A Low-Energy Wastewater Treatment Process for Producing High Quality Reuse Water. Eric Marchand Andrea Achilli Sage Hiibel

Transcription

1 A Low-Energy Wastewater Treatment Process for Producing High Quality Reuse Water Eric Marchand Andrea Achilli Sage Hiibel

2 About WateReuse The mission of the WateReuse Research Foundation is to build support for water reuse through research and education. More information Research Reports 2

3 Logistical Notes Today s webcast will be 60 minutes A PDF of today s presentation can be downloaded when you complete the survey at the conclusion of this webcast There is one Professional Development Hour available If you have questions for the presenters, please send a message by typing it into the chat box located on the panel on the left side of your screen If you would like to enlarge your view of the slides, please click the Full Screen button in the upper right corner of the window To use the chat box, you must exit full screen 3

4 Today s Presenters Eric Marchand, Ph.D., P.E. University of Nevada, Reno Andrea Achilli, Ph.D., P.E. Humboldt State University Sage Hiibel, Ph.D. University of Nevada, Reno 4

5 Project Overview Dr. Eric Marchand

6 Acknowledgements Project Manager Kristan Cwalina Project Advisory Committee Chris Haney, Senior Vice President Gresham, Smith and Partners Paul Westerhoff, Professor Arizona State University Charles Bott, Research and Development Manager Hampton Roads Sanitation District (HRSD) Katherine Dahm, Engineer Bureau of Reclamation Industry Partners Hydration Technologies Incorporated (HTI) Porifera Washoe County Department of Water Resources Truckee Meadows Water Reclamation Facility (TMWRF) 6

7 Presentation Overview Project Objectives Coupled Forward Osmosis and Membrane Distillation Wastewater Concentration by Forward Osmosis Anaerobic Membrane Bioreactor Discussion and Questions 7

8 Project Objectives Conceptualize a novel treatment scheme to reduce energy associated with domestic wastewater treatment Conduct a literature review to establish operating conditions for each unit process Develop a process model for the treatment scheme and compare performance to an existing water reclamation facility Perform laboratory-scale experiments to optimize operating parameters of individual unit processes 8

9 Relevance to WateReuse RFP 10-06: Challenge Projects on Low Energy Treatment Schemes for Water Reuse The goal of the project is to conceptualize and evaluate alternatives to energy intensive aerated activated sludge systems for providing suitable water for one or more reuse applications, ranging from irrigation to cooling tower water to pretreatment for reverse osmosis or other reuse treatment processes. The project would include two phases, which will be funded separately, a development phase and a testing phase. Phase 1 Research Collect literature data and perform preliminary modeling Phase 2 Research Test system components in lab setting 9

10 Energy for Wastewater Treatment Source: Water Environment Energy Conservation Task Force: Energy Conservation in Wastewater Treatment 10

11 Low-Energy System Principles Wastewater Forward osmosis dewatering unit 11

12 Low-Energy System Principles Anaerobic Anammox biological wastewater treatment Solutes Wastewater Forward osmosis dewatering unit Water Membrane distillation water production 12

13 Low-Energy System Principles Energy from carbon Anaerobic Anammox biological wastewater treatment Solutes Wastewater Forward osmosis dewatering unit Water Membrane distillation water production Product water 13

14 Low-Energy System Principles Energy from carbon Anaerobic Anammox biological wastewater treatment Nutrient recovery Solutes Wastewater Forward osmosis dewatering unit Water Membrane distillation water production Product water 14

15 New Conceptual Process Diagram Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 15

16 New Conceptual Process Diagram Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 16

17 New Conceptual Process Diagram Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 17

18 New Conceptual Process Diagram Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 18

19 New Conceptual Process Diagram Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 19

20 Phase 1: Proof of Concept Testing Perform literature review for system components Forward Osmosis Membrane Distillation Anaerobic MBR Sharon Anammox Struvite Precipitation Identify typical operating conditions for each process Develop BioWin Model Perform simulation at two FO recoveries (50% and 70%) 20

