Regarding the canteen waste, the greatest fraction was organic
matter in both periods, with an average value of 61.03% in wet
weight in the first period and 72.33% in the second period (Table 3),
the reason being that food waste is mainly generated in the canteens.
These food waste contained unavoidable trimmings (fruit
and vegetable peelings, etc.), although some of them were food
scraps that were left by diners. Therefore, it would be important
to adapt food portions in order to minimize food waste generated
at canteens. The second fraction generated is dirty paper (13.99%
and 14.22% for the two periods, respectively) that comes from
tablecloths and napkins. These results are similar to those obtained
by Mason et al. (2004) and Armijo de Vega et al. (2008) in their
research for the same waste stream. Furthermore, the percentage
of glass is smaller than the percentage of plastics and metals, as
plastic packaging and beverage cans are used more often than glass
bottles in the canteens. Finally, hazardous as well as inert waste
represents the smallest fraction and the two types are collected
separately.