Characterization and monitoring of EfOM through UV/H 2 O 2 and ozonation processes

Transcription

1 Characterization and monitoring of EfOM through UV/H 2 O 2 and ozonation processes O. González, A. Justo, J. Bacardit, E. Ferrero, J. J. Malfeito and Carme Sans : carmesans@ub.edu Page 1 Fourth IWA Specialty Conference on Natural Organic Matter: From Source to Tap and Beyond. July 27 th, 2011

2 INDEX OF CONTENTS 1. Introduction: water scarcity in Catalunya (Spain) 2. Objective 3. Materials and methods 4. Results and discussion 5. Conclusions Page 2

3 1. Introduction WATER SCARCITY IN CATALUNYA Catalunya (Capital: Barcelona). Spain Mediterranean climate Water supplied from dams Page 3

4 1. Introduction WATER SCARCITY Technological and industrial development + Barcelona Population growth and density Implies the need of large amounts of water Situation of water scarcity Situation is getting worse during long periods of drought Page 4

5 1. Introduction 2008 DROUGHT IN CATALUNYA (I) Embassament de La Baells (La Baells Dam) July 2007 February : Free Powerpoint 32% capacity!! Templates Page 5

6 1. Introduction 2008 DROUGHT IN CATALUNYA (II) Embassament de SAU (Sau Dam) July 2007 February 2008 Catalunya periodically suffers of water scarcity!! Page 6

7 WHAT IS DONE? New water resources: 300 hm 3 /year Water reclamation & reuse: 75 hm 3 /year Aquifiers refill: 25 hm 3 /year Sea water desalination: 200 hm 3 /year Page 7

8 1. Introduction CHALLENGE IN CATALUNYA Page 8

9 STRATEGY 1. Introduction Water Reuse Reclaim the already used water in order to reduce the use of fresh water WWTP Primary treatment Secondary treatment Tertiary treatment ADVANCED OXIDATION PROCESES Restore suitable water quality REUSE Regulations will become more severe everyday Different degree of treatment depending on the final use Some disadvantages in Free the currently Powerpoint applied Templates tecnologies Page 9

10 ADVANCED OXIDATION PROCESSES 1. Introduction HO O 3 + OH - O HO 2 O 3 + HO 2 HO + O 2 + O 2 H 2 O 2 + hv (254 nm) 2 HO Ozone and UV/H 2 O 2 have been widely used for disinfection and organic matter removal in drinking water treatments and in tertiary treatments for reuse. Page 10

11 WHAT IS IN THE SECONDARY EFFLUENT? NATURAL ORGANIC MATTER EfOM MICROORGANISMS Lack of information about AOP transformation products Disinfection by AOP PHARMACEUTICALS AND PERSONAL CARE PRODUCTS PPCP s AOP application for emerging pollutants removal OTHERS: PESTICIDES, FLAME RETARDANTS, FUEL ADDITIVES. Emerging contaminants Page 11

12 2. Objective OBJECTIVE To contribute to the knowledge in water reuse by studying the behavior of the different NOM fractions present in two different secondary effluents (Conventional Activated Sludge and Membrane BioReactor) when being oxidized through UV/H 2 O 2 and ozonation processes. Both typical physicochemical parameters and the powerful technique Liquid Chromatography-Organic Carbon Detection (LC-OCD) will be used Page 12

13 3. Materials and methods Ozonation Set-up UV/H 2 O 2 Set-up Q gas = 60 L h -1 C O3 = 40 g Nm -3 V = 2 L V = 2 L T controlled = 25 ºC T controlled = 25 ºC Gas phase O 3 meters 3 Hg low pressure lamps (8W) ( = 254nm) Dissolved O 3 meter Photon flow Monitoring of ph -5 Einstein s -1 Page 13

14 3. Materials and methods ANALYTICAL METHODS Typical physicochemical parameters: TOC DOC COD BOD 5 SUVA ph NH 4+ and anions Alkalinity TSS Turbidity This information is not enough or satisfactory. Liquid Chromatography Organic Carbon Detection (LC-OCD) Provides both quantitative and qualitative information about the different organic fractions present in our effluents. Page 14

