Vitor J. P. Vilar Principal Researcher Associate Laboratory LSRE/LCM Faculty of Engineering University of Porto

Transcription

1 Departamento de Engenharia Química Rua Dr. Roberto Frias, S/N Porto Portugal Integration of Electrochemical Advanced Oxidation Processes in a Multistage System For Sanitary Landfill Leachate Remediation 1st Summer School on Environmental Applications of Advanced Oxidation Processes University of Salerno Vitor J. P. Vilar (vilar@fe.up.pt) Principal Researcher Associate Laboratory LSRE/LCM Faculty of Engineering University of Porto 17/06/2015 vilar@fe.up.pt

2 CONTENTS INTRODUCTION Sanitary landfill leachate Electrochemical advanced oxidation processes (EAOPs) Objective EXPERIMENTAL Biological and coagulation treatments EAOPs system at lab-scale EAOPs system at pilot-scale RESULTS AND DISCUSSION Raw, bio-treated and coagulated landfill leachate EAOPs Influence of current density Influence of initial total dissolved iron content Influence of ph Influence of temperature Influence of radiation source Comparative application of EAOPs EAOPS vs AOPs Influence of anode material Biodegradability enhancement Zahn-Wellens test CONCLUSIONS 2

3 INTRODUCTION SANITARY LANDFILL LEACHATE DISPOSAL OF SOLID WASTES IN SANITARY LANDFILL RAINWATER PERCOLATION PRODUCTION OF LEACHATE HUMIC ACIDS FULVIC ACIDS PHARMACEUTICALS HORMONES PHTALATES PESTICIDES HEAVY METALS POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) A. Baun, A. Ledin, L.A.,Reitzel, P.L. Bjerg, T.H. Christensen, Xenobiotic organic compounds in leachates from ten Danish MSW landfills-chemical analysis and toxicity tests. Water Research 38 ( 2004)

4 INTRODUCTION OBJECTIVE To incorporate an EAOP stage in the following multistage strategy system for sanitary landfill leachate remediation: 1 st BIOLOGICAL PROCESS COAGULATION EAOP 2nd BIOLOGICAL PROCESS!BIODEGRADABLE ORGANIC FRACTION DEGRADATION! NITRIFICATION!ALKALINITY REMOVAL!HUMIC ACIDS REMOVAL!SUSPENDED SOLIDS REMOVAL!RECALCITRANT ORGANIC FRACTION DEGRADATION!BIODEGRADABILITY ENHANCEMENT!EAOP BIODEGRADABLE ORGANIC FRACTION DEGRADATION!DENITRIFICATION 4

5 INTRODUCTION ELECTROCHEMICAL ADVANCED OXIDATION PROCESSES (EAOP) PEF PHOTOELECTRO-FENTON SPEF SOLAR PHOTOELECTRO-FENTON EF ELECTRO-FENTON AO-H2O2 ANODIC OXIDATION WITH ELECTROGENERATED H2O2 WATER OXIDATION ON THE ANODE SURFACE: H2O2 ELECTROGENERATION AT THE CATHODE: FENTON S REACTION: Fe2+ REGENERATION AT THE CATHODE: M + H2O M( OH) + H+ + eo2(g) + 2 H+ + 2 e- H2O2 Fe2+ + H2O2 Fe3+ + OH + OHFe3+ + e- Fe2+ PHOTOLYSIS OF FeOH2+: FeOH2+ + hν Fe2+ + OH PHOTOLYSIS OF Fe(III)-ORGANICS COMPLEXES: Fe3+(L)n + hν Fe2+(L)n-1 + Lox E. Brillas, I. Sirés, M.A. Oturan, Electro-Fenton process and related electrochemical technologies based on Fenton s reaction chemistry. Chemical Reviews 109 (2009)

6 EXPERIMENTAL EAOPs SYSTEM AT LAB-SCALE PEF-UVA SPEF or AO-H2O2 and EF or BDD/CARBON PTFE AIR-DIFFUSION CELL 10 cm2 active area Electrochemical Filter-Press MicroFlowCell 6

