Blog #7

On Monday, we had a guest speaker (Stefano Milia) talk to us about remediation of contaminated sites. At my co-op back in Boston, one of the groups in the company does remediation so I was curious to see what methods the engineers use in Italy. Stefano told us that they try and keep the contaminant on the site and treat it or contain it there instead of transporting it, which is cheaper and also reduces the risk of the contaminant spreading. I personally think that the permeable reactive barrier is a creative way to treat groundwater that has been contaminated. The way one works is to first analyze the direction of groundwater flow, and then put a barrier in the path of the groundwater that removes the contaminants as the water flows through. I also enjoyed the second part of the lecture because it refreshed my knowledge of chemistry when we were working on the problems involving contaminated water.

On Tuesday, we went sailing on a J-24 and it made me realize how much I like (and miss) sailing! The sailor on the boat with us, Vito, did not speak very much English, but I was able to help him hoist the sails and cast off from the dock because the process was very similar to when I was sailing on my family's Catalina-30. At first there wasn't too much wind, but fortunately once we got closer to the cliffs the wind started to pick up. I steered the boat at first, but I had to reapply my sunscreen so Danielle offered to steer, and then Cat tried after her and it was fun teaching them about sailing too because neither of them had done that before and they enjoyed it! Also, after a little bit I was able to communicate with Vito by just pointing at ropes or sails or gesturing with my hands when I had a question, and he would answer back with a yes or no or show me something on the boat that would answer my question. There was one time that Vito asked me a question in Italian and I didn't know what he was asking, but then he pulled out a spinnaker (a big third sail that goes in front of the boat) and I knew then that he was asking me if we wanted to try sailing with it! We did sail with it, which was a learning experience for me. Even though there was a language barrier between Vito and I, we were still able to communicate through sailing, which I thought was pretty neat.

Today we drove to northwest from Cagliari to Villacidro to visit the Villaservice Anaerobic Digestion plant. There are four main components: three landfills, the anaerobic digestion treatment plant, the composting plant, and the sewage plant. Before we walked around the site, I thought that it was just going to be an anaerobic treatment plant; I didn't realize that all of the different plants that are a part of this process were going to be right next to each other. I like that they are taking advantage of the fact that they are close together and using resources that are produced by one area in another area. They are reusing effluent from the sewage plant in the anaerobic digestion process to make sure that mix that goes through anaerobic digestion is less than 20% solids (which is a criteria for the wet treatment process). Also, they use water from the cooling system in the landfill (87 degrees Celsius) to warm the reactors in the anaerobic plant. I believe that using both of these methods is much more sustainable than using new water to mix with the organic waste or new water to heat up and warm the reactors.

Out of all of the buildings that we saw, I thought that the double membrane biogas storage dome was the most interesting. There is a grey bubble inside that fills up with biogas, and then there is a bigger white bubble that is already inflated with air (pressure is about 1 atm, atmospheric pressure) to protect the grey bubble from the elements. Our guide also showed us some safety torches that have an open flame to burn the gas before it is released into the atmosphere to reduce green house gas emissions. He said that in an emergency, they would be able to burn all of the gas that they have stored in two hours. They must have a lot of safety procedures that they follow and measures that they take since there is a lot of big equipment on the site, and the site itself is very large. Our guide also showed us a pit of eucalyptus branches and trunks that they use to absorb the smell from the plants, because when they do a air quality analysis there cannot be too much smell in the air (good or bad). I liked this method because it is a very natural way of fixing the problem.