Schraa, Oliver

Oliver Schraa is the Chief Technical Officer at inCTRL Solutions and is a licensed professional engineer in the Province of Ontario. He has over 26 years of experience in wastewater treatment plant design and costing, modeling and simulation, optimization, and process control. Oliver is the vice-chair of the WEF Plant Operations & Maintenance Committee and the chair of the Instrumentation and Control Workgroup in WEFs Municipal Resource Recovery Design Committee.

Titles from this speaker

Description: Dynamic Blower Design: Using Modeling to Establish the Blower Operating Window Under...

Dynamic Blower Design: Using Modeling to Establish the Blower Operating Window Under Varying Loading Scenarios

Abstract

The San Jose Creek East Water Reclamation Plant (SJCWRP) is a tertiary treatment plant designed to treat 237 ML/d (62.5 MGD) with the actual dry weather flow being around 164 ML/d (43.3 MGD). As part of a planned upgrade of the plant’s aeration system, SJCWRP contracted inCTRL Solutions Inc. to undertake a modeling and simulation study to support decision-making during the project. An integrated dynamic model of the treatment process, the aeration system, and the process controls was developed in SIMBA#. The model was used to determine the cause of effluent ammonia spikes, to develop system curves for the aeration piping network, to select the best blower curve from the manufacturers’ options, to test a proposed blower control strategy and find the location of the most-open valves, and to identify pipes causing relatively large pressure drops in the system. The integrated dynamic model of the process and its aeration system allowed analysis of the system under realistic dynamic loading and accounted for interactions between the treatment process, the aeration system, and the aeration system controls. This type of analysis is not possible if the different systems are modeled separately and at steady-state conditions only. The work is significant because it shows the benefits of using an integrated model of a water resource recovery facility, that includes a detailed and fully dynamic aeration piping network model, when analyzing and upgrading aeration systems and their controls.

SpeakerSchraa, Oliver

Presentation time

13:00:00

13:30:00

Session time

11:00:00

12:00:00

SessionNot Just Blowing Hot Air: Aeration Design and Optimization

Session number7A

TopicEnergy Production, Conservation, and Management, Facility Operations and Maintenance, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

L. RiegerO. SchraaO. SchraaG. HopeB. LouieT.E. Weiland

Author(s)L. Rieger1; O. Schraa2; O. Schraa2; G. Hope3; B. Louie4; T.E. Weiland4;

Author affiliation(s)inCTRL Solutions Inc, ON1; inCTRL Solutions Inc., ON2; LACSD, CA3; LA County Sanitation District, CA4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157550

Volume / Issue

Content sourceWEFTEC

Word count16

Performing a High-Level Risk-Assessment for an Activated Sludge Aeration System

Abstract

In this study a high-level risk assessment was performed for the aeration system at the Village Creek Water Reclamation Facility (VCWRF). Current issues include the lack of blower redundancy, the age of the blowers, and the presence of significant air leaks that could not be quantified. The objectives of the study were: (1) to perform a risk assessment of the current blowers and aeration system, (2) to develop a detailed aeration system and treatment process model to establish air demands, calculate air leaks, and evaluate current blower capacity, and (3) to evaluate the options to upgrade the aeration system and perform a life-cycle cost evaluation. The risk assessment illustrated the need to make the system more reliable. Due to the lead time associated with both new blowers and blower rehabilitation, an emergency plan to rent temporary blowers was developed. Dynamic simulations quantified the air demands and air leaks, established the need for more blower capacity in the future, and demonstrated the location of the most-open valves in the system. The air demands calculated by the model were used as inputs in the evaluation of the upgrade options for the aeration system. The life cycle cost evaluation found that adding two new blowers to handle the base load and using rehabilitated blowers to handle the peak loads was the best option. The significance of the work is that it shows how detailed modeling of processes, aeration systems and controls can support aeration system risk assessments to allow more informed decision-making. The detailed aeration model was essential to the study as it quantified the system’s air capacity and the air leaks in the system, identified inaccurate flow meters, demonstrated control system performance under realistic dynamic loading, and allowed evaluation of the impact of other air consumers on the DO control system performance.

