Astrand, Niclas

Niclas is a Wastewater industry professional with over 20 years of experience in application of innovative technologies. Specialized in biological nutrient removal, biofilm processes (MABR, zeeDENSE), advanced process modelling/simulation and optimization.

Titles from this speaker

Densification Index/SVI Model: An Efficient Way to Predict Benefits of Biomass Densification in Full-scale MBR and MABR Wastewater Treatment Plants

Abstract

Abstract Densification of biomass is an efficient technology to improve sludge settleability which benefits wastewater treatment plants (WWTPs) by increasing the capacity of the secondary clarifiers. In this study, a densification model was developed and validated to predict the level of densification performance to help capture expected benefits and new capacity limits for operations. The first version of the VWTS (Veolia Water Technologies & Solutions)-SUMO model was developed based on the growth kinetic for various microorganisms (e.g., nitrifiers and polyphosphate-accumulating organisms). Then the model was calibrated with the filed data collected from full-scale WWTPs (WWTPs with membrane-aerated biofilm reactors and WWTPs with membrane bioreactors). Although more filed data under steady-state operating conditions need to be collected to validate the model, the current simulation results demonstrated the settleability in the full-scale WWTP can be improved significantly by the densification processes. In addition, the proposed model can predict the settleability reliably. 1.INTRODUCTION Densification and granulation of biomass have been demonstrated to be efficient in improving sludge settleability which determines the design and performance of secondary clarifiers (i.e., the hydraulic capacity) in wastewater treatment plants (WWTPs). For instance, a full-scale granule-floc hybrid process in Dijon (France) proved that 20% of aerobic granular sludge (AGS) guarantees a sludge volume index (SVI) lower than 100 mL/g while 30% of AGS reduced the SVI to 50 mL/g [1]. The improved settleability (i.e., lower SVIs) further contributed to a better performance of clarifiers with two to three times higher surface loading rates (SLR) and surface overflow rates (SOR). However, the densification and granulation processes, configurations, and mechanisms still need to be understood more deeply. Thus, a densification model is needed to predict the level of densification performance (i.e., SVI) to help capture expected benefits and new capacity limits for operations. Densification Index (DI), which is the percentage of biomass larger than 200 µm in the mixed liquor, was proposed to quantify the level of biomass densification and partial granulation in continuous-flow biological treatment systems. In this study, a simple and reliable protocol was built to capture the DI in a full-scale WWTP with selective wasting (i.e., densification). These sites' DI and SVI data were used to implement and validate an SVI prediction model. With the predicted SVI from this model, the hydraulic capacity in WWTPs can be upgraded to reach new levels of process intensification. 2.METHODS 2.1 VWTS-SUMO Model The VWTS (Veolia Water Technologies & Solutions)-SUMO model [2][3] provides a simple method of calculating and predicting DI on the state variables from the process simulator. The model introduced separate growth kinetics for granular nitrifiers (i.e., ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB)), polyphosphate-accumulating organisms (PAOs), and ordinary heterotrophic organisms (OHOs) that contribute significantly to the formation of denser and granular biomass (> 200 µm). The half-saturation coefficient (Ks) of PAOs, AOBs, NOBs, and OHOs and their effects on granular growth were implemented based on the previous framework [4]. The contribution of influent inorganic suspended solids (ISS, > 200 µm) was also added to the model. 2.2 Field Data Collection and Calibration A simple and reliable protocol (i.e., sieve tests) has been implemented to measure the DI of a full-scale A2O (anaerobic-anoxic-aerobic)-MABR (membrane aerated biofilm reactor) WWTP and a full-scale A2O-MBR (membrane bioreactor) WWTP. The configuration of the treatment plant is shown in Figure 1. A SUMO model was developed and validated by the influent wastewater characteristics using VWTS blocks specially designed and developed for MABR, Secondary Settler, and External selector. RESULTS AND DISCUSSION The first version of the DI-SVI prediction model was proposed based on the VWTS-SUMO model (Table 1). The VWTS-SUMO model was re-calibrated by the collected data from the full-scale WWTPs. According to the site data, the model can reliably predict SVI before the densification process (Figure 1) for both MABR and MBR applications. However, modified equations should be used after the densification process since the SVI (i.e., settleability) in the full-scale WWTPs was improved significantly. For instance, the SVI can be reduced from 101 mL/g to 65 mL/g while the DI increases from 30% (typical DI in an aeration tank of CAS) to 50% in a densified MABR WWTP (Figure 2a). It should be noted that the densification process in this full-scale WWTP has not reached a steady state since the operating time for the densification process was around 7 months for the MABR plant and 5 months for the MBR plant. An updated model will be proposed by VWTS with more field data. In addition to the settleability improvement by the densification process, a modified VWTS-SUMO model will be developed to predict carbon, nitrogen, and phosphorus removal.

