and plants are fed.
 
Once the wastewater is processed in the upper two constructed wetlands, it flows via gravity to the bottom two constructed wetlands. In total, a lot of digestion happens in the wetlands of the Eco Machine™ at the OCSL. There is a 75 percent increase in the water's clarity and a 90 percent reduction in the water's odor by the time it is ready to leave the wetlands to move to step 5, the aerated lagoons. However, not all the water that enters the wetlands travels to the aerated lagoons. The plants absorb some of the water during the purification process in the constructed wetlands, and some of the water evaporates.

From the constructed wetlands, the water is pumped into two highly oxygenated aerated lagoons of the Eco Machine™ at the OCSL. The aerated lagoons are divided into four cells, each 10 feet deep. At this stage, the water looks and smells clean, but it's not safe to touch. The plants, fungi, algae, snails, and other microorganisms of the aerated lagoons are busy converting ammonia into nitrates and toxins into harmless base elements.
 
There is no soil in the aerated lagoons at the OCSL, yet beautiful tropical plants thrive here. The plants live on metal racks and their roots extend up to five feet into the water. The roots of the plants act as a habitat for the organisms in the lagoon, and are sustained by them. The flowers of these tropical plants illustrate the beauty that naturally treated "wastewater" can yield. The blooms are abundant and are a source of flowers for Omega's classrooms.

We've learned many lessons from the aerated lagoons since we began operating the Eco Machine™ at the Omega Center for Sustainable Living in 2009. One important development was getting to know the microcommunity of bugs that needs to be in balance in the lagoons. We discovered how to identify and treat their overpopulation sustainably, so the aerated lagoons can work optimally.

From the aerated lagoons of the Eco Machine™ at the OCSL, the water is sent to a recirculating sand filter. There, sand and microorganisms absorb and digest any remaining particulates and small amounts of nitrates that may still be present, and provide a final "polishing" to the water. The sand filter completes a tertiary level of water processing meeting standards for disposal into rivers, lakes, and wetlands. The effluent can also be used for irrigation.

After the water has been through the recirculating sand filter, it is pumped to two dispersal fields under Omega's parking lot, each about the size of a basketball court. In the dispersal fields, the reclaimed water is released back into the groundwater table, located below the surface. The reclaimed water is further purified by nature as it trickles down to the aquifer that sits 250-300 feet beneath campus.

With this final step in the Eco Machine™ process at the Omega Center for Sustainable Living, Omega completes a closed hydrological loop in our water use. We draw water from deep wells that tap the aquifer; use the water in sinks, toilets, and showers; naturally reclaim the used water with the Eco Machine™ at OCSL; and release the purified water back to the aquifer, where the process can begin again.