Messologitis, Katerina

Katerina Messologitis was a speaker at the WEFTEC 2024 conference in New Orleans, LA October 5-9, 2024.

Titles from this speaker

Performance Evaluation of an Online Membrane Integrity Monitor for Flat Plate MBRs

Abstract

Incorporating membrane bioreactors (MBR) into potable reuse treatment trains is gaining interest due to increasing concerns over water scarcity and the need for high quality effluent for downstream treatment technologies. However, membranes are vulnerable to breaches which necessitates real-time monitoring of membrane integrity. Turbidity monitoring is applied ubiquitously in the field, but it is difficult to correlate with microbial reduction performance. To this end, a novel online integrity monitor was developed and evaluated at a 30,000 gal/d MBR pilot in Canton, OH. This monitor detects changes in permeate quality by quantifying the fouling of a dead-end membrane external to the MBR treatment process via flow and pressure measurements. Figure 1 details the configuration of the integrity monitor. The performance of the integrity monitor was validated by intentionally creating membrane breaches. Slits were cut into the membranes of one module prior to installation and were protected with tape and tied to strings that could be removed by operators for control of breach timing. The intensity of damage was controlled by varying the number of slits in three phases separated by 24 hours; three slits (Phase 1), followed by 28 slits (Phase 2) and finally 63 slits (Phase 3), totaling 94 slits (Table 1.). Membrane integrity was monitored using two online instruments: a commercially available laser-based turbidimeter and the novel membrane integrity monitor. The integrity monitor provided two parameters used for comparison with turbidity including the resistance (transmembrane pressure/flux) and the graphical first derivative of the resistance. Log reduction values (LRV) of male specific and somatic coliphages, E. Coli and total coliforms were assessed before and after breaches for comparison with the real-time data. Baseline MBR effluent turbidity was <0.04 NTU; after Phase 1 damage was uncovered, turbidity briefly spiked above 1.0 NTU, but recovered to pre-damaged conditions. Initial results (Figure 2) suggest that membrane breaches can be reliably detected by the prototype integrity monitor. Breaches were detected when the derivative of the resistance (αR) was > 1.05; turbidity and microbial results corroborated the response of the integrity monitor. The resistance increased positively over the three phases from 0.5 to > 8.0 psi/gal/ft2/d while αR detected the second phase breach (28 slits) with a marked response (Figure 2). It is possible that the three slits of Phase 1 did not produce a response because it was simply too small of a breach; it is possible that the mixed liquor may have provided a 'band-aid' effect in where the slits were covered by mixed liquor during filtration, disallowing particle passage into the permeate. Work is ongoing to determine the lower limits of sensitivity of the monitor by varying parameters and configuration. LRVs of male specific coliphages fell from approximately 3- to < 2-log but recovered after approximately one hour of operation. Total coliform and E. Coli LRVs reduced from 7.2 and 6.7-log, to 4.2 and 3.8-log, respectively; the LRVs remained stable after this initial drop. Microbial response to the breaches can be seen in Figure 3. This presentation and paper show progress towards developing a sensitive, integrity monitor that will reliably detect membrane breaches in real time. Work is ongoing to improve the sensitivity of the device, identify patterns in the data it produces, and correlate its results to microbial reduction performance.

A membrane integrity monitor for flat plate MBR has been developed and tested in a pilot scale MBR-RO treatment train. The monitor detects changes in permeate quality by quantifying the fouling of a dead-end membrane external to the MBR treatment process via flow and pressure measurements. The performance of the integrity monitor was validated by intentionally creating membrane breaches, observing the instrumental response and comparing with online turbidity measurements as well as as data

SpeakerMorris, Larry

Presentation time

09:15:00

09:30:00

Session time

08:30:00

10:00:00

SessionEnhancing Water Safety: MBR & RO Technologies for Achieving LRV Credits

Session number315

Session locationRoom 349

TopicAdvanced Level, Disinfection and Public Health, Microconstituents and Contaminants of Emerging Concern (Non-PFAS), Municipal Wastewater Treatment Design, Water Reuse and Reclamation

Author(s)

Morris, Larry, Terao, Yasushi, Shimizu, Nao, Jacangelo, Joseph, Lehman, Geno, Adelman, Michael, Messologitis, Katerina, Bruce, Eric, Glover, Caitlin, Ryan, Donald

Author(s)L. Morris1, Y. Terao1, N. Shimizu1, J. Jacangelo2, G. Lehman3, M.J. Adelman3, K. Messologitis4, E. Bruce3, C. Glover5, D. Ryan6

Author affiliation(s)1Kubota Membrane USA Corporation, OH, 2, VA, 3Stantec, CA, 4Stantec, OR, 5Stantec, 6, WI

