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Technique Sewer Collection System Bioaugmentation The existing sewer system can be employed as a biological reactor to enhance the microbiology before entering to the WWTP through external bioaugmentation. It is demonstrated in previous studies that a 23.1 km gravity collection system contains as much as 9,500 m2 (1.7 x 104 m2/MGD) wetted biofilm surface area, which is equivalent to a 105 m3 stone- filled trickling filter reactor. Also, since 99.9% of the fecal bac- teria are strict anaerobes and possess slower metabolic activ- ity, the improvement of the microbiology in the sewer can cause significant changes in the ratio of hydrolysable COD to rbCOD and the reduction of influent loads to the WWTP. To enhance the microbial activity in the sewer collection system and to provide enhanced microbiology to the WWTP, In-Pipe Technology (IPT) employs the sewer col- lection system as an inte- gral part of the waste- water treatment system and uses the collection system as a biological reactor. The IPT bio- augmentation process consists of the automatic continual addition (twen- ty-four hours per day, seven days per week) of high concentrations of naturally occurring, non- pathogenic, facultative Bacillus soil bacteria at tion system in order to: grow beneficial bacteria in the biofilm throughout the surface of the sewer pipes and thereby enhance the sewer biofilm activity with beneficial bacteria; improve the ability of the sewer biofilm and bulk phase bacteria to improve the wastewater quality through hydrolysis of the slowly biodegradable COD to rbCOD and/or reduce the load to the WWTP by consuming rbCOD through respiration or fermentation; take advantage of the retention time of the wastewater within the sewer pipes allowing the added bacteria additional time to degrade the waste; and continuously supply vegetative beneficial bacteria to the WWTP to improve operational efficiencies. COLLECTION SYSTEM BIOAUGMENTATION CASE STUDY Prior to 2007, The City of Crown Point, IN, was planning a $1.5 million expansion to add an anaerobic digester and expand the sludge residuals storage facility. The city selected a sewer collection system bioaugmentation to improve the WWTP operation efficiencies (i.e., reduce energy consump- tion, reduce chemical use, and reduce sludge production), 12 Water Online The Magazine, Wastewater Edition ■ wateronline.com enabling the City of Crown Point to forestall the $1.5 million in capital improvements required to increase sludge diges- tion and solids storage capacity. Additional city goals were to improve the condition of the collection system by eliminating FOG from the lift station wet wells and reduce system odors. Approach Figure 2: Production of primary sludge and WAS from the WWTP. multiple points (i.e., manholes, lift stations) within the collec- The City of Crown Point wastewater treatment process is an extended aeration activated sludge process with a rated capacity of 5.2 MGD and a peak flow capacity of more than 9 MGD. The wastewater average daily flow rate to the WWTP is ~4.0 MGD. The wastewater collection system in the city comprises gravity sewers, long gravity interceptors, and force mains feeding the WWTP. Twenty three G2 dosing units have been installed in the Crown Point sewer collection system at strategic locations. Each G2 panel holds a one liter replaceable reservoir with a 30-day supply of microbes. The G2 panel dispenses a preset volume of microbial formula per day on regular time intervals. The microbial formula contains the proper blend of Bacillus bacteria to establish a beneficial sewer biofilm, digest and remove FOG deposits, and inhibit sulfate reducing bacteria (SRB) in the collection system while improving treatment performance at the plant. Performance Analysis With Collection System Bioaugmentation Aeration Energy Savings — The average daily influent CBOD load to the WWTP reduced approximately 12% to 15% with treatment. The influent ammonia-nitrogen (NH3-N) load decreased by ~45% to 50%. The influent NH3-N and CBOD loadings to the WWTP determine the amount of air that must be delivered into the activated sludge system to facilitate oxidation of these two pollutants. The WWTP is running with a 50% reduction in aeration energy consumption since implementation began due to the reduction in influent CBOD and NH3-N loads and the presence of improved IPT microbiology in the biological processes. As a result, the WWTP is capable of running biological processes by turning off half of the blowers, which reduces the monthly aeration energy costs approximately $6,850.