What's Up With Our Waste

Today was a long and exhausting day. We visited 3 different plants that all handled waste in different ways. Seeing that we are environmental engineers, we need to learn about current methods in order to help improve them or see beyond them for better systems.

Cagliari currently deals with waste by collecting it at first and placing it in containers on the street as seen in the Figure 1 below. Then, depending on what type of waste it is, paper, plastic, organic. It is taken to the appropriate facility for proper disposal.

Figure 1: Street Collection Containers

The first plant we went to recycled cardboard and paper to produce new ones. We walked with the manager of the plant, he showed us the intricate process that the materials go through. Figure 2 on the right shows the cardboard and paper piles created which are then compacted.

Figure 2: Cardboard Compaction

The paper is then put through several steps in order to be clean again and then remade into new paper which they sell and is one of the ways the plant stays running.

My initial reaction when I saw this obscene amount of paper product piled up like this was shock. I thought about how many trees this all equaled to. And then I got a headache thinking about how can the environment be saved?






Next we visited a compost facility called Tecnosaic which was very high tech and apparently smelt as foul as a monkey's butt. They walked us through the collection facility and the procedure that aids in the foul smell. The compost has to lay indoors for a month under a pressurized heat system that canonizes the toxins and then is laid outside for another 2 months (see Figure 3) to be cleaned and stabilized. What I found the most amazing about this facility was that it costs them around $120 per ton to make fertilizer out of this compost and they sell it for $2. The operating costs of the facility come from taxation. They are non-profit!

Figure 3: Tecnosaic Compost

By this time we were fighting the exhaustion that came after touring two facilities but we managed to get one final tour in, this was the incinerator plant. This visit was probably my favourite but also the most perplexing. It's my favorite because I really like the idea of turning waste into energy which is electricity in this case. They generate around 5600 MW of electricity from incinerating the trash. Half of that electricity powers the plant and the other half is sold back to the energy grid for a profit. Did I mention the government also pays them to do this? So one way to say it is, I like it because I think its nifty and the trash is gone. They also control and stabilize any fumes that the plant produces. 

Figure 4: Incinerator Plant

It was the most perplexing because as can be seen in Figure 4, its an intense system with several components far beyond that of the paper or compost facilities. Just the sheer structure of the facility intimidated me.

There were several machines heating, cooling, storing throughout the various phases of the incineration.

Figure 5: Incinerator Chimneys

The chimney's that controlled the fumes seemed to be as tall as sky-line towers in Boston as can be seen in Figure 5.

I wondered how long it took to build the plant and what kind of regulations were imposed on them. What would happen if one part of the system went wrong? Like today for example, they found radioactive waste in a diaper. The whole plant had to stop because regulations restrict radioactive waste incineration as it could be dangerous. They all had to find this diaper in order to resume work.

Figure 6: Incinerator Garbage

When I saw this mound of garbage my jaw (Figure 6)  dropped. How do we put out that much waste into the world? Annalisa told us that each person produces about 1.5 kg of waste a day but I never visualized what happens to the trash after its collected by the trucks. "Out of sight, out of mind" I guess. 

Soon all this garbage will be converted into electricity to light several homes and businesses alike and the trash will be gone. 

Seeing all these different procedures to dispose of waste in an efficient way is very inspiring and motivating as an environmental engineer. I hope that one day I can contribute to this ever changing field.