Partners and Clients

– CH2M Hill
– Black and Veatch
– Malcolm Pirnie
– Brown and Caldwell
– Mongomery Watson
– Watstech
– Stearns & Wheler
– Waterways
– InCtrl Solutions Inc.

– Pima County, Arizona
– Grand Forks, North Dakota
– Bridgeport, Connecticut
– Los Angeles, California
– Northeast Ohio Regional Sewer District, Ohio
– Gatineau, Quebec
– Athens, Greece
– Bucharest, Romania
– Semidao, France


Water Companies
– Severn Trent Water
– Yorkshire Water Services
– Mekorot Water Co Ltd
– Waterschap de Dommel

– Organica Water Inc.
– Praxair
– Environmental Operating Solutions, Inc.

Sample Projects

Project: MSDGC modelling support (QA/QC)
Plant location: Cincinnati, OH
Client: Metropolitan Sewer District of Greater Cincinnati (MSDGC) (Primodal contracted through Malcolm Pirnie / Arcadis).
The Metropolitan Sewer District of Greater Cincinnati (MSDGC) is developing calibrated process models for its seven treatment plants. The model development will be executed in two phases by Hazen&Sawyer and Hydromantic. During the first phase models for four plants will be developed, namely Taylor Creek, Indian Creek, Polk Run, and Little Miami. Primodal is providing advice to MSDGC on the model objectives, model reliability and applicability. Primodal is also providing QA/QC services on the delivered models. The process models will be used for a wide variety of tasks such as future planning for wet weather and nutrient removal, operations assistance, and upgrade design.

Project: Supplemental Carbon Model Development
Client: Environmental Operating Solutions (EOSi)
Environmental Operating Solutions manufactures and markets external carbon additives for enhanced denitrification and biological phosphorus applications in the wastewater treatment field. With the onset of process model use for design, EOSi saw a need to develop a model that could be used in conjunction with their products. Primodal was hired to develop this customized biokinetic model for both GPS-X and BioWin (the two most widely used simulation packages in the North American market). A conceptual model drawn from Primodal’s experience with biological systems in general and the modeling of those systems specifically was developed and implemented in these two packages by Primodal. Primodal’s work on the model at full-scale facilities is on-going with an aim to ensure that the model is able to predict the actual behavior of a system that requires an EOSi product. Once verified, the model will prove to be a valuable tool for optimization of the carbon feed system as well as a means to quantitatively compare carbon alternatives.

Project: Strongford Storm Flow Modelling
Plant location: England, UK
Client: Severn Trent Water (STW)
The Strongford Wastewater Treatment Plant (WWTP) treats domestic wastewater from two main areas; Newcastle under Lyme and the southern part of Stoke on Trent. The plant has occasionally exceeded its BOD permit during storm flows. The goal of this project was to investigate the reasons for these failures using the existing process model, provided by Severn Trent.
However, a new model of the Strongford WWTP was developed due to deficiencies in the provided model for the project purpose. A storm profile constructed from Strongford flow data and real storm concentration data from a UK municipal wastewater treatment plant was incorporated into the layout. The storm profile also included a first flush event. Unequal flow splitting of the SAS centrate and unequal influent flow splitting during rain events were coded into the model and simulated. The modelling work suggested that the BOD compliance issues could be the direct result of flow splitting issues and the overloading of one of the trains during storm events. With equalised flow splitting the model suggested that the plant could cope with the simulated storm and could cope with untreated digester centrate even during a storm.

Project: Modelling the Dan Region WWTP
Plant location: Tel Aviv, Israel
Client: Mekorot Water Co. Ltd.
The Dan Region WWTP is unique in its significance to Israel’s water supply. The plant produces very high quality effluent that is used for aquifer re-charge and irrigation. Mekorot Water Co. Ltd. has decided to use a mathematical model to investigate the impact of the planned future upgrades. These upgrades will add a full sludge treatment chain to the existing plant including primary sedimentation. In addition, Mekorot wanted to investigate the potential for operational optimisation of the Dan Region WWTP. In summary, the main objectives of this project were to develop a dynamic, calibrated model for the Dan Region WWTP; to use the developed plant model to investigate the planned upgrades; to investigate potential operational savings by using the model to optimise plant operations and finally to use the model for general knowledge acquisition and operational support. The project is currently in progress.

Project: Modelling the Psyttalia WWTP
Plant location: Athens, Greece
Client: Hydroelectrica Ltd.
Psyttalia WWTP serves the greater metropolitan area of Athens, Greece and is located on a dedicated island off the coast of Attica. The plant has a design flow of 1,000,000 m3/d and includes liquid and solids treatment lines. Hydroelectrica Inc. serves as special advisor to the owner (the Greek water authority, EYDAP). They wanted to use a mathematical model to investigate options for the optimisation of the treatment plant as well as alternatives for future upