The NEORSD Demonstration of a Cost-Effective Solution

Transcription

1 2015 OWEA Technical Conference Advancing Wet Weather Treatment The NEORSD Demonstration of a Cost-Effective Solution June 24, 2015

2 Advancing Wet Weather Treatment The NEORSD Demonstration of a Cost-Effective Solution Greg Binder, P.E., Northeast Ohio Regional Sewer District Nick Bucurel, P.E., Brown and Caldwell

3 Agenda 1. Project overview 2. Technology background and application 3. Results and challenges 4. Process evaluations for design and operation 5. Questions Brown and Caldwell 2015 OWEA Technical Conference 3

4 Project Overview Thank you!

5 Northeast Ohio Regional Sewer District Who we are Regional wastewater utility created in 1972 by court order Separate and distinct from the City of Cleveland and Cuyahoga County What we do Servicing all or part of 62 member communities 1 million customers 90+ billion gallons wastewater treated each year Easterly WWTP Westerly WWTC Southerly WWTC Brown and Caldwell 2015 OWEA Technical Conference 5

6 Northeast Ohio Regional Sewer District 355 square miles Brown and Caldwell 2015 OWEA Technical Conference 6

7 CSO Long-Term Control Plan Consent Decree Consent Decree in 2010 to implement LTCP $3 billion over 25 years Typical Year CSO Volume Remaining (BG) Baseline (1970s) Current Target (2036) 98% Capture Brown and Caldwell 2015 OWEA Technical Conference 7

8 Consent Decree Requirements Implement planning, pilot/demonstration using CEHRT CEHRT Chemically Enhanced High-Rate Treatment CEPT Chemically Enhanced Primary Treatment HRD High-Rate Disinfection Effluent criteria Solids 40 mg/l total suspended solids (rolling seven event average) Bacteria 126 CFU/100 ml E. coli (recreation season geomean) 284 CFU/100 ml E. coli (rolling seven event geomean) 7 Events Implement ballasted flocculation if criteria not met Brown and Caldwell 2015 OWEA Technical Conference 8

9 Current testing program bridges the gap to consent decree implementation Easterly Facilities Plan Easterly CEHRT Facility Southerly Facilities Plan CEHRT Pilot & Demonstration Jar Testing, Work Plans, Design, Construction Southerly CEHRT and Parallel Treatment Westerly CSOTF Evaluation CEHRT Pilot & Demonstration Operation Westerly CSOTF Expansion & CEHRT Consent Decree Brown and Caldwell 2015 OWEA Technical Conference 9

10 Project objectives go beyond regulatory compliance Meet consent decree requirements Inform future design and operations EPA Requirements NEORSD Confidence Brown and Caldwell 2015 OWEA Technical Conference 10

11 Technology Background & Application Chemically Enhanced Primary Treatment (CEPT) & High-Rate Disinfection (HRD) Thank you!

12 Chemically Enhanced Primary Treatment (CEPT) Enhanced performance through chemical addition Convert slow settling and colloidal solids into rapidly settleable solids Two-step chemical addition process Metal coagulant neutralizes particle charge Polymer flocculant aggregates coagulated particles Coagulant1 Flocculant2 Brown and Caldwell 2015 OWEA Technical Conference 12

13 Objective is to create a floc like This: Not this: Flocculated primary influent Normal primary influent Brown and Caldwell 2015 OWEA Technical Conference 13

14 High-Rate Disinfection (HRD) Bacteria reductions achieved at detention times less than conventional minutes HRD detention time can be as low as ~ 5 minutes High intensity, rapid mix for instantaneous chlorine dispersion Typically higher doses of disinfectant Develop dose-kill relationship Brown and Caldwell 2015 OWEA Technical Conference 14

15 CEHRT Facilities

16 Facility Size Comparison Southerly PST No. 18 Demo Westerly CSTOF Scale Construction Tank A Demo Plant Easterly Pilot Ongoing Limits Flow & Events Southerly PST No. 18 Easterly WWTP Pilot Yes No Southerly WWTC Westerly WWTC Full Scale + Pilot Partial Scale + Pilot Westerly CSOTF Tank A Yes Easterly Pilot Tank No Onsite Storage Affects Event Duration Yes Yes Brown and Caldwell 2015 OWEA Technical Conference 16

17 Easterly WWTP CEHRT General Configuration Headworks Building N Influent pump Pilot influent pipe CEHRT Pilot Facility Brown and Caldwell 17

