Odor Control A Successful Case Study of an Evaluation and Assessment at a Wastewater Treatment Plant in Gallup, New Mexico

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1 Odor Control A Successful Case Study of an Evaluation and Assessment at a Wastewater Treatment Plant in Gallup, New Mexico PNCWA 2012 Annual Conference and Exposition October 24, 2012 Presented by Fred Kriess

2 My Goal Help You in Providing Some Interesting Information and Have Fun in the Process Life is Short and Make the Most of Every Minute!

3 What Will We Cover Today? Project Background and History Odors/Hydrogen Sulfide Facts Overview of Technology Used What did we Learn? Action Plan/Corrective Actions

4 What is the # 1 Cause of Traffic Accidents?

5 City of Gallup New Mexico WWTP 3.5 MGD Biological Treatment Facility Effluent Reuse to Golf Course Currently Treating about 2.3 MGD Receives Septage From City and Surrounding Areas Collection system with long detention times 5 lift stations

6 Gallup New Mexico Wastewater Treatment Plant Drying Beds Belt Filter Press/Dryer Aerobic Digesters/ Thickener

7 I 40 Commercial Business & Hotels

8 Sludge Disposal Land Site Residential Subdivision

9 The Task Severn Trent began to provide operational services on July 1, 2010 Required to complete an assessment within 30 days to determine sources of odors and develop action plan Historical odor complaints What was the source?

10 Some Facts About Hydrogen Sulfide 15 ppb Human Odor Detection Threshold 10/ppm/10 minutes NIOSH recommended maximum exposure 15 ppm/15 minutes OSHA short term maximum exposure limit 50 ppm Peak OSHA instantaneous maximum exposure 300 ppm Immediate danger to life and health >1000 ppm Deadly and Fatal upon inhalation with as little as one breath

11 Water Factoid #1 How Much Water Does It Take to Make a Ton of Steel?

12 Answer about 63,000 gallons

13 Initial Areas of Concern

14 The collection system and gravity trunk sewer main to the plant Long Detention Times in Collection System

15 I Influent Metering Structure

16 Influent Pump Station

17 Solids Dewatering

18 Sludge Digestion/Thickening

19 Sludge fields located adjacent (due west) of plant site. Sludge was liquid injected or land (pressed cake) applied Nearby residential community Historical Odor Complaints

20 Overview of Technology Used Jerome 605X OdaLog L2 Gas Loggers

21 Sensors detect sulfide/sulfur species, 90% bound as H 2 S H 2 S is an indicator for presence of other odorous compounds

22 OdaLog Data Loggers 0 50 ppm and 0 1,000 ppm units were used Captures continuous data which may be downloaded to PC using OdaStat software Can be used for collection system, structure monitoring 22

23 Can be hung or mounted most anywhere 23

24 Representative Log of H 2 S Concentrations and Temperature over Time (0 50 ppm range unit) Average 14.2 ppm (sample at 1 minute intervals) Max - > 50 ppm 24

25 Jerome Handheld Unit for Field Very low sensitivity; can sense atmospheric H 2 S concentrations as low as 3 ppb (non detect) Used for field monitoring, grab data samples throughout plant site and surrounding areas Assessments 25

26 Field Data Collection Daily Logs Completed 26

27 Monitoring Locations 0 1,000 ppm OdaLog Upstream Manhole Headworks Metering Structure Influent Pump Station

28 Selected Monitoring Locations 0 50 ppm OdaLog Primary Clarifier Digesters/Sludge Thickener Belt Filter Press Room

29 Water Factoid #2 How much of the earth s water supply is ocean or sea water?

30 Answer 97%

31 Data and Conclusions

32 Collection System a Key Source >1,000 ppm levels found in immediate upstream manhole to plant Observed levels were well above OSHA limits

33 Influent Manhole Many H 2 S spikes > 1,000 ppm

34 Influent Metering Structure Levels exceeded 400 ppm

35 Stripping of H 2 S was occurring at Influent Pump Station Average 63 ppm Peak 265 ppm

36 Average H S Levels of 2 63 ppm with peak recorded level of 656 ppm in Belt Filter Press Room

37 Additional Findings Intermittent H 2 S spikes in and around plant process units that exceeded OSHA short term exposure limits

38 H2S levels around the plant site frequently exceeded 15 ppb

39 Water Factoid #3 How many gallons of water would you get in 1 inch of rainfall per square mile?

40 Answer 17.4 million gallons!

41 Action Plan

42 Employee Safety Purchased continuous H 2 S monitors to be worn by all plant employees Developed H 2 S site specific exposure control SOP with recommended maximum exposure limits for areas within plant

43 Installed Weather Station Helpful to plant staff to determine if plant was source of odor complaints (wind direction)

44 Sludge Disposal Site Now using liquid sludge injection rather than sludge cake spreading

45 Ongoing Efforts Working with City for further evaluation of collection system and ways to reduce H 2 S formation Process control optimization of solids inventory

46 Modifications to Sludge Digester Operations Recirculation of sludge to minimize septic conditions Feeding of primary and secondary sludges to primary digester

47 Purchased Industrial Fan for Ventilation of Belt Filter Press Building

48 Conclusion: Progress and Ongoing Work Employee safety issues were addressed Odors minimized from plant process units (after headworks) A significant reduction in odor complaints from what had been reported historically Sludge disposal fields and headworks on going areas of concern implemented odor complaint hot line. Headworks and collection system evaluation continues

49 Thank You! May I answer any questions? fkriess@stes.com

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