Recycling Treated Municipal Wastewater for Industrial Water Use

Appendix B
Status of Water Reuse Regulations and Guidelines
treatment does not include a sedimentation process between the chemical coagulation
and filtration processes. Monthly sampling is required for the first year of operation,
and quarterly sampling is required during the second year of operation. Sampling may
be discontinued after the second year of operation with approval of the California
Department of Health Services (DHS).
Currently, there are no states with monitoring requirements for other pathogens.
Disinfection Requirements
Where chlorine is used as the disinfectant, several states require continuous monitoring of
chlorine residual and specify both the chlorine residual and contact time that must be met,
particularly for reclaimed water uses where human contact with the water is likely to
occur. Required chlorine residuals and disinfection contact times differ substantially from
state-to-state ranging from 1 to 5 mg/L and 15 to 90 minutes at peak flow, respectively.
Where UV is used for disinfection, most states do not specify UV dosage or design or
operating conditions, although some state regulations require compliance with the
Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse [National Water
Research Institute, 2003].
While the need to maintain a chlorine residual in reclaimed water distribution systems to
prevent odors, slimes, and bacterial regrowth was recognized early in the development of
dual water systems [Okun, 1979], only in the last decade or so have regulatory agencies
begun to require such residuals. A few states now require maintenance of a chlorine
residual (typically 0.5 or 1.0 mg/L) in distribution systems carrying reclaimed water.
Facilities using UV disinfection will need to add chlorination facilities to meet residual
requirements.
Treatment Facility Reliability
Some states have adopted treatment reliability requirements to insure that inadequately
treated reclaimed water is not reused. Generally, requirements consist of alarms
warning of power failure or failure of essential unit processes, automatic standby power
sources, emergency storage or disposal provisions, and the provision that each
treatment process be equipped with multiple units or a back-up unit. Reliability
requirements for California and Florida are presented below as examples.
California Requirements. California’s Water Recycling Criteria provide design and
operational considerations covering alarms, power supply, emergency storage and
disposal, wastewater treatment processes, and chemical supply, storage and feed
facilities. For treatment processes, a variety of reliability features are acceptable. For
example, for all biological treatment processes one of the following is required: (1) alarm
(failure and power loss) and multiple units capable of producing oxidized wastewater
(i.e., secondary treatment) with one unit not in operation; (2) alarm (failure and power
loss) and short-term (at least 24 hours) storage or disposal provisions and stand-by
replacement equipment; or (3) alarm (failure and power loss) and long-term (at least 20
days) storage or disposal provisions. Similar reliability requirements apply to other
treatment processes.
Craddock Consulting Engineers B-11
In Association with CDM & James Crook
WWReuse Tm1_Appendix B_Regulatory.doc