SpeakerSchraa, Oliver

Presentation time

10:10:00

10:30:00

Session time

08:30:00

10:30:00

SessionOptimizing Energy Through Advanced Aeration Control

Session number508

TopicEnergy Production, Conservation, and Management, Facility Operations and Maintenance, Intelligent Water, Municipal Wastewater Treatment Design

Author(s)

O. SchraaO. SchraaJ. GassV.T. GuntupalliA. ShawA. Pena-TijerinaR. Redder

Author(s)O. Schraa1; O. Schraa1; J. Gass2; V.T. Guntupalli2; A. Shaw3; A. Pena-Tijerina4; R. Redder5;

Author affiliation(s)inCTRL Solutions Inc., ON1; Black & Veatch, MO2; Black & Veatch, TX3; Fort Worth Water, TX4; Village Creek Water Reclamation Facility, TX5; N/A, TX6; inCTRL Solutions Inc, ON7; inCTRL Solutions Corp, CT8; Dundas, Canada, L9H7H9, CT9; Black & Veatch, PR10

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157482

Volume / Issue

Content sourceWEFTEC

Word count11

Predicting Full-Scale MABR Performance: How Good Are MABR Models?

Abstract

Background
The Yorkville Bristol Sanitary District (YBSD) wastewater treatment plant converted from a fully aerobic conventional activated sludge configuration to a hybrid membrane aerated biofilm reactor (MABR) in the Fall of 2017. The MABR upgrade was chosen to increase the capacity of the plant and to meet a tighter effluent limit while utilizing the existing aeration tank volume and not increasing the plant's energy consumption. The plant is now configured as an A2O process with an anaerobic tank, an anoxic tank with MABR cassettes, and eight aerobic tanks in series. The plant also includes mechanical bar screens, wedge wire drum screens, final clarifiers, ultraviolet disinfection, gravity belt thickening (GBT), autothermal thermophilic aerobic digestion (ATAD), and dewatering centrifuges. The full scale YBSD MABR has been in operation for four years, which makes it the largest and the longest operating MABR in the world. The design, construction, and start-up of the YBSD MABR installation was discussed in detail by Underwood et al. (2018). The MABR process uses a selectively permeable membrane as a media to provide two main functions: 1) to support the growth of a biofilm, and 2) to provide aeration to the biofilm by molecular diffusion through the membrane wall which has high selectivity to oxygen. The biofilm is counter-diffusional where oxygen is supplied from the membrane media (inner) side of the biofilm and substrate, namely ammonia, enters the biofilm from the bulk wastewater.
The counter-diffusion provides a favorable environment for nitrifiers near the membrane surface due to the high concentration of oxygen and protection from detachment, predation, and competition (Cole et al., 2002). At the same time, denitrifying heterotrophic bacteria are favored in the anoxic region of the biofilm near the interface with the bulk liquid and within the suspended biomass allowing for simultaneous nitrification and denitrification within the same reactor (Cole et al., 2002). Oxygen transfer is highly efficient because of the large surface area for oxygen transfer provided by the membrane and the high permeability of the membrane to oxygen. The water resource recovery industry is becoming increasingly interested in the mathematical modeling of MABR systems to assist with their design and operation. For MABR models to be trusted and adopted by engineers and operators, it is important that they be calibrated and validated using full-scale data. To date, few published studies have validated MABR models against full-scale dynamic data. As a result, the YBSD MABR dataset represents an ideal opportunity to calibrate and validate an MABR model.
Objective
The current study focuses on long-term modeling of the YBSD MABR. The objective is to calibrate and validate a dynamic MABR model using operating data from the YBSD MABR to demonstrate the model's predictive capabilities so that it can be trusted for process design, troubleshooting, control strategy design, and optimization.
Model Calibration and Validation