The study developed a densification model to predict the performance of biomass densification, a technology that improves sludge settleability and increases the capacity of secondary clarifiers in wastewater treatment plants. The model, based on the growth kinetics of various microorganisms, was calibrated with data from full-scale wastewater treatment plants.

SpeakerGuo, Hui

Presentation time

13:30:00

13:50:00

Session time

13:30:00

15:00:00

SessionMechanistic Modeling Developments for Newer Processes

Session number410

Session locationRoom 244

TopicAdvanced Level, Biosolids and Residuals, Industrial Issues and Treatment Technologies, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

Guo, Hui, Donnaz, Sylvain, Shaw, Chris, Astrand, Niclas, Houweling, Dwight

Author(s)H. Guo1, S. Donnaz2, C. Shaw3, N. Astrand4, D. Houweling5, H. Guo1, S. Donnaz2

Author affiliation(s)1Veolia WTS, Ontario, 2Veolia WTS, MT, 3Veolia Water Technologies and Solutions, Ontario, 4Veolia Water Technologies & Solutions, ON, 5Dynamita North America Inc., QC

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159686

Volume / Issue

Content sourceWEFTEC

Word count21

Effect of Hydrocyclones on Floc Size, Morphology, and Microbial Community

Abstract

Objectives Hydrocyclones can intensify activated sludge processes by retaining larger, faster settling flocs and eliminating smaller, slower settling flocs. This can result in lower sludge volume indices (SVIs), higher mixed liquor solids concentrations, higher solids retention time (SRT), and modified mixed-liquor microbial community structures (Roche et al., 2021; Regmi et al., 2022; Li et al., 2020). While it is clear that hydrocyclones improve SVIs, what factors impact separation, and how separation impacts microbial communities, is less obvious. For example, does the relative abundance of heterotrophs, AOB/NOB, and PAOs determine whether a floc is retained in the hydrocyclone underflow? What is more important for floc retention: floc density, size, or shape? Do hydrocyclones affect protozoa? Such information could help program hydrocyclones to promote a desired treatment objective. In order to answer the above questions, we are using dynamic floc imaging, molecular tools, activity test, and floc density analyses to explore the effect of hydrocyclones at a full-scale wastewater treatment plant. We have completed four sampling events and expect to have four more by the time of the conference. This abstract includes our ongoing results. We expect to have full results in time for WEFTEC. Methodology Samples were collected from a full-scale municipal wastewater treatment plant in the Midwest region of the US. The plant was configured for EBPR and implemented a densified activated sludge (DAS) process using hydrocyclones in November of 2022. Starting in May 2023, sampling campaigns for floc analysis were carried out approximately every two months. Four samples have been collected and analyzed at the time of this abstract submission. Sampling included hydrocyclone influent, overflow, and underflow, and MLSS. Floc characterizations were carried out with an integrated laser diffraction analyzer with synchronous dynamic image analysis, i.e., diffraction and imaging were carried out on a single sample at the same time (Microtrac, Germany). By analyzing thousands of individual flocs in each sample, this provides classical particle size histograms, but also a large range of morphological particle parameters, such as circularity, sphericity, roughness, aspect ratio, roundness, and fractal dimension. Microbial community characterization was carried out by 16S rRNA gene sequencing of VSS from the MLSS, hydrocyclone influent, overflow, and underflow. qPCR and FISH were used to quantify AOB, NOB and PAOs. Findings A plot of SVI30, SVI5, and densification index over time is shown in Figure 1. SVIs decreased, and the densification index increased, over time after implementing the hydrocyclones. Floc size characterizations showed that the 50th percentile area-based diameter (D50) increased progressively from 108 µm (May 2023) to 163 µm (December 2023) (data not shown). Based on floc size histograms (Figure 2):

*Hydrocyclones appeared have little separation effect on the smaller flocs (0 — 50 µm). These were present in similar amounts in both overflow and underflow.

*The impact of hydrocyclones on larger flocs increased with time, i.e., there needed to be more large-sized flocs in the MLSS in order for the hydrocyclones to separate them into the underflow. Based on an analysis of floc circularity (Figure 3).

*Smaller flocs tended to be more circular than larger flocs, both in underflow and overflow

*Larger flocs in the underflow tended to be more circular than similarly sized flocs in the overflow, suggesting that floc morphology can play an important role in retention by hydrocyclones.

