Environmental Engineering Reference
In-Depth Information
production in comparison to aluminum made from mineral ore (Martchek, 2006), and a reduc-
tion of energy consumption reduces all the other impact factors as well.
Data from Table 12.4 shows that different packaging materials produce different impacts.
However, with the exception of glass bottles, which have higher impact across all catego-
ries, all the indicators in each category are close in range. So for instance, switching from
glass to PET bottles would reduce energy consumption by 16 percent, and 23 percent if
switched to aluminum. A similar trend can be observed in other categories. The relative
impact of packaging can be reduced by choosing alternative materials; however, it is impor-
tant to recognize that the impact is still high and caution should be exerted when making
environmental claims.
Recycling
Recycling makes sense from both the energy viewpoint and nonrenewable resources sav-
ings. Table 12.3 shows the difference of energy needed to produce 1 kg of packaging mate-
rial from virgin and recycled sources. Aluminum and steel are at the top of energy savings
because they can be recycled repeatedly without suffering degradation. At the lower end,
recycling glass has the lowest energy advantage in relationship to using virgin materials, and
its recyclability is impacted by transportation distance. Glass containers are the heaviest
among all packaging systems, so when recycled glass needs to be transported for long dis-
tances, then the energy and emissions generated by the transport cancel out the savings from
using recycled material.
Realistically speaking, the success of recycling depends strictly on economics. If it does
not make economic sense, then there is no encouragement for recycling; but the economic
incentive can be put into place by deposits, taxes, and regulations. However, successful recy-
cling depends not only on individual initiatives but also on collective efforts and the coordina-
tion of multiple players including:
1.
The consumer, who must have the willingness to separate and recycle. Consumers can be
encouraged to recycling through education and economic incentives, such as pay-as-you-
throw, where residents are charged by bag of trash and no charge for recycling.
2.
The collector, who picks the materials at the consumers' sites or receives material deliv-
ered by consumers (Selke, 2002).
3.
The processor, who separates, sorts, and transforms the recycled materials into useful raw
materials for the manufacturing of the same or different products (Selke, 2002).
4.
The user, who transforms recycled materials into the same product or more often into dif-
ferent products of lesser quality, which is referred to by many as “downcycling.”
In the United States, of the municipal solid waste generated (see Fig. 12.4) 32.5 percent
is recycled, 12.5 percent is combusted with energy recovery, and 55 percent discarded
(Environmental Protection Agency [EPA], 2007). Figure 12.5 shows the recycling rates for
selected materials in the United States in 2006. It is important to observe that auto batteries
have a rate of recycling of 99 percent, which is due mainly to regulations and scarcity. So, with
the right incentives, the rates of recycling of other materials, such as aluminum, steel, and
plastics, can be boosted to similar levels.
Besides the economics of recycling, energy is a factor that needs to be considered into the
equation. As shown in Table 12.3, recycling saves energy in most cases. However, heavy mate-
rials, such as glass, in terms of energy are easily affected by distance they need to be trans-
ported to a processor or user. And the only positive way of deciding the best option of
discarding or recycling would come from life cycle assessments conducted on individual bases.
