Murthy, Sudhir, Murthy

Dr. Sudhir Murthy is Chief Executive Officer of NEWhub. NEWhub is a cleantech company that specializes in developing, managing and commercializing...

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About Murthy, Sudhir

Dr. Sudhir Murthy is Chief Executive Officer of NEWhub. NEWhub is a cleantech company that specializes in developing, managing and commercializing technologies and know-how for licensed distributors and helps utilities and industries navigate their internal innovation and planning process. Until May 2018, Sudhir was the Innovations Chief for DC Water and led the development and implementation of the Authority’s innovation strategy. Sudhir has a M.S. in Environmental Engineering and Ph.D. in Civil Engineering from Virginia Tech. He is a Professional Engineer and a Licensed treatment plant operator in the USA. Sudhir has approximately 250 publications and 20 patents.

Murthy, Sudhir

Titles from this speaker

Description: Bin the Floc, Boost the Rock: Increasing Activated Sludge Wet Weather Treatment...

Bin the Floc, Boost the Rock: Increasing Activated Sludge Wet Weather Treatment Capacity using Densified Activated Sludge

Abstract

Introduction
The Mangere Wastewater Treatment Facility (WWTF) is a 365 mgd (16 m3/s) hydraulically-rated facility servicing about 1.3 million population equivalents (PE) in Auckland, New Zealand, with plans to add another 250,000 PE. The Mangere WWTF is owned and operated by Watercare Services Limited, which provides drinking, storm, and wastewater services for nearly one-third of all New Zealanders. In addition to its ocean discharge with strict solids, nutrient, and pathogen limits, the WWTF experiences significant and extended hydraulic events due to the combined collection system and the region's propensity for intense and/or extended wet weather events. The management of peak flows, specifically the retention of total suspended solids (TSS) in the secondary process, was identified as a critical facility bottleneck, and planning efforts determined significant capital costs (approximately $160M+ New Zealand Dollars) would be required to construct a new dedicated wet-weather treatment facility using ballasted-floc technology.

To avoid or delay the future ballasted-floc improvements costs and lower carbon emissions associated with construction, Watercare began investigating ways to improve the peak hydraulic capacity in the secondary process. Continuous flow, densified activated sludge (DAS) with selective wasting hydrocyclones (HCs) was identified as a technology approach that may provide the desired secondary hydraulic uplift due to its ability to condition sludge to 'settle like a rock.' However, due to the lack of similar installations, there was uncertainty over the effectiveness of the DAS improvements on Mangere's four-pass, step-feed secondary process. A full-scale DAS trial on about one-tenth of the total facility capacity began operation in the third quarter of 2021 to demonstrate DAS improvement performance at the WWTF. After about 18 months of operation, the trial improvements were successful at reliably lowering the sludge volume index (SVI) from the historical values of 125 to 225 mL/g down to around 75 mL/g or below. This presentation seeks to share design and operational approaches used to gain about 35 percent in additional peak flow treatment capacity within an existing secondary process so that other facilities facing similar challenges may benefit from these efforts.

Liquid Stream Overview
The WWTF's liquid stream consists of influent pumping, preliminary treatment, primary treatment, activated sludge secondary treatment, tertiary filtration, and ultra-violet (UV) disinfection. The secondary process consists of reactor-clarifiers (R/Cs) with circular secondary clarifiers located in the center of the activated sludge reactors. Like many facilities, the secondary process capacity is limited by the settling performance within the clarifiers. The reactors are configured as four-pass, step-feed consisting of eight zones of alternating unaerated and aerated volume. Each of the unaerated zones is fed a portion of primary effluent. Figure 1 displays a layout of three R/Cs, including the DAS trial train (R/C#8). To test the ability to uplift the secondary peak flow capacity, trial DAS improvements on one R/C were developed utilizing reactor mixed-liquor rather than clarifier underflow for the HC feed. Figure 2 contains a photograph of the inDENSE™ HCs installed on temporary scaffolding adjacent to R/C#8.

