Industrial WWTP Operational Support: Nitrification Upset During the Polar Vortex. Leigh-Ann Dudley. NC AWWA-WEA 2014 Annual Conference

Transcription

1 Industrial WWTP Operational Support: Nitrification Upset During the Polar Vortex Leigh-Ann Dudley NC AWWA-WEA 2014 Annual Conference

2 Agenda Facility Overview Upset Event Risk Factors Causes Recovery strategy 2

3 Facility Overview Pharmaceutical facility in NC Wastewater profile: 0.2 MGD ~ 10,000 mg/l tcod ~ 500 mg/l TKN Contains complex organics at 1,000 s mg/l level Treatment plant includes: Equalization Activated sludge with nitrification & denitrification Clarification Discharges to a POTW 3

4 Facility Overview Aerobic 1 Equaliza0on Anoxic 1 Aerobic 3 Aerobic 2 Discharge to POTW Clarifier Anoxic 2 Solids to RAS and WAS 4

5 Agenda Facility Overview Upset Event Risk Factors Causes Recovery strategy 5

6 Risk Factors for an Upset Acute Risk Factors Full scale trial to evaluate using lime instead of MagOx winter was very cold Chronic Risk Factors High strength organics in wastewater Potential for slug discharges from production Stratification of organics in unmixed equalization tank 6

7 Lime Trial Lowered Reactor ph Optimum ph at this facility is Reactor ph decreased during lime trial ph (s.u.) Lime Trial Begins Lime Trial Ends Switch Back to MagOx /3/ /23/ /12/ /2/ /22/2013 1/11/2014 1/31/2014 Aerobic Reactor 1 Aerobic Reactor 2

8 Aerobic Reactor 1 Concentration (mg/l) /3/ /2/ /2/2013 1/1/2014 1/31/2014 3/2/2014 4/1/2014 Ammonia Nitrate ph ph (s.u.) 8

9 Aerobic Reactor 1 Concentration (mg/l) /3/ /2/ /2/2013 1/1/2014 1/31/2014 3/2/2014 4/1/2014 Ammonia Nitrate ph ph (s.u.) 9

10 Low Reactor Temperatures Reactor temperatures were at historical lows for this WWTP Temperature ( C) /28/ /28/ /27/ /27/2013 1/26/2014 2/25/2014 3/27/2014 4/26/2014 Anoxic Temperature Aerobic 1 Temperature Aerobic 2 Temperature

11 Aerobic Reactor 2 Concentration (mg/l) /2/2013 1/1/2014 1/31/2014 3/2/2014 4/1/2014 Ammonia Nitrate Temperature Temperature (C) 11

12 Aerobic Reactor 2 Concentration (mg/l) /2/2013 1/1/2014 1/31/2014 3/2/2014 4/1/2014 Ammonia Nitrate Temperature Temperature (C) 12

13 Agenda Facility Overview Upset Event Risk Factors Causes Recovery strategy 13

14 Bench Testing Temperature Impact Objective Identify if temperature is the primary cause of inhibition Protocol (2) 2-L reactors seeded with sludge from Aerobic Reactor 2 Varied the reactor temperature 30ºC to simulate normal operating condition 21ºC to simulate current operating condition 14

15 Bench Testing Temperature Impact Concentration (mg/l) Elapsed Time (hours) Ammonia 30C Ammonia 21C Nitrate 30C Nitrate 21C 15

16 Agenda Facility Overview Upset Event Risk Factors Causes Recovery strategy 16

17 Other Sources of Heat? Heat introduced through blowers Heat generated through heterotrophic carbon removal Facility has no other way to add heat to the reactors 17

18 Managing Loading Rates NH3- N Loading (lbs/d) Forward FLow (gpm) Axis Title NH3- N Loading Forward Flow 18

19 Managing Loading Rates 25, , COD Loading (lbs/day) 15,000 10, Forward Flow (gpm) 5, COD Loading Forward Flow

20 Limited Storage Capacity Equalization Tank Level (ft) Full Comfort Level

21 Limited Storage Capacity Diminishing storage capacity threatened production Increase forward flow as aggressively as possible Diverted select waste streams Negotiated to discharge stripper bottoms directly to the POTW Groundwater recovery wells temporarily turned off 21

22 Seeding with Supplemental Sludge Another local pharmaceutical facility was successfully nitrifying in the cold weather Bench testing indicated nitrification rates would be increased with addition of the supplemental sludge Facility provided several trucks of WAS which were put into both aerobic reactors 22

