Water Environment & Technology (WE&T) is the premier magazine for the water quality field. WE&T provides information on what professionals demand: cutting-edge technologies, innovative solutions, operations and maintenance, regulatory and legislative impacts, and professional development.
At a crossroads
Upcoming changes to the U.S. Environmental Protection Agency (EPA) stormwater program will be “the greatest in a generation,” according to one EPA official. Considering this statement, it’s worth examining the history of the regulations in relation to their current directions.
Unstratified filtration medium
By using unstratified filters with a large effective size, as well as air and water backwash, the Sioux Falls (S.D.) Water Reclamation Plant maximized filter run lengths and still met effluent requirements. The plant tested this type of media to replace dual-media filters in its final clarifiers. Read full article (login required)
The brine stops here
State legislatures put forward bills to ban fracking wastewater treatment
Though the U.S. Congress and the U.S. Environmental Protection Agency are still wrangling over the issue of hydraulic fracturing and what to do with fracking wastewater, states have made their own attempts to respond to these issues.
Coming in the next issue:
Efficient, effective odor control
Residents of the neighborhoods near treatment plants and along the collection systems don’t care how odor control systems work, as long as the air remains fresh. But for utilities, odor solutions need to be both effective and efficient. The July issue looks at how two utilities made sure they got the most out of their odor control efforts.
At an Oregon wastewater treatment plant, designers and operators weighed the pros and cons of “green” bark media versus inorganic media for its biofilter. While the bark media is organic, may be recycled for landscape use, and has a low initial cost, it presented some operational challenges.
At a different utility, this one in California, cost increases and short-term supply limits for iron salts prompted a project to minimize iron use, but still control collection system odors. The utility found a solution in the synergy between two chemicals. It demonstrated that adding the right amount of magnesium hydroxide boosted the performance of ferrous chloride, enabling efficient, effective odor control.
New turns on clarification
The principle of how clarifiers work is simple, but ensuring the best performance can be difficult. Good results require good design, careful testing, and practical adjustments.
To that end, with secondary clarifier upgrades in Cincinnati one-third complete, planners paused to measure how well the new designs were operating. They combined field testing and computational fluid dynamic modeling to assess the new operation and find some additional measures to fine-tune the project.
And in Poland, a biological nutrient removal plant faced bulking problems in its secondary clarifiers. To solve this, the plant installed a mixed liquor vacuum degassing system, which removes gas bubbles from mixed liquor and reduces the concentration of dissolved gases. The new technology improved secondary clarifier settling, eliminated floating scum, and improved plant operations overall.