DAS Trial Results
Once the HC system was installed and commissioned, the volumetric flow and mass splits for the HC equipment were tested, and minor modifications were completed to fine-tune the operation. Watercare operated the DAS upgrades for about one year (until October 2022) before significant improvements in SVI were recorded, but even then, the impact was highly variable with the trial train with higher SVIs than the remaining control basins. Starting in April 2023, SVI values reduced to about 100 mL/g, and over the next three months, SVIs dropped further to between 50 and 100 mL/g, averaging about 75 mL/g. A particle size distribution analysis completed at about 75 mL/g indicated an average granule size of about 100 micron, which is consistent with small DAS granules. Figures 3 and 4 display the DAS particle size results and SVI results from the trial period, respectively. With the improved settling, Watercare realized about a 35 percent uplift in the existing secondary processes' peak flow capacity through a full-scale peak wet-weather demonstration. Throughout the testing period, optimizations were made within the R/Cs to improve DAS performance until the 75 mL/g SVIs were achieved, including:
- Addressed faulty aeration valve actuators
- Increased the dissolved oxygen setpoints in the aerated zones to 1.5 mg/L
- Implemented supplemental clarifier underflow wasting
- Increased HC feed pressure from 30 to 35 psig (2.1 to 2.4 bar)

Next Steps
Given the successes of the DAS trials, Watercare is currently designing plant-wide DAS improvements with HC facilities located on additional R/Cs. Significant hydraulic structure improvements are required to achieve the hydraulic uplift expected with the DAS improvements. Coupled with the hydraulic uplift improvements efforts, new aeration equipment and controls, in-basin equipment, and supporting facilities will be upgraded to improve Mangere's ability to remove nitrogen as well.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

15:30:00

15:40:00

Session time

15:30:00

17:00:00

SessionDensified Activated Sludge Full Scale Performance and Optimization

Session locationMcCormick Place, Chicago, Illinois, USA

TopicLiquid Stream Treatment Technology - Secondary & Tertiary Treatment

Author(s)

Brown, Nathan, Brian, Kevan, Regmi, Pusker, Murthy, Sudhir

Author(s)N. Brown1, K. Brian2, P. Regmi1, S. Murthy3

Author affiliation(s)Stantec Inc.1, Watercare Services Limited2, NEWhub Corp3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Sep 2025