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159560

Volume / Issue

Content sourceWEFTEC

Word count13

RO Fouling Assessment of MBR-RO Trains using Flat-Plate MBR Membranes

Abstract

There is growing interest in using membrane bioreactors (MBR) for potable reuse because of their improved effluent quality and pathogen removal compared to conventional secondary processes. Therefore, using an MBR as the main treatment process upstream of reverse osmosis (RO) is often desirable for advanced treatment facilities. Most advanced treatment studies with MBRs employ hollow fiber or tubular membranes. In this 12- month pilot study, an alternative flat-plate MBR was employed as the pretreatment method to assess downstream biological and colloidal RO fouling in a MBR-RO train. The study evaluated RO performance under varying operational parameters such as MBR and RO flux conditions, biological process conditions in the MBR, and chloramine dose in the RO feed. The RO system was also subject to known MBR membrane breaches. The two-stage RO system was operated at ~70% recovery to avoid mineral scaling so the effects of fouling driven by MBR filtrate quality could be observed. Typical RO permeate flux values used in reuse applications (10-14 gfd) were used in this study. Key monitoring parameters included MLSS, TMP, and filtrate water quality for the MBR as well as normalized RO specific flux. A novel online integrity monitor was also used to detect small colloidal particles in the RO feed using differential pressure across a filter. RO membranes were also periodically sent for autopsy to evaluate the type of fouling observed on the RO membranes prior to a clean-in-place. Normalized RO data has shown evidence of periods with both higher and lower rates of fouling. RO flux decline data was plotted against key MBR operating and filtrate quality parameters. The MBR filtrate turbidity and integrity monitor data showed notable correlations. Lowest RO fouling rates (< 0.0003 gfd/psi-day) were observed with lower filtrate turbidity and lower differential pressure from the integrity monitor. Higher fouling rates (> 0.0003 gfd/psi-day) took place at higher MBR permeate sCOD (>30 mg/L) and low chloramine levels, both of which would favor biofilm growth as a driver of fouling. However, autopsy results showed mostly organic material as the foulant with minimal biofilm coverage suggesting that colloids were the main driver of fouling with biological growth as a secondary factor. Normalized RO data was evaluated individually for stage 1 and stage 2. Conventional knowledge would suggest that colloidal fouling in RO systems is more prevalent at the first stage than in subsequent stages. However, the results from this study suggests that the RO fouling pattern is similar between stage 1 and stage 2 membranes, as shown in Figure 1. The performance of the MBR-RO pilot using flat-plate MBR membranes was compared to existing data from MBR-RO treatment processes using hollow fiber or tubular MBR membrane, which suggests that the type of MBR membrane used upstream of the RO system does not impact the overall performance of the RO system. Table 1 provides RO performance data from two reference facilities compared to the performance observed during this pilot study. This presentation will provide insights into the drivers of RO fouling as well as operational strategies for improved RO performance, and will compare the performance of this pilot study against existing process data from other advanced water treatment plant facilities. Target values for MBR filtrate turbidity, MBR tank MLSS, and feed chloramines were identified as parameters that promote low fouling rates and reasonable CIP intervals. The novel integrity monitor was shown to provide useful insight into whether colloid passage was sufficient to increase RO fouling rates.

There is growing interest in using MBRs upstream of RO for potable reuse because of their improved effluent quality & pathogen removal compared to conventional secondary processes. Well-developed models exist to predict mineral scaling in RO systems, however, biological & colloidal fouling in MBR-RO trains is less understood. A 12-month pilot study was conducted to evaluate fouling of RO membranes when used in combination with a flat-plate membrane bioreactor upstream of a pilot RO system.

SpeakerMessologitis, Katerina

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionEffective Strategies for Managing Organics in IPR/DPR Systems

Session number216

Session locationRoom 340

TopicIntermediate Level, Water Reuse and Reclamation

Author(s)

Messologitis, Katerina, Morris, Larry, Terao, Yasushi, Jacangelo, Joseph, Adelman, Michael, Shimizu, Nao, Bruce, Eric, Lehman, Geno, Glover, Caitlin, Ryan, Donald

Author(s)K. Messologitis1, L. Morris2, Y. Terao2, J. Jacangelo3, M.J. Adelman4, N. Shimizu2, E. Bruce4, G. Lehman4, C. Glover5, D. Ryan5

Author affiliation(s)1Stantec, OR, 2Kubota Membrane USA Corporation, OH, 3, VA, 4Stantec, CA, 5Stantec

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159588

Volume / Issue

Content sourceWEFTEC

Word count11

Base text size -

Messologitis, Katerina

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