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Combined coagulation and ultrafiltration process to counteract increasing NOM in brown surface water

Keucken, Alexander LU ; Heinicke, Gerald; Persson, Kenneth M. LU and Köhler, Stephan J (2017) In Water (Switzerland) 9(9).
Abstract

Membrane hybrid processes-coagulation coupled with ultrafiltration (UF)-have become a common method to comply with the legal, chemical, and microbiological requirements for drinking water. The main advantages of integrating coagulation with membrane filtration are the enhanced removal of natural organic matter (NOM) and reduced membrane fouling. With in-line coagulation, coagulants are patched into the feed stream directly prior to the membrane process, without removing the coagulated solids. Compared with conventional coagulation/sedimentation, in-line coagulation/membrane reduces the treatment time and footprint. Coagulant dosing could be challenging in raw water of varying quality; however, with relatively stable specific ultraviolet... (More)

Membrane hybrid processes-coagulation coupled with ultrafiltration (UF)-have become a common method to comply with the legal, chemical, and microbiological requirements for drinking water. The main advantages of integrating coagulation with membrane filtration are the enhanced removal of natural organic matter (NOM) and reduced membrane fouling. With in-line coagulation, coagulants are patched into the feed stream directly prior to the membrane process, without removing the coagulated solids. Compared with conventional coagulation/sedimentation, in-line coagulation/membrane reduces the treatment time and footprint. Coagulant dosing could be challenging in raw water of varying quality; however, with relatively stable specific ultraviolet absorbance (SUVA), dosing can be controlled. Recent studies indicate that UV absorbance correlates well with humic substances (HS), the major fraction to be removed during coagulation. This paper describes and evaluates a 30-month UF pilot trial on the surface water of Lake Neden (Sweden), providing drinking water to 60,000 residents. In this study, automatic coagulant dosing based on online measurement was successfully applied. Online sensor data were used to identify the current optimal aluminium coagulation conditions (0.5-0.7 mg L-1) and the potential boundaries (0.9-1.2 mg L-1) for efficient future (2040) NOM removal. The potential increase in NOM could affect the Al dose and drinking water quality significantly within 20 years, should the current trends in dissolved organic carbon (DOC) prevail. UV absorbance, the freshness index, and liquid chromatography-organic carbon detection (LC-OCD) measurements were used to optimise the process. Careful cross-calibration of raw and filtered samples is recommended when using online sensor data for process optimisation, even in low-turbidity water (formazin nephelometric unit (FNU) < 5).

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Coagulation, Hollow fibre, Natural organic matter (NOM), Optical sensors, Ultrafiltration
in
Water (Switzerland)
volume
9
issue
9
publisher
MDPI AG
external identifiers
  • scopus:85029758274
  • wos:000411567200070
ISSN
2073-4441
DOI
10.3390/w9090697
language
English
LU publication?
yes
id
9e9c5e77-1dee-4039-b74e-305209aed5f1
date added to LUP
2017-10-05 14:41:04
date last changed
2018-05-29 10:57:11
@article{9e9c5e77-1dee-4039-b74e-305209aed5f1,
  abstract     = {<p>Membrane hybrid processes-coagulation coupled with ultrafiltration (UF)-have become a common method to comply with the legal, chemical, and microbiological requirements for drinking water. The main advantages of integrating coagulation with membrane filtration are the enhanced removal of natural organic matter (NOM) and reduced membrane fouling. With in-line coagulation, coagulants are patched into the feed stream directly prior to the membrane process, without removing the coagulated solids. Compared with conventional coagulation/sedimentation, in-line coagulation/membrane reduces the treatment time and footprint. Coagulant dosing could be challenging in raw water of varying quality; however, with relatively stable specific ultraviolet absorbance (SUVA), dosing can be controlled. Recent studies indicate that UV absorbance correlates well with humic substances (HS), the major fraction to be removed during coagulation. This paper describes and evaluates a 30-month UF pilot trial on the surface water of Lake Neden (Sweden), providing drinking water to 60,000 residents. In this study, automatic coagulant dosing based on online measurement was successfully applied. Online sensor data were used to identify the current optimal aluminium coagulation conditions (0.5-0.7 mg L<sup>-1</sup>) and the potential boundaries (0.9-1.2 mg L<sup>-1</sup>) for efficient future (2040) NOM removal. The potential increase in NOM could affect the Al dose and drinking water quality significantly within 20 years, should the current trends in dissolved organic carbon (DOC) prevail. UV absorbance, the freshness index, and liquid chromatography-organic carbon detection (LC-OCD) measurements were used to optimise the process. Careful cross-calibration of raw and filtered samples is recommended when using online sensor data for process optimisation, even in low-turbidity water (formazin nephelometric unit (FNU) &lt; 5).</p>},
  articleno    = {697},
  author       = {Keucken, Alexander and Heinicke, Gerald and Persson, Kenneth M. and Köhler, Stephan J},
  issn         = {2073-4441},
  keyword      = {Coagulation,Hollow fibre,Natural organic matter (NOM),Optical sensors,Ultrafiltration},
  language     = {eng},
  month        = {09},
  number       = {9},
  publisher    = {MDPI AG},
  series       = {Water (Switzerland)},
  title        = {Combined coagulation and ultrafiltration process to counteract increasing NOM in brown surface water},
  url          = {http://dx.doi.org/10.3390/w9090697},
  volume       = {9},
  year         = {2017},
}