DOI10.2175/193864718825160103

Volume / Issue

Content sourceWEFTEC

Word count18

Converting Rectangular and Circular Primary Tanks Into An AAA Settler

Abstract

INTRODUCTION
As water resource reclamation facilities (WRRFs) look to upgrade or expand carbon removal or nitrification only facilities, they have two paths, one that needs larger biological tank volumes and more energy and to expanding upon existing treatment concepts, or, to otherwise develop a virtuous cycle of technologies that both reduce footprint and intensify treatment but also need less energy and use the chemical oxygen demand wisely. The key to achieving this virtuous cycle is optimizing the first major treatment step of wastewater treatment. Most conventional plants in the United States have a 'primary process' with clarifiers for TSS removal followed by a secondary process for carbonaceous BOD or COD removal to achieve TSS and cBOD5 limits of 30 mg/L. Our value proposition is to enhance the primary treatment step to an alternating activated adsorption (AAA) settler instead to
1) make better use of this infrastructure within the existing hydraulic profile,
2) intensify the biological step,
3) use less energy in the biological step,
4) to produce more gas in a digester,
5) produce 5% thickened solids and
6) replace cumbersome primary mechanical equipment such as chain and flights with air lift sludge withdrawal Carbon Redirection: The goal of the AAA settler is to convert influent soluble COD and ammonia through assimilatory means to particulate heterotrophs in a very compact design (0.5 days solids residence time and two-hour hydraulic retention time) to achieve both carbon and nitrogen redirection. The famous 'Strass' case study of energy positive BNR facility exemplifies this virtuous cycle brought about by the A-stage process combined with deammonification (Wett et al, 2004.). The problem for most A-stage processes is that they are 'bioflocculation' limited (Jimenez et al, 2015) and unable to properly trap this nitrogen containing heterotrophic organisms in a colloidal state. Any process that could improve colloid capture at the same SRT and surpass A-stage performance could provide savings through intensification, aeration and more methane gas production and more resilient series/parallel operations. The rethinking of this primary clarifier removal has been variously proposed with many approaches such as chemically enhanced primary treatment, primary microfiltration sieves, primary fabric filters and contact dissolved air flotation treatment being considered to decrease the carbonaceous inventory to the downstream secondary or biological nutrient removal (BNR) step. The problem with such treatment steps is that they are 'add-on' physical processes that focus on carbon redirection only. Instead, the conversion of the primary into a AAA biological settler can also provide wet weather parallel secondary treatment thus possibly addressing 'blending' considerations. Thus, an optimized 'biological primary' concept should remove and redirect not only carbon but also provide an opportunity for 'parallel' wet weather operations, and 'series' dry weather operation modes to allow for resilience and flexibility in removal of soluble COD. Objectives: The goal of this paper is to describe the design, commissioning and operations of the AAA settler as implemented in 4 plants in Europe and in design in 10 additional plants. The paper will describe the implementations in both rectangular and circular configurations. Mass and energy balances will be provided to help engineers understand opportunities to realize both energy savings and space savings to enhance treatment capacity.
METHODOLOGY
The AAA settler uses a floc-filter to improve colloid capture by feeding the influent at the bottom while withdrawing the treated effluent at the top in a primary converted into a constant water level reactor with an alternating feed/withdraw cycle that spans half the time and a react/settle/waste cycle that spans the other half of the overall cycle (see Figure 1). The AAA settler needs a minimum of two primary clarifiers in parallel that are converted to sequenced operation. The primary clarifiers can be either circular or rectangular to achieve this conversion. Fine bubble diffusers are installed at the bottom of the tank to provide both air and mixing. No mechanical equipment is needed and the existing and often troublesome sludge scraper equipment is removed. A replacement sludge withdrawal manifold using an air lift system is used to remove the settled sludge and wasted to an adjoining gravity thickener. Thus the effluent half pipe, process reactions, and the sludge withdrawal are managed using the same blower/air system considerably simplifying operations. A gravity thickener is installed in the inner conical section of a circular primary or in the sludge hopper of a rectangular primary to achieve thickening to 5% or greater solids content. Figure 1 shows the schematic of this process with alternating operating cycles and the bottom feed piping.
RESULTS Figure 2 shows the performance of the AAA process in Rottenburg, Germany with influent and effluent COD and Nitrogen (left y-axis) and 67% COD removal and 30% nitrogen removal. This high removal in the absence of any chemicals is attributed to the floc-filtration phenomenon where the colloids that contain mostly heterotrophic organisms that have nitrogen containing proteins and usually escape in the effluent are now trapped within the sludge blanket of the AAA process. This enhanced removal is a key feature of the AAA process. Figure 3 shows a Sankey diagram comparing a conventional primary + BNR plant, an A-stage + BNR plant, and a AAA + AvN controlled BNR plant. The figure shows A-stage 54% COD removal and 22% nitrogen removal with a downstream COD/N ratio = 6.7. The AAA removes 61% COD and 30% N with a downstream COD/N ratio = 6.1. The secondary volume requirements with a AAA settler is roughly 50-60% of the volume required with a conventional primary, resulting in a very compact overall process that can be seamlessly employed for nitrification, phosphorus removal or nitrogen removal permits.
CONCLUSIONS
There are now 14 AAA settlers in various stages of implementation with 4 fully operational in both circular (one plant at Strass, Austria, Figure 4) and rectangular configurations (three plants operational) in Europe. The AAA settler is now one of the fastest growing new technologies in Europe, doubling every 0.5 years, as simultaneous concerns of urban growth and climate change mitigation increase its attractiveness to utilities. The AAA settlers uses existing primary tank hydraulic profile and infrastructure (of two-hour hydraulic retention time) and converts it into a constant water level process, sequenced contact stabilization biological process with no mechanical equipment and with an included gravity thickener. The full presentation will describe the learnings from these conversions with particular attention paid to regulatory drivers from a systems perspective for design.

The Triple A settler is an 'activated primary' and stands for Alternating Activated Adsorption (AAA) and can be retrofitted into existing primary tanks t a hydraulic retention-time of 2 hours and a solids residence time of 0.5 days to achieve approximately 50% increase in capacity of downstream biological process. Biosorption and bioflocculation provides the key added value in pre-treatment efficiencies of ca. 60/25/33 in %COD/%N/%P removal.

SpeakerMurthy, Sudhir

Presentation time

09:00:00

09:20:00

Session time

08:30:00

10:00:00

TopicAdvanced Level, Energy Production, Conservation, and Management, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

Murthy, Sudhir

Author(s)Bernhard Wett1; Peter Aichinger2; Sudhir Murthy3

Author affiliation(s)ARAconsult, Innsbruck, Austria1; ARAconsult, Innsbruck, Austria2; NEWhub Corp., Herndon, VA3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158519

Volume / Issue

Content sourceWEFTEC

Word count11

Description: DAS in cold wastewater BNR to increase capacity at Gold Bar WWTP — myth or...

