Daily Archives: November 14, 2011

City of Alcoa, Tennessee building new prestressed concrete water reservoirs

Two new above-ground prestressed concrete tanks….$5 million….click here.

Press Spin: Another arsenic article, this time in Iowa

A familiar story line….republished in a political year on a slow news day….click here for a typical drinking water article that highlights the problems of some to cause alarm for everyone else……What real useful purpose do such articles serve other than political posturing?

Congressional Letter: “Utility MACT” rule

Press Spin: “Environmental activists” are now “conservationists”?

California water agencies are considering tapping the aquifer under the Cadiz ranch to serve water for southern California.The Sierra club, an environmental activist group doesn’t like it, of course. But in this article (click here) such groups are now referred to as “conservationists.” huh?

Certainly valid environmental concerns regarding such a project should be addressed. But the “conservationist” spin is a public relations facade. The wizard behind the PR mask has not changed….

Bryant et al 2011: Solving the problem at the source: Controlling Mn release at the sediment-water interface via hypolimnetic oxygenation

L.D. Bryant, H. Hsu-Kim. P.A., Gantzer, and J.C. Little. Solving the problem at the source: Controlling Mn release at the sediment-water interface via hypolimnetic oxygenation. Water Research. 2011 Dec 1;45(19):6381-92.
Absract: One of the primary goals of hypolimnetic oxygenation systems (HOx) from a drinking water perspective is to suppress sediment-water fluxes of reduced chemical species (e.g., manganese and iron) by replenishing dissolved oxygen (O(2)) in the hypolimnion. Manganese (Mn) in particular is becoming a serious problem for water treatment on a global scale. While it has been established that HOx can increase sediment O(2) uptake rates and subsequently enhance the sediment oxic zone via elevated near-sediment O(2) and mixing, the influence of HOx on sediment-water fluxes of chemical species with more complicated redox kinetics like Mn has not been comprehensively evaluated. This study was based on Mn and O(2) data collected primarily in-situ to characterize both the sediment and water column in a drinking-water-supply reservoir equipped with an HOx. While diffusive Mn flux out of the sediment was enhanced by HOx operation due to an increased concentration driving force across the sediment-water interface, oxygenation maintained elevated near-sediment and porewater O(2) levels that facilitated biogeochemical cycling and subsequent retention of released Mn within the benthic region. Results show that soluble Mn levels in the lower hypolimnion increased substantially when the HOx was turned off for as little as ∼48 h and the upper sediment became anoxic. Turning off the HOx for longer periods (i.e., several weeks) significantly impaired water quality due to sediment Mn release. Continual oxygenation maintained an oxic benthic region sufficient to prevent Mn release to the overlying source water.