VORTEX SOLIDS SEPARATORS FOR TREATING STORM WATER RUNOFF

Revision Date: 01/04
Process Code: Navy/Marines: N/A; Air Force: N/A; Army: N/A
Usage List: Navy: Low; Marines: Low; Army: Low; Air Force: Low
Alternative For: N/A
Compliance Impact: Low
Applicable EPCRA Targeted Constituents and CAS Numbers: N/A
Overview: A vortex solids separator is used to remove solids from liquids, such as stormwater runoff and overflows as well as sewer overflows (CSOs). It may be used for pre- or supplementary treatment in wastewater treatment plants. It also is suited to situations where overflow will occur into storage tanks, equalization basins, and surface detention areas.

Generally the separator is a cylindrical device with no moving parts. Water enters the cylinder from the top and is rotated (or swirls) about a vertical axis. Solids are discharged or pumped out of the outlet located at the bottom of the device. Liquid, on the other hand, is sent spiraling back up the middle of the vessel prior to discharge.

The design of a vortex solids separator should be based on the anticipated type and quantity of pollutants to be removed, as well as the settleability characteristics of those pollutants. The quantity of flow to be treated should be established prior to the design phase to achieve the desired treatment level. Pilot-scale testing should be conducted during the design phase to determine the treatability at each site.

Unit performance is based on the vortex separation mechanism for which each type has its own design criteria for solids/liquids separation. The design criteria for the swirl, which is available to the public from the U.S. Environmental Protection Agency (EPA), is based on hydraulic studies developed in the 1970s. Design specifications and pilot-scale treatability studies are required for each site-specific application.

Data collected from solids removal studies indicate vortex solids separators are effective at removing gritty materials, heavy particulates, and floatables from wastewater flow, but ineffective in removing materials with poor settleabilities. The net solids have been calculated for various units in use for CSO applications. Net suspended solids removal accounts for the relatively large underflow volume and solids collected as a result of swirl concentrating. Net suspended solids removal ranged between 7 and 34 percent. The following table presents average performance characteristics of vortex separators collected from three units.

Table 1. Performance Characteristics of Three Types of Vortex Separators

Unit Location Effluent Hydraulic Loading Rate (gpm/sf) Volume Reduction % Total Suspended Solids Removal % Net Suspended Solids Removal %
Swirl Washington, DC

10

24

38

12

Fluid sep Tengen, Germany

11

47

54

7

Storm King James Bridge, UK

7.5

39

53

14

Disadvantages of vortex solids separators are limited effectiveness as evidenced by comparing percent-suspended solids to net suspended solids removal. Vortex separators have an underflow that requires further treatment. The documented removal rates for vortex separators may not meet water quality treatment objectives for proposed locations. Little information is available for vortex solids separators treating pollutants other than suspended solids.

These units are best used in conjunction with other controls throughout the sewer system, either as upstream controls or end-of-pipe treatments; however, they should never be placed downstream of detention or treatment facilities.


Compliance Benefit: The use of a vortex solids separator for treating stormwater runoff may help facilities meet the conditions and requirements contained in stormwater permits and stormwater pollution prevention plans as well as 40 CFR 122.26. In addition, the vortex solids separators can be used in CSOs to help facilities meet the national CSO control policy.

The compliance benefits listed here are only meant to be used as general guidelines 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: No materials compatibility issues were identified.


Safety and Health: Proper design, operation, and maintenance of the equipment is required for its safe use. Consult your local industrial health specialist, your local health and safety personnel, and the appropriate MSDS prior to implementing any of these technologies.


Benefits:
  • Vortex solids separators are able to separate suspended solids and floatables from stormwater and CSO using a swirling vortex.
  • They can be used in instances where a solid/liquid separation technology is limited by space or land constraints.
  • Vortex separators have no moving parts and no power requirements; therefore, they are not maintenance intensive.


Disadvantages:
  • Vortex solids separators have limited effectiveness in use with wet-weather flows.
  • May not meet water quality treatment objectives for some locations.
  • Limited information is available for vortex solids separators treating pollutants other than solids.
  • Require sufficient head room to operate effectively.


Economic Analysis: Budgeting for construction of a vortex separator unit should include predesign costs, capital costs, and operation and maintenance costs. As of 1997, the predesign costs for a Storm King are typically $21,000, and between $27,000 and $106,000 for the Fluidsep. Settleability curves published for the Swirl can be used as the basis for design and eliminate predesign costs. Capital costs for vortex solid separator treatment facilities in the US are site specific and vary between $3,200 and $5,600 per acre of drainage basin. The capitol cost for an individual unit alone is approximately $5,200 per million gallons per day.