DAS in cold wastewater BNR to increase capacity at Gold Bar WWTP — myth or reality?

Abstract

ABSTRACT: This paper presents two years of operational data at a large full-scale facility in cold climate for implementation and optimization of DAS.

BACKGROUND: The Gold Bar WWTP in Edmonton Canada, operated by EPCOR, treats average and peak flows of 78 and 264 MGD, respectively. Secondary treatment consists of 11 BNR bioreactors each with their own clarifier. Seasonal settleability constrains system capacity with poor settling (SVIs over 250 mL/g - Figure 1) occurring during the cold wastewater period (Figure 2) when spring run-off and wet weather events occur. With the WWTP nearing capacity and facility expansion constrained, DAS was identified as the preferred intensification approach. However, DAS is an emerging technology with site-specific results and limited full-scale applications for cold wastewater BNR facilities the size of Gold Bar WWTP. To address the risk, EPCOR proceeded with a full-scale DAS pilot on a single train. Installation and commissioning of the inDENSE™ hydrocyclone technology, as depicted in Figure 3, was completed in June 2023 and the technology validation program commenced. Methodology and findings from Year 1 of the full-scale trial has been presented (Hunter, et al. 2024). As per the Year 1 results, the test train average SVI during cold wastewater was 150 mL/g, consistently 50 to 90 mL/g lower than the control. Sludge settling speed analysis indicate significant improvement and potential capacity increase of 12.5 to 22.5%. However, stress testing was limited to a 10% increase before unforeseen circumstances were encountered. To confirm the capacity increase, EPCOR extended the full-scale pilot to address the unforeseen challenges and stress test the system in cold wastewater. The intent of this paper is to present the objectives, methodologies, and findings of Year 2 of the testing program.

METHODOLOGY: Year 2 of the testing program includes four phases: 1) Optimization, 2) Benchmarking, 3) Stress Testing, and 4) Wet Weather. Stress Testing includes a phased approach to increase the flow and load to the test and control train. Wet Weather operates at the newly defined treatment capacity during the extended spring run off period. Monitoring of parallel operation is completed with routine analysis and intensive testing as described in the Year 1 testing work. In addition, bioreactor sCOD profiles were added for Year 2 testing to indicate carbon utilization through the bioreactor. Monthly biomass microscopic analysis (imaging, morphology, filamentous) and particle size distributions (PSD) were completed on the test and control ML and the inDENSE™ underflow and overflow.

RESULTS: The first two phases of the Year 2 testing program have been completed. The Year 1 detrimental challenges were addressed including:
- Challenging SRT control. With high RAS solids concentrations and long SRTs, the wastage rate reduced below pump system limits. Intermittent feeding was implemented but SRT control was inconsistent. Dilution water was incorporated into the inDENSE™ feed sludge line.
- Unconditioned sludge transfer. When a parallel secondary treatment train was removed from service, a significant portion biomass was transferred to the test train and negatively impacted settleability and clarifier blanket stability. New dewatering pumping systems were employed.

Process optimization changes included:
- Reduced RAS rates were employed in Year 1 of testing. With notable DAS performance improvements including increased RAS compaction, reduction in nitrate load to the anaerobic zone, and improved plug flow conditions, the Year 2 testing program continued with reduced RAS rates.
- Intermittent mixing of the first two unaerated zones was implemented in Year 1 of testing to improve biological phosphorus removal by decoupling the anaerobic SRT and providing inline fermentation. Without notable improvements to phosphate release, the zones were returned to continuous mixing for Year 2 to target a higher F/M ratio.
- Partial swing zone aeration was implemented in Year 2 of testing. The second anoxic zone has mixers and two aeration grids but is typically mix only. By aerating the second grid, the aerobic SRT increases for more stable nitrification and enhanced feast to famine. In addition, partial nitrification and free ammonia have been correlated to the growth of M. Parvicella which is the dominant cold wastewater filament at the facility.
- High DO concentration in the first aerobic zone was implemented in Year 2 of testing to mitigate M. Parvicella growth. High DO concentrations in the swing zone target immediate oxidization of residual carbon following the biological phosphorus and denitrification processes.
- Reduced NMLR rates were employed in Year 2 of testing to improve plug flow conditions and limit continuous anoxic/aerobic sequencing. NMLR rates were reduced by 50% to match average primary effluent rates. The settleability results for Year 2 (Figure 4) with a notable SVI reduction of 30 to 80 mL/g (15 to 45%). Microscopic imaging completed in Dec 2024 (Figure 5), clearly reveals the presence of granules in the test train and an abundance in the inDENSE™ underflow. PSD analysis confirms the microscopic imaging results.

