| Source
newsletter spring 1997 |
|
 |
Equipment for Recovering Raw Materials
and Reducing Wastewater
When dealing
with wastewater, equipment is available to help recover process
materials or to help reduce the volume of wastewater that
needs to be treated as hazardous waste.
Select equipment
to meet your specific goals, such as lowering overall treatment
cost per liter or better removal of specific contaminants.
Evaporators
can be part of a closed-loop system used to concentrate process
fluids. For example, evaporating water from a plating bath
allows chemicals to be added without overflowing the tanks.
Evaporators
also can be used to remove water from liquid waste, reducing
the volume of waste that needs to be disposed. Consider them
when: 1) other treatment systems do not meet your needs, 2)
there are no hazardous components that can evaporate, and
3) sewers are unavailable or discharge is prohibited.
Evaporators
are simple and work for wide range of fluids. But, because
they are energy intensive they are usually only appropriate
for concentrating relatively low volumes of waste for disposal.
Filters or
particle separators can be used to remove contaminants
from wastewater--improving the quality of water for sewering--or
to recover process fluids for reuse.
Simple filters
remove solids.
| Molecular
membrane filters are specialized to separate dissolved
particles, particularly on the molecular level. They force
solutions through a membrane by applying pressure. |
| 1. |
Microfiltration
is used to separate out bacteria, very small particles
and some emulsions. |
| 2. |
Ultrafiltration
is often used to separate water and semisynthetic or synthetic
fluids from oily waste. They are also good for removing
all emulsions, proteins, viruses and colloidal solids.
The concentrate from ultrafiltering may be processed for
oil recovery or incinerated. Ultrafilters are helpful
in maintaining coolants, cleaning chemistries and surfactants. |
| 3. |
Reverse osmosis
(RO) filters remove metal ions, salts and small organic
molecules. They are easily fouled by organics, especially
oil. |
Ion exchange
uses specialized resins to remove metal ions and other dissolved
chemicals based on their ionic charge.
To receive assistance
with recovering process materials from your wastewater, call
Karl DeWahl, MnTAP,
at 612/624-4645.
|
