Recycling Treated Municipal Wastewater for Industrial Water Use

TM3: Recycled Wastewater System Components and Costs
Recycling Treated Municipal Wastewater for Industrial Water Use
effluent quality and type of membrane selected. Pretreatment processes can be
required for iron and manganese removal (to avoid scaling on the membranes),
disinfection to avoid biofouling (some membranes are sensitive to chlorine), pH
adjustment to avoid scale formation, and antiscalants. ED membranes have the least
pretreatment requirements, with cartridge filtration recommended.
In addition to pretreatment considerations, there is the management and disposal of
the waste streams. The amount of product water resulting from the treatment of the
incoming water, also called recovery, can range from 50-85 percent for RO, 70-90
percent for NF facilities, and 80-90 percent for ED. Disposal options for the
concentrated waste streams vary from energy intensive thermal evaporation
processes to ocean discharge. As concern for trace constituents grows, surface water
discharges may be less likely. Concentrate disposal and flexibility of options should
be incorporated in the planning stages to assure it is the optimum choice for a specific
site and application.
VRTX Technologies has a product that prevents scale and biofouling in cooling water
systems without the use of chemicals. It relies on localized effects of hydrodynamic
cavitation to create high temperatures and pressures that break the bonds between the
dissolved mineral and water. Minerals (including calcium) are precipitated out of the
water stream as solids for disposal. Most microbiological cells are also destroyed at
these extreme temperatures and pressures and dissolved gases leading to corrosion
are stripped away. This technology may be an appropriate application for reclaimed
waters where hardness is an issue; but may not apply to high dissolved salt waters.
This unit process will likely be located on the industry site. A major benefit of the
technology is the reduction in chemical use. If it is at the WWTP site, then disinfectant
may need to be added for transmission to the industry, which may not be costeffective
or meet other industry goals.
3.2.5 Residual and Specific Trace Constituent Removal (Multiple Processes)
Residual amount of organic and inorganic constituents can still remain after reverse
osmosis and may need to be removed for specific industrial applications. Other
constituents occur in trace amount in conventionally treated secondary effluent. These
trace constituents are of concern because of known or suspected toxicity. Of
heightened interest, is the environmental impact of several emerging contaminants of
concern, such as:
pharmaceutically active chemicals (PhACs)
endocrine disrupting compounds (EDCs)
disinfection by products (DBPs) such as N-nitrosodimethylamine (NDMA)
a host of groundwater supply contaminants such as 1,4-dioxane and methyl
tertiary-butyl ether (MTBE)
new and reemerging pathogenic microorganisms such as Legionella pneumophila,
Cryptosporidium, and Giardia
Craddock Consulting Engineers 15
In Association with CDM & James Crook
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