SUMMARY: Year 2 results clearly demonstrate that the use of a hydrocyclone and biological selection result in denser sludge with increased settling speeds. With promising results, the Year 2 Stress Testing is targeting 20% capacity at 12 C.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

15:40:00

15:50:00

Session time

15:30:00

17:00:00

SessionDensified Activated Sludge Full Scale Performance and Optimization

Session locationMcCormick Place, Chicago, Illinois, USA

TopicLiquid Stream Treatment - Nutrient Removal and Recovery

Author(s)

Hunter, Mike, Xheko, Julian, Opyr, Luke, Regmi, Pusker, Molla, Saif, Shu, Trevor, Sanche, Dagny, Katyal, Ranveer, Murthy, Sudhir

Author(s)M. Hunter1, J. Xheko1, L. Opyr1, P. Regmi1, S. Molla2, T. Shu2, D. Sanche2, R. Katyal2, S. Murthy3

Author affiliation(s)Stantec Inc.1, EPCOR Water Services2, NEWhub Water Corporation3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Sep 2025

DOI10.2175/193864718825160117

Volume / Issue

Content sourceWEFTEC

Word count16

Description: Process Densification and Emerging Contaminant, PFAS and EE2, Management in...

Process Densification and Emerging Contaminant, PFAS and EE2, Management in Wastewater Treatment using Reactive Migrating Carriers

Abstract

Abstract
In addressing stringent environmental regulations, aging wastewater treatment infrastructure, and heightened sustainability goals, advanced biological nutrient removal (BNR) systems have emerged as essential components for modern water reclamation facilities (WRFs). This abstract delves into the innovative application of reactive migrating biocarriers for process intensification to combat increased flows. The objective of this study was to utilize granular activated carbon as migrating carrier to simultaneous achieve nitrogen management and micropollutants removal. The model micropollutants used were short and long chain PFAS compounds, and one synthetic estrogen EE2. The findings outline operational strategy, key findings, challenges, and valuable lessons derived from this effort.

Background
There is an urgent need to increase the capacity of existing WWTPs and achieve process intensification through densification and efficient nitrogen management. Much of the infrastructure associated with WWTPs was built between the 1940s and 1970s. Most Wastewater Treatment Plants (WWTPs) in the U.S. need significant upgrades in terms of the treatment of wastewater to accommodate population growth (e.g., increased flows), industrialization, and more stringent effluent regulations for nitrogen management. There is an increase in concern for managing micropollutants, especially for treatment plants discharging into sensitive waterbodies. Expanding existing WWTPs through new construction is often not feasible due to space and budget limitations related to high infrastructure costs. We use granular activated carbon (GAC) as migrating reactive carriers to accomplish densification-intensification. The reactive or absorptive media such as cellulosic plant-based such as hemp or kenaf and granular activated carbon add to the removal mechanisms and are less expensive, and environmentally friendly compared to the use of plastic carriers. The use of migrating carrier allowed for SRT decoupling between slow (such as nitrifiers) and fast-growing organisms (thus enabling shorter floc-based SRT), as well as enabled the sorption of micropollutants to increase their localized concentrations.

Approach
Two identical lab-scale plexiglass SBRs (2H/D ratio, 3L working volume) were operated at room temperature (22±1oC) in Dr. Goel's lab. 2 g/L of GAC was added in RAC. Both RAC and RC were operated in an anaerobic-anoxic-oxic (A2O) process. Each cycle was comprised of 6-h, involving 9-min of anaerobic synthetic wastewater feeding, 51-min of anaerobic, 50-min anoxic (by dosing nitrate to mimic internal recycling), 229-min of aerobic, 20-min of settling, and 1-min of effluent discharge. The DO levels were maintained in the 0.4 to 0.6 mg/L range in oxic phase to achieve simultaneous nitrification and denitrification (SND) with P removal. The targeted feed concentrations of EE2 and each PFAS were 5 µg/L and 50 ng/L, respectively. The hydraulic retention time (HRT) was 10-h, and the solids retention time (SRT) was maintained at 10-d by wasting sludge through a 500 µm sieve.

