In the past ten to fifteen plus years, the concept of major seawater ion toxicity (MSIT) has gone
from its infancy to near maturity as a general concern with membrane concentrates. Concerns with MSIT are relevant only in those
situations where membrane concentrate disposal is through discharge to waters that
require compliance with state and/or Federal toxicity standards. In those cases where
membrane concentrate disposal is through deep well injection or some other means that
does not require toxicity testing, MSIT is generally not an issue or concern.
Although the concept had been identified and studied in relation to other industries and
toxicity analysis, the earliest applications of MSIT evaluation in relation to membrane
concentrates were formally conducted by the Florida Department of Environmental
Protection (FDEP) in the early 1990s. This effort culminated in the FDEP publication of
a 1995 guidance document entitled "Protocols for Determining Major-Seawater-Ion
Toxicity in Membrane-Technology Water-Treatment Concentrate". The guidance was
based on evaluations of concentrate from a variety of facilities around the state ranging
from low TDS concentrates from membrane softening facilities up through higher
salinity (20 to 25 ppt) concentrates from brackish water RO facilities.
Since the publication of the 1995 guidance, evaluation of MSIT in membrane
concentrates has become more and more popular in Florida. The concept has gained
acceptance in both the regulatory arena as well as the regulated facilities. In fact, in the
last several years legislation has been introduced in Florida to codify exemptions and
specific regulatory mechanisms to streamline the application of MSIT evaluation in
review of membrane concentrate surface discharge.
Due to increasing popularity, testing techniques
and permit evaluations for MSIT have been under way in several states in the southeast
and elsewhere. The US Environmental Protection Agency has been reviewing the issue on a case by case basis in the
general context of Toxicity Identification Evaluation techniques and determinations. In
general, the observed toxicity that results from MSIT is short-lived in the environment,
with one to one dilution often more than enough to erase any toxicity that may be
attributable to MSIT. Includes tables.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 250 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 5 |
| Published : | 06/17/2004 |
