Broadening the Wastewater Treatment Scope

In the summer of 2013, the Anaerobic Wastewater Treatment team was created as a subteam within AguaClara when a group of students and professors recognized that AguaClara had grown large enough to expand its scope from focusing solely on supplying clean water to also dealing with the waste produced after the water is used. The Wastewater Treatment team is unique within AguaClara because it is the only subteam which uses biological treatment. The team researches the use of bioreactors to treat wastewater while also finding ways to use it as a source of energy.

Imhoff Tank in San Nicolas

Activated Sludge

This winter break, all six of the Anaerobic Wastewater Treatment team members from last semester were able to join the trip to Honduras, where they saw three different types of wastewater treatment. The largest one they visited used the same upflow anaerobic 
sludge blanket (UASB) technology that the team has focused its research on. The UASB technology the team uses in its reactors allows the wastewater to flow upward while undergoing anaerobic digestion and creating a 'blanket' of sludge. Anaerobic digestion uses bacteria to break down the organic material found in wastewater that makes it unsafe to release into natural bodies of water. Methane, a product of the anaerobic digestion, can be captured and used as a source of energy. Last semester the team focused its research on the UASBs while also experimenting with dispersing sand within the reactors to provide increased surface area for the bacteria to grow on, allowing for more efficient treatment. 

Oxidation Lagoons in Jesus de Otoro

The other wastewater treatment methods the team encountered while in Honduras included less technological processes such as oxidation lagoons and constructed wetlands. These aerobic treatments take up much more land than the UASB's, but the smaller, rural communities that use these techniques prefer the low-maintenance and visual appeal. Upon visiting these smaller communities, the team realized the need to find new and innovative ways to provide adequate sanitation to more isolated areas.

This semester, the goals for the Wastewater Treatment team have expanded. Because it is one of the largest teams they will be able to split up into three groups, each of which will focus on a different aspect of the team’s goals. One group will continue with the UASB research from the past year.

Another group will be rethinking the reactor designs. Last semester the experimentations with sand failed because the grains were too small and clogged the reactors and the methane capturing device was found to be not as efficient as the team would hope. Therefore, one goal is to redesign the methane capturing device to optimize capture and the other is to experiment with different inlet geometry to allow for the use of sand without obstructing the reactor.

The last group will research combining anaerobic digestion with aerobic digestion. Until now, the team has overlooked aerobic digestion because it is much more energy, space, and cost intensive than anaerobic. However, aerobic digestion is a much faster and efficient method of treating wastewater and the ultimate goal is to be able to use the energy produced from the anaerobic processes to fuel the aerobic processes.