21 Forward Osmosis (FO) FO serves as a pre-concentration step, as clean water in the influent wastewater diffuses across the forward osmosis membrane, into the draw solution. Parameter Typical Values Flux (L/m 2 *hr, LMH) Draw Solution NaCl or MgCl 2 Solute Ionic Strength (M) Water Recovery (%) Reverse Salt Flux Variable, ~0.15*Flux 21

22 Reverse Osmosis vs. Forward Osmosis Hydraulic Pressure, P Osmotic Pressure, π Water Brine Water Brine Reverse Osmosis Δπ < ΔP Forward Osmosis Δπ 22

23 Membrane Distillation (MD) MD uses a porous hydrophobic membrane to facilitate the transfer of clean water from a heated feed solution to a cold distillate stream. Parameter Typical Values Feed Temp ( o C) Permeate Temp ( o C) Flux (L/m 2 *hr, LMH) Water Recovery (%) Salt Rejection (%) >

24 Membrane Distillation Hydrophobic membrane Thermally driven process Low energy input 40 C 20 C ΔT = 20 C 24

25 Anaerobic Membrane Bioreactor (AnMBR) An AnMBR serves two main purposes: removal of chemical oxygen demand (COD) and production of methane biogas. Parameter Typical Values Methane (L/g COD) MLSS (g/l) 5 30 Flux (L/m 2 *hr, LMH) 5 8 COD Removal (%) >80 SRT (days) >

26 Sharon Process The SHARON (single-reactor highyield ammonium removal over nitrite) process is known as partial nitrification. The target result of SHARON is an even molar ratio of ammonium to nitrite. Parameter Typical Values Temp ( o C) Nitrogen Load (kg/m 3 *d) NO 2- :NH + 4 1:1 HRT & SRT (hr) Incomplete nitrogen oxidation reduces the oxygen required. NH NH NO O 2 26

27 Anammox Process In the ANAMMOX process (ANaerobic AMMonium OXidation), ammonium is used as an electron donor while nitrite is used as an electron acceptor. Nitrogen is released from the ANAMMOX process as nitrogen gas. Parameter Typical Values Temp ( o C) SNR (g N/g VSS*d) NO 2- :NH 4+ :NO : 1.2 : 0.2 NH NO 2 - N H 2 O 0.5 NH NO 2 - N 2 (g) NO O 2 Required 27

28 Struvite Precipitation Struvite (MgNH 4 PO 4 *6 H 2 O) naturally precipitates from wastewater through the addition of magnesium and by increasing ph. Phosphorus can effectively be forced to precipitate as struvite, and then the struvite can be sold. Parameter Typical Values ph 8 9 Temp ( o C) Mg:P Molar Ratio 1:1 HRT (hr) <

29 Comparison with Water Reuse Facility in Reno Selected 100% water reuse facility for comparison (South Truckee Meadows Water Reclamation Facility, STMWRF) Developed BioWin model for conceptual facility Evaluated BioWin model with STMWRF inputs Varied FO recovery (50% and 70%) Evaluated model for extreme operating ranges Compared costs between facilities 29

30 BioWin Model Development 30

31 BioWin Input Conditions B Parameter Value Parameter Value Flow 3 MGD COD 300 mg COD/L TKN 20 mg N/L Total Phosphorus 5 mg P/L Nitrate 0.3 mg N/L ph 7.3 Alkalinity 5.5 mmol/l Calcium 45 mg/l Magnesium 15 mg/l Dissolved Oxygen 0 mg/l 31

32 Model Results Cost Breakdown Projected cost varied between $86.3K $199.4K per MGD per year 50% Recovery 70% Recovery Process (Minimum / Maximum) (Minimum / Maximum) $/MGD treated / year $107,397 $199,435 $86,329 $188,803 Comparison facility cost: $96.3K per MGD per year Important distinction: Product water from membrane distillation is high quality reuse water 32

33 Transition to Phase 2 Research Overall feasibility of conceptual model facility was validated Cost estimates are reasonable when compared with traditional reuse facility Research needed to answer the following questions: 1. How does the coupled FO-DCMD system respond to transient operating conditions? 2. What are the limitations of concentrating domestic wastewater with a FO module? 3. Is AnMBR performance affected by FO pre-concentration? 33

