John C. Clausen

Seasonal performance of a wetland constructed to process dairy milkhouse wastewater in Connecticut

Constructed wetlands are gaining increased attention for treatment of nonpoint sources of water pollution. Although constructed wetlands have been utilized for wastewater treatment in warm climates, their performance in cold climates has been questioned. A surface-flow wetland, designed to treat 2.65 m3 d−1 of milkhouse wastewater, was constructed on the University of Connecticut’s Storrs campus in 1994. The purpose of the project was to determine the efficiency of the system in reducing nitrogen, phosphorus, five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), and fecal coliform bacteria (FC). The wetland was designed to process an estimated BOD5 loading rate of 7.3 g m−2 d−1, which was less than half of the average actual loading rate. The overall percentage of mass retention was 94, 85, 68, 60 and 53% for TSS, BOD5, total phosphorus, nitrate–nitrite and total Kjeldahl-nitrogen, respectively. Although the wetland became a net source of ammonia nitrogen (NH3–N) following plant die back in fall 1994, NH3–N outflow concentrations have gradually declined over time. Mass retention was significantly greater (P<0.05) during the summer than during the winter for all variables except FC. Denitrification rates measured using the acetylene block method have shown denitrification to be a minor removal mechanism (<1%) for nitrogen in this wetland. The mass balance indicated that settling and increased storage was the largest removal mechanism. The treatment of wastewater in this wetland did not meet design outflow concentration criteria, most likely due to BOD5 overloading.

Seasonal effectiveness of a constructed wetland for processing milkhouse wastewater

Constructed wetlands are gainign increased attention for treatment of nonpoint source pollution. Although constructed wetlands have been used for wastewater treatment in warm climates, their performance in cold climates has been questioned. A surface-flow wetland, designed to treat 2.65 m3d−1 of milkhouse wastewater, was constructed on the University of Connecticut’s Storrs campus in 1994. The purpose of the project was to determine the efficiency of the system to reduce nutrients, five-day biochemical oxygen demand (BOD5), bacteria, and total suspended solids and to reduce fecal coliform bacteria. During the first ten months of operation, outflow volume was 90% of inflow. Although the wetland was designed to process a BOD5 loading rate of 1500 mg/L, the average actual loading rate was 3000 mg/L. The overall percent mass retention of total suspended solids was 45% and for nutrients was 28%, 27%, 47%, and 6%, for total phosphorus, total Kjeldahl-N, nitrate-N, and ammonia-N, respectively. The percent reduction of fecal coliform and BOD5 was 31% and 28% respectively. Mass retention was significantly greater (p < 0.05) during the growing season than during plant senescence for total suspended solids, total phosphorus, total Kjeldahl, ammonia, and nitrate/nitrite nitrogen. Effluent ammonia nitrogen concentrations often exceeded influent values during the winter. Preliminary indications are that the treatment of the wastewater does not meet design standards, especially in the winter, probably due to overloading of BOD5.

CLASSIFICATION OF WETLANDS IN A PATAGONIAN NATIONAL PARK, CHILE

Wetlands in Torres del Paine National Park in Patagonia, Chile were studied to determine their variety and type because resident wetlands had not been previously described. In 2001, 88 wetlands were sampled for vegetation, water chemistry, water depth, substrate type, and hydroperiod to develop a classification system using a combination of factor, discriminant, and cluster techniques. In 2002–2003 the classification system was applied to an additional 323 wetlands. Types were named for floristic characteristics but were cross-typed with NWI and Ramsar classifications. Types described include Carex-Nothofagus, Juncus-Glyceria, Hippuris-Myriophyllum, Ranunculus, and Schoenoplectus marshes; peatlands; and vegas. Lake/ponds and mudflats were also identified. Wetlands were found in basins, slopes, and channels and have water regimes varying from saturated to permanently flooded. Differences were found in the chemical characteristics of water among wetland types and regions of the Park. Torres del Paine National Park is rich in its diversity of wetland types.

Effectiveness of Agricultural Best Management Practices in Reducing Phosphorous Loading to Lake Champlain

Phosphorus is an essential element for the growth of terrestrial and aquatic plants. But in P-limited freshwater lakes, increased P loading can accelerate eutrophication and an associated growth of undesirable algae and aquatic weeds (Carpenter et al., 1998). Eutrophication has been blamed for the decline in water quality in freshwater lakes and estuaries in the Northeast over the past decades. The issue has received increased public attention recently as a result of human health problems, such as the impaired drinking water supply for New York City and outbreaks of the dinoflagellate Pfiesteria in waters off the east coast (Sharpley et al., 2000). The role of excessive P levels in water quality degradation in Lake Champlain is well documented (LCBP, 1996; Smeltzer, 1992). Phosphorus concentrations in parts of Lake Champlain (Missisquoi and St. Albans Bays and the South Lake, in particular) are highly eutrophic (Medalie and Smeltzer, 2003), with P concentrations as high as those in the most polluted parts of the Great Lakes (e.g. western Lake Erie) in the 1970s (Smeltzer, 1992).