The WEF Sustainable Utilities Task Force presents a resource for utility managers seeking examples of succesful sustainability practices

Using Whey as a Supplemental Carbon Source under Real Time Control Conditions

J.D Phillips Water Reclamation Facility
Colorado Springs, Colorado

The COD:TKN ratio in the influent wastewater to the J.D Phillips Water Reclamation Facility
(WRF) in Colorado Springs is too low to allow sufficient denitrification to meet the discharge
limit for pH. To reduce the reliance on adding caustic to the effluent to raise the effluent pH,
Colorado Springs Utility (CSU), began a search of local industries to find a source of local
supplemental carbon to increase denitrification, and hence alkalinity recovery. Simultaneously, a
local dairy approached CSU requesting relief from significant monthly excess BOD and TSS
surcharges. The dairy manufactures cottage cheese, producing acid whey as a waste. A full scale
pilot test was initiated at the WRF to investigate the opportunity to use whey as a supplemental
carbon source to enhance denitrification. During this test, it was discovered that fermented whey
provided superior results to unfermented whey.
The costs of implementing and operating advanced aeration control systems have to be justified
by the reduction in energy consumption and/or improvements of the effluent quality. Control
measures should also not introduce operational problems like foaming or bulking or higher green
house gas emissions (mainly N2O). In addition to the effluent pH issues, as with all utilities, CSU
is faced with reducing operating costs as much as possible. The effluent ammonia limit for the
WRF varies on a monthly basis, which raised the question – “With the use of on-line analyzers,
could the activated sludge process be operated to produce an effluent just below the permit limit
to save aeration power?” A desktop analysis using BioWin™ and the BioWin™ Controller was
performed to predict which of feed-forward or feed-back control would provide the best control.
On-line ammonia and nitrate probes were installed at various locations and programmed into the
aeration blower and mixed liquor recycle pump control systems to determine if aeration blower
airflow and whey feed rates could be optimized. This paper will summarize the results achieved
through the full scale pilot test, list future activities at the WRF and briefly discuss the outcome
of the pretreatment permit negotiations with the dairy.


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Posted: May 20th, 2011 | Filed under: 100K-500K, Waste Water Treatment, Water Treatment | Tags: , , , , , , | No Comments »

Low Cost Solutions that Combine Process Modeling, Optimization, and Pilot Testing to Comply with LOT Nitrogen and Phosphorus Standards at Two BNR Plants

City of Durham WWTF
Durham, North Carolina

The objective of this study was to utilize process modeling to predict effluent quality at design
flow for two biological nutrient removal (BNR) facilities, and determine what additional
improvements would be needed at each facility to meet limit of technology (LOT) nitrogen and
phosphorus standards. Then, optimization, pilot-testing, and bench-testing were conducted to
support this approach.
Process modeling using calibrated BioWin models determined that side stream treatment and
equalization, supplemental carbon addition, and increased nitrified recycle (NRCY) rates would
optimize nitrogen and phosphorus removal at both plants. Zone dissolved oxygen (DO) control
will also enhance denitrification and the effectiveness of the supplemental carbon. Both plants
are also considering the Ostara process to improve BPR.


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Posted: May 20th, 2011 | Filed under: 100K-500K, Stormwater, Waste Water Treatment, Water Treatment | Tags: , , , , , | No Comments »

Evaluation of Crude Glycerin as a Supplemental Carbon Source for a High Rate Step-Feed BNR Process

26th Ward WPCP
New York City, New York

The use of crude glycerin was evaluated as an alternative supplemental carbon source to methanol to enhance denitrification in a step-feed BNR process. Two of the four pilots were integrated with separate centrate treatment tanks to oxidize centrate ammonium; centrate was fed to the head of the step-feed process in two other pilot systems. The pilot treatment trains received primary effluent and centrate from the 26th Ward WPCP. Under normal operating conditions, it was demonstrated that crude glycerin could be used to achieve 5-10 mg/L of final effluent TN. Specific denitrification rates determined by the bench-scale batch tests were comparable to that achieved with methanol as the supplemental carbon source. A COD-to-N ratio in the range of 6 to 7 grams/gram was used, resulting in a chemical cost of ~ $1/kg-NOx-N removed with a cost basis of $0.22/L, compared to ~ $1.60/kg-NOx-N for 100% methanol at ~ $0.40/L. Source: WEFTEC 2008 Proceedings


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Posted: August 27th, 2010 | Filed under: 100K-500K, Waste Water Treatment | Tags: , , | No Comments »