Pilot-scale aerated submerged biofilm reactor for organics removal and nitrification at cold temperatures.
This research describes pilot-scale experiments for efficient removal of dissolved organic and nitrogen compounds in domestic wastewater using aerated submerged biofilm (ASBF) reactors. These reactors could enhance the performance of shallow wastewater treatment lagoons through the addition of specially designed structures. The structures are designed to encourage the growth of a nitrifying bacterial biofilm on a submerged surface. They also force the direct contact of rising air bubbles against the submerged biofilm. This direct gas-phase contact is postulated to increase the oxygen transfer rate into the biofilm and increase the microclimate mixing of water, nutrients, and waste products into and out of the biofilm. This research investigated the efficiency of dissolved organic matter and ammonia-nitrogen removals. Specifically, the effects of cold temperatures on the dissolved organic matter and ammonia-nitrogen performance of the ASBF pilot plant (see Figure 1) was investigated for the batch system. Over a period of 3.5 months, a total of 11 batch runs were performed. By the fourth run, the biofilm had matured to the point that it consumed all the ammonia in 40 hours. On the ninth run, the air supply was left off as a control run. This time, the ammonia was barely consumed, with the level dropping from 24 to 18 mg/L in 40 hours. By the middle of December, the average water temperature during the runs had dropped to approximately 6 degrees C and, at one point, was as low as 3.3 degrees C. The biofilm continued to perform even at these low temperatures, reducing ammonia levels from approximately 25 mg/L to basically zero within 40 to 48 hours.
Department of Civil and Environmental Engineering, University of Utah, Salt Lake City, Utah, USA.
Youngik
Y
Choi
Kraig
K
Johnson
Donald
D
Hayes
Hua
H
Xu
D000641:Ammonia / Q000378:metabolism*; D001420:Bacteria, Aerobic / Q000378:metabolism*; D019149:Bioreactors; D003080:Cold Temperature; D009930:Organic Chemicals / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010865:Pilot Projects; D014865:Waste Disposal, Fluid / Q000295:instrumentation*
D009930:Organic Chemicals; D000641:Ammonia; D010100:Oxygen