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Occurence of transparent exopolymer particles (TEP): case-study in re-use plant for drinking water

Sam Van Nevel UGent, Tom Hennebel UGent, Gijs Du Laing UGent, Willy Verstraete UGent and Nico Boon UGent (2012) Wastewater Purification and Reuse, IWA Regional conference, Proceedings.
abstract
TEP are gel-like and extremely sticky particles, consisting of polysaccharides and formed out of exudates from algae and bacterial mucus. Membrane technologists recently started recognizing the importance of these particles as biofouling initiators since they are ubiquitous in all natural waters, sticky and well colonised by bacteria and hereby ideally designed to induce biofouling. Once attached to membrane surfaces, these particles start poreblocking and serve as both an attachment site and nutritious substrate for microbial growth. Earlier studies observed 70% of TEP in influent water sticking on reverse osmosis (RO) membranes and limited TEP removal efficiency in RO-pretreatment systems. It was also seen that early EPS deposition on membranes only originates from TEP present in the feed water, an indication that TEP can be an important factor for the initiation of biofilms. However, not a single study described the occurrence of TEP in drinking water treatment trains. The limited removal efficiencies in several systems and the conclusions about TEP as a possible important factor in biofilm initiation suggest that TEP can be present in drinking water and play a role in drinking water safety. Therefore, this study was the first one to evaluate the occurrence of TEP in drinking water facilities. The TEP concentrations in raw water and throughout different drinking water production trains were measured and common water treatment methods were evaluated on their TEP removal. A focus was laid on ‘Torreele’, a Belgian installation treating effluent from a wastewater treatment plant via ultrafiltration (UF) and RO. This water is infiltrated in the dunes and recharges the local groundwater reserves. After infiltration, this water is pumped up and treated to drinking water. Hereby, this is one of the only installations worldwide based on the re-use of wastewater to drinking water. Next to this plant (‘Plant A’), 2 other plants treating respectively surface water and groundwater were comprised in this research (‘Plant B’ and ‘Plant C’). The waste water effluent in plant A contained the considerable amount of 1571 μg/L TEP. In comparison, Plant B had raw water containing 699 μg/L TEP while not any considerable amount of TEP could be detected in the groundwater of plant C. In plant A, TEP-concentrations were raised after addition of chlorine. This was probably due to cell lysis and TEP release induced by chlorine. In this installation, UF proved to be a very efficient abatement technique for TEP. RO is known to be a very powerful method and completely removed the whole TEP fraction, however the aquatic life in the infiltration pond caused the reappearance of TEP. Infiltration reduced the TEP amounts again until a minimal and stable level. In plant B, coagulation efficiently sticked the TEP together, enabling the double sand filtration to efficiently remove this bigger TEP-fraction. The following ozonation, activated carbon filtration and chlorination was able to minimize TEP concentrations so that only a very limited amount of TEP could reach the final drinking water. Finally, 13 more chemical and biological parameters were measured: pH, conductivity, COD, TOC, Ca2+, Mg2+, Na+, K+, NO3-, SO4 2-, Cl-, viable and total bacteria concentration. All data was merged together in one data set and statistics were used in search for significant associations between TEP and other parameters. A significant association was found for TEP versus either viable or total cell concentrations, TOC and COD. It could be concluded that limited or no TEP could reach the final drinking water. In the re-use system, TEP was not a possible contaminant endangering the final drinking water quality. The applied membrane treatments proved efficient for a total TEP removal, dune infiltration completed this task once again.
Please use this url to cite or link to this publication:
author
organization
year
type
conference
publication status
published
subject
in
Wastewater Purification and Reuse, IWA Regional conference, Proceedings
editor
Thrassyvoulos Manios, Nikolaos Kalogerakis, Charilaos Papamattheakis, Emmanouil Mavrakis, Daniel Mamais, Charalambos Papadogiannis and Anna Troulinou
pages
8 pages
conference name
IWA Regional conference on Wastewater Purification and Reuse (WWPR 2012)
conference location
Heraklion, Crete, Greece
conference start
2012-03-28
conference end
2012-03-30
ISBN
9789609988926
language
English
UGent publication?