34 Coupled Forward Osmosis and Membrane Distillation Dr. Andrea Achilli

35 Forward Osmosis and Membrane Distillation Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 35

36 Forward Osmosis and Membrane Distillation Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 36

37 FO/DCMD Bench-Scale Investigation Feed Solution FO DCMD Draw Solution Distillate HX 37

38 Physical System Forward Osmosis Direct Contact- Membrane Distillation DI water dd dd Feed Draw Distillate dd dd 38

39 Physical System Forward Osmosis Direct Contact- Membrane Distillation DI water dd dd Feed Draw Distillate dd dd Experimental Conditions Draw Solution = g/l NaCl Pump Flow Rates = 1 Liter per minute Forward Osmosis Membrane Area = 170 cm 2 Membrane Distillation Membrane Area = 140 cm 2 Heated Stream Temperature = o C Distillate Stream Temperature = o C 39

40 Physical System Forward Osmosis Direct Contact- Membrane Distillation DI water dd dd Feed Draw Distillate dd dd Experimental Conditions Draw Solution = g/l NaCl Pump Flow Rates = 1 Liter per minute Forward Osmosis Membrane Area = 170 cm 2 Membrane Distillation Membrane Area = 140 cm 2 Heated Stream Temperature = o C Distillate Stream Temperature = o C 40

41 Membranes and Spacers Forward Osmosis Membrane Membrane Distillation Membrane Woven Grid Membrane Support 41

42 Water and Solute Fluxes DI water dd dd Feed Draw Distillate dd dd Forward Osmosis Direct Contact- Membrane Distillation 42

43 Water and Solute Fluxes DI water dd dd Feed J w J w Draw J w Distillate dd dd Where: Forward Osmosis Direct Contact- Membrane Distillation V = Volume [L] t A m = Time [hr] = Effective Membrane Area [m 2 ] J w = WWWWW FFFF = dv dd A m 1 L m 2 h 1 A FO = FO Membrane Area [m 2 ] C p, C f = Concentration of Permeate, Feed [mg/l] 43

44 Water and Solute Fluxes DI water dd dd Feed J w J w Draw J w Distillate dd dd Where: Forward Osmosis Direct Contact- Membrane Distillation V = Volume [L] t A m A FO C p, C f = Time [hr] = = = Effective Membrane Area [m 2 ] FO Membrane Area [m 2 ] Concentration of Permeate, Feed [mg/l] J w = WWWWW FFFF = dv dd A m 1 RRRRRRRRR = 1 C p C f 111 % L m 2 h 1 J s = RRRRRRR SSSS FFFF = dc f dd V 1 f A FF g m 2 h 1 44

45 Monitor and Control System INPUTS: Time, Max temperatures, Target temperature for heater LabVIEW Monitoring and Control Automatic Data Collection: temp, pressure, water volumes, conductivity Automatic Control of Heater and Proportional Control Valve OUTPUT: Data written into Excel File. 45

46 Feed and Draw Solutions Surrogate Wastewater Feed Solution Constituent C (mg/l) Nutrient Broth 180 Urea 70 Ammonium Chloride 50 Monopotassium Phosphate 30 Calcium Chloride 30 Ferrous Sulfate 30 46

47 Feed and Draw Solutions Surrogate Wastewater Feed Solution Constituent C (mg/l) Nutrient Broth 180 Urea 70 Draw Solutions Sodium Chloride (NaCl) Magnesium Chloride (MgCl2) Sodium Propionate (NaC3H5O2) Ammonium Chloride 50 Monopotassium Phosphate 30 Calcium Chloride 30 Ferrous Sulfate 30 47

48 Water Fluxes and System Stability DCMD Water Flux FO Water Flux DCMD Feed Temperature Draw Solution Concentration Water Flux (LMH) Temperature ( C ) Concentration (g/l) Elapsed Time (hour) 0 48

49 Water Fluxes and System Stability DCMD Water Flux FO Water Flux DCMD Feed Temperature Draw Solution Concentration Water Flux (LMH) Temperature ( C ) Concentration (g/l) Elapsed Time (hour) 0 49

50 Water Fluxes and System Stability DCMD Water Flux FO Water Flux Draw Solution Concentration DCMD Feed Temperature Water Flux (LMH) Temperature ( C) Concentration (g/l) Elapsed Time (hour) 0 50

