Layer aeration is a depth-discrete artificial circulation technique. The method
"redistributes" water temperature (heat) and oxygen at middle depths of the water
column. A "layer" is created which is bounded above and below by thermoclines. Layer
aeration has been used to reduce epilimnetic nutrient loading from the hypolimnion, to
restore cool water habitats suitable for cold water fisheries and as zooplankton refuge, and
for managing water supply sources. Relative thermal resistance to mixing (RTRM)
profiles have demonstrated that stable stratification with multiple thermocline peaks.
Layer aeration of a 523 acre, 70 ft deep, eutrophic water supply lake has been
performed annually since 1987. An 18-year data record identifies very significant
improvements in resource quality and raw water supply quality. The response to layer
aeration occurred in several stages. Overall, summer Secchi disk transparency increased
from <1.8 m (<6 ft) to >4.6 m (>15 ft), due to elimination of bluegreen algae blooms
(Anabaena sp. and Aphanizomenon sp.). Deepening of the "compensation depth" into the
hypolimnion contributed to restoration of 3300 acre-ft of aerobic cool water habitat. The
habitat improvement resulted in the re-establishment of large-bodied Cladocera (Daphnia
sp.) which increases the rate of algal biomass removal by grazing and further improved
raw water supply quality. Several long-term water supply reservoir hypolimnetic and
layer aeration cases are reviewed in this paper that are relative to limnological characteristics and water
treatment relationships. Includes reference, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 320 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 11/02/2003 |