yes
classification
C1
copyright statement
I have transferred the copyright for this publication to the publisher
id
2940476
handle
http://hdl.handle.net/1854/LU-2940476
date created
2012-06-27 15:50:39
date last changed
2012-07-31 10:39:36
@inproceedings{2940476,
  abstract     = {TEP are gel-like and extremely sticky particles, consisting of polysaccharides and formed out of exudates from algae and bacterial mucus. Membrane technologists recently started recognizing the importance of these particles as biofouling initiators since they are ubiquitous in all natural waters, sticky and well colonised by bacteria and hereby ideally designed to induce biofouling. Once attached to membrane surfaces, these particles start poreblocking and serve as both an attachment site and nutritious substrate for microbial growth. Earlier studies observed 70\% of TEP in influent water sticking on reverse osmosis (RO) membranes and limited TEP removal efficiency in RO-pretreatment systems. It was also seen that early EPS deposition on membranes only originates from TEP present in the feed water, an indication that TEP can be an important factor for the initiation of biofilms. However, not a single study described the occurrence of TEP in drinking water treatment trains. The limited removal efficiencies in several systems and the conclusions about TEP as a possible important factor in biofilm initiation suggest that TEP can be present in drinking water and play a role in drinking water safety. Therefore, this study was the first one to evaluate the occurrence of TEP in drinking water facilities. The TEP concentrations in raw water and throughout different drinking water production trains were measured and common water treatment methods were evaluated on their TEP removal. A focus was laid on {\textquoteleft}Torreele{\textquoteright}, a Belgian installation treating effluent from a wastewater treatment plant via ultrafiltration (UF) and RO. This water is infiltrated in the dunes and recharges the local groundwater reserves. After infiltration, this water is pumped up and treated to drinking water. Hereby, this is one of the only installations worldwide based on the re-use of wastewater to drinking water. Next to this plant ({\textquoteleft}Plant A{\textquoteright}), 2 other plants treating respectively surface water and groundwater were comprised in this research ({\textquoteleft}Plant B{\textquoteright} and {\textquoteleft}Plant C{\textquoteright}). The waste water effluent in plant A contained the considerable amount of 1571 \ensuremath{\mu}g/L TEP. In comparison, Plant B had raw water containing 699 \ensuremath{\mu}g/L TEP while not any considerable amount of TEP could be detected in the groundwater of plant C. In plant A, TEP-concentrations were raised after addition of chlorine. This was probably due to cell lysis and TEP release induced by chlorine. In this installation, UF proved to be a very efficient abatement technique for TEP. RO is known to be a very powerful method and completely removed the whole TEP fraction, however the aquatic life in the infiltration pond caused the reappearance of TEP. Infiltration reduced the TEP amounts again until a minimal and stable level. In plant B, coagulation efficiently sticked the TEP together, enabling the double sand filtration to efficiently remove this bigger TEP-fraction. The following ozonation, activated carbon filtration and chlorination was able to minimize TEP concentrations so that only a very limited amount of TEP could reach the final drinking water. Finally, 13 more chemical and biological parameters were measured: pH, conductivity, COD, TOC, Ca2+, Mg2+, Na+, K+, NO3-, SO4 2-, Cl-, viable and total bacteria concentration. All data was merged together in one data set and statistics were used in search for significant associations between TEP and other parameters. A significant association was found for TEP versus either viable or total cell concentrations, TOC and COD. It could be concluded that limited or no TEP could reach the final drinking water. In the re-use system, TEP was not a possible contaminant endangering the final drinking water quality. The applied membrane treatments proved efficient for a total TEP removal, dune infiltration completed this task once again.},
  author       = {Van Nevel, Sam and Hennebel, Tom and Du Laing, Gijs and Verstraete, Willy and Boon, Nico},
  booktitle    = {Wastewater Purification and Reuse, IWA Regional conference, Proceedings},
  editor       = {Manios, Thrassyvoulos and Kalogerakis, Nikolaos and Papamattheakis, Charilaos and Mavrakis, Emmanouil and Mamais, Daniel and Papadogiannis, Charalambos and Troulinou, Anna },
  isbn         = {9789609988926},
  language     = {eng},
  location     = {Heraklion, Crete, Greece},
  pages        = {8},
  title        = {Occurence of transparent exopolymer particles (TEP): case-study in re-use plant for drinking water},
  year         = {2012},
}

Chicago
Van Nevel, Sam, Tom Hennebel, Gijs Du Laing, Willy Verstraete, and Nico Boon. 2012. “Occurence of Transparent Exopolymer Particles (TEP): Case-study in Re-use Plant for Drinking Water.” In Wastewater Purification and Reuse, IWA Regional Conference, Proceedings, ed. Thrassyvoulos Manios, Nikolaos Kalogerakis, Charilaos Papamattheakis, Emmanouil Mavrakis, Daniel Mamais, Charalambos Papadogiannis, and Anna Troulinou.
APA
Van Nevel, S., Hennebel, T., Du Laing, G., Verstraete, W., & Boon, N. (2012). Occurence of transparent exopolymer particles (TEP): case-study in re-use plant for drinking water. In T. Manios, N. Kalogerakis, C. Papamattheakis, E. Mavrakis, D. Mamais, C. Papadogiannis, & A. Troulinou (Eds.), Wastewater Purification and Reuse, IWA Regional conference, Proceedings. Presented at the IWA Regional conference on Wastewater Purification and Reuse (WWPR 2012).
Vancouver
1.
Van Nevel S, Hennebel T, Du Laing G, Verstraete W, Boon N. Occurence of transparent exopolymer particles (TEP): case-study in re-use plant for drinking water. In: Manios T, Kalogerakis N, Papamattheakis C, Mavrakis E, Mamais D, Papadogiannis C, et al., editors. Wastewater Purification and Reuse, IWA Regional conference, Proceedings. 2012.
MLA
Van Nevel, Sam, Tom Hennebel, Gijs Du Laing, et al. “Occurence of Transparent Exopolymer Particles (TEP): Case-study in Re-use Plant for Drinking Water.” Wastewater Purification and Reuse, IWA Regional Conference, Proceedings. Ed. Thrassyvoulos Manios et al. 2012. Print.