&EPA
United States
Environmental Protection
Agency
EPA/540/F-92/003
February 1992
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Emerging Technology Bulletin
Removal and Recovery of Metal Ions from Groundwater
Bio-Recovery Systems, Incorporated
Technology Description: This biological sorption process
using AlgaSORB is designed to remove heavy metal ions from
aqueous solutions. AlgaSORB is composed of a nonliving algal
bio-mass immobilized in a silica polymer. It is a hard material
where the algal cells are protected from decomposition by other
microorganisms and can be packed into columns which, when
pressurized, exhibit good flow characteristics. The technology is
based on the natural affinity of algae cell walls for heavy metal
ions and functions well for removing heavy metals from
groundwaters that contain high levels of dissolved solids and/or
organic contaminants.
The system functions as a biological ion-exchange resin to bind
both metallic cations and metallic oxoanions. Anions such as
chlorides or sulfates are weakly bound or not bound at all. The
algae-silica system can be recycled. After saturation, metals are
stripped from the algae using acids, bases, or other suitable
reagents. High concentrations of metals are contained in a small
volume of solution and require subsequent treatment.
Waste Applicability: Bio-Recovery's technology can be used
to remove metal ions from groundwater or surface leachates
without interference from components of hard water or high
levels of dissolved solids. The technology can also be applied to
rinse waters from electroplating, metal finishing, and printed cir-
cuit board manufacturing industries. The system, using various
AlgaSORB preparations, can be utilized to remove heavy metals
including aluminum, cadmium, chromium, cobalt, copper, gold,
iron, lead, manganese, mercury, molybdenum, nickel, platinum,
silver, uranium, vanadium, and zinc from aqueous media.
Test Results: The AlgaSORB process was tested on mercury-
contaminated groundwater in the Fall of 1989 at a hazardous
waste site in Oakland, California. Testing was designed to
determine optimum flow rates, binding capacities, and the effi-
ciency of stripping agents. Different AlgaSORB resins, com-
prised of the cell walls of different algae, were tested for mercury
removal from the groundwaters. Both mercuiy concentration and
chemical speciation appeared to change over the sampling pe-
riod. Removal performance was inconsistent when a single
immobilized alga was used on waters collected at different times.
For the onsite, pilot-scale demonstration, two different AlgaSORB
adsorbents (624 and 640) in 1 in.-diameter columns, arranged in
series, were used to remove the mercury contamination. Each
column had a 0.4L volume. Flow rate was 10 bed volumes per
hour. Effluent samples were collected from a sample port be-
tween the two columns and from the second column exit port.
AlgaSORB 624 exhibited high mercury binding capacity and high
mercuiy leakage rates while AlgaSORB 640 showed low binding
and low leakage rates.
In tests prior to the demonstration, sample pH was adjusted to
the collection value of 7.9. In the first test using the two columns
(AlgaSorb 624 followed by Algasorb 640), a total of 230 bed
volumes (5.75L) was passed through the columns. A total of
6,820 u.g of mercury was extracted by the two columns without
breakthrough. In a repeat of the test, a total of 33 bed volumes
(8.3L) were treated without column breakthrough. The ultimate
capacity of the test design was not challenged in either test.
During the 3-week demonstration, 588 bed volumes (235L) were
passed through the test apparatus (see Figure 1). The demon-
stration was continued until the effluent mercury exceeded the
discharge limit of 10 u.g/L At least 534 bed volumes (214L) were
successfully treated prior to column breakthrough. Data con-
firmed previous tests that AlgaSORB 624 was capable of remov-
ing the majority of the mercury and AlgaSORB 640 was capable
of polishing effluent from AlgaSORB 624 below permitted dis-
charge limits.
As a result of the success of this technology in the SITE Emerg-
ing Technology Program, Bio-Recovery Systems, Inc., has been
invited to participate in the SITE Demonstration Program. The
process is being commercialized for groundwater treatment and
industrial point source treatment. Treatability studies are required.
Printed on Recycled Paper
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For Further Information:
EPA Project Manager:
Naom! P. Barkley
U.S. EPA Risk Reduction Engineering Laboratory
28 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7854 (FTS: 684-7854)
Technology Developer Contact:
Thomas Powers
Bio-Recovery Systems, Inc.
Las Cruces, NM 88005
505-523-0405
Influent
Stream
I
Sample
Port
AlgaSORB-624
AlgaSORB-640
Sample
Port
Effluent Stream
Figure 1. Schematic of Portable Water Treatment System for Onsite Testing.
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/54WF-92/003
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