Important findings and discussion
The migrating reactive carrier concept is fundamentally different from moving bed biofilm reactors (MBBR). Unlike inert plastic carriers, the reactive migrating carrier concept is a novel concept. In reactive migrating carriers, the media supporting biofilm is reactive (i.e., adsorptive). Reactive or absorptive carriers can interact with various dissolved contaminants, especially micropollutants.
- Both RC and RAC showed nearly similar removal efficiencies for organic carbon (represented by COD), ammonium, ortho-P, and total inorganic nitrogen (TIN). TIN and ortho-P removals signify the presence of active denitrification and enhanced bio-P removal (EBPR) activities in both reactors. A typical complete cycle analysis for both reactors in terms of nutrients, organic carbon and EE2 is shown in figure 1. GAC supplemented migrating carrier reactor had much higher granulation >500µm (nearly 87 % as compared to 52 % in the control based on volatile suspended solids) than in the conventional reactor.
- The short-chain PFAS compounds passed through both reactors without showing any removal (figure 2). However, nearly 40 to 50 % removal of long-chain PFAS compounds was recorded consistently in both reactors, with the GAC-supplemented reactor (red dots) showing consistently higher removal than the other reactor (blue dots) over more than 100 days of feeding. Similar observation for EE2. The primary removal mechanism of both types of micropollutants from the bulk liquid was adsorption on GAC and granules followed by potential biodegradation revealed by batch tests. The long-chain PFOA and PFOS concentrations in the biomass (including GAC biofilm) were 413.58±12.3 and 474.39±11.7 ng/g TSS in the RAC- and 31.2±8.8 and 36.3±3.9 ng/g TSS in the RC control SBR respectively. We also conducted a mass balance on long-chain PFAS in RAC based on concentrations in the influent, effluent and measured concentrations of both long-chain PFAS in the biomass. Based on this estimate, we concluded that although the immediate mechanism of removal is sorption to the biomass/biofilm, other processes, such as biodegradation, are also contributing to the disappearance of PFAS parent compounds.

Conclusion: The use of GAC intensify the process and micropollutant management is creative and presents the next generation of innovation in wastewater.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

08:30:00

08:45:00

Session time

08:30:00

10:00:00

SessionInnovative Approaches to Micropollutant Removal in Wastewater

Session locationMcCormick Place, Chicago, Illinois, USA

TopicResearch

Author(s)

Goel, Ramesh, Quereshi, Tayyab, Goswami, Anjan, Murthy, Sudhir, Giraldo, Eugenio

Author(s)R. Goel1, T. Quereshi1, A. Goswami4, S. Murthy2, E. Giraldo3

Author affiliation(s)University of Utah1, NEWhub Corp2, Carbon Materials LLC3, Bron and Coldwell4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825159976

Volume / Issue

Content sourceWEFTEC

Word count17

Seeking Nitrification and Excess Biological Phosphorus Removal in Cold Weather Using Densified Sludge Control