A full-plant model for the YBSD wastewater treatment plant, including the MABR process, was developed in SIMBA# (See Figure 1). The MABR is modeled using a 1-D biofilm reactor model with counter-diffusion and membrane aeration. The SIMBA# MABR model combines three sub-models: (1) the aeration sub-model, (2) the biofilm sub-model, and (3) the bulk liquid sub-model. The biofilm sub-model allows input of oxygen from the membrane-side of the biofilm and counter-current diffusion. The aeration sub-model is based on differential mass and momentum balances along the length of the membrane that include a term for oxygen transfer across the membrane. The bulk liquid sub-model is a completely mixed activated sludge reactor with diffusion into and out of the biofilm. The bulk liquid sub-model optionally can be aerated with normal diffused aeration. More than one year of operating data from the YBSD wastewater treatment plant were used to calibrate and validate the model. The measured influent flowrate and daily composite concentrations, wastewater temperature, RAS and WAS flowrates, membrane airflows and inlet and outlet pressures, were used as inputs to the model. The measured reactor and effluent concentration data, and the oxygen transfer efficiency data were compared to the predicted values from the model. The calibration procedure consisted of the following steps: 1) influent fractionation, 2) entering of the physical dimensions of the plant's tanks and equipment, 3) specification of the membrane surface area and volume, and 3) adjustment of the mass-transfer boundary layer thickness to match the nitrogen concentrations throughout the plant. All other biofilm reactor and bio-kinetic parameters were left at default values. The initial conditions for the dynamic simulation were generated by running a steady-state simulation.
Results and Discussion
The results of the calibration for the mixed liquor suspended solids (MLSS), MABR total ammonia nitrogen (NHx-N), MABR oxygen transfer efficiency (OTE), effluent NHx-N, and effluent nitrite and nitrate nitrogen (NOx-N) are given in Figures 2 to 6, respectively which show the measured and simulated data. As shown, there is a good agreement between the measured and simulated MLSS, NHx-N, NOx-N concentrations and the OTE considering that no bio-kinetic or biofilm model parameters were adjusted from their default values other than the mass-transfer boundary layer thickness. Figure 4 shows that the fit between the modeled and measured OTE is quite good overall, but that the fit is not quite as good between about 80 and 140 days and this will be further investigated in the full paper. The trends in the one-year data set are captured very well and indicate that the model can simulate the nutrient removal processes occurring in the system and the membrane aeration process. In the full paper, additional results will be presented on the calibration of the model to the excess biological phosphorus removal observed in the plant and the validation of the model using additional data from the YBSD wastewater treatment plant.
Conclusions and Significance
The dynamic MABR model in SIMBA# was calibrated using more than a year of full-scale operational data from the Yorkville-Bristol Sanitary District wastewater treatment plant. With the adjustment of only the boundary layer thickness, the model was able to predict the dynamic performance of the MABR across a range of loading conditions and temperature. Model validation has been done and will be shown in the full paper. The work is significant because it enables engineers to confidently use the model in the design, operation, and control of MABR processes which are becoming attractive due to their potential to increase plant capacity within existing footprints while minimizing any additional energy requirements. The model will allow the analysis of optimization potentials and subsequently support the more wide-spread use of MABR technology in wastewater treatment and resource recovery.

The dynamic MABR model in SIMBA# was calibrated using more than one year of full-scale operational data from the Yorkville-Bristol Sanitary District wastewater treatment plant. The MABR model predicts the dynamic performance of the MABR across a wide range of loading conditions and temperatures. The work is significant because it enables engineers to confidently use the model in the design, operation, and control of MABR processes.

SpeakerSchraa, Oliver

Presentation time

14:40:00

14:50:00

Session time

13:30:00

15:00:00

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

Author(s)

Schraa, Oliver

Author(s)Oliver Schraa1; Matthew Reeve2; Niclas Astrand2; Cyrus McMains3; Leiv Rieger1; Carsten Owerdieck1; Jens Alex4

Author affiliation(s)inCTRL Solutions Inc., Dundas, Ontario, Canada1; SUEZ Water Technologies & Solutions, Ontario, Canada2; Yorkville Bristol Sanitary District, Yorkville, IL3; ifak e.V., Magdeburg, Germany4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158677

Volume / Issue

Content sourceWEFTEC

Word count10