51 Water Quality Rejection Results of Total Nitrogen (TN) and Total Organic Carbon (TOC) Forward Osmosis (FO) Rejection Membrane Distillation (MD) Rejection System Rejection TOC TN TOC TN TOC TN 97% 68% 68% 97% 98% 98% 51

52 Wastewater Concentration by Forward Osmosis Dr. Sage Hiibel

53 Wastewater Concentration by FO Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 53

54 Wastewater Concentration by FO Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 54

55 Wastewater Concentration by FO Primary Effluent FO RO Draw Solution Product Water 55

56 Wastewater Concentration by FO Product Water Draw Solution Primary Effluent RO FO 56

57 Wastewater Concentration by FO Product Water Draw Solution Concentrate primary effluent Monitor wastewater characteristics Evaluate reverse salt flux Primary Effluent RO FO 57

58 Wastewater Concentration by FO Product Water Draw Solution Concentrate primary effluent Monitor wastewater characteristics Evaluate reverse salt flux Primary Effluent RO FO 58

59 Membrane Flux Flux (LMH) FO Flux RO Flux RO Pressure RO Pressure (psi) Time (hr)

60 Conductivity Draw Conductivity (ms) Draw Conductivity Feed Conductivity Time (hr) Feed Conductivity (ms) 60

61 Reverse Salt Flux 4.0 Reverse salt flux (g/m 2 /hr) Draw NaCl (g/l) 61

62 Nutrient Rejection TOC and TN Pilot-Scale FO FO-RO System TOC TN TOC TN 90% 84% 94% 85% NH 3 and PO 4 3- Pilot-Scale FO FO-RO System NH 3 PO 4 3- NH 3 PO % 72% 85% 99% 62

63 Anaerobic Membrane Bioreactor Wastewater FO DCMD Supernatant return Draw Solution HX Distillate #2 Effluent Concentrated WW Phosphorus removal Anaerobic MBR Sharon/ ANAMMOX Potable quality effluent Struvite 63

64 Anaerobic Membrane Bioreactor Biogas Recirculation Effluent Feed Effluent Return 64

65 Anaerobic Membrane Bioreactor Biogas Recirculation Feed Effluent Biogas recirculation Control membrane fouling Four experimental conditions Temperature Wastewater strength Effluent Return 65

66 Anaerobic Membrane Bioreactor Biogas Recirculation Feed Effluent Biogas recirculation Control membrane fouling Four experimental conditions Temperature Wastewater strength Effluent Return 66

67 Reactor Performance COD Percent Removed Time (days) R1 R2 Percent Removed Time (days) R3 R4 67

68 Reactor Performance COD Percent Removed Heaters added, day Time (days) R1 R2 Percent Removed Heaters added, day Time (days) R3 R4 68

69 Reactor Performance COD Percent Removed Heaters added, day Time (days) R1 R2 Primary Effluent Percent Removed Heaters added, day Time (days) Conc. WW, day 239 R3 R4 Concentrated Wastewater 69

70 90 Day Average COD Removal Primary Effluent Concentrated Wastewater Influent COD 248 mg/l 357 mg/l Condition Ambient 37 C Ambient 37 C Effluent COD 36 mg/l 37 mg/l 35 mg/l 34 mg/l Percent Removal 86% 86% 90% 91% 70

71 Specific Energy Comparison FO MD AnMBR Bench scale Pilot Scale Bench Scale Pilot Scale Bench Scale Bench-Scale Pumping SE (kwh/m 3 ) Pumping SE (kwh/m 3 ) Thermal and Pumping SE (kwh/m 3 ) Thermal SE (kwh/m 3 ) Biogas and Hydraulic Pumping SE (kwh/m 3 ) Biogas Recirculation SE (kwh/m 3 ) ,664 2,

72 Conclusions FO/DCMD High nutrient removal Feed temperature has strongest influence over flux FO wastewater concentration 2-4 g/m 2 /hr reverse salt flux High rejection of nutrients AnMBR 85-90% removal of COD Comparable operation with FO-concentrated wastewater 72

73 Discussion Submit questions via ChatBox Eric Marchand Andrea Achilli Sage Hiibel