Recycling Treated Municipal Wastewater for Industrial Water Use

TM3: Recycled Wastewater System Components and Costs
Recycling Treated Municipal Wastewater for Industrial Water Use
These emerging contaminants of concern have been an issue for aquifer recharge and
reuse applications that affect potable water supplies. They are likely not an issue for
industrial water reuse except for applications with potential for human or animal
consumption. They are mentioned because it is a concern for potable water treatment
and water reuse in general and could affect future regulations and the direction for
best management practices that would impact the entire water reuse industry.
While NF and RO are able to remove or reduce most of these emerging contaminant
compounds, there are some processes and groups of processes that may be more
effective and/or economical. The treatment processes with the widest range of
application include:
Adsorption
Ion Exchange
Advanced Oxidation – hydrogen peroxide, ultraviolet radiation (UV), and ozone
Other processes used to destroy or remove trace constituents include: distillation,
chemical oxidation, photolysis and advanced biological treatment.
Adsorption
Activated carbon is the most commonly used adsorbent in water reuse treatment
systems and will serve as the general reference for adsorption technologies.
Adsorption is used in water reuse treatment systems for either the continuous
removal of compounds or as a barrier to protect against breakthrough from other unit
processes. Organic compounds are the most commonly removed constituent with
adsorption processes, but adsorption has been used to remove nitrogen, sulfides,
heavy metals, and odor compounds.
A fixed-bed downflow reactor configuration is the most typical for activated carbon
adsorption. This configuration is assumed for the cost information presented in
Section 4.
Ion Exchange
Ion exchange involves the replacement of an ion in the aqueous phase for an ion in
the solid phase. In the case of water reuse systems, the goal is to remove specific ions
from the treated wastewater effluent to the solid material in the ion exchange column.
The applications expected for water reuse systems supplying industries include:
Softening: Industrial water uses such as recycled cooling water require removal
of calcium and magnesium ions. Ion exchange units with a cationic exchange
resin, exchange sodium for calcium and magnesium ions in the water. Several
industries surveyed for this project used softening ion exchange units for various
uses including cooling water.
Nitrogen Control: Typically synthetic resins are used to remove ammonium and
nitrate.
16 Craddock Consulting Engineers
In Association with CDM & James Crook
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