18 Easterly WWTP CEHRT CEPT Tank and Chemical Application CEPT effluent to HRD Influent pipe Settling zone Coagulant addition (diffuser) Polymer flocculant addition (diffuser) Brown and Caldwell 2015 OWEA Technical Conference 18

19 Easterly WWTP CEHRT HRD Tank Sodium Hypochlorite Induction Mixer Brown and Caldwell 2015 OWEA Technical Conference 19

20 Westerly CSOTF CEHRT General Configuration Bar Screens Quad A Quad B Quad C CEPT Demonstration in Tank A Effluent Junction Quad D Outfall Conduit

21 Westerly CSOTF CEHRT General Configuration Coagulant addition in wet well HRD Pilot HRD equipment & lab Polymer flocculant addition CEPT Demonstration in Tank A

22 Westerly CSOTF CEHRT Chemical Application & Process Influent pumped to Tank A (coagulant added in wet well) Polymer flocculant addition (diffuser at influent) CEPT effluent pumped to HRD Tank Brown and Caldwell 2015 OWEA Technical Conference 22

23 Results & Challenges Thank you!

24 Calendar and Types of Events Captured Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Seasonal variations Range in storm types and influent conditions Rainfall and flow ranges Total rainfall: inches Peak intensity: inches/hour Peak plant flow: Easterly: 215 mgd 1.5 bgd Westerly: mgd Easterly Westerly Brown and Caldwell 2015 OWEA Technical Conference 24

25 Easterly Average TSS Influent Effluent Total Suspended Solids (mg/l) mg/l 0 Event 1 Event 2 Brown and Caldwell 2015 OWEA Technical Conference Event 3 Event 4 Event 5 Event 6 Event 7 Event 8 Event 9 Event 10 Event 11 Event 12 Event 13 Event 14 Event 15 Event 16 Event 17 Event 18 Event 19 Event 20 Event 21 Event 22 Event 23 Event 24 Event 25 Event 26 25

26 Easterly Rolling Average TSS 50 Total Suspended Solids (mg/l) SOR = 2,400 3,000 gpd/sf Brown and Caldwell 2015 OWEA Technical Conference Event 1 Event 2 Event 3 Event 4 Event 5 Event 6 Event 7 Event 8 Event 9 Event 10 Event 11 Event 12 Event 13 Event 14 Event 15 3,000 3,400 Modified Baffles 4,000 4,500 Improved Polymer Mixing Alternate Coagulant Event 16 Event 17 Event 18 Event 19 Event 20 Event 21 Event 22 Event mg/l 5,000 7,000 Event 24 Event 25 Event 26 26

27 Easterly Limitations of Pilot Scale Modified Baffles Initial flow short-circuiting & rolling CFD analysis to guide modifications Flow Flow Brown and Caldwell 2015 OWEA Technical Conference 27

28 Easterly Limitations of Pilot Scale Modified Baffles Improved Polymer Mixing Southerly WWTC PST No. 18 influent gate Settling zone Coagulant addition Polymer flocculant diffuser Polymer flocculant diffuser Brown and Caldwell 2015 OWEA Technical Conference 28

29 Easterly Limitations of Pilot Scale Modified Baffles Improved Polymer Mixing Settling zone Water jet Coagulant polymer addition mixing Polymer flocculant diffuser Polymer flocculant diffuser Water jet polymer mixing Brown and Caldwell 2015 OWEA Technical Conference 29

30 Easterly Limitations of Pilot Scale Modified Baffles Improved Polymer Mixing Alternate Coagulant Small, poor settling floc Control (no chemical) Large, rapidly settling floc Brown and Caldwell 2015 OWEA Technical Conference 30

31 Easterly Limitations of Pilot Scale Modified Baffles Improved Polymer Mixing Alternate Coagulant Modifications made to optimize pilot performance for more representative operation Brown and Caldwell 2015 OWEA Technical Conference 31

32 Westerly Average TSS , Influent Effluent Total Suspended Solids (mg/l) mg/l 0 Event 1 Event 2 Event 3 Brown and Caldwell 2015 OWEA Technical Conference Event 4 Event 5 Event 6 Event 7 Event 8 Event 9 Event 10 32

