Recycling Treated Municipal Wastewater for Industrial Water Use

TM3: Recycled Wastewater System Components and Costs
Recycling Treated Municipal Wastewater for Industrial Water Use
Process water quality requirements can dictate a range of treatment requirements. For
the industry categories represented in Table 10, the base supply is sufficient for sand
and gravel washing. It could also be an acceptable source for use in other processes
that are not concerned with hardness and dissolved salts, as in the Non-Metals and
Other industry categories. Process water is not listed for agricultural processing
because most of these products are for human consumption and similar to some
state’s practices, is expected to be lower on the list of practices for approval. If
reclaimed water is used in food products, Tertiary 4 water with final UV would likely
be required.
Reclaimed water with tertiary treatment is expected to be required for water supplies
used by the pulp and paper, mining, petroleum, chemical, ethanol, and metals
industries. It is possible that a base supply could be used in the iron mining industry,
but the separation processes for iron ore include use of chemicals and excessive
dissolved constituents may cause problems. Likewise, some processes in pulp and
paper production could use a base reclaimed water supply, but typically dissolved
constituents are not desired because of potential effects on attributes such as color
quality. These industries, along with petroleum, chemical, ethanol, and metals
industries typically require process water with low dissolved solids and the absence
of trace constituents. Tertiary processes such as reverse osmosis followed by GAC, ion
exchange or other technologies may be required.
4.0 Storage and Transmission
4.1 Overview
An integral part of the planning, operation, and maintenance of water reuse systems
is for the transmission of the reclaimed water to the customer. Transmission costs,
both capital and O&M, are often the largest cost component of projects for centralized
systems. Transmission systems include on-site storage, pump station(s), piping, offsite
storage, diversion structures to off-site storage ponds, service connections, and
metering. Most states with regulations and guidelines include standards for the
design, installation, operation, and maintenance of the transmission systems. There
are very specific guidelines for prevention of cross-connections to other systems,
including use of backflow preventions devices and other plumbing features.
4.2 Storage
This study assumes only storage for diurnal, daily or weekly industrial demand
patterns that the WWTP cannot meet with their continuous supply. The conceptual
water reuse system presented in Figure 1 provides for storage facilities on the WWTP
to meet a range of storage volumes. The base water reuse system assumes that no
storage is required. This assumption is valid for a larger WWTP serving smaller
industrial demands.
Storage requirements for industrial applications can vary widely. Some industries
may have adequate storage to meet peak hour requirements, but most would not
have storage to handle significant volumes. The need for storage is most likely with
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