*Differences in circularity between underflow and overflow increased progressively over time (data not shown) Sampling sequencing data is available for one sampling date (July 2023). Based on these results, the hydrocyclone underflow had higher abundances of AOB, NOB, and PAOs than the overflow (data not shown). Interestingly, NOB (Nitrospira sp.) were more abundant than AOB. Preliminary qPCR and FISH (Figure 4) results are consistent with the sequencing. FISH is currently being used to differentiate the microbial communities for different floc sizes and shapes. Percoll density separation is also being used to quantify and sequence flocs by density. These results will be included in the final paper and presentation. Significance The results suggest that hydrocyclones separate not only based on floc density, but also size and shape. The role of microbial community is currently being analyzed and will be presented at the conference.

This paper was presented at the WEFTEC 2024 conference in New Orleans, LA October 5-9.

SpeakerNerenberg, Robert

Presentation time

11:30:00

12:00:00

Session time

10:30:00

12:00:00

SessionProcess Intensification Using Hydrocyclones

Session number521

Session locationRoom 343

TopicAdvanced Level, Facility Operations and Maintenance, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

Nerenberg, Robert, Schiaffino Pereira, Francisca, Wilburn, Cason, Astrand, Niclas, Badilla Aguilar, Andrei, Bibby, Kyle, Nerenberg, Robert

Author(s)R. Nerenberg1, F. Schiaffino Pereira1, C. Wilburn1, A. Badilla Aguilar1, N. Astrand2, K. Bibby3, F. Schiaffino Pereira1

Author affiliation(s)1University of Notre Dame, IN, 2Veolia Water Technologies & Solutions, ON, 3, IN

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159684

Volume / Issue

Content sourceWEFTEC

Word count11

Description: Floc, Film & Densified Sludge: Combining MABR & Continuous Flow...

Floc, Film & Densified Sludge: Combining MABR & Continuous Flow Densification at the Yorkville-Bristol Sanitary District

Abstract

Membrane Aerated Biofilm Reactor (MABR) and continuous flow densification employ unique mechanisms to deliver process intensification. MABR uses a gas-transfer membrane for oxygen delivery that also serves as a biofilm support to grow a nitrogen removal biofilm that reduces the tank volume required for nitrogen removal. Continuous flow densification selects for densified biomass with improved settling characteristics to increase secondary clarifier throughput. These two intensification approaches have been successfully applied independently. This paper explores how combining the technologies delivers complementary benefits and has the potential to yield process synergies that deliver more value for utilities.

MABR uses a gas-transfer membrane for oxygen delivery that also serves as a biofilm support to grow a nitrogen removal biofilm that reduces the tank volume required for nitrogen removal. Continuous flow densification selects for densified biomass with improved settling characteristics to increase secondary clarifier throughput. This paper explores how combining the technologies delivers complementary benefits and has the potential to yield process synergies that deliver more value for utilities

SpeakerAstrand, Niclas

Presentation time

14:30:00

14:50:00

Session time

13:30:00

15:00:00

SessionApplying Hydrocyclones for Densification

Session locationRoom S501a - Level 5

TopicFacility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design, Nutrients, Research and Innovation

Author(s)

Astrand, Niclas

Author(s)N. Astrand 1; C. McMains 2 ; L. Melcher 2; J. Haggard 3; K. Law 4; J. Gagnon 5; J. Peeters 1; S. Donnaz 5; N. Astrand 1;

Author affiliation(s)Veolia Water Technologies 1; Yorkville-Bristol Sanitary District 2 ; Yorkville-Bristol Sanitary District 2; Yorkville-Bristol Sanitary District 3; Donohue & Associates 4; Veolia Water Technologies 5; Veolia Water Technologies 1; Veolia Water Technologies 5; Veolia Water Technologies 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159209

