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Maine DEP Monthly
Maine and WEF's
Penobscot Watershed and Development of a TMDL
Maine Rural Water
Maine
Wastewater Control Association |
Utilizing the Bullhead
for Sludge Management
In the early 1990's, the Vermont
Department of Environmental Conservation became aware of the work that was being
done by Terry Welch at the Bethlehem, New Hampshire wastewater treatment plant.
Terry was attempting to incorporate as many natural control systems into his
lagoons as possible, not just bullhead but also crayfish, Daphnia for algae
control, even bladderwort for Daphnia control. The introduction of hundreds of
bullhead into his ponds did significantly reduce the large accumulation of
sludge on the lagoon floors. Since the removal of sludge is a major expense for
the small municipalities that typically own aerated lagoons in Vermont, we felt
it would be worthwhile to investigate this "natural" treatment. In the spring of 1994, Paul Olander worked with John Hall, John Claussen, and Rich Kern to capture some of the 165 adult bullhead in Baker Pond and move them to treatment lagoons at the Royalton WWTF. The Royalton was chosen because they had significant sludge deposits in all three cells and needed to do a sludge removal but the town did not have sufficient money. We stocked most in the last pond, some in the middle pond, and a few in the first pond. We had done a significant amount of baseline data gathering and continued to gather data through the summer and fall. What we saw was a complete reduction of the 10" of sludge in the third cell and a decrease in the second cell. There was some evidence that some of the sludge went out in the effluent as a slightly higher Total Suspended Solids, but the effluent was well within permit limitations. There also seemed to be an increase in algae in the cells. The following spring the bullheads died during the spring benthal release ( probably due to ammonia from the increased anaerobic activity in winter deposited sludge). The fish that were 10" in length the previous year were running in the rage of 13 to 14 inches with massive heads. Minks, raccoons, eagles, and gulls were observed picking up the fish. The conclusions drawn were that the fish did seem to reduce the sludge accumulations, but that heavy deposits would release ammonia in the spring and up to 30 mg/l concentrations were found at times. Conclusions were drawn to the fact that ponds with heavy accumulations of sludge may not support the survival of the fish. The mechanism for sludge reduction appeared to be that the fish, on feeding on aquatic insect larvae in the sludge, were rolling the sludge into the upper layers of the aerobic zone. Further stabilization takes place there, and some "ash" goes back to the bottom or out in the effluent. The feeling was the fish did not have a serious deleterious effect on effluent quality and probably would aid in reducing the frequency of cleanouts even though the fish may not survive the spring release well. VTDC staff advised operators considering the use of fish that their use would be permittee, but that the operators must seek permission from their District Fisheries Biologists. Some facilities did try stalking bullhead, most seeking permission first. Plant specifics follow. The results seem to be inline with conclusions made by the VTDC staff, and that the chief benefit of socking bullheads would be reduction of sludge handling costs. Removal of sludge from the Hardwick WWTF cost about $90,000. In a recent survey of plants, many of the operators expressed a strong interest in stalking bullhead if the F & W Department resumes the granting of letters of authorization. Bullhead-Stocked Wastewater Plants Specifics
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