| Revision Date: | 9/01 |
| Process Code: | Navy/Marines: N/A; Air Force: N/A; Army: N/A |
| Usage: | Navy: Medium; Marines: Medium; Army: Medium; Air Force: Medium |
| Compliance Impact: | Low |
| Alternative for: | N/A |
| Applicable EPCRA Targeted Constituents: Heavy Metals | |
PRECIPITATION AND MICROFILTRATION WASTEWATER TREATMENT SYSTEMS
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| Overview: | The precipitation and
microfiltration process uses a combination of treatments on a variety of
wastes. Chemical precipitation of heavy metals is the first treatment in
this process. Precipitates and all particles larger than 0.1 to 0.2 micron
size are filtered through a unique tubular fabric crossflow microfilter.
Concentrate is dewatered using conventional processes, such as filter
press or centrifuge.
Microfiltration modules are fabricated from a tubular woven polyester material. Wastes pumped into these polyester tubes form a dynamic membrane that produces a high quality filtrate and removes all particles larger than 0.1 to 0.2 micron. Turbulence continually maintains the membrane and maximizes treatment efficiency. Metals are removed via precipitation by adjusting the pH in a reaction tank. Metal hydroxides or oxides form a dynamic membrane with other suspended solids. The concentrate, which contains up to 50 percent solids by volume, is periodically discharged to solids concentration and drying systems (filter press, centrifuge, or sludge thickener). Water from solids concentration is recycled to the feed tank. Constituents are removed using seeded slurry methods in the microfilter. Hardness can be removed through traditional precipitation reactions. Oil and grease can be removed by adding adsorbents. Organics and solvents can be removed using activated carbon, bone char, or powdered ion exchange resins as adsorbents. Commercial applications include removal of heavy metals from semiconductor and components manufacturing, oil and grease removal from industrial laundry effluent, and silica removal through water softening reactions from reverse osmosis concentrate. |
| Compliance Benefit: | The use of precipitation and
microfiltration treatment system can help facilities meet pretreatment
standards for discharges of wastewater to a POTW (40 CFR 403) or
meet effluent limits of a NPDES permit (40 CFR 122). In addition,
this treatment process may help facilities meet the requirements of waste
reduction under RCRA, 40 CFR 262, Appendix.
The compliance benefits listed here are only meant to be used as a general guideline and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g. the amount of workload involved. |
| Materials Compatibility: | The polyester membrane support cloth is suitable for use in all conditions except high concentrations of caustic at elevated temperatures. All other system components are either plastic (PVC, polyethylene, or fiberglass) or type 316 stainless steel. |
| Safety and Health: | Care should be taken when
handling wastewater contaminated with heavy metals. They can be poisonous,
and skin absorption is the major route. Proper personal protection
equipment is, therefore, highly recommended.
Consult your local Industrial Health specialist, your local health and safety personnel, and the appropriate MSDS prior to implementing any of these technologies. |
| Benefits: |
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| Disadvantages: |
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| Economic Analysis: | The capital cost of the
precipitation, microfiltration, and sludge dewatering treatment process
will vary, depending on the particular removal challenge presented. A
typical capital cost is approximately $1.00 to $2.00 per gallon per day of
capacity. For example, the capital cost of a system to treat a wastewater
flow of 100,000 gallons per day would be between $100,000 and $200,000.
Operating costs consist of normal mechanical maintenance, neutralization
chemicals, and adsorbents. Typical operating costs are in the range of
$1.00 to $2.50 per 1,000 gallons.
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| Approving Authority: | Approval is controlled locally
and should be implemented only after engineering approval has been
granted. Major claimant approval is not required.
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| NSN/MSDS: |
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| Points of Contact: | Army: Ms. Tracy Williams Pollution Prevention Coordinator Department of the Army, Anniston Army Depot 7 Frankford Avenue Anniston, AL 36201-4199 Phone: (256) 235-7947 FAX: (256) 235-7726 Email: williamst@anad.army.mil |
| Vendors: | This is not meant to be a
complete list as, there are other manufacturers of this type of
equipment.
EPOC, Inc. |
| Sources: | None listed
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