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Emerging Technologies for Louisiana Waste Processing: Serpentine Plug-flow Reactor (SPFR) Dr. J. Sansalone, P.E. Civil & Environmental Engineering Dr.

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Presentation on theme: "Emerging Technologies for Louisiana Waste Processing: Serpentine Plug-flow Reactor (SPFR) Dr. J. Sansalone, P.E. Civil & Environmental Engineering Dr."— Presentation transcript:

1 Emerging Technologies for Louisiana Waste Processing: Serpentine Plug-flow Reactor (SPFR) Dr. J. Sansalone, P.E. Civil & Environmental Engineering Dr. V. Srinivasan Biological Science Louisiana State University Baton Rouge, Louisiana USA SPFR originally developed from $12,000 of LA Sea Grant funds

2 Waste sludge generally has high concentrations of TSS, VSS and COD and pathogens Current designs for completely-mixed anaerobic digesters require large footprints and long hydraulic retention times varying from 30 – 60 days (Metcalf and Eddy 1991) Problem Statement

3 Objectives 1.Develop a small-scale anaerobic serpentine plug-flow reactor (SPFR) utilizing a force-fed fast rate digestion process for waste residual treatment 2.Demonstrate the technical feasibility at different organic loading rates and temperatures. 3.Evaluate the potential for methane production of the anaerobic digestion process

4 Typical bacterial growth curve in terms of numbers Time Log number of cells Lag phase Log growth phase Stationary phase Death phase Source: Metcalf & Eddy, 1991

5 Advantages of Anaerobic Digestion - High efficiency of organic mass removal - Effective sludge volume reduction (30-50%) - Energy is produced as methane - Pathogens are destroyed

6 Anaerobic Digestion Microbiological pathway of anaerobic digestion Glucose Amino Acids Fatty Acids PO Carbohydrate Proteins Lipids Phosphorylated Organics -3 4 Cells Stabilized Organics Acetic Propionic Lactic + Cells Complex organics Hydrolysis Soluble Organics Acids Methane CO 2 AcidogenesisMethanogenesis

7 Low Rate Anaerobic Digester Standard-rate digesters or conventional anaerobic digesters No mixing and thus a stratified condition High rate With heating, auxiliary mixing, thickening and uniform feeding Two Stage Separation of Methanogenesis from the other two phases, Hydrolysis and Acidogensis Advanced reactors Up-flow anaerobic sludge blanket (UASB), Anaerobic Filter (AF) Fluidized bed (FB), Anaerobic baffled digester (ABR) Expanded granular sludge bed (EGSB), etc. Development History of Anaerobic Digester Low RateHigh RateTwo StageAdvanced Reactors

8 Schematic of Serpentine Plug-flow Reactor (SPFR) Gas Vent Effluent to biological treatment Primary Sludge Influent Storage Tank

9 Advantages of Serpentine Plug-flow o Plug-flow pattern to partially separate the various phases of anaerobic catabolism o Longer biomass retention time, lower sludge yields o Resilience to hydraulic and organic shock loading o Increased resistance against toxic materials

10 A flow rate of 500 GPD with a corresponding HRT of 48 hours was applied to investigate the feasibility of the reactor for sludge treatment Parameters measured: TSS, VSS, Total COD, Dissolved COD, Alkalinity, pH, Temperature Experimental Design

11 Results

12 Statistical Data for Digester Performance Total CODTSSVSS Influent [mg/L]35,47832,08818,343 Effluent [mg/L]9,8084,4823,532 Removal Efficiency67%84%80% pHAlkalinity [mg/L] Temperature ( 0 C) Dissolved COD (% of Total) VSS (% of TSS) Influent6.098628.910.554.6 Effluent5.585029.175.875.4

13 Probability Densities for Total COD Reactor InfluentReactor Effluent Total COD [10 3 mg/L] 020406080100120 0.0 0.1 0.2 0.3 0.4 Observed Predicted Normal Distribution = 35477.9 mg/L = 18328.8 mg/L n = 63 2 r= 0.98 Total COD [10 3 mg/L] 05101520 Relative Frequency 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Observed Predicted Normal Distribution = 9808.2 mg/L = 4363.1 mg/L n = 63 r 2 = 0.94 Relative Frequency

14 Selected Performance Data from other Studies Wastewater Raw molasses Molasses alcohol stillage Swine waste Whisky distillery Influent COD (g/l)990115.858.551 HRT (hours)850138-636360 Reactor volume150 156.3 Temperature (0C)37 3530 OLR (kg/m3.d)284.3-2042.2-3.46 COD removal (%)5070-8862-69>90 Biogas production (v/v/d) >5>2.32.9-3.21.2-3.6 Ref. Boopathy and Tilche, 1991 Boopathy and Tilche, 1992 Boopathy and Sievers, 1991 Boopathy et al., 1988

15 Gas Production Total Gas Production = C * Q * (VSS IN – VSS EFF ) Methane Production = 0.7 Total Gas Production Where, Q = 500 gal/day C = 12 to 18 ft 3 /lb (0.75 to 1.12 m 3 /kg), Metcalf & Eddy, 1991 70% of the gas is Methane Average Gas Production = 28.6 m 3 /d Average CH 4 production = 0.7 * 28.6 = 20 m 3 /d Gas (m 3 /day) Time (day) 050100150200250300350 0 20 40 60 80 100 120 516 mg/L 258 mg/L 0 mg/L

16 Conclusions 1. The anaerobic digester performed well at a relatively low HRT of 48 h without temperature control. 2. The removal efficiency for Total COD, TSS and VSS is 68.9%, 88.5% and 84.7% respectively. 3. The reactor showed great economical prospective for the natural gas production and low construction and operation cost.