33 Westerly Pushing Full-Scale Limits Total Suspended Solids (mg/l) Average Effluent TSS 7-Event Rolling Average 40 mg/l Highest 7-Event Rolling Average = 27 mg/l 0 Event 1 Event 2 Event 3 Event 4 Event 5 Event 6 Event 7 Event 8 Event 9 Event 10 Brown and Caldwell 2015 OWEA Technical Conference 33

34 Westerly Pushing Full-Scale Limits Total Suspended Solids (mg/l) ,700 Event 1 Average Effluent TSS 7-Event Rolling Average 3,000 Event 2 3,700 Event 3 Brown and Caldwell 2015 OWEA Technical Conference 4,000 Event 4 4,300 Event 5 4,500 Average Effluent TSS = 27 mg/l Consistent Effluent Quality Event 6 5,300 Event 7 6,100 Event 8 7,000 Event 9 8,000 Event 10 34

35 Westerly Pushing Full-Scale Limits Total Suspended Solids (mg/l) Event 1 Event 2 Westerly WWTC Average Effluent TSS 7-Event Rolling Average Average Effluent = 27 mg/l Event 3 Brown and Caldwell 2015 OWEA Technical Conference Event 4 Total Suspended Solids (mg/l) Event Event 6 Event 1 Southerly WWTC Event 7 Event 2 Event 3 Event 8 Event 4 Event 5 Event 9 Event 6 Event 7 Event 10 Event 8 Average Effluent TSS 7-Event Rolling Average Average Effluent = 25 mg/l Event 9 Event 10 Event 11 35

36 Westerly Disinfection Performance 126 cfu/100 ml Brown and Caldwell 2015 OWEA Technical Conference 36

37 CEPT Impacts Disinfection Performance Reduced chlorine demand with CEPT Brown and Caldwell 2015 OWEA Technical Conference 37

38 Process Evaluations for Design and Operation Thank you!

39 Factors Affecting CEPT Performance Alkalinity Wet weather flow dilution can lower alkalinity Certain coagulants reduce alkalinity even further ph Low ph rain water lowers ph of wet weather flow Impacts coagulation if below optimal range Temperature Affects optimal ph for coagulation and reaction times Brown and Caldwell 2015 OWEA Technical Conference 39

40 Temperature Effects on CEPT Performance 55 F 38 F 55 F 38 F Coagulation time = 90 sec Coagulation time = 150 sec Jar tests show that increased coagulation time improves performance at low temperature Brown and Caldwell 2015 OWEA Technical Conference 40

41 Impact of Coagulation Contact Time Control Less CCT More CCT Jar 2 Jar 3 Jar 4 Jar 5 Jar 6 Coagulant, mg/l FeCl Flocculant Coagulation Time, sec Providing sufficient minimum coagulation time is critical to CEPT performance Brown and Caldwell 2015 OWEA Technical Conference 41

42 Jar Testing for Chemical Selection Jar tests show that not all anionic polymers are equal in terms of consistent performance across storm events Brown and Caldwell 2015 OWEA Technical Conference 42

43 Combining Treatment for Cost Savings Simultaneous high rate treatment CEPT and HRD simultaneously within same tank to achieve solids and bacteria removal performance goals CEPT Influent CEPT Tank CEPT Treated Effluent HRD Tank Disinfected Effluent Coagulant Flocculant Disinfectant Brown and Caldwell 2015 OWEA Technical Conference 43

44 Combining Treatment for Cost Savings Simultaneous high rate treatment CEPT and HRD simultaneously within same tank to achieve solids and bacteria removal performance goals CEPT Influent CEPT/HRD Tank Tank CEPT Treated / Disinfected Effluent Effluent HRD Tank Disinfected Effluent Coagulant Flocculant Disinfectant Brown and Caldwell 2015 OWEA Technical Conference 44

45 Simultaneous High Rate Treatment Previous work in Hartford, Omaha, Utica, NEORSD Similar performance & results Simultaneous HRT Bacteria Dose Response Curves Preliminary testing shows equivalent performance is feasible Brown and Caldwell 2015 OWEA Technical Conference 45

46 Summary Comments and Conclusions Successful implementation of CEHRT at pilot and full-scale Achieved results less than target criteria Diagnosed process challenges Developed criteria for full-scale Continue to collect data at Westerly through 2015 Continue to push hydraulic conditions Simultaneous high rate treatment Brown and Caldwell 2015 OWEA Technical Conference 46

47 Questions Greg Binder, P.E. Nick Bucurel, P.E.