7 EXPERIMENTAL EAOPs SYSTEM AT PILOT-SCALE PS UV- R (-)(+) V9 AP EC V6 NRV V4 CPCs FI R Air V7 Air V8 V5 ph TM C- PTFE Pt ph TM TR V3 V10 FI RT- 10L RT- 20L R TC Pt/CARBON PTFE AIR-DIFFUSION CELL ELECTRODE SPACER CP CARBON- PTFE AIR- DIFFUSION CATHODE FLOW FRAME ELECTRODE SPACER END FRAME 3 1 V2 Outflow / Sampling Point ph ph- meter TM Temperature Meter RT- 20L Recirculation Tank with 20 L capacity RT- 10L Recirculation Tank with 10 L capacity CP Centrifugal Pump R Rotameter PS Power Supply EC Electrochemical Cell V1 CP Outflow / Sampling Point AP Air Pump C- PTFE Carbon- PTFE air- diffusion cathode Pt Platinum anode TR Thermostated Reactor TC Temperature Controller CPCs Compound Parabolic Collectors UV- R UV Radiometer AIR INLET SOLUTION OUTLET 1 3 Main path Alternative path GASKET V1, V2 Recirculation / Discharge valves V3, V4 Flow rate control valves 3 AIR V5 EC feeding valve OUTLET V6, V7 EC air regulation valves SOLUTION V8, V9 CPCs configuration valves INLET V10 RTs feeding valve STAINLESS NRV Non- Return Valve STEEL END GASKET GASKET GASKET FLOW FRAME GASKET STAINLESS STEEL END PLATE PLATINUM ANODE BACK PLATE CATHODE END FRAME PLATE 100 cm2 active area 7

8 RESULTS AND DISCUSSION RAW, BIO-TREATED AND COAGULATED LANDFILL LEACHATE PARAMETER (UNIT) RAW AFTER 1 st BIOLOGICAL TREATMENT AFTER COAGULATION ph DIC (mg L -1 ) DOC (mg L -1 ) COD (mg O 2 L -1 ) BOD 5 (mg O 2 L -1 ) TSS (mg L -1 ) N-NH 4 (mg L -1 ) < < N-NO 2 (mg L -1 ) N-NO 3 (mg L -1 ) SO 4 (mg L -1 ) Cl - (mg L -1 ) st BIOLOGICAL TREATMENT COAGULATION CONSUMPTION OF INORGANIC CARBON AND ALKALINITY 13-33% OF DOC REMOVAL AND 90-95% OF BOD 5 REMOVAL CONVERSION OF NH 4 + TO NO 3 - LARGE DECOLORIZATION DUE TO HUMIC ACIDS PRECIPITATION TSS REMOVAL OF 47-57% 63-65% OF DOC REMOVAL 8

9 RESULTS AND DISCUSSION - EAOPs INFLUENCE OF CURRENT DENSITY Parasitic Reactions: Anodic Oxidation of BDD( OH) to O 2 [DOC]/[DOC] time (min) BEST CURRENT DENSITY: 200 ma cm -2 ( ) 25 ma cm -2 ( ) 100 ma cm -2 (p ) 200 ma cm -2 ( ) 300 ma cm -2 PEF-UVA Lab-scale BDD anode 20 ºC ph = mg Fe 2+ L ma cm ma cm ma cm ma cm -2 FINAL DOC REMOVAL (%) ENERGY CONSUMPTION (kwh m -3 ) FINAL [H 2 O 2 ] (mg L -1 ) SIMILAR EFFICIENCY ON DOC REMOVAL FOR CURRENT DENSITIES ABOVE 200 ma cm -2 H 2 O 2 ALWAYS ACCUMULATED IN EXCESS FOR ALL APPLIED CURRENT DENSITIES 9

10 RESULTS AND DISCUSSION - EAOPs INFLUENCE OF INITIAL TOTAL DISSOLVED IRON CONTENT [DOC]/[DOC] time (min) ( ) 20 mg Fe 2+ L -1 ( ) 40 mg Fe 2+ L -1 (p ) 60 mg Fe 2+ L -1 ( ) 80 mg Fe 2+ L -1 PEF-UVA Lab-scale BDD anode 200 ma cm ºC ph = 2.8 BEST INITIAL DISSOLVED IRON CONCENTRATION: 60 mg Fe 2+ L -1 SIMILAR EFFICIENCY ON DOC REMOVAL FOR INITIAL TOTAL DISSOLVED IRON CONCENTRATIONS ABOVE 60 mg Fe 2+ L -1 10

