Vellacott, Aprilia, Vellacott

Aprilia is a Principal Process Engineer with experience in the planning, design, commissioning and optimisation of sewage treatment plant. In...

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About Vellacott, Aprilia

Aprilia is a Principal Process Engineer with experience in the planning, design, commissioning and optimisation of sewage treatment plant. In particular, over the past 3 years Aprilia has concentrated on high energy efficiency plants, from WTP Stage 2 and Stage 3, Wollert STP options assessment to operational assistance during commissioning of the Sarina MBR in Queensland. She has specialised interest in advanced biological nitrogen removal, including ‘nitrite shunt’ and Anammox / Mainstream Deammonification processes. ########She has significant experience in the modelling of odour and corrosion in sewers, strategy development, air emission modelling, conducting environmental design risk assessment and project management.

Vellacott, Aprilia

Titles from this speaker

Description: Low Energy Nitrogen Removal: A New Industry Benchmark For Above 35 MGD Wastewater...

Low Energy Nitrogen Removal: A New Industry Benchmark For Above 35 MGD Wastewater Treatment Plants

Abstract

INTRODUCTION
Melbourne Water's Western Treatment Plant (WTP) treats approximately 140 MGD (530 ML/day). As population increases, the flows and loads to the WTP increase applying pressure to existing treatment assets. This presents an ongoing challenge to Melbourne Water meeting its environmental obligations, whilst minimizing energy usage in line with Melbourne Water's Net Zero GHG target. The Joint Venture (JV) of CPB/UGL and Jacobs was selected by Melbourne Water following an 18 month Innovation Competition. The new 37 MGD (140ML/d) advanced step feed process, called 160S Nutrient Removal Plant (NRP), was constructed over 2017/2018, and commissioned in early 2019. The JV, with assistance from Jacobs and under the review of Melbourne Water, operated the plant for a two year Proof of Performance (PoP) Period. Over this two year period the plant achieved the stringent requirements prescribed by Melbourne Water including effluent quality and energy usage requirements. This paper provides an overview of the design and key learnings over two years of operation including: efficient process and advanced controls design (including ammonia based aeration control) and carbon efficient nitrogen removal (enabling higher upstream carbon diversion), significant energy savings compared with the Water Services Association Australia (WSAA) guideline targets for energy efficient treatment processes, setting a new benchmark in energy efficient operations. In North America the typical benchmark for energy usage is based on treated flow, this example provides a best practice data point for nitrogen removal energy efficiency.
CASE STUDY DETAIL
The $AU153M project (total project cost), added 37 MGD (140ML/d) of treatment capacity and was commissioned in April 2019 (See Figure 1). The following highlights the key features of the facility design: 1) An atypical 'doughnut' circular reactor clarifier design, considered beneficial due to its lower footprint and concrete requirements per unit of treatment capacity. 2) The step-feed BNR process selected for the design allowed for significantly reduced tankage requirements, due to the higher biomass retained in the first three passes at higher MLSS concentrations. 3) The facility included a simple single feed pump station (capable of feeding one or two feed sources from the upstream lagoons to the bioreactors), followed by gravity flow through the bioreactor, clarifier and finally to the downstream maturation lagoons. Moreover, the only other pumping required was for return activated sludge (RAS), as WAS is removed by gravity flow back to the upstream lagoons and no internal mixed liquor recycle pumping is required again owing to the step-feed nature of the process design. 4) The design included advanced aeration controls for efficient low dissolved oxygen process which minimized the aeration requirements (including ammonia based aeration control, ABAC), which results in both capital (reduced blower and diffuser sizing) and operating (minimized the aeration requirements) costs. The advanced controls and monitoring provides three key benefits: 1) Allows the facility to maximize endogenous carbon utilization efficiency per tonne of nitrogen removed. This provides the opportunity to maximize carbon captured in the upfront anaerobic lagoons for supporting overall site energy neutrality objectives, 2) Provides extremely high efficiency aeration per tonne of nitrogen removed, and, 3) Provides an operator friendly process for the Melbourne Water Operations team. The 2 year PoP Period was an innovative contractual approach that ensured whole of life cost and performance objectives for the new facility would be achieved. Over this two year