Energy requirements for most vortex solid separators are nil unless the facility requires pumping. Washdown costs for vortex separators primarily include labor or energy costs for an automatic washdown. The Surrey Heath Storm King facility lacks a foul sewer line and collects residuals in a collection zone. These residuals are periodically emptied every 2 to 3 years, at an estimated cost of between $300 and $500 per cleaning.


NSN/MSDS: None identified.
Approving Authority: Appropriate authority for making process changes should always be sought prior to procuring or implementing any of the technologies identified herein.


Points of Contact: For more information>


Vendors: This is not meant to be a complete list, as there may be other manufacturers of this type of equipment.

Hydro International Inc.
94 Hutchins Drive
Portland,  ME   04102
Phone: (800) 848-2706 or (207) 756-6200
FAX:  (207) 756-6212
Contact: Mr. Steve Hides
E-mail:  hiltech@hil-tech.com
URL:  http://www.hil-tech.com/

Hansjđrg Brombach
Umwelt- und Fluid-Technik
Steinstrae 7
D-97980 Bad Mergentheim,  Germany
Phone: (07) 931 97 10 

Grande, Novac & Associates, Inc.
3532 Ashby, Montreal, Quebec
Canada  H4R 2P4
Phone:  (514) 339-1131
FAX:  (514) 339-9720
E-mail:  gnainc@gnainc.com


Related Links: Do You Discharge Non-Point Source Pollution To Water Supplies? -- Navy Environmental Quality Initiative (EQI)
Do You Maintain A Storm Water Pollution Prevention Plan? -- Navy Environmental Quality Initiative (EQI)
Storm Water Phase II Final Rule Fact Sheet Series, EPA


Sources: Richard Field, U.S. Environmental Protection Agency, January 2000.
Mr. Thomas O’Connor, U.S. Environmental Protection Agency, May 1999.
American Public Works Association,1978. The Swirl Concentrator as a CSO Regulator Facility. US EPA Report. No. EPA-430/9-78-006.
Brombach, H., 1992. Solids Removal From CSOs With Vortex Separators. Novatech 92, Lyon, France, pp. 447-459.
Engineering-Science, Inc. and Trojan Technologies, Inc., 1993. Modified Vortex Separator and UV Disinfection for CSO Treatment. Prepared for the Water Environment Research Foundation, VA.
Hedges, P. D., P. E. Lockley, and J. R. Martin, 1992. A Field Study of an Hydrodynamic Separator CSO. Novatech 92, Lyon, France.
H.I.L. Technology, 1993. Informative brochures and memos.
NKK Corporation, 1987. Solid-Liquid Separation by Swirl Concentration. Brochure.
O’Brien and Gere, 1992. CSO Abatement Program Segment 1: Performance Evaluation. Prepared for the Water and Sewer Utility Administration, Washington, D.C.
Pisano, William., 1992. Survey of High Rate Storage and Vortex Separation Treatment for CSO Control. For the Daly Road High Rate Treatment Facility Demonstration Project, Cincinnati, Ohio.
Pisano, William C., 1993a. Summary: The Fluidsep Vortex Solids Separator Technology. WK Inc. Marketing Brief, Belmont, Massachusetts.
Purcell Associates, 1975. Pollution Abatement Plan, Newark, New Jersey. Prepared for the City of Newark, Department of Public Works.
Randall, Clifford W., Kathy Ellis, Thomas J. Grizzard, and William R. Knocke, 1983. "Urban Runoff Pollutant Removal by Sedimentation." Proceedings of the Conference on Storm Water Detention Facilities. American Society of Civil Engineers. New York, New York.
Smith and Gillespie Engineers, Inc., 1990. Engineer’s Study for Storm Water Management Demonstration Project No. 2 for Evaluation of Methodologies for Collection, Retention, Treatment and Reuse of Existing Urban Storm Water. S&G Project No. 7109-133-01.
Sullivan, R. H., et al., 1974. The Swirl Concentrator as a Grit Separator Device. EPA Report No. EPA-670/2-74-026. Sullivan, R. H., et al., 1974. Relationship Between Diameter and Height for the Design of a Swirl Concentrator as a CSO Regulator. EPA Report No. EPA-670/2-74-026.
US EPA, 1982. Swirl and Helical Bend Pollution Control Devices. EPA-600/8-82-013. NTIS# PB82-266172.
US EPA, 1984. Swirl and Helical Band Regulator/Concentrator for Storm and CSO Control. EPA-600/2-84-151. NTIS# PB85-102523.
Water Environment Federation Manual of Practice, 1992. Design and Construction of Urban Storm Water Management Systems. MOP FD-20. Water Environment Federation, Alexandria, Virginia; American Society of Civil Engineers, New York, New York.