ANALYSIS OF THE CHARACTERISTICS OF EXTRACELLULAR POLYMERIC SUBSTANCES (EPS) OF ACTIVATED SLUDGE MIXED LIQUOR.

Transcription

1 ANALYSIS OF THE CHARACTERISTICS OF EXTRACELLULAR POLYMERIC SUBSTANCES (EPS) OF ACTIVATED SLUDGE MIXED LIQUOR. D. BANTI, G. LIONTA, C. TSIOPTSIAS, P. SAMARAS, A. ZOUBOULIS, M. MITRAKAS Department of Food Technology Alexander Technological Education Institute of Thessaloniki 26 October 2013

2 Contents 1. Introduction 2. Purpose/Objectives of this work 3. Methods for characterisation of EPS 4. Results 1 st case of experiments 5. Results 2 nd case of experiments 6. Conclusions 2

3 Contents 1. Introduction 2. Purpose/Objectives of this work 3. Methods for characterisation of EPS 4. Results 1 st case of experiments 5. Results 2 nd case of experiments 6. Conclusions 3

4 Characteristics of EPS Τhe major component of the Acivated Sludge matrix. Μatrix of biopolymers with high molecular mass. They are located on or outside the surface of the cells and in the intracellular space. They form a 3D, gel-like, highly hydrated and charged biofilm matrix, in which the microorganisms are embedded and immobilized. EPS are composed of organic substances, such as proteins, polysaccharides, humic substances, DNA and RNA. 4

5 Classification of EPS EPS can be classified into soluble EPS and Bound EPS. Bound EPS consist of a dynamic double-layered structure (Loosely Bound EPS and Tightly Bound EPS). Πηγή: Wang et al.,

6 Importance of EPS in Wastewater Treatment Important role of EPS in: flocculation, sedimentation and dewaterability in wastewater treatment systems and also they are highly responsible for membrane fouling in membrane bioreactors (MBR). Lots of research Conflicting results More research has to be carried out 6

7 Contents 1. Introduction 2. Purpose/Objectives of this work 3. Methods for characterisation of EPS 4. Results 1 st case of experiments 5. Results 2 nd case of experiments 6. Conclusions 7

8 Purpose of This Work Selection of the appropriate method for: extraction of EPS and measurement of proteins and polysaccharides content. Use of the selected methods in order to study the synthesis of EPS for domestic wastewater originated from different treatment phases of a wastewater treatment plant or with different content (with or without molasses).

9 Objectives of This Project Analysis and comparison of the characteristics of EPS for two different cases of experiments. 1 st case Vs

10 Objectives of This Project Analysis and comparison of the characteristics of EPS for two different cases. 2 nd case EPS in the activated sludge mixed liquor of pilot tanks, which follow the biological treatment cycle (feed, anoxic phase, aerobic phase, sedimentation, outflow). 100% domestic wastewater (ww) Vs 90% domestic ww & 10% ww with high molasses content

11 Contents 1. Introduction 2. Purpose/Objectives of this work 3. Methods for characterisation of EPS 4. Results 1 st case of experiments 5. Results 2 nd case of experiments 6. Conclusions 11

12 Methods for characterisation of EPS. 1 st step: Extraction of EPS resulting in 3 fractions: 1. seps or SMP, 2. LB-EPS and 3. ΤB-EPS Πηγή: Le-Clech et al., nd step: Measurement of each extracted EPS fraction. Concentration of proteins EPSp & polyssacharides (in the form of carbohydrates) ΕPSc. Πηγή: Le-Clech et al.,

13 1 st. EPS extraction methods Different methods have different extraction efficiencies. The optimal EPS extraction method should be: effective, causing minimal cell lysis and not disintegrating the EPS structure. Methods for EPS extraction: 1. Physical methods (use of external forces, such as centrifugation or heating) 2. Chemical methods (adding of chemical compounds, such as cation exchange resin) 3. Their combination 13

14 2 nd. Methods for quantification of proteins & polysaccharides Conventional chemical colorimetric analyses should be used. Lowry method Proteins Bradford method Bovine serum albumin as standard. Polysaccharides Glucose as standard. Dubois method Anthrone method Standard Addition Method: to study eventual interferences between sample and method. 14

15 Contents 1. Introduction 2. Purpose/Objectives of this work 3. Methods for characterisation of EPS 4. Results - 1 st case of experiments 5. Results - 2 nd case of experiments 6. Conclusions 15

16 Results - 1 st case of experiments Vs 16

17 Weight ratio (%) EPS total concentr. (mg/g VSS) Weight ratio (%) EPS total concentr. (mg/g VSS) seps LB-EPS TB-EPS Proteins Polysaccharides EPS total concentr. Aeration tank Recirculation stream seps LB-EPS TB-EPS

18 Proteins > polysaccharides, as it was expected. C EPS,total in the recirculation stream < C EPS,total in the aeration tank, because VSS concentration increases in the recirculation stream. 18

19 Results - 2 nd case of experiments 2 nd case EPS in the activated sludge mixed liquor of pilot tanks, which follow the biological treatment cycle (feed, anoxic phase, aerobic phase, sedimentation, outflow). 100% domestic wastewater (ww) Vs 90% domestic ww & 10% ww with high molasses content

20 Weight ratio (%) EPS total concentr. (mg/g VSS) Weight ratio (%) EPS total concentr. (mg/g VSS) % domestic wastewater 0 0 seps LB-EPS TB-EPS Proteins Polysaccharides EPS total concentr. 90% domestic ww & 10% ww with high mollases content seps LB-EPS TB-EPS

21 Proteins > polysaccharides, as it was expected. C EPS,total in tank with high molasses content < C EPS,total in tank with domestic wastewater (especially LBEPS), because VSS concentration increases in tank with high molasses content. 21

22 Contents 1. Introduction 2. Purpose/Objectives of this work 3. Methods for characterisation of EPS 4. Results - 1st case of experiments 5. Results - 2nd case of experiments 6. Conclusions 22

23 Conclusions 1. Studying of EPS synthesis is important for the optimum design of wwt systems. 2. Selection of the appropriate EPS extraction method is significant stage in studying EPS. 3. Aeration tank Vs recirculation stream: Always PN>PS with weight ratio PN/PS=70%/30%. C EPS,total increasing tendency from seps to TBEPS with variation 3-39mg/g VSS for both cases. C EPS,total in the recirculation stream < C EPS,total in the aeration tank. 23

24 Conclusions 4. Tank with domestic ww Vs tank with mixing of domestic ww & molasses: Always PN>PS with weight ratio PN/PS 70%/30%. C EPS,total shows decreasing tendency from seps to TBEPS. Tank with domestic ww: mg/g VSS tank with mixing of domestic wwt & molasses: mg/gVSS. C EPS,total in the tank with the mixing of domestic wastewater and molasses << C EPS,total in the tank with domestic ww. 24

25 Thank you for your attention! Acknowledgements The financial support through the co - Financed by the European Union and the Greek State Program EPAN-II (OPC-II) / ESPA (NSRF): 'SYNERGASIA II', Project (FOUL-MEM) - "New processes for fouling control in membrane bioreactors (11SYN ), are gratefully appreciated. 25