period (April 2019 - April 2021), the plant achieved all treated water discharge quality requirements, including a greater reduction in total nitrogen concentration than its target (see concentration limit Figure 2). With advanced controls the low DO operation provided stable and complete ammonia removal, with the stringent monthly average effluent ammonia requirement of <1.0 mgN/L being achieved (see Figure 4). This enhanced nitrogen removal performance was achieved by: 1) Flexibility to feed from two feed sources, namely the middle and the end of the upstream anaerobic lagoon as this provided different carbon (COD) feed concentrations and COD fractions to the process. The ability to control the blending of the two feed sources using online influent TOC and effluent nitrate monitoring ensured that the target total nitrogen removal was achieved whilst minimizing carbon and energy requirements. This maximized carbon capture in the anaerobic lagoon which increased biogas production and resulted in greater electricity generation from on-site power generation. This was critical to the overall plant achieving almost energy neutrality. A trend of the kg rbCOD per kg TN removed is shown in Figure 3. 2) Low DO operation using advanced aeration controls promoted stable Simultaneous Nitrification and Denitrification (SND) and maximized aeration efficiency whilst meeting nitrification requirements (See Figure 5). The advanced controls and low DO operation also provided stable and complete ammonia removal, with the stringent monthly average effluent ammonia requirement of <1.0 mgN/L consistently met (see Figure 4). SND operation at low DO is being assessed for N2O emissions to further optimize process controls for reduced GHG emissions. Table 1 compares the 160S NRP energy usage to that of recently published Australian wastewater treatment plant energy benchmarking data (de Haas et al, 2018). The energy use is materially lower than the benchmarking study average and proposed (interim) target values. The WSAA guidelines provide alternative benchmarking targets based on specific energy use relative to nitrogen load removed. This allows for comparison of energy use for nitrogen load removed providing an important efficiency indicator where influent characteristics vary across plants. In North America energy use at wastewater treatment facilities is typically evaluated based on kWhr per ML treated. The WEF MOP 38 (Sustainability and Energy Management for Water Resource Recovery Facilities) includes a table of on-site energy production unit estimates including Best Practices. Based on the process steps of Influent pumping, Activated sludge with nitrification and secondary clarification, typical energy usage for the plant would be 341.3 kWhr/ML, or 195 kWhr/ML for Best Practice (Best Practice based on a 50% improvement). The Melbourne Water plant's Year 2 energy usage per ML of 233 kWhr/ML is slightly higher than the Best Practice target value, however it is important to note that the influent wastewater strength to the plant is significantly higher than typical North American with an average COD of 986 mg/L and TKN of 86 mgN/L.
SUMMARY
The innovative cost effective design, efficient process performance and elegant layout makes 160S NRP a benchmark example facility for other water utilities faced with similar challenges including constrained capacity, energy neutrality, GHG emissions reduction and stringent discharge quality compliance. This Case Study provides confidence that stringent effluent ammonia limits can be reliably met using low DO SND operations as part of cost effective and innovative major augmentation solution.

A new 37 MGD (140ML/d) advanced step-feed treatment plant has been constructed to augment Melbourne Water's Western Treatment Plant (WTP). The plant includes innovative design concepts to reduce CAPEX and advanced controls to optimise both carbon and energy utilisation efficiency. This Case Study provides confidence that stringent effluent ammonia limits can be reliably met using low DO SND operations and establishes a new benchmark in energy use of 3.2 kWhr/kgN removed.

SpeakerVellacott, Aprilia

Presentation time

14:25:00

14:40:00

Session time

13:30:00

15:00:00

TopicAdvanced Level, Energy Production, Conservation, and Management, Facility Operations and Maintenance, Municipal Wastewater Treatment Design, Nutrients

Author(s)

Vellacott, Aprilia

Author(s)Aprilia Vellacott1; Guy Fazzino2; James McLeod2; Ajay Sharma3; Andrew Kennedy4; Damien Sharland1; John Myers1; David Lynch1

Author affiliation(s)Jacobs, Melbourne, Australia1; Melbourne Water Corporation, Melbourne, Australia2; formerly CPB/UGL JV, Melbourne, Australia3; CCPB/UGL JV, Melbourne, Australia4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158661

Volume / Issue

Content sourceWEFTEC

Word count16

Description: Short Cut Nitrogen Removal — Design for and Initial Results from Full Scale...

