TY - JOUR
T1 - Aluminum-humic colloid formation during pre-coagulation for membrane water treatment
T2 - Mechanisms and impacts
AU - Wang, Zhengyang
AU - Teychene, Benoît
AU - Abbott Chalew, Talia E.
AU - Ajmani, Gaurav S.
AU - Zhou, Tao
AU - Huang, Haiou
AU - Wu, Xiaohui
N1 - Funding Information:
Mr. Zhengyang Wang and Dr. Benoit Teychene were visiting scholars at The Johns Hopkins University (JHU) where this research was conducted. The authors would like to thank Mr. Mark Kontz for conducting SEM imaging of membrane samples, Ms. Jana Mihalic for performing the ICP-MS analysis for Al concentration, and Dr. Kai Loon Chen for providing access to the instrument for electrophoretic mobility measurement. We are also grateful to the anonymous reviewers who patiently read through our manuscript and provided critical comments on our work. This research was primarily supported by an internal grant to Dr. Haiou Huang from JHU Bloomberg School of Public Health. Mr. Zhengyang Wang was also supported by the Fundamental Research Funds for the Central Universities Foundation of China (NO. 2012QN127 and 2014QN145 ), and Key Project in the National Science & Technology Pillar Program during the Twelfth Five-year Plan Period of China (No. 2012BAC02B04 ) to perform the research at JHU.
PY - 2014/9/15
Y1 - 2014/9/15
N2 - Precoagulation has been widely used by low pressure membrane filtration (LPMF) plants to reduce membrane fouling and increase natural organic matter (NOM) removal. Formation of aluminum and aluminum-NOM moieties plays a fundamental role in this important water treatment process. This study comprehensively investigated the mechanisms of aluminum-NOM species formation during precoagulation and their impacts on LPMF performance. The results show that, at low alum doses, e.g. 0.5mg and 1.0mgAlL-1, humic substances (HS) and Al species (amorphous Al(OH)3, or Al(OH)3(am)) reacted to form small Al(OH)3(am)-HS colloids. Increases in alum dose resulted in sequential transitions of the Al-HS moieties to larger particles and, eventually, precipitates. Compared to waters containing only naturally occurring organic colloids (OC) or HS, the coexistence of OC and HS facilitated the formation of Al-HS precipitates, thereby increasing the removal of HS by 7-15%, but the removal of OC was decreased by 3-20%. Interestingly, these transitions in Al-HS moieties did not affect membrane fouling. Both short-term and long-term filtration results demonstrate that OC, rather than the Al(OH)3(am)-HS colloids, primarily caused membrane fouling. These findings highlight the dynamics of particulate Al-NOM formation during precoagulation and its relationship with membrane fouling, which can be utilized to optimize the operation of integrated precoagulation-LPMF systems on full-scale installations.
AB - Precoagulation has been widely used by low pressure membrane filtration (LPMF) plants to reduce membrane fouling and increase natural organic matter (NOM) removal. Formation of aluminum and aluminum-NOM moieties plays a fundamental role in this important water treatment process. This study comprehensively investigated the mechanisms of aluminum-NOM species formation during precoagulation and their impacts on LPMF performance. The results show that, at low alum doses, e.g. 0.5mg and 1.0mgAlL-1, humic substances (HS) and Al species (amorphous Al(OH)3, or Al(OH)3(am)) reacted to form small Al(OH)3(am)-HS colloids. Increases in alum dose resulted in sequential transitions of the Al-HS moieties to larger particles and, eventually, precipitates. Compared to waters containing only naturally occurring organic colloids (OC) or HS, the coexistence of OC and HS facilitated the formation of Al-HS precipitates, thereby increasing the removal of HS by 7-15%, but the removal of OC was decreased by 3-20%. Interestingly, these transitions in Al-HS moieties did not affect membrane fouling. Both short-term and long-term filtration results demonstrate that OC, rather than the Al(OH)3(am)-HS colloids, primarily caused membrane fouling. These findings highlight the dynamics of particulate Al-NOM formation during precoagulation and its relationship with membrane fouling, which can be utilized to optimize the operation of integrated precoagulation-LPMF systems on full-scale installations.
KW - Coagulation mechanism
KW - Fractionated natural organic matter
KW - Membrane fouling
KW - Microfiltration
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U2 - 10.1016/j.watres.2014.05.022
DO - 10.1016/j.watres.2014.05.022
M3 - Article
C2 - 24911563
AN - SCOPUS:84902013397
VL - 61
SP - 171
EP - 180
JO - Water Research
JF - Water Research
SN - 0043-1354
ER -