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Volume 7, Number 4
August/September 2008
FEATURES
Best Arsenic Technology
A power-generating facility upgrades its wastewater treatment system to meet stricter limits
Jean-Claude Younan and Joseph Chwirka
Regulators are paying more attention to arsenic in industrial wastewater. Depending on total maximum daily loads and other factors, a facility’s National Pollutant Discharge Elimination System discharge permit limit for arsenic may be lower than the drinking water standard (10 μg/L). One industrial facility in the northeastern United States, for example, now has a monthly average discharge limit of 4 μg/L of arsenic (6 μg/L daily maximum).
This facility, a coal-fired power generator, produces a byproduct, fly ash, that often contains significant amounts of arsenic. When sluice water used to convey the fly ash is discharged to surface water, it can contain significant levels of soluble arsenic.
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Cost-Effective Metals Removal
Constructed wetlands can help industries meet lower heavy-metals limits
Wes Bramlett, Rex Robbins, and Sammy Bates
Discharge regulations for heavy metals have become more stringent during the past 10 years. Although many industrial facilities already treat their wastewater to comply with categorical standards, the heavy-metals limits for new or renewed permits are based on water quality criteria, which often are near laboratory detection levels. Most industrial treatment systems were not designed to meet the new effluent limits.
Constructed wetlands may help. When used as a polishing step, constructed wetlands can be a viable, cost-effective method for achieving the new effluent limits for heavy metals.
NEWS
Nanosilver’s Possible Effects on Wastewater Treatment Prompt Concerns
As nanotechnology continues to make inroads into commercial products, the possibility that one of its most common applications might impair wastewater treatment plant (WWTP) operations increasingly is attracting attention. Nanosilver, or silver particles sized in terms of nanometers, can be found in hundreds of products, ranging from clothing to computers. Touted for its antimicrobial properties, nanosilver could harm the bacteria that effect biological treatment of wastewater. This possibility, along with the potential for other untoward outcomes, has prompted research and a call for the federal government to halt the sale of such products until questions about their safety can be answered.
General Permit Challenges Cruise-Ship Wastewater Systems
The Alaska Department of Environmental Conservation (DEC) in March issued the first-ever general permit for wastewater discharges from large cruise ships operating in Alaska’s waters. The Large Commercial Passenger Vessel Wastewater Discharge General Permit (No. 2007DB0002) was developed from a voters’ ballot initiative that was passed in October 2006.
According to the Alaska Cruise Association (ACA; Anchorage), the general permit “imposes limits on some trace metals so stringent that no ship can meet them, nor can any land-based wastewater facility in Alaska.”
PROBLEM SOLVERS
Treatment System Provides High-Quality Water to Laboratory
Problem: Research laboratory needs a high-purity water system with a small footprint.
Solution: New laboratory water treatment system.
Aureon Laboratories Inc. (Yonkers, N.Y.), which develops predictive tests for cancer recurrences and provides research services to biopharmaceutical companies in developing cancer treatments, needed to design, build, and equip a new research laboratory within 4 months. The new laboratory required a water treatment system that could produce specified water quality using as little space as possible.
TECH TALK
Heavy-Metal Removal Using Cactus Skin
Cactus. Jewel of the desert. A model of water efficiency. Skin that can remove metals from industrial wastewater? “Yes,” says Bryan Bilyeu, an assistant professor at Xavier University of Louisiana (New Orleans).
In his research, Bilyeu, along with Carlos Barrera Diaz — a professor at the Autonomous University of the State of Mexico (Toluca) in central Mexico — analyzed the absorption properties of prickly pear cactus.
BRIEFS
Quick updates on news of interest to the industrial wastewater management professional.