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 68C and, at one point, was as low as 3.38C. 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. Water Environ. Res., 80, 292 (2008).

This report examines the anaerobic biodegradation potentials of PAHs in dredged river sediments under several redox environments. Batch biodegradation tests were conducted in bioslurry reactors containing sediment samples from Jones Island, WI. Tests with unamended sediments relied on PAH biodegradation by native bacteria utilizing background nutrients and electron donors and acceptors in the sediment. The amount of degradation of 15 PAH compounds found in the sediment, ranging from naphthalene to benzo(ghi)perylene, was measured. It was observed that all 15 PAH congeners biodegraded to some extent in unamended sediments. Acenaphthene showed the highest degradation at 79% disappearance. Indeno(123cd)pyrene showed the lowest at 8%. A general trend was observed with more disappearance in the lower molecular weight PAHs than the higher molecular weight PAHs. Addition of sulfate as an electron acceptor somewhat enhanced PAH biodegradation, whereas addition of nitrate did not. Induction of methanogenic conditions by adding dextrene (a simple sugar) did not appreciably enhance biodegradation of any of the 15 measured PAH congeners. It was speculated that the relatively high background sulfate levels, accompanied by sulfate-reducing bacteria native to the sediment may have played a significant role in effecting PAH biodegradation.

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