Volume / Issue

Content sourceWEFTEC

Word count17

MABR-DAS: Coupling MABR & Densification for Enhanced Biological Selection

Abstract

Introduction Membrane Aerated Biofilm Reactor (MABR) and Densified Activated Sludge (DAS) employ different mechanisms to deliver process intensification, both of which are applied independently at full-scale (Astrand 2023). Coupling MABR and DAS (MABR-DAS) is an area of opportunity to bring more value for WRRFs. The first opportunity is to combine the individual features of the technologies to de-bottleneck plant operations where MABR intensifies the biological reactor and DAS intensifies secondary clarification (Donnaz 2020; Roche 2021) and uncouples SRT -- floc and granules which helps with even further intensification of BNR. The second opportunity is to exploit synergies between the technologies to enable intensification that is greater than the sum of the parts and expand the range of WRRF plant configurations that can benefit from intensification. MABR and DAS Process synergies The hybrid MABR-DAS process offers several unique features that enhance biological selection compared to conventional BNR. These features promote a virtuous cycle with densification. Maximize Substrate Gradient in the Feast Zone A high substrate gradient in the feast zone favors the growth of densified biomass. MABR maximizes substrate gradient by reducing recycle flows that dilute substrate concentration. SND in the anoxic zone of an MABR enables nitrate recycle to be eliminated or reduced. Densified sludge enables RAS rates to be reduced. Enhance Anaerobic Conditions and Bio-P MABR enables and improves bio-P and the biological selection of PAOs and GAOs by enhancing or creating anaerobic conditions. Elimination or reduction of nitrate recycle by MABR increases anaerobic HRT. SND and complete denitrification in the MABR zone reduces NOx return in the RAS. The MABR anoxic zone can serve as an extension of the anaerobic volume due to: An ORP gradient along the length of the MABR zone enabled by the attached biofilm, Use of the unaerated volume below the MABR cassettes for fermentation, BNR intensification by MABR enables aerobic volume to be cannibalized for anaerobic and/or anoxic fractions. This allows CAS plants with no or small unaerated volumes to increase the unaerated volume fraction necessary for biological selection. Reduce rbCOD Bleed into the Famine Zone SND in MABR consumes rbCOD for denitrification, preventing it from entering the famine zone. MABR enables increased F/M compared to conventional BNR systems. The seeding effect of the nitrifying MABR biofilm enables operation at lower suspended growth Aerobic SRT and thus higher total F/M for the system. Full-Scale Implementation at the Yorkville-Bristol Sanitary District A full-scale implementation of MABR-DAS has been in operation at the Yorkville-Bristol Sanitary District (YBSD) since 2023. The YBSD MABR-DAS upgrade has occurred in the following stages (Figure 1). (1) Nitrifying CAS. Prior to 2017 the plant was a nitrifying CAS system rated for 3.62 MGD with the biological reactor arranged as ten aerobic tanks in series. (2) MABR. In 2017 the plant was upgraded to MABR and Enhanced Biological Phosphorus Removal (EBPR) to increase the biological capacity by 25% and meet a new phosphorus limit. The biological process was reconfigured to A2O with one reactor anaerobic and one reactor anoxic with MABR cassettes. The plant does not have nitrate recycle. (3) MABR-DAS. In January 2023 densification was implemented to increase the hydraulic capacity by 40% to 5 MGD and improve bio-P performance. In the future, MABR cassettes could be added to increase biological capacity by an additional 20% (145% total). Results from 11 months of operation of the MABR-DAS system are provided below. Sludge Settleability During the first 11 months of MABR-DAS operation, SVI30 decreased from 100 mL/g to 60 mL/g and SVI5 decreased from 250 ml/g to < 100 mL/g. The granule fraction (GF, fraction of solids > 250 µm in size) increased from 35% to 55%, see Figure 3. Figure 4 summarizes the correlation between SVI and GF. The gray data points are from before implementation of MABR-DAS and the blue points are after implementation. The data suggests two phases in the transition of the plant. Phase 1 indicates densification, with selective wasting and washout of filaments when SVI30 decreased from 110 mL/g to 60-75 ml/g with no corresponding change in GF. During Phase 2, GF increased from 35% to around 55%, and this was coincident with a further decrease in SVI. Figure 5 summarizes phosphorus removal performance before and after operation of the MABR-DAS system. Phosphorus removal is achieved by a combination of bio-P and chem-P with bio-P limited by a 10% anaerobic mass fraction. A decrease in coagulant dose since the start of MABR-DAS indicates that bio-P performance has improved with MABR-DAS. Phosphorus release profiles from a kinetic & CFD model demonstrate that the MABR anoxic zone serves as an extension of the anaerobic volume (Figure 6). Alternative mixing strategies in the anaerobic zone improve phosphorus release by a further 15-30% (Duchi 2023). Knowledge Gaps & Opportunities Physical Selection of Nitrifiers Sloughed from MABR Biofilm Adding a Third Dimension to SRT Uncoupling MABR introduces another form of biomass (biofilm) in the activated sludge process. This brings an additional lever to the principle of SRT uncoupling, control the SRT of the biofilm independently from the SRT of the suspended growth

Coupling MABR and DAS (MABR-DAS) is an area of opportunity to bring more value for WRRFs. The first opportunity is to combine the individual features of the technologies, where MABR intensifies the biological reactor and DAS intensifies secondary clarification and uncouples SRT – floc and granules which helps with even further intensification of BNR. The second opportunity is to exploit synergies between the technologies to enable intensification that is greater than the sum of its parts.

SpeakerAstrand, Niclas

Presentation time

09:30:00

10:00:00

Session time

08:30:00

10:00:00

SessionFull-scale Intensification Experience

Session number510

Session locationRoom 343

TopicFacility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design, Nutrients, Research and Innovation

Author(s)