17 Reactor in operation currently near Mobile, AL

18 Thank you ! QUESTIONS ?

19 Total COD, TSS, and VSS Profile at Sugar Effect Influent Effluent Removal (%) Time (day) 050100150200250300350 Total COD [10 3 mg/L] 0 20 40 60 80 100 120 140 Removal (%) 0 20 40 60 80 100 120 516 mg/L258 mg/L0 mg/L Time (day) Removal (%) 050100150200250300350 TSS [10 3 mg/L] 0 20 40 60 80 100 0 20 40 60 80 100 120 516 mg/L258 mg/L0 mg/L Time (day) 050100150200250300350 VSS [10 3 mg/L] 0 10 20 30 40 50 60 Removal (%) 0 20 40 60 80 100 120 516 mg/L258 mg/L0 mg/L

20 Hydraulic Characteristics Study (by Grobicki and Stuckey) Method - A series of residence time distribution studies by tracking the fate of an inert tracer (Li + ) in the effluent Models - Dispersion and Tanks In Series Results intermediate between plug-flow and ideally mixed Simulated as a series of perfectly-mixed compartments

21 Comparisons with Other Reactors ABR Anaerobic filter CSTR Without Biomass With Biomass Dead Space (%) < 8% 18% (at 8gVSS/l) 50-93%>80% Ref. Grobicki and Stuckey, 1992 Yong and Young, 1988 Stuckey, 1983

22 pH and Alkalinity Profile at Sugar Effect Influent Effluent Time (day) pH 050100150200250300350 0 2 4 6 8 10 516 mg/L258 mg/L0 mg/L Time (day) 50100150200250300350 Alkalinity 0 500 1000 1500 2000 2500 516 mg/L258 mg/L0 mg/L

23 Anaerobic Baffled Reactor (ABR) ABR -- A reactor design, with a series of baffles to force a wastewater to flow under and over (or through) the baffles as it passes from the inlet to the outlet Two significance of the specific configuration o Two-phase system with low cost -- Acidogensis and the methanogensis partially separated o High solids retention capacity, high bacteria activities (increase by a factor of up to four)

24 Wastewater HR T (h) COD (mg/l) COD removal (%) OLR (kg/m 3 /d) Gas Produced (v/v/d) Ref. INEFF Greywater84438109750.130.025 Witthauer and Stuckey, 1982 Greywater48492143710.250.05 Witthauer and Stuckey, 1982 Greywater8444572840.130.025 Witthauer and Stuckey, 1982 Sucrose6.847374 1.670.49Orozco, 1988 Sucrose847366861.420.43Orozco, 1988 Sucrose1144133930.960.31Orozco, 1988 Slaugherhouse26.473080890.670.72Polprasert et al., 1992 Slaugherhouse7.2550110801.820.33Polprasert et al., 1992 Slaugherhouse2.5510130754.730.43Polprasert et al., 1992 Selected Low Strength Performance Data

25 Co-substrate Initiation When fed two different substrates with high strength, one readily biodegradable and the other refractory, the microbes would utilize the readily biodegradable substrate rapidly, followed by the refractory compound Related Research Review Appropriate dose addition of a readily-degradable co-substrate improved the process performance 1. Pepton (Kobayashi et al., 1989) 2. Glucose (Satsangee and Ghosh, 1996)), 3. Glucose (Joo-Hwa Tay et al., 2001)

26 Sugar Effect at Digestion Performance Sugar Concentration (mg/L) 516 (10%)258 (5%)0 (0%) Influent Total COD [mg/L]36192.235927.836423.6 Effluent Total COD [mg/L]8904.414783.89492.0 Removal of Total COD (%)68.956.673.6 Influent TSS [mg/L]32638.033598.532020.0 Effluent TSS [mg/L]2919.810207.34272.1 Removal of TSS (%)88.568.186.5 Influent VSS [mg/L]19088.318946.615934.6 Effluent VSS [mg/L]2276.97406.22965.6 Removal of VSS (%)84.760.281.0

27 New Challenge Changes in quantity and quality Due to - Increase of domestic and industrial activities - Evolution of more efficient wastewater treatment plants Public tolerance towards environmental pollutions Land available for sludge disposal Inherent limitation of current digesters (10-30 days HRT) High cost of advanced anaerobic reactors (i.e. FB) More cost-efficient technologies are required

28 Historical Profile of Natural Gas Prices Source: www.energyonline.com Date (month) Price (dollars/10 3 ft 3 ) 0 2 4 6 8 10 12 Residential Prices Commercial Prices Industrial Prices 1998 1999 2000 2001 4 8 4 812 4 8

29 Probability Densities for VSS VSS [10 3 mg/L] 0510152025303540455055 Relative Frequency 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Observed Predicted Reactor Influent Normal Distribution = 18343.2 mg/L = 10104.5 mg/L n = 56 r 2 = 0.97 VSS [10 3 mg/L] 024681012141618 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Observed Predicted Reactor Effluent Lognormal Distribution = 3319.1 mg/L = 3532.3 mg/L n = 56 r 2 = 0.97 Relative Frequency

30 Reactor Influent Reactor Effluent Probability Densities for TSS

31 Resilience to Organic Loading and Temperature Shocks Time (d) TSS [10 3 mg/L] Removal Efficiency % Time (d) 050100150200250300 0 20 40 60 80 100 0 20 40 60 80 100 InfluentEffluent% Removal Efficiency Time (d) 050100150200250300 0 10 20 30 40 50 60 0 20 40 60 80 100 VSS [10 3 mg/L] Removal Efficiency % Time (d) 050100150200250300 0 10 20 30 40 Influent Effluent Air Temperature Temperature ( 0 C)


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