11 RESULTS AND DISCUSSION - EAOPs INFLUENCE OF ph [DOC]/[DOC] time (min) [Total Dissolved Iron] (mg L - 1 ) time (min) ( ) ph = 2.8 ( ) ph = 3.5 (p ) ph = 4.0 PEF-UVA Lab-scale BDD anode 200 ma cm mg Fe 2+ L ºC BEST ph: 2.8 FASTEST MINERALIZATION AT ph = 2.8 TOGETHER WITH ALMOST NULL IRON PRECIPITATION 11

12 RESULTS AND DISCUSSION - EAOPs INFLUENCE OF TEMPERATURE PEF-UVA BDD anode; 200 ma cm -2 PHOTO-FENTON-UVA [H 2 O 2 ] = mg L -1 [DOC]/[DOC] [DOC]/[DOC] ( ) 15 ºC ( ) 20 ºC (p ) 30 ºC ( ) 40 ºC Lab-scale 60 mg Fe 2+ L -1 ph = time (min) time (min) PEF-UVA: SIMILAR MINERALIZATION FOR TEMPERATURES FROM 20 TO 40 ºC, ALTHOUGH TEMPERATURES ABOVE 20 ºC LED TO IRON PRECIPITATION PHOTO-FENTON-UVA: FASTER MINERALIZATION AT 30 AND 40 ºC THAN AT 20 ºC LARGER PARTICIPATION OF ELECTROCHEMICAL REACTIONS ON THE EFFLUENT MINERALIZATION AT 20 ºC THAN AT 30 AND 40 ºC 12

13 RESULTS AND DISCUSSION - EAOPs INFLUENCE OF RADIATION SOURCE [DOC]/[DOC] time (min) ( ) UVA LAMP ( ) UVA-Vis LAMP (p ) UVC LAMP ( ) NATURAL SUNLIGHT PEF/SPEF Lab-scale BDD anode 200 ma cm ºC ph = 2.8 SIMILAR MINERALIZATION USING UVA AND UVC LAMPS AND NATURAL SUNLIGHT LOWER MINERALIZATION USING UVA-Vis LAMP MAINLY FOR LONGER REACTION TIMES 13

14 RESULTS AND DISCUSSION - EAOPs COMPARATIVE APPLICATION OF EAOPs [DOC]/[DOC] time (min) [DOC]/][DOC] Q (kj UV L- 1 ) EFFICIENCY OF EAOPs: AO-H 2 O 2 < AO < EF < PEF-UVA SPEF (ê ) AO ( ) AO-H 2 O 2 ( ) EF (p ) PEF-UVA ( ) SPEF Lab-scale BDD anode 200 ma cm mg Fe 2+ L ºC ph = 2.8 LARGE PARTICIPATION OF BDD( OH) ON THE EFFLUENT MINERALIZATION AO vs AO-H 2 O 2 : LOSS OF OH VIA H 2 O 2 + OH H 2 O + HO 2 IN AO-H 2 O 2 AND/OR FORMATION OF MORE RECALCITRANT BY-PRODUCTS IN AO-H 2 O 2 SLIGHTLY MINERALIZATION IMPROVEMENT FROM OH PRODUCED BY FENTON S REACTION CRUCIAL ROLE OF RADIATION PROVIDED IN PEF AND SPEF ON THE EFFLUENT MINERALIZATION BECAUSE OF THE ADDITIONAL OH PRODUCTION AND Fe 2+ REGENERATION FROM PHOTOREDUCTION OF Fe(III) COMPLEXES 14 14