Short Cut Nitrogen Removal — Design for and Initial Results from Full Scale Implementation at Melbourne Water's Western Treatment Plant

Abstract

Introduction
As part of an augmentation of the Western Treatment Plant (WTP) in Melbourne, Australia, Melbourne Water ran a successful Short-cut Nitrogen Removal (SCNR) demonstration plant from 2017 to 2020. The demonstration plant achieved sustained Nitrite Oxidising Bacteria (NOB) out-selection resulting in highly carbon efficient nitrogen removal (Vellacott et. al, WEFTEC, 2019).

Carbon diversion for energy recovery is already practiced at WTP with methane capture from the anaerobic lagoons generating electricity for on-site use, achieving 80 to 100% energy neutrality historically. To meet tightening effluent Total Nitrogen requirements, more carbon efficient nitrogen removal is required, or carbon will need to be diverted from energy recovery to provide additional carbon required for increased nitrogen removal.

The SCNR trial demonstrated a 40% reduction in the carbon required for nitrogen removal, meeting the required lower effluent nitrogen targets, with a lower feed COD:TKN than typically fed to the existing activated sludge plants. The trial also demonstrated that the effluent quality targets, including effluent ammonia <1mgN/L and nitrite <1mgN/L were met without effluent polishing. Based on these results the key findings from this trial have been adopted in the design of a 150 ML/d activated sludge plant augmentation, called the 5W Nutrient Removal Plant (NRP). The plant is currently under construction (refer Figure 3), with process commissioning to commence in late January 2025.

#This paper will outline the key findings from the trial and their impact on the detailed design of the 5W NRP, the modelled achievement of plant energy neutrality and the results of the first 8 months of operation.

#Background/Method
A SCNR demonstration plant was designed with extensive Biowin™ modelling (Regmi et. al, 2017, WEFTEC) and constructed comprising a primary sedimentation tank (used only when feed solids exceed design levels), secondary treatment comprising a bioreactor configured as A/O and secondary clarifiers, with Anammox MBBR polishing to meet the effluent quality requirements.

The demonstration plant was designed to promote NOB out-selection including use of the findings of the WERF Mainstream Deammonification report on the recipe for suspended growth short-cut nitrogen removal, which included; 'a residual ammonia (>2mg/L) to ensure high AOB activity and continuous DO competition for NOB. Facilities with a lower ammonia limit will require a polishing step to remove ammonia' (WERF, 2015). The demonstration plant operated for approximately 2.5 years. During this time NOB out-selection was achieved over four distinct periods, the first three of shorter duration, before a sustained period of 205 days (until the end of the trial).

Over the key sustained period of NOB out-selection, the trial plant operated with an average influent COD:TKN ratio of 6.0, maintained an average NOB:AOB activity rate ratio of 0.26 and achieved an 86% TN removal with a 'COD efficiency' of 5.6 kgCOD/kgN removed. This compares with the best baseline period where the plant operated with an average influent COD:TKN ratio of 6.9, maintained an average NOB:AOB activity rate ratio of 1.05 and achieved 78% TN removal with a 'COD efficiency' of 8.4 kgCOD/kgN removed. Improved results were observed over a shorter period where the plant operated with a lower influent COD:TKN ratio. With an average influent COD:TKN ratio of 4.3, maintained an average NOB:AOB activity rate ratio of 0.17 and achieved 89% TN removal with a 'COD efficiency' of 4.2 kgCOD/kgN removed. (Refer Figure 1).

