The Bio2-Bloc Submerged Attached Growth Bioreactor:
An Innovative Wastewater Treatment Technology
October 22, 2002
The Pennsylvania Department of Environmental Protection does not endorse or recommend any of the technologies described herein. The technical articles are provided for informational purposes only. Persons seeking additional information about the described technologies should contact the parties listed in the article.
For decades, discharge permits for treated wastewater have been very relaxed for ammonia limits during the winter months. However, in Pennsylvania, the Department of Environmental Protection reduced the ammonia discharge limits to 1.5 and 4.5 mg/L for summer and winter months, respectively. With the reduction in NPDES limits for effluent ammonia, many systems had to employ a new method for removing the ammonia, particularly during cold weather months when the system effluent can contain as much as 20 mg/L of ammonia. The Bio2-Bloc system from FBC Technologies is a fixed-film system that enables cold-weather nitrification of ammonia and CBOD removal from wastewater in lagoons, retention basins and tanks.
In general, the activity of bacteria that convert ammonia (nitrifiers) becomes very slow as wastewater temperatures decrease. Correspondingly, the nitrification process slows. However, when the same bacteria are immobilized and protected in an attached-growth environment, their productivity at low water temperatures is enhanced. This is the philosophy used by FBC Technologies for the Bio2-Bloc system. The technology uses a patented dual diffusion system. A fine bubble system delivers wastewater to the biomass and a coarse bubble system sloughs the biomass growth.
How It Works
The Bio2Bloc system consists of a bed of media submerged in the wastewater and aerated from the bottom. As air passes through the media bed, it carries with it a flow of water that contains the food and nutrients eaten by the film that attaches to the media. The media bed is suspended under a floating compartment filled with waterproof foam. The bed is continuously aerated by an array of fine-bubble diffusers under the media bed. A second, coarse-bubble system is also fitted on each unit for periodic scouring and flushing of sediments from the media bed. The system protects nitrifiers in a fixed-film environment and warm air from the blower is flushed through the media bed to keep the bacteria aerated, fed and productive. As the ammonia is cleared from wastewater during warmer weather, the system also reduces algae growth. The Bio2-Bloc system units are floated into place and air connections are made from a shore-based blower. Each of the diffusion systems is valved from the shore for ease of operation.
The number of Bio2-Bloc units used per system depends on treatment needs to remove BOD and/or ammonia. One unit can remove approximately 2.5 to 3 pounds of ammonia per day in warm water (200C) and about 0.5 to 0.75 pounds of ammonia per day in cold water (4 to 100C). For BOD, one unit can remove about 6 pounds per day in warm water (200C) and 0.3 to 1.5 pounds per day in cold water (4 to 100C).
Reported Advantages Over Conventional Technology
· can be installed within 2-3 days
· requires no routine cleaning or maintenance
· has no mechanical moving parts
· made of marine-grade aluminum or stainless steel and will not corrode
· provides effluent quality and odor control which meet or exceed discharge permit
· adapts readily to existing facilities without major cost outlay for land or system housing
Potential Disadvantages / Concerns
• none known as of the present
Technology Verification and Usage
Installation – Elverson, Pennsylvania
The Elverson wastewater treatment plant serves a small rural community and was built with a designed flow rate of 75,000 GPD. Influent BOD averages 240 mg/L and ammonia averages 30 mg/L. The plant’s flow is channeled through three lagoons. The total capacity of the lagoons is 3.6 MG. Given the low average daily flow, the lagoon retention time is 48 days. Each of the lagoons is equipped with a 10-hp splasher. Over the winter months, the effluent ammonia averaged 30 mg/L. Borough officials and their engineers decided to install the Bio2Bloc Submerged Attached-Growth Bioreactor by FBC Technologies to reduce the ammonia levels. The Bio-Bloc installation consisted of seven (7) Bio-Bloc floating modules. Powered by a single 5-hp positive displacement blower, the system was installed in three days. It was designed to provide sufficient fixed-film nitrification capacity to bring effluent ammonia below NPDES limits of 4.5 mg/L. The media beds were preseasoned for faster formation of the biofilm favored by nitrifying organisms. The FBC system was installed in mid-March, 2002 with water temperatures at 4oC and an NH3 effluent value of 15 mg/L. Within 10 days of operation, the ammonia level had dropped below the 4.5 mg/L limit. The Borough leases the Bio2BlocÔ system for $1,850/month. This cost includes system installation and blower.
Installation – Silver Lake Township, Pennsylvania
For years, Silver Lake Township considered a variety of options for addressing the rising level of ammonia in the wastewater effluent from its two wastewater treatment plants: Laurel Lake and Quaker Lake. At the Laurel Lake WWTP, the flow rate is 64,000 GPD and, at the Quaker Lake WWTP, the flow rate is 42,000 GPD. Typical influent loads are 200 mg/L of BOD5 and 35 mg/L of ammonia. The effluent ammonia for the systems ranged from 9.9 to 31.9 mg/L. (The NPDES permit limits the plants to 2.5 mg/L and 7.5 mg/L in the summer and winter, respectively.) In September of 2001, Bio2-Bloc systems were installed at the treatment plants. Within 3 weeks of installation, each of the systems was in complete nitrification and ammonia levels were zero mg/L. As the water temperature dropped from 28oC to 8oC, ammonia levels remained below 2 mg/L. As the temperature dropped to –4oC, the Laurel Lake effluent level for ammonia was 20 mg/L and will be expanded to handle the remaining 13 mg/L of ammonia. The Quaker Lake system kept ammonia levels within permit levels. The cost for the Silver Lake system was $29,500 and, for the Quaker Lake system, $63,000. These costs include system installation and blowers.
Currently, there are eight (8) Bio2-Bloc systems installed in New York, Pennsylvania, and in Ontario. The first installation was in 1999 at the Wastewater Treatment Plant in Marion, New York.
Capital and O&M costs for the system vary by the type and size of facility. On the average, one unit costs approximately $10,000. This cost includes the positive displacement blower, factory installation, manifold, and all fittings, hoses, cables and clamps. Average O&M costs include only blower maintenance and associated utility costs based on blower hp and the customer’s price per kW/hr). For site-specific unit design and costs, it is recommended to contact the manufacturer directly.
Sources of Additional Information about the Bio2-Bloc submerged attached-growth bioreactor can be obtained from FBC Technologies, Inc., 57 North Street, LeRoy, NY 14482, (585) 768-4530, by e-mail at firstname.lastname@example.org, or by web site at www.fbctech.com.
This report has been prepared and submitted by Renee Bartholomew, PA Department of Environmental Protection, Bureau of Water Supply and Wastewater Management, Division of Municipal Financial Assistance, Innovative Technology Section, at (717) 787-3481 or e-mail at email@example.com.
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