15 RESULTS AND DISCUSSION - EAOPs EAOPs vs AOPs [DOC]/[DOC] time (min) HIGH SUPERIORITY OF EF OVER FENTON HIGH SUPERIORITY OF PEF-UVA OVER PHOTO-FENTON-UVA SIMILARITY BETWEEN SPEF AND SOLAR PHOTO-FENTON ( ) EF ( ) FENTON (p ) PEF-UVA (r ) PHOTO-FENTON-UVA ( ) SPEF ( ) SOLAR PHOTO-FENTON Lab-scale BDD anode (in EAOPs) 200 ma cm -2 (in EAOPs) [H 2 O 2 ] = mg L -1 (in AOPs) 60 mg Fe 2+ L ºC ph = 2.8 MORE IMPORTANT ROLE OF OXIDANTS PRODUCED BY PHOTOREDUCTION OF Fe(III) COMPLEXES COMPARATIVELY TO THE ELECTROCHEMICAL GENERATED OXIDANTS 15

16 RESULTS AND DISCUSSION - EAOPs INFLUENCE OF ANODE MATERIAL [DOC]/[DOC] time (min) BEST ANODE MATERIAL: BDD ( ) AO-H 2 O 2 -BDD ( ) AO-H 2 O 2 -Pt ) EF-BDD ( ) EF-Pt (p ) PEF-UVA-BDD (r ) PEF-UVA-Pt ( ) SPEF-BDD ( ) SPEF-Pt PEF-UVA Lab-scale 200 ma cm mg Fe 2+ L ºC ph = 2.8 FASTER MINERALIZATION FOR ALL EAOPs WITH BDD ANODE THAN WITH Pt ANODE IMPORTANT ROLE OF BDD( OH) ON THE ORGANICS DEGRADATION EVEN UNDER SOLAR LIGHT 16

17 RESULTS AND DISCUSSION - EAOPs BIODEGRADABILITY ENHANCEMENT ZAHN-WELLENS TEST D t (%) time (days) SPEF Pilot-scale Pt anode 200 ma cm -2 (in EAOPs) 60 mg Fe 2+ L ºC ph = 2.8 BEST DOC TO STOP SPEF: 163 mg L -1 ELECTRICAL CONSUMPTION: 36 kwh m -3 S 0 S 1 S 2 S 3 S 4 S 5 S 6 S 7 S 8 S 9 DOC (day 0) (mg L -1 ) DOC (day 28) (mg L -1 ) COD (day 0) (mg O 2 L -1 ) COD (day 28) (mg O 2 L -1 ) BOD 5 (day 0) (mg O 2 L -1 ) D t (day 28) (%) LEGISLATION LIMITS: 125 (EU) 150 (PT) 17

18 CONCLUSIONS The remediation of a raw sanitary landfill leachate by the application a multistage treatment strategy composed of biological treatment/ coagulation/eaop/biological treatment was successful concerning the elimination of organic matter and nitrogen compounds. Best PEF operational conditions: 200 ma cm -2, 60 mg Fe 2+ L -1, ph of 2.8, ºC, UVA, UVC or natural sunlight and BDD anode. High superiority of EF over Fenton, high superiority of PEF-UVA over photo-fenton-uva and similarity between SPEF and solar photo-fenton in terms of oxidation ability. Need of performing the electrochemical treatment up to reach 163 mg DOC L -1 to couple a further biological process. 18

19 ACKNOWLEDGEMENTS 19

20 Departamento de Engenharia Química Rua Dr. Roberto Frias, S/N Porto Portugal FRANCISCA MOREIRA Ph.D. STUDENT FEUP-LSRE JUAN SOLER POST-DOCTORAL FEUP-LSRE 20

21 EPOA/CIPOA The conference topics will include: Fenton; Photo-Fenton; Photocatalysis; Ozonation; AOPs/Biological Oxidation; AOPs/Membrane; Electrochemical Processes; Process Monitoring and Control; Solar-Driven Applications; Pilot Plant Scale Applications; AOP Applied to Contaminated Soil and Air; AOP Applied to Water Disinfection; AOP Applied to Wastewater Decontamination. 8 Encontro sobre Aplicações Ambientais de Processos Oxidativos Avançados (VII EPOA) 2 Congresso Ibero-americano de Processos Oxidativos Avançados (II CIPOA) 3 a 6 de Novembro de Belo Horizonte MG - Brasil 8ºEPOA CHAIRWOMAN of EPOA- Prof. Camila Amorim 2ºCIPOA CHAIRMAN of CIPOA Doutor Vítor Vilar 21