The Dirty Work
As Peter has explained in an earlier blog, we chose to do our sustainability project on surfactants. So after learning what surfactants actually are and how common they are we decided to go for it. We realized that this would be difficult to measure and find an effect. We started out just wanting to calculate our output of greywater into the ocean. Since we don’t shower on the boat the main greywater output is from washing dishes. So how do you collect greywater? Well since we were on a catamaran and the drain from our sink is between the two hulls above water that should be easy to collect right? I thought so when I volunteered to take the dinghy under the boat and collect the grey water from dishes one night after dinner. I quickly learned this was more difficult than I anticipated. First I tied a rope to the stern of the boat and had the other end of it in the dinghy with me. Then I tied the bow line of the dinghy to the bow of the boat so that I could pull myself back and forth under the boat and make it easier to position myself for the water collection. Once I was under the boat I realized that the space between the water and the boat is not as big as it looks. Once I was under the boat I managed to get the dinghy to a spot where the bucket was under the drain. I quickly learned that the water didn’t run out of the drain in a nice stream. It splattered and ran along the bottom of the boat for a few centimeters before falling. So I had to hold the bucket under the drain with one hand and hold the dinghy in place with the other.
My set-up
collecting the water
When the dishes were done the bucket had 4 gallons of water (~12 liters). We then collected and filtered about 4 milliliters to take into Russel Barsh’s lab to test the concentration. We found that the concentration of our grey water was 55 parts per million (ppm). So grey water is extremely concentrated. After washing dishes from one night we produced 4 gallons of greywater with a concentration of 55 ppm!
Then we started thinking, we know what we are putting into the water, but we don’t know what is already there. So we decided to take samples from some of the different Harbors we stay at overnight. After running a test sample using water from Friday Harbor we quickly realized that areas with good circulation will not have high concentrations even if they have higher inputs because it is mixed better. Our focus soon became harbors that have poor circulation but still have a lot of boats inhabiting them throughout the summer. The more people and the more boats in the harbors, the more surfactants are put into the water. The harbors we sampled were Mitchell Bay, Reid Harbor, Prevost Harbor, and Roche Harbor. Friday Harbor was also tested but there was no detectable amount of surfactants in the water. We are currently still waiting for the results. This information will be very useful as far as management goes. It is possible that some of these popular Harbors with poor circulation might need to have maximum amount of boats allowed in the Harbor at any given time to keep the concentrations from building up too much.
Results to be posted soon!
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