A benchmark simulation model for membrane bioreactors

Transcription

1 Model-based analysis and optimization of bio-processes DEPARTMENT OF APPLIED MATHEMATICS, BIOMETRICS AND PROCESS CONTROL A benchmark simulation model for membrane bioreactors Ingmar Nopens, Lorenzo Benedetti, Phuong Thu Pham

2 Content Introduction Exploring BSM-MBR Open loop system Steady state case Dynamic case Closed loop system (with control strategies) DO control Conclusions and future perspectives 2/18

3 Benchmark simulation model A plant layout Simulation models BSM-MBR BSM1 Influent data a simulation environment Simulation procedures Performance index used for applying and comparing different control strategies in WWTP 3/18

4 Thesis Objectives To set up a new configuration and update the performance index of BSM with MBR To test the performance of BSM-MBR by simulating in steady state and dynamic cases (open-loop) in program WEST To implement a BSM-MBR control loop and compare with open-loop 4/184

5 Plant layout 18446m 3 /d BSM-MBR BSM m 3 /d T1 T m3/d T3 T4 T5 Membrane unit 18446m 3 /d m 3 /d 120m 3 /d 18446m3/d 385m 3 /d Tank Condition BSM1 BSM-MBR Volume (m 3 ) K L a (d -1 ) Volume (m 3 ) K L a (d -1 ) T1 Anoxic T2 Anoxic T3 Aerobic T4 Aerobic T5 Aerobic /18

6 Performance indices Effluent quality index (EQ) based on concentrations of different effluent components Similar to BSM1 Operational cost Sludge production (SP) - based on waste sludge similar to BSM1 Pumping energy (PE) - based on pumped flows extension: addition eq for membrane unit PE memb Aeration energy (AE) - based on oxygen transfer coefficient K L a extension: addition eq for membrane unit AE memb 6/18

7 Pumping and Aeration energy Pumping energy basic equation: p * Q PE = * η t rec PE memb = 1 T t [ 0.04* Q ( t) * Q ( t) 0.022* Q ( t) ] 7days rec perm + t 0 bw dt Aeration energy basic equation: AE memb ( kw ) = w* R * T in 29.7 * 0.283* e p p out in *1000 AE memb = t t 7days 0 A( t) dt 7/18

8 Open-loop system Configurations Steady state case Membrane unit T1 T2 T3 T4 T5 Membrane unit T1 T2 T3 T4 T5 Buffer tank BT_2 8/18

9 Open-loop system Steady state case Simulation results Unit BSM-MBR BSM-MBR BSM1 no BT_2 with BT_2 Effluent COD gcod/m BOD gcod/m TKN gn/m NO gn/m N_tot gn/m TSS gss/m Membrane unit Q-in m 3 /d 43, ,072 Q-permeate m 3 /d 20,307 20,275 Q-concentrate m 3 /d 23, ,229 Q-backwash m 3 /d 1,725 1,722 9/18

10 Open-loop system Dynamic case Configuration Membrane area controller Q_BT_2 controller Membrane unit Q_BT_1 controller T1 T2 T3 T4 T5 10/18

11 Open-loop system Dynamic case Performance indices Units BSM-MBR BSM1 EQ kg poll.units/d Sludge production kg SS Sludge production per day kg SS/d Aeration energy - In bioreactors* - In membrane unit kwh/d Pumping energy - In bioreactors - In membrane unit** kwh/d *:AE_tank3 + AE_tank4 + AE_tank5 **: PE_recyc + PE_per + PE_bw 11/18

12 Open-loop system Dynamic case Energy (kwh/d) AE PE 0 BSM1 BSM-MBR 12/18

13 Closed-loop system DO control Configuration PI Controller DO sensor DO setpoint = 1 or 2 mg/l Manipulated variable = K L a 13/18

14 Closed-loop system Performance indices DO control Unit Closed loop BSM-MBR DO sp = 1 DO sp = 2 Open loop BSM-MBR EQ kg poll.units/d P_total_sludge kg SS P_total_sludge day per kg SS/d Aeration energy kwh/d In bioreactors* In membrane unit Pumping energy kwh/d In bioreactors In membrane unit /18

15 Closed-loop system DO control Energy (kwh/d) DO1 DO2 Open loop AE PE 15/18

16 Conclusions New simulation benchmark model with MBR has been developed Good performance of BSM-MBR In comparison with BSM1, BSM-MBR has: better effluent quality much higher operational cost Closed loop studies illustrated the potential of BSM-MBR for evaluation of control strategies 16/18

17 Future perspectives Extension of the membrane model to better reflect the operation of MBR in practice (e.g. airlift). Submerged alternative. Further update the performance criteria Rain and storm weather cases 17/18

18 Thank you for your attention! Questions? 18/18