Recycling Treated Municipal Wastewater for Industrial Water Use

Section 2
Implementation Considerations
requirements can lead to inconsistencies in permit requirements across the state and
may result in requirements that represent “moving targets,” leaving proponents
unsure (and perhaps unable) to determine the requirements that may be placed on
them. A statewide set of comprehensive water reuse regulations would provide
definitive information to assist industries and municipalities in the planning and
implementation of projects. On the other hand, a case-by-case system can allow for
greater flexibility in developing reuse projects.
2.3 Technical Considerations
The main technical issues that must be addressed with water reuse involve water
quality and conveyance of water from the WWTP to the industry. The most costeffective
source would be one where the wastewater effluent water quality meets all
the industrial water quality criteria and conveyance requirements are minor. In most
cases, some additional treatment is required to meet the industrial process
requirements or health-related criteria. This section will provide some general
industry water quality requirements and issues with reclaimed water use. Treatment
requirements and technologies are summarized for several industrial uses.
Conveyance considerations are very site specific and are not discussed in this
Technical Memorandum. However, an assessment of conveyance requirements will
be conducted as part of Task 2 of this project.
Water Quality
Industrial Water Quality Concerns
Due to the myriad of industrial processes that use water and site-specific conditions,
regulatory agencies generally prescribe water reuse requirements on an individual
case basis, except for some common widespread uses such as cooling water.
Reclaimed water from conventional wastewater treatment processes is of adequate
quality for many industrial applications that can tolerate water of less than potable
quality, and it has the important advantage of being a reliable supply. Industries are
often located near populated areas that generate large volumes of wastewater.
Industrial uses of reclaimed water include cooling, process water, stack scrubbing,
boiler feed, washing, transport of material, and as an ingredient in a product. Cooling
is the predominant reuse application, accounting for more than 90 percent of the total
volume of reclaimed water used for industrial purposes.
Cooling Water. Pathogenic microorganisms in reclaimed water used in cooling
towers present potential hazards to workers and to the public in the vicinity of
cooling towers from aerosols and windblown spray. In practice, however, biocides
are usually added to all cooling waters onsite to prevent slimes and otherwise inhibit
microbiological activity, which has the secondary effect of eliminating or greatly
diminishing the potential health hazard associated with aerosols or windblown spray.
Aerosols produced in the workplace or from cooling towers also may present hazards
from the inhalation of VOCs, and although little definitive research has been done in
this area, there has been no indication that VOCs have created health problems at any
existing water reuse site. Closed-loop cooling systems using reclaimed water present
2-14 Craddock Consulting Engineers
In Association with CDM & James Crook
TM1-Sec2_0707.doc