15 LC-OCD 3. Materials and methods Allows to obtain more specific information about NOM SEC Biopolymers (BP) UV detection OCD DOM fractions: Humic Substances (HS) Building Blocks (BB) LMM organic Acids (LMMA) LMM Neutrals (LMMN) WWTP Hydrophobic Organic Compounds (HOC) Results from the alteration of OM that comes from plants and animals Cellulose Tannin Cutin Lignin Proteins Lipids Sugars NOM from the original water source + soluble microbial products EfOM DOM BASIC STRUCTURE Typical Chromatogram for a surface water Page 15

16 CHARACTERIZATION OF EFFLUENTS Conventional Activated Sludge effluent (CAS) WWTP Gavà Pretreatment Primary treatment 4. Results and discussion CAS (Nitrification + Denitrification) Membrane Biological Reactor effluent (MBR) WWTP Vallvidrera Pretreatment MBR Page 16

17 Average physicochemical parameters 4. Results and discussion LC-OCD chromatograms Biopolymers CAS 13.3 % MBR 1.3 % Page 17

18 CAS Ozonation 4. Results and discussion LC-OCD Similar removal rate for BP, HS and N The High bigger aromaticity With fractions the of BP HSwere completely removed, Glycosidic bonds and NH 2 in BP A, BB and N reach HS a plateau and N degradation continues Also slight hydrophobicity and aromaticity of Neutrals However a decrease A of continues BB and accumulated N is expected (see MBR case) BB removal masked by new formation due to HS break-down High alkalinity and [Cl - ] minimize BB begins indirect to dropozone attack (via OH) Accumulation of A (low reaction rate of molecular ozone) First stage Second stage Third stage Page 18

19 CAS UV/H 2 O 2 4. Results and discussion LC-OCD Attack more UV/Hselective 2 O 2 oxidize for sequentially BP than HS Bigger size Once of BP the biggest fractions had been reduced, the removal of the rest fractions started BB, N and A concentration increase at the beginning BB The due oxidation to the HS process break-down occurred basically via HO Page 19

20 MBR Ozonation 4. Results and discussion LC-OCD Attack focused in HS in absence of BP N conc. decreases from the beginning (similar to the CAS) Remarkable accumulation of A also observed Accumulation of BB due to HS break-down is not observed Lower initial conc. of HS Higher O 3 availability Page 20

21 MBR UV/H 2 O 2 4. Results and discussion LC-OCD Attack centered in HS in absence of BP No significant change in A concentration N conc. decreased continuously until the end No increment in BB fraction was observed Lower initial conc. of HS Higher oxidant availability Page 21

22 CAS Physicochemical parameters Consumed oxidant (mmol) % TOC % DOC % COD O UV/H 2 O MBR Consumed oxidant (mmol) 4. Results and discussion Physicochemical parameters % TOC % DOC % COD O UV/H 2 O Higher mineralization by means of ozonation and similar oxidation degree. Turbidity: UV/H 2 O 2 ozonation Both effluents: Higher mineralization though UV/H 2 O 2, although oxidation degree was lower. NH 4+ : UV/H 2 O 2 only 50% ozonation 100% ph: UV/H 2 O 2, ozonation Biodegradability (BOD 5 /COD): UV/H 2 O 2 and ozonation after ozonation (BOD5/COD 0.5): In accordance with the acids accumulation Main analyzed anions did not experiment changes SUVA (UV 254 /DOC): specially during the first 30 minutes Page 22

23 5. Conclusions CONCLUSIONS UV/H 2 O 2 and O 3 : effective elimination of bigger fractions (biopolimers and humic substances) from the first steps of oxidation (reduction of aromaticity). O 3 : High alkalinity and Cl - concentration (scavenging effect) of real effluents seems to potentiate the ozone molecular attack leading to the accumulation of LMM acids (high biodegradability biofouling). UV/H 2 O 2 : turbidity decreased O 3 : turbidity increased, for both effluents LC-OCD appears as an interesting tool to study changes in organic matter fractions in this kind of wastewaters. Page 23

24 Thank you for your attention! UB Page 24