Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1016/j.watres.2011.09.011
Title (Primary) Water reuse: >90% water yield in MBR/RO through concentrate recycling and CO2 addition as scaling control
Author Joss, A.; Baenninger, C.; Foa, P.; Koepke, S.; Krauss, M. ORCID logo ; McArdell, C.S.; Rottermann, K.; Wei, Y.; Zapata, A.; Siegrist, H.
Source Titel Water Research
Year 2011
Department WANA
Volume 45
Issue 18
Page From 6141
Page To 6151
Language englisch
Keywords Water reuse; Municipal wastewater; Reverse osmosis; Micropollutants; Inorganic precipitation

ver 1.5 years continuous piloting of a municipal wastewater plant upgraded with a double membrane system (ca. 0.6 m3 d−1 of product water produced) have demonstrated the feasibility of achieving high water quality with a water yield of 90% by combining a membrane bioreactor (MBR) with a submerged ultrafiltration membrane followed by a reverse osmosis membrane (RO). The novelty of the proposed treatment scheme consists of the appropriate conditioning of MBR effluent prior to the RO and in recycling the RO concentrates back to the biological unit.

All the 15 pharmaceuticals measured in the influent municipal sewage were retained below 100 ng L−1, a proposed quality parameter, and mostly below detection limits of 10 ng L−1. The mass balance of the micropollutants shows that these are either degraded or discharged with the excess concentrate, while only minor quantities were found in the excess sludge. The micropollutant load in the concentrate can be significantly reduced by ozonation. A low treated water salinity (<10 mM inorganic salts; 280 ± 70 μS cm−1) also confirms that the resulting product has a high water quality.

Solids precipitation and inorganic scaling are effectively mitigated by lowering the pH in the RO feed water with CO2 conditioning, while the concentrate from the RO is recycled to the biological unit where CO2 is stripped by aeration. This causes precipitation to occur in the bioreactor bulk, where it is much less of a process issue. SiO2 is the sole exception. Equilibrium modeling of precipitation reactions confirms the effectiveness of this scaling-mitigation approach for CaCO3 precipitation, calcium phosphate and sulfate minerals.

Persistent UFZ Identifier
Joss, A., Baenninger, C., Foa, P., Koepke, S., Krauss, M., McArdell, C.S., Rottermann, K., Wei, Y., Zapata, A., Siegrist, H. (2011):
Water reuse: >90% water yield in MBR/RO through concentrate recycling and CO2 addition as scaling control
Water Res. 45 (18), 6141 - 6151 10.1016/j.watres.2011.09.011