Abstract

Introduction The Gold Bar wastewater treatment plant, operated by EPCOR in Edmonton, is an advanced secondary treatment facility with a capacity to process an average of 310 MLD (82 MGD) and a peak capacity of 420 MLD (111 MGD). As one of the largest cold climate treatment plants, it faces operational challenges during temperature drops, particularly in maintaining nitrification processes, which has led to periodic issues with the sludge volume index (SVI) averaging 270 ml/g, prompting the testing of inDENSETM hydrocyclone technology to enhance treatment capacity and maintain low SVIs during colder weather. Continuous flow wastewater treatment processes using biological and physical selectors, including density selectors like hydrocyclones, optimize treatment by accumulating dense biomass while removing lighter forms, leading to improved process efficiency and the retention of crucial organisms for effective nutrient removal (Regmi, et al., 2022) (Gemza, Janiak, Zieba, Przyszlak, & Kusnierz, 2022) (Roche, Donnaz, Murthy, & Wett, 2021) (Daigger, et al., 2023) (Regmi, et al., 2022). This full-scale application will confirm the effectiveness of the plant's design that utilizes InDENSE technology. Additionally, the full-scale pilot seeks to investigate the impact of selective wasting on two process parameters: 1) Increasing the treatment capacity (flows and loads) of a continuous flow activated sludge system through improved settleability and improving the quality and kinetics of the biomass inventory. 2) Understanding the structure of the densified sludge and slow growers at a biological level through DNA sequencing and microbial ecology. Methodology The inDENSETM hydrocyclone technology has been added to Train #2 as depicted in Figure 1. The implementation of inDENSE technology in this full-scale pilot encompasses: 1) commissioning of the inDENSE system and gathering data, 2) Making operational changes to the return activated sludge (RAS) flow and adjusting the feast and famine ratio, and 3) Separating the anaerobic SRT by intermittently mixing for 30 minutes per day. This is aimed at enhancing the anaerobic mass fraction, sustaining nitrification, and improving treatment efficiency. One objective of the technology validation is to quantify the sludge settling speed and compactability improvement using tall settling column tests and developing the Vesilind relationship. At increased settling speeds and higher compaction, the secondary clarifier can operate safely at higher solids loading rates (SLR) without risk of thickening failure. At higher SLRs, the bioreactor MLSS concentration and biological treatment capacity can be increased. Results and Discussion The data from Train #2 (Figure 2) between June and December 2023 shows that using an external selector, such as a hydrocyclone, led to significant improvements in the quality and densification of the sludge. Initially, the sludge had bulking issues with SVI values ranging from 100 to 250 ml/g. However, in addition to inDENSE implementation, applying intermittent mixing and reducing RAS rates, the SVI improved dramatically, stabilizing in the range of 100-150 ml/g, even as the temperature dropped from 19ºC to 14º over the five-month period. Moreover, the hydrocyclone allowed for the separation of the SRT, resulting in the denser granular fraction having a higher SRT compared to the flocculent fraction. This separation, made possible by the hydrocyclone, improved the settling characteristics of the overall biomass as the flocculent particles were more effectively removed. The data clearly demonstrates that the use of an external selector, particularly a hydrocyclone, had a positive impact on the quality and densification of the sludge in Train #2, as seen in the improved SVI values and the enhanced settling behavior of the biomass. The data presented in Figures 3 and 4 demonstrates that the system effectively meets effluent nitrogen requirements despite variability, and the use of a hydrocyclone in enhanced biological phosphorus removal (EBPR) results in consistent effluent phosphorus concentrations below 1 mg P/L with a higher capacity and abundance of phosphorus accumulating organisms (PAOs). The hydrocyclone's operation allows for the retention of denser, more-desirable PAO fractions in the system, creating favorable selection pressure for enhanced biological phosphorus removal. To gain further insights into the EBPR stability and reliability and nitrification performance, this study will extend to perform various stages of tests which further intends to provide sufficient information to allow an assessment of the performance improvement. The information will allow a rational determination of the additional flows and loads that could be accommodated by a bioreactor/secondary clarifier system equipped with selective sludge wasting versus the baseline provided by a conventional treatment train. Conclusion The introduction of hydrocyclones led to an improvement and stabilization in settling, to reduce seasonal variations, allowing for increased process capacity, and supporting higher mixed liquor suspended solids (MLSS), while uncoupled SRT enhanced process resiliency and improved carbon and energy efficiency, although further research is required for validation.

With population growth, stricter effluent criteria, and the Gold Bar WWTP footprint, an inDENSETM hydrocyclone pilot was initiated. Continuous flow BNR treatment with biological and physical selectors, facilitate accumulation of dense biomass, allowing for intensification. This paper presents densification results to improve settleability and biological performance for cold wastewater. Results indicate a capacity increase of 12.5 to 22.5 percent but stress testing was limited to 10 percent.

SpeakerHunter, Mike

Presentation time

11:00:00

11:30:00

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)

Hunter, Mike, Xheko, Julian, Tang, Esmond, Opyr, Lukian, Izadi, Parnian, Andalib, Mehran, Molla, Saif, Sanche, Dagny, Katyal, Ranveer, Lester, Amy, Murthy, Sudhir

Author(s)M. Hunter1, J. Xheko2, E. Tang3, A. Lester4, L. Opyr5, P. Izadi6, M. Andalib7, S. Molla4, D. Sanche4, R. Katyal8, S. Murthy9

Author affiliation(s)1Stantec, AB, 2, AB, 3Stantec LtD, 4EPCOR Water Services, AB, 5Stantec Ltd, 6Stantec LtD, ON, 7Stantec, MA, 8EPCOR, Alberta, 9NEWhub Water Corporation, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159622

Volume / Issue

Content sourceWEFTEC

Word count15

Base text size -

Murthy, Sudhir

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