Transitions - Sustainable Design: The Science of Sustainability and Green Engineering - page 114

allowed to place a “bubble” over an entire manufacturing complex or allowed
to trade pollution credits with other companies in their industry instead of a
“stack-by-stack” and “pipe-by-pipe” approach (i.e., called the command and con-
trol approach ). Such policy and regulatory innovations call for some improved
technology-based approaches as well as better quality-based approaches, such as
leveling out the pollutant loadings and using less expensive technologies to re-
move the first large bulk of pollutants, followed by more effective operation and
maintenance technologies for the more difficult-to-treat stacks and pipes. But
the net effect can be a greater reduction of pollutant emissions and effluents than
that obtained by treating each stack or pipe as an independent entity. This is a
foundation for most sustainable design approaches: conducting a life-cycle anal-
ysis, prioritizing the most important problems, and matching the technologies
and operations to address them. The problems will vary by size (e.g., pollutant
loading), difficulty in treating, and feasibility. The easiest ones are the big ones
that are easy to treat (so-called “low-hanging fruit”). You can do these first
with immediate gratification! However, the most intractable problems are often
those that are small but very expensive and difficult to treat (i.e., less feasible).
Thus, green thinking requires that expectations be managed from both a techni-
cal and an operational perspective, including the expectations of the client, the
government, and oneself.
Green engineering is not limited to preventing problems but can also be applied
to solving those that already exist. Pollution control strategies must complement
control technologies with pollution prevention. Pollution controls are a neces-
sary part of modern engineering. Power plants have electrostatic precipitators and
scrubbers, large cities and small towns build and maintain wastewater treatment
plants, groundwater cleanup from hazardous wastes is ubiquitous, military opera-
tions have left contaminated soils that must be remediated, and radioactive wastes
remain after weapons manufacturing and energy production. Environmental en-
gineering continues to evolve and to find ways to collect and treat myriad con-
taminants, which in turn reduces the impact of these substances on public health
and ecological conditions. Engineers, biologists, and other scientists also work to
reduce the overall toxicity of waste, to decrease exposures, and ultimately, to elim-
inate or at least to treat properly the risks from hazardous substances in the waste.
The type of pollution control technology applied depends on the intrinsic
characteristics of the contaminants and the substrate in which they reside. The
choice must factor in all of the physical, chemical, and biological characteristics
of the contaminant with respect to the matrices and substrates (if soil and sedi-
ment) or fluids (air, water, or other solvents) where the contaminants are found.
The approach selected must meet criteria for treatability (i.e., the efficiency and
effectiveness of a technique in reducing the mobility and toxicity of a waste). The
comprehensive remedy must consider the effects that each action taken will have
on past and future steps.