Introduction - Principles of Chemical Separations with Environmental Applications - page 7

Procedural Changes
Technology Changes
Chemical Separations
Input Material Changes
Product Changes

SOURCE
REDUCTION

MOST
PREFERRED

Mass Transfer
Operations

RECYCLING OR
REUSE

ON-SITE
OFF-

Mass Transfer
Operations

ON-SITE
OFF-

WASTE SEPARATION

Mass Transfer
Operations

WASTE
CONCENTRATION

ON-SITE
OFF-

WASTE
EXCHANGE

Incineration
Non-Incineration

ON-SITE
OFF-

WASTE TREATMENT

Land Farming
Deep Well Injection
Landfilling
Ocean Dumping

ULTIMATE DISPOSAL
(UD)

UD MONITORING
AND CONTROL

Figure 1.1 Pollution Prevention Hierarchy [5]. (Copyright c 1993, John Wiley
& Sons, Inc.) This material is used by permission of John Wiley & Sons, Inc.

The separation cost is often related directly to the degree of dilution for the component of
interest in the initial mixture. This cost includes the fact that most separations use 50 times
the minimum energy requirement based on the ideal thermodynamic requirements. To put
the energy consumption in perspective, the chemical and petroleum refining industries
in the US consume approximately 2.9 million barrels per day of crude oil in feedstock
conversion [1]. One method to visualize this cost factor is with the Sherwood plot shown
in Figure 1.2.
This log-log plot shows that there is a reasonable correlation between the initial con-
centration of a solute in a mixture and its final price. For environmental applications, this
correlation would translate to the cost of removal and/or recovery of a pollutant based on
its initial concentration.