Environmental Engineering Reference
In-Depth Information
Table 10.2
Organic and inorganic solid wastes frequently found in food-
processing plants.
Organic
Inorganic
Rejects from sorting of fruits and vegetables
Peels and skins
Rinds
Seeds
Stems
Hulls
Pomace
Filter cakes
Spoiled and expired food without the
packaging
Sludge from wastewater treatment
Animal tissue
Skimmed materials from flotation cells
Soil from cleaning operations
Plastics
Packaging
Metals
Glass
Pallets
Cardboard
Batteries
Electronic equipment
Other types of equipment
Plastic totes and bins
not exist, a common practice is the direct discharge to surface water bodies that produce con-
tamination with nutrients, antibiotics, and harmful microorganisms that can affect wild fish
populations.
From food-processing plants
Food-processing plants produce two types of solid waste: organic and inorganic. These
denominations have no parallel with organic and inorganic chemistry or with the concept of
organic food. Instead
organic waste
refers to solid waste that is biodegradable and can be
composted in the presence of air or digested in anaerobiosis (Table 10.2).
Inorganic waste
includes materials that are not easily degraded in the short term, such as plastics, metal, glass,
stones, and soil. Even when cardboard and wood are biodegradable, they are both included in
the inorganic waste group.
It is important to make clear that waste are those leftovers after processing that have no
immediate application. There are other leftovers that occur during processing that have no
edible human application but are considered waste “by-products” or “co-products” of the
industry. Representative examples are the extraction of edible oils from seeds and the meat
and poultry industries. The content of oil in oilseeds depends on the variety, which varies from
17 percent for cottonseed to 40 percent for sunflower and canola. Once the oil is extracted, the
leftover material (“meal”) is sold as animal feed. Depending on the market conditions some-
times the meal has more value in monetary terms than the oil.
The success of the meat and poultry industries depends on the use of the remaining parts
after harvesting edible tissues. Those remaining parts are subjected to a process known as
rendering
in which fat and protein are separated, stabilized, and sold as ingredients for the
formulation of animal feed. Without an effective way of treating and using the nonedible parts,
it is likely that the poultry and meat industries would not exist in the way they are known today.
During distribution and retailing
Distribution and retailing create inorganic solid wastes consisting fundamentally of materials
related to transportation and handling, such as cardboard from secondary and tertiary packag-
ing, pallets, plastic bin and totes, and other types of containers.