For the detailed design of the 5W NRP detailed process modelling was undertaken in BioWin and Sumo. Due to the variable effluent quality from the anaerobic lagoons, a number of influent quality scenarios were modelled. It was estimated from process modelling that operating the 5W NRP with a high level of SCNR, with a low COD:TKN influent (average COD:TKN of 4.3) results in a 40% aeration saving compared with operation at a higher COD:TKN influent (average COD:TKN of 8.5) and full nitrification/denitrification, resulting in an approximate 30% reduction in plant energy demand. In addition to the energy savings from operating the plant with the lower feed COD:TKN ratio, SCNR allows for the primary treatment process to be operated to maximise carbon diversion to biogas (to achieve the lower influent COD:TKN), resulting in an average of 52 MWhr/day in potential additional energy generation, compared with operation at the higher COD:TKN range to achieve the effluent TN target without SCNR. The plant has been designed with the flexibility to operate to promote SCNR, as well as conventional full nitrification and denitrification.

Conclusions
Trialling of the emerging SCNR process at WTP resulted in key findings that have been adopted in the full scale detailed design of the 150 ML/d 5W NRP augmentation at WTP. Successful operation, under low feed COD:TKN with SCNR is expected to provide an unprecedented energy efficient nitrogen removal process and allow for greater upstream carbon diversion to increase energy generation by approximately 52 MWhr/day (for the 150 ML/d plant capacity), providing ~180% energy neutrality. Refer Figure 3. The plant will commence process commissioning in January 2025, the final paper and presentation will include the results of the first 8 months of operation.

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

Presentation time

16:00:00

16:15:00

Session time

15:30:00

17:00:00

SessionFull-Scale Shortcut Nitrogen Removal

Session locationMcCormick Place, Chicago, Illinois, USA

TopicLiquid Stream Treatment - Nutrient Removal and Recovery

Author(s)

Vellacott, Aprilia, Christy, Nathali, Kar, Josh, Short, Tony, Tipping, Andrew, Coventry, Kris, Sharland, Damien, Lynch, David

Author(s)A. Vellacott1, N. Christy2, J. Kar2, T. Short2, A. Tipping2, K. Coventry2, D. Sharland1, D. Lynch1

Author affiliation(s)Jacobs Engineering Headquarters Office1, Melbourne Water2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Sep 2025

DOI10.2175/193864718825159984

Volume / Issue

Content sourceWEFTEC

Word count20

Tacking Fugitive Methane Emissions at WRRFs - Global Lessons

Abstract

Fugitive methane emissions from sludge treatment and biogas handling processes are a significant source of GHG emissions, particularly critical for WRRFs with anaerobic digestion. Sewer methane production can also contribute to significant GHG emissions for the entire wastewater systems. There is lack of consistent methodologies for quantifying and monitoring these emissions in North America, which could lead to over- or (more likely) underestimation of their contributions to the overall GHG footprint. Ongoing work in Europe show the criticality of direct methane emissions monitoring, and operational approaches to mitigate methane emissions through regular survey, proactive leak detection and repair and independent certification. This session will present an overview of the sources of fugitive methane emissions in collection systems and at WRRFs, available methodologies in monitoring and quantifying fugitive methane emissions (including challenges and issues), and practical tips for reducing methane emissions based on global case studies.

This paper was presented at WEFTEC 2023 in Chicago, IL.

SpeakerLake, Amanda

Presentation time

13:30:00

15:00:00

Session time

13:30:00

15:00:00

SessionGlobal Approaches to Tackling Fugitive Methane Emissions

Session locationRoom S402a - Level 4

TopicIntermediate Level, Sustainability and Climate Change, Water Reuse and Reclamation

Author(s)

Lake, Amanda

Author(s)A. Lake 1; C. Scheutz 2 ; B. Beelen 3; E. Shen 4; P. Nielsen 5; A. Vellacot 6; A. Fredenslund 7; K. Kraemer 8;

Author affiliation(s)Jacobs 1; Technical University of Denmark 2 ; GHD 3; Jacobs 4; VCS Denmark 5; Jacobs 6; Technical University of Denmark 7; GHD 8;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825158977

Volume / Issue

Content sourceWEFTEC

Word count10

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