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Session Chair: Lazaro Eleuterio, Washington State Department of Ecology;
Location:Boise Centre East 410B
ID: 188 / Session 04A part 1: 1 Main Technical Program Topics: Headworks Keywords: Clarifier, Hydraulics, DSS, FSS, Testing
Practical Field Techniques and Methods to Assess Secondary Clarifier Performance
Frank Dolemeyer1, Joyce Chang2, Theresa Gregonia1, Vince Chiu1, Kim Fries2
1Metro Vancouver; 2Jacobs; ,
In a secondary wastewater treatment facility, clarifiers are the final critical step for solids/liquid separation producing effluent that meets regulatory limits for total suspended solids prior to discharge. In-situ clarifier hydraulics are crucial to a clarifier’s efficiency and performance. Typical measures of secondary clarifier performance include effluent suspended solids concentration and solids capture efficiency at varying flow rates. Other clarifier performance indicators include surface overflow rates, solids loading rate, sludge blanket depth, and return sludge rate. This presentation covers the application of practical field techniques and methods on which operators can assess a clarifier’s hydraulic performance.
In 2001, the Water Environment Research Foundation (WERF) and Clarifier Research Technical Committee (CRTC) published a guidance document on protocols for evaluating secondary clarifier performance. The document outlines detailed steps for testing a clarifier and troubleshooting clarifier issues. Metro Vancouver operations staff have been regularly assessing the performance of secondary clarifiers at the Northwest Langley Wastewater Treatment Plant using the dispersed suspended solids/flocculated suspended solids (DSS/FSS) tests described in the WERF/CRTC protocol. In addition to the regular tests, Metro Vancouver also conducted a 2-month intensive test program in 2017 to further evaluate clarifier performance under different flow conditions.
This presentation will provide an overview of the test program, demonstrate DSS/FSS sampling techniques using a Kemmerer sampler, present two years of data, and highlight key lessons learned. The results from the 2017 intensive test program, including additional DSS/FSS test points beyond the standard WERF/CRTC protocol and dye test results, combined with microscopic observations of microorganisms, illustrate how test data can be used to assess a clarifier’s hydraulic performance and assist operators in identifying where to focus efforts on improving overall plant performance.
Brief Biography and/or Qualifications Frank Dolemeyer is currently Operations Supervisor at Metro Vancouver’s Northwest Langley Wastewater Treatment. Frank has 30 years of operating experience in secondary wastewater treatment at Metro Vancouver’s Lulu Island (70 MLD) and Annacis Island (500± MLD) Wastewater Treatment Plants in addition to Northwest Langley (12.5 MLD). Frank was involved with the commissioning of new secondary clarifiers at Northwest Langley which included performance testing and working with Jacobs in the clarifier testing program.
Joyce Chang is a wastewater process engineer with Jacobs. She has 15 years of experience in the design and commissioning of water resource recovery facilities in North America. Based in Vancouver, British Columbia, Canada, Joyce has been working closely with Metro Vancouver operations staff to assess secondary clarifier performance at the Northwest Langley Wastewater Treatment Plant and led the engineering effort in setting up the clarifier testing program.
ID: 230 / Session 04A part 1: 2 Main Technical Program Topics: Headworks Keywords: Seconcary Clarifier, Blanket Filtration, Adaptive Inlet
Stress Testing of a Secondary Clarifier with an Adaptive Inlet Structure
Mario Benisch1, JB Neethling2
1HDR Portland, OR , United States of America; 2HDR Folsom, CA, United States of America;
Conventional clarifiers are generally limited in their performance by the settling characteristics of the biological sludge and hydraulic conditions in the clarifier. In general, secondary clarifier (SCL) effluent total suspended solids (TSS) less than 10 mg/L are difficult to achieve consistently. The Hydrograv Adapt variable inlet structure (HA) changes that.
Unlike traditional inlet structures, mixed liquor is introduced near the bottom of the clarifier below the sludge blanket. In addition the inlet elevation and opening height adapts to the load thus always operating in ideal hydraulic conditions. Embedded in the functioning principal is the blanket filtration. Since MLSS is introduced near the bottom of the sludge blanket, all flow has to travel (filter) through the blanket. The results are impressive.
At Moers-Gerdt the average annual TSS concentration for 2017 is 1.5 mg/L. To investigate the performance of an HA clarifier under peak load conditions a full scale stress test was conducted at the Moers-Gerdt facility Nov 14th 2017. Pushing 100% of the plant through one of three clarifiers, effluent turbidity never exceeded 1.0 ntu and was closer to 0.5 most of the time.
The technology has the potential to reduce the compliance cost for utilities to meet lower effluent limits by improving solids capture in the clarifier. Upgraded clarifiers have demonstrated a 60% to 95% reduction of clarifier effluent solids. Full scale experiences show effluent from a HA clarifier can rival that of a sand filters. In fact, at two installations plant staff have since taken the effluent dual media filters offline as they are no longer required for compliance. To quote the lead Operator at Moers Gerdt, Guido Hammer “In my opinion this best innovation in wastewater treatment in the last 30 years”.
Brief Biography and/or Qualifications 1998: Graduated from University of Stuttgart, Germany with MS in Environmental Engineering
Since 1998 with HDR in Portland OR
Now senior wastewater process engineer with focus on nutrient removal and recovery.