24 November 2013

Open Source: A Grand Experiment for a Grand Challenge

Seminar presentation video.
The AguaClara program has been open source from the very early days and that has opened doors and served us very well. The AguaClara  approach is to create a global solution that is sustainable, that can adapt to the local context, and to share the knowledge. Open source eliminates the transaction costs of sharing ideas and is a powerful way to promote idea sex. Although we have numerous inventions we chose to not patent them because patents are condoms for idea sex. Our ability to rapidly innovate and our proven ability to develop new technologies and deploy them is largely due to our free sharing of ideas. I presented my reflections on the municipal drinking water infrastructure challenge and the advantages of open source at a recent seminar.

An example of our innovation process is illustrated below. I learned about molding PVC while on assignment in the Salvadoran refugee camp at Colomoncagua, Honduras  in 1983. I observed Hondurans fixing a water transmission line by making an improvised pipe coupling out of a piece of pipe by heating the pipe over a fire of corn husks. We brought that idea to Cornell to create the diffuser pipes that are essential for the creation of a floc blanket in the AguaClara sedimentation tanks. Cornell students improved the technology and developed the idea of using hot vegetable oil to carefully heat the PVC to a temperature where it can be molded easily. Tim Brock and Paul Charles helped design and fabricate molds in the Civil and Environmental Engineering machine shop. We delivered those molds to Agua Para el Pueblo in Honduras. Below you can see an aluminum mold that is used to decrease the diameter of the end of pipe for insertion into the manifold. The worker in the center of the photo is using the wedge mold to create a rectangular slot.
Operator candidates form pipes heated with hot vegetable oil using aluminum molds. The pipes serve to direct the jets of water that enter the sedimentation tank in order to suspend sediment that creates a fluidized bed called a "floc blanket".

The operator candidates assemble
 the inlet manifolds for the sedimentation

The sharing of ideas between Honduras and the AguaClara Cornell labs provides a rich environment for innovation. And in this collaborative team environment it is never possible to assign an invention to a single person or even a single organization. Together we Research, Invent, Design, and Empower to make the world a better place.

21 November 2013

A Possible Solution for Treating Arsenic in Groundwater

In many places in the world, surface water is either contaminated to the point of being undrinkable or exists in a quantity that is potable but scarce. A popular solution is to instead extract groundwater from deep underground. The issue with this is that despite being cleaner, oftentimes this groundwater will be contaminated with heavy metals such as arsenic due to its contact with the surrounding soil.

AguaClara’s research in arsenic treatment first began in the form of a capstone idea presented in a previous semester of our CEE 4540 course, “Small-Scale Sustainable Water Supplies.” The goal was to direct AguaClara’s research efforts to address the problem of widespread arsenic poisoning in communities around the world that rely on contaminated groundwater as their primary water source. A team of students was formed the following semester to research possible solutions to this large-scale problem.

This semester, the Arsenic Team has begun testing methods for separating arsenic from water in order to render the water potable. One of the team’s goals is to see if their idea of using AguaClara’s process of water treatment as a base could, with some adjustments, work similarly effectively for arsenic.

Flocculation, as it works in the AguaClara plant, entails dosing pre-treated water with a coagulant so that unwanted particles will stick to one another to form larger masses called flocs. As they become heavier than the water, these flocs are pulled to the bottom of our tank by gravity through a process called sedimentation. The water is then filtered.

In modifying this process for arsenic removal testing, the team will first dose a sample of mock groundwater with known concentrations of arsenic and coagulant. The samples with then be mixed at a low speed in a tumbler to simulate flocculation. After flocs form, the container with the sample will then be placed into a centrifuge and rotated at a high enough velocity that the flocs—hopefully containing the arsenic—will be distinctly separated from uncontaminated water. The sample will then be analyzed using a spectrometer to measure the remaining concentration of arsenic in the sample.

From left: Imtiaz, Tanapong, and Michelle preparing a sample for the spectrometer.
Most recently, the team has been testing to see if a combination of filtration and sedimentation by centrifuge­—with varying coagulant dosage—will aid in the removal of arsenic from mock groundwater.

15 November 2013

A Pump to Aid Plant Operators

The Ram Pump team, like Foam Filtration, will be bringing the results of their research to our partner in Honduras come January.

