Environmental Engineering Reference
In-Depth Information
10 SolidWaste
GENERATION OF SOLID WASTE
Food production and consumption generate solid waste that can be classified as “food waste”
and “nonfood waste.” The former is any plant or animal tissue in a raw or cooked state that was
intended for human consumption but needs disposal as a result of spoilage, expiration, con-
tamination, or excess. The Environmental Protection Agency (EPA) defines food waste as:
“Uneaten food and food preparation wastes from residences and commercial establishments
such as grocery stores, restaurants, and produce stands, institutional cafeterias and kitchens,
and industrial sources like employee lunchrooms” (EPA, 1997). Nonfood waste encompasses
all the solid waste generated in addition to food during food production, distribution, and
consumption, which includes plant and animal nonedible parts, dead animals, manure, and
packaging material.
When discussing food waste it is common to think about the wastes at the end of the supply
chain generated during consumption. However, food waste takes place along the whole supply
chain due to inefficiencies in the system, the perishable nature of food products, and human
factors. The primary causes of food losses are biological and microbiological deterioration,
unwanted chemical reactions, mechanical damage, inadequate physical conditions, physio-
logical changes, and psychological reasons. Secondary causes of deterioration occur as a con-
sequence of deficient treatment or technology, such as inadequate drying, inappropriate
storage facility, deficient transportation, inadequate storage temperatures and atmospheres, as
well as poor management, and sometimes, laws (Bourne, n.d.).
Food losses take place all around the world. In developed countries, losses range between
5 and 25 percent, whereas in developing countries that range can have a floor of 20 percent
and rise to 50 percent (Kader, 2002). In developing countries, the highest losses take place at
the lower stages of the supply chain because of inadequate technology to handle and preserve
the food and unsatisfactory storage units. In contrast, in developed countries, highest food
losses occur toward the end of the food supply at retail and consumer levels (Fig. 10.1)
(Lundqvist et al., 2008).
In the United States, it is estimated that the volume of food waste, calculated as the differ-
ence between the calories produced and the calories consumed, is equivalent to 1400 calories
per person per day (Hall et al., 2009). These authors estimate that food waste accounts for
25 percent of total water consumption for food production and 300 millions of barrels of oil
per year. Globally, for every 4600 calories of edible crop harvested, it is estimated that only
