Abstract
The main objective of this study was to evaluate the effectiveness of reverse osmosis (RO) and nanofiltration (NF), under various solution chemistries, on bacterial regrowth potential as quantified by assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC). The bench-scale experiments, using tap groundwater spiked with acetate as organic carbon, revealed that AOC removals by RO/NF membranes were strongly dependent on charge repulsion. AOC removals were greater at conditions of low ionic strength and low hardness, and were slightly higher at high pH values. BDOC removals by NF membrane also increased with decreasing hardness and ionic strength, and increasing pH. However, the RO membrane showed less dependence on feed solution chemistry for BDOC removal, suggesting that BDOC removal was determined by the combined effect of both size exclusion and charge repulsion. The bench-scale observations were compared to a full-scale drinking water treatment plant that used nanofiltration as a primary treatment process. From full-scale operation, it was observed that nanofiltration was a very effective means to reduce BDOC, but conversely, did not reject the bulk of raw water AOC. The high BDOC rejection by NF membranes at full scale can be explained by size exclusion, since a significant fraction of BDOC in raw surficial ground water consists of compounds, such as humic and fulvic acids, which are larger than the pores of NF membranes. The insignificant AOC rejection observed in the full-scale system was probably due to the low pH, high hardness, and high ionic strength (TDS) of the raw groundwater combined with acid addition during pretreatment. These solution environments repress the electrostatic interaction between charged organic compounds and membranes, allowing passage of small molecular weight compounds and thus reducing AOC rejection. (C) 2000 Elsevier Science B.V.
| Original language | English |
|---|---|
| Pages (from-to) | 1-17 |
| Number of pages | 17 |
| Journal | Journal of Membrane Science |
| Volume | 175 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2000 Aug 1 |
| Externally published | Yes |
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Keywords
- Assimilable organic carbon (AOC)
- Biostability
- Organic separation
- Reverse osmosis (RO)
- Water treatment
ASJC Scopus subject areas
- Filtration and Separation
- Polymers and Plastics
Cite this
Removal of assimilable organic carbon and biodegradable dissolved organic carbon by reverse osmosis and nanofiltration membranes. / Escobar, Isabel C.; Hong, Seungkwan; Randall, Andrew A.
In: Journal of Membrane Science, Vol. 175, No. 1, 01.08.2000, p. 1-17.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Removal of assimilable organic carbon and biodegradable dissolved organic carbon by reverse osmosis and nanofiltration membranes
AU - Escobar, Isabel C.
AU - Hong, Seungkwan
AU - Randall, Andrew A.
PY - 2000/8/1
Y1 - 2000/8/1
N2 - The main objective of this study was to evaluate the effectiveness of reverse osmosis (RO) and nanofiltration (NF), under various solution chemistries, on bacterial regrowth potential as quantified by assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC). The bench-scale experiments, using tap groundwater spiked with acetate as organic carbon, revealed that AOC removals by RO/NF membranes were strongly dependent on charge repulsion. AOC removals were greater at conditions of low ionic strength and low hardness, and were slightly higher at high pH values. BDOC removals by NF membrane also increased with decreasing hardness and ionic strength, and increasing pH. However, the RO membrane showed less dependence on feed solution chemistry for BDOC removal, suggesting that BDOC removal was determined by the combined effect of both size exclusion and charge repulsion. The bench-scale observations were compared to a full-scale drinking water treatment plant that used nanofiltration as a primary treatment process. From full-scale operation, it was observed that nanofiltration was a very effective means to reduce BDOC, but conversely, did not reject the bulk of raw water AOC. The high BDOC rejection by NF membranes at full scale can be explained by size exclusion, since a significant fraction of BDOC in raw surficial ground water consists of compounds, such as humic and fulvic acids, which are larger than the pores of NF membranes. The insignificant AOC rejection observed in the full-scale system was probably due to the low pH, high hardness, and high ionic strength (TDS) of the raw groundwater combined with acid addition during pretreatment. These solution environments repress the electrostatic interaction between charged organic compounds and membranes, allowing passage of small molecular weight compounds and thus reducing AOC rejection. (C) 2000 Elsevier Science B.V.
AB - The main objective of this study was to evaluate the effectiveness of reverse osmosis (RO) and nanofiltration (NF), under various solution chemistries, on bacterial regrowth potential as quantified by assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC). The bench-scale experiments, using tap groundwater spiked with acetate as organic carbon, revealed that AOC removals by RO/NF membranes were strongly dependent on charge repulsion. AOC removals were greater at conditions of low ionic strength and low hardness, and were slightly higher at high pH values. BDOC removals by NF membrane also increased with decreasing hardness and ionic strength, and increasing pH. However, the RO membrane showed less dependence on feed solution chemistry for BDOC removal, suggesting that BDOC removal was determined by the combined effect of both size exclusion and charge repulsion. The bench-scale observations were compared to a full-scale drinking water treatment plant that used nanofiltration as a primary treatment process. From full-scale operation, it was observed that nanofiltration was a very effective means to reduce BDOC, but conversely, did not reject the bulk of raw water AOC. The high BDOC rejection by NF membranes at full scale can be explained by size exclusion, since a significant fraction of BDOC in raw surficial ground water consists of compounds, such as humic and fulvic acids, which are larger than the pores of NF membranes. The insignificant AOC rejection observed in the full-scale system was probably due to the low pH, high hardness, and high ionic strength (TDS) of the raw groundwater combined with acid addition during pretreatment. These solution environments repress the electrostatic interaction between charged organic compounds and membranes, allowing passage of small molecular weight compounds and thus reducing AOC rejection. (C) 2000 Elsevier Science B.V.
KW - Assimilable organic carbon (AOC)
KW - Biostability
KW - Organic separation
KW - Reverse osmosis (RO)
KW - Water treatment
UR - http://www.scopus.com/inward/record.url?scp=0034257237&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034257237&partnerID=8YFLogxK
U2 - 10.1016/S0376-7388(00)00398-7
DO - 10.1016/S0376-7388(00)00398-7
M3 - Article
AN - SCOPUS:0034257237
VL - 175
SP - 1
EP - 17
JO - Jornal of Membrane Science
JF - Jornal of Membrane Science
SN - 0376-7388
IS - 1
ER -