23 Recovery Strategy Concentration (mg/l) Reactor Seeded with External Sludge Lowest Reactor Temperature 16 C /22/201312/12/2013 1/1/2014 1/21/2014 2/10/2014 3/2/2014 3/22/2014 4/11/2014 5/1/2014 Ammonia Nitrate 23

24 Supplemental Nitrate for Anoxic Reactor 24 Reduced nitrification meant a decrease in nitrate recycled to the anoxic reactor Less nitrate for denitrification in the anoxic reactor meant less organic removal in the anoxic reactor Risks of passing organics through anoxic Increased nitrification inhibition Potential color formation in the aerobic reactors Added calcium nitrate to the anoxic reactor to increase organic carbon removal in that reactor

25 Recovery Strategies Hoping for warmer weather 25

26 Aerobic Reactor 2 Concentration (mg/l) /2/2013 1/1/2014 1/31/2014 3/2/2014 4/1/2014 Ammonia Nitrate Temperature Temperature (C) 26

27 Summary Cold weather caused nitrification inhibition Recovery was slow Several mitigation strategies employed to keep the plant running through the remainder of winter No loss of production time during upset recovery 27

28 Questions?

29 Full Scale Nitrogen Data Concentration (mg/l) Aerobic Reactor 1 Ammonia Aerobic Reactor 2 Ammonia Aerobic Reactor 1 Nitrate Aerobic Reactor 2 Nitrate 29

30 Agenda Client Introduction Upset Event Operational assistance Recovery strategy Routine Operational Support Data management Staff evaluation and augmentation 30

31 Data Management Number of Files Data Entry Trending Capability Process Calcula0ons Exis%ng Data Management 3 Excel files resaved monthly 36 files per year Mul0ple places Time and Error! Only within each monthly file Only within each monthly file New Data Management 1 file used con0nuously Only once automa0cally referenced if required other placed Automa0cally graphs process cri0cal parameters Automa0cally calculated process cri0cal parameters and compares between operator and lab data DMRs Required manual entry Automa0cally generated when compliance data is entered 31

32 Data Management Number of Files Data Entry Trending Capability Process Calcula0ons Exis%ng Data Management 3 Excel files resaved monthly 36 files per year Mul0ple places Time and Error! Only within each monthly file Only within each monthly file New Data Management 1 file used con0nuously Only once automa0cally referenced if required other places Automa0cally graphs process- cri0cal parameters Automa0cally calculates process- cri0cal parameters and compares between operator and lab data DMRs Required manual entry Automa0cally generated when compliance data is entered 32

33 Data Management Advantages of the new data management Reduces man-hours spent on data management Reduced the possibility of error by only requiring data entry once Process data and trends are quickly accessible to plant personnel and their consultants Reduced time required to prepare DMRs 33

34 Agenda Client Introduction Routine Operational Support Data management Staff evaluation and augmentation Upset Event Operational assistance Recovery strategy 34

35 Staff Evaluation Client requested a review of staffing requirements due to reorganization of personnel Evaluation included: Reviewing required operator attention Reviewing field and laboratory data collection Identifying process critical data (organics, nitrogen species) Reducing the frequency of some parameters (TSS, phosphorus) Eliminated data that was collected but not reviewed by anyone (color) 35

36 Staff Evaluation Operator Requirements Operators Data Collec0on Exis%ng Staff Requirements 24/7 wastewater operator Manually collected data for ph, temperature, and DO at 6 loca0ons 4x per day Measuring ammonia and nitrate at 6 loca0ons 4x per day Revised Staff Requirements Reduc0on in sampling/field data collec0on freed operators to work between wastewater and u0lity func0ons Reduced the frequency of sampling, data collec0on, and data entry Laboratory Data Collec0on Required 1 full- 0me posi0on 13 samples analyzed daily for 14 parameters Requires ~12 hours per week Transferred some responsibili0es to operators (collec0ng compliance samples) 36

37 Staff Evaluation Operator Requirements Operators Data Collec0on Exis%ng Staff Requirements 24/7 wastewater operator Manually collected data for ph, temperature, and DO at 6 loca0ons 4x per day Measuring ammonia and nitrate at 6 loca0ons 4x per day Revised Staff Requirements Reduc0on in sampling/field data collec0on freed operators to work between wastewater and u0lity func0ons Reduced the frequency of sampling, data collec0on, and data entry Laboratory Data Collec0on Required 1 full- 0me posi0on 13 samples analyzed daily for 14 parameters Requires ~12 hours per week Transferred some responsibili0es to operators (collec0ng compliance samples) 37