The City of Brandon, Manitoba, along with CH2M (a wholly owned subsidiary of Jacobs Engineering Group), is currently completing the design for an upgrade to the City’s existing lime softening water treatment facility using a dual membrane treatment process (ultrafiltration followed by nanofiltration). The existing facility requires additional treatment to meet future capacity needs and to reduce the disinfection by-product formation in the distribution system, while still providing softening treatment. This is particularly challenging as the source water for the facility, the Assiniboine River, is typically high in organic carbon and turbidity, especially during the spring runoff when TOC values can exceed 20 mg/L, and turbidity can reach levels above 200 NTU. Initially, a membrane process was selected as the preferred alternative for the expansion, with reverse osmosis membranes recommended as the high-pressure membrane. However, given the potentially high-pressure requirements of RO in cold water (determined from membrane projection software), and that this is a surface water with low TDS, there is potential for the use of nanofiltration (NF) membranes as an effective alternative in this softening application. As part of the preliminary design, a bench scale treatability testing program was completed as means of comparing NF membranes and “low-pressure” RO membranes in terms of operating pressure, NOM removal, hardness reduction and DBP precursor reduction, along with several other operational and water quality characteristics, for a variety of NF/RO bypass scenarios, and blend ratios with the existing softening plant effluent. This testing also provided an opportunity to validate membrane projection information for the NF/RO membranes. Optimizing the UF pre-treatment regime was also completed with examining membrane fouling index (MFI) rates for a variety of UF pre-treatment conditions. This study also provided information on the expected corrosion potential of the NF/RO effluent only, as well as that for NF/RO effluent blended with the existing softening plant effluent, to determine potential effects on the existing distribution system with the expanded facility. Further to this, initial pilot water quality and data from the proof pilot study will be available and will be presented to supplement the treatability testing, and to show fouling characteristics of both the UF and NF membranes on this challenging source water. Overall, this paper will be of keen interest to Utility Owners, Research Professionals, Operators and Engineers interested in using dual membrane systems with NF membranes for softening and organics reduction, with a focus on cold, high TOC and high turbidity source waters. It also provides data on the removal of NOM, TOC, and DBP precursors, for which only limited data exists and cannot be simulated with projection software. Since energy optimization and DBP reduction are high interest topics, this paper provides real world data giving insights into the comparative effectiveness of NF for these, along with other, key parameters.
This presentation is available to AMTA Members only.
- The City of Brandon, Manitoba, along with CH2M (a wholly owned subsidiary of Jacobs Engineering Group), is currently completing the design for an upgrade to the City’s existing lime softening water treatment facility using a dual membrane treatment proces
- AMTA/AWWA Membrane Technology Conference, Las Vegas
- AMTA/AWWA Membrane Technology Conference
- NOM, DBP, NF and RO Membranes