Our ram pump.
The team is currently working on building a ram pump that will serve to pump clean water from AguaClara’s plant back up to a higher elevation for use in chemical stock tanks and bathrooms, with the goal of lessening the burden on the plant operator. In order to do this, however, we needed to figure out a way to pump water up a vertical distance of 7 meters using only gravity. Integral to this endeavor is the “hammer effect,” in which immense pressure is generated from a sudden change in the momentum of the water. This pressure is known to sometimes result in broken pipes but the Ram Pump team is looking to utilize this energy to AguaClara's benefit.

Reuben (left) and Ariel (right) testing the pump.
Much of the system seen on the left was built this semester; the only exception is the actual ram pump. The pump works by having pressure—or the lack of it—operate a set of valves that control water intake and delivery. Ariel, Kelly, and Reuben picked up where the previous team left off, and part of that was to construct an environment that would adequately simulate the ram pump’s operation in the field.

The problem was that our labs don’t have seven-meter ceilings. To compensate for this, the team sought to create a system that would accurately simulate that vertical displacement. Their result, the series of pipes you see on the left-hand side of the picture, successfully emulates the elevation that water would need to reach after running through the ram pump. 

14 November 2013

Foam Filtration for Smaller Communities

Foam filtration isn’t a new idea but it has been troublesome to implement; unlike a sand filter, running water at a high velocity through the filter column isn't enough to clean the foam filter properly, which poses an inconvenient design constraint.

Otherwise, foam filtration is very effective. The team has, through a series of experiments, discovered that having contaminated water run through a piece of foam with thirty pores per inch (30 PPI) and subsequently through a piece of foam with ninety pores per inch (90 PPI) gave the best results, delivering water quality that exceeds both U.S. EPA and World Health Organization standards. While our stacked rapid sand filter is preferable under most circumstances, the team is seeking other uses for foam filtration.

From left to right: 30 PPI foam and 90 PPI foam
One idea was to implement foam filtration as a point-of-use system designed for personal use instead of community use. However, while the foam filter increases the clarity of the water, it can't effectively deactivate pathogens without the help of a chemical doser. Another idea was to build an emergency water filtration system using the foam filter. While the larger size allows room for the chemical doser, our model ultimately proved too unstable for actual use.

The team's most recent plan considered the fact that while some communities may find it economically feasible to construct and maintain an AguaClara plant, others might not be able to afford it. Foam filtration seems like a good compromise between efficacy and affordability. The team is currently working on designing a system aimed at serving smaller communities, with populations of around a hundred families. Their objective is to find the optimal method for cleaning the foam given the system's larger size. The team will be communicating the results of their work to Agua Para el Pueblo, our partner in Honduras, this coming January.

08 November 2013

Wastewater as an Energy Source

As much as AguaClara likes clean water, we also wanted to do something about the waste that inevitably comes as a result of people using that water. The Anaerobic Wastewater Treatment team was born out a desire to examine and make use of wastewater, whether as a potential source of energy or otherwise treating it.

Originally, two options presented themselves: aerobic and anaerobic digestion. Digestion in this context refers to the process by which bacteria or other microorganisms decompose biodegradable matter, and the Wastewater team wanted to use this process towards treating the organic material present in wastewater.

However, it was found that aerobic digestion (digestion in the presence of oxygen) required too much in the way of resources, with lackluster results. On the other hand, anaerobic digestion captured gainful amounts of methane, a potent greenhouse gas and source of energy. From a review of prior research o, it was discovered that we could capture the methane present in wastewater and not only prevent it from going out and acting as a greenhouse gas, but also do something productive with it.

Above: We currently have six reactors. Only the one that's black is fully operational. The black that you see in the first reactor is actually the bacteria we're using to process the wastewater, and it's commonly referred to as "biomass".

One of the major goals this semester concerns sand. The group hypothesized that by dispersing sand uniformly inside the reactors, under proper conditions, biomass will have more surfaces to grow on and therefore the reactor will treat the wastewater more effectively. Their advisor, Ruth Richardson, is also currently in Indonesia working with the engineers there to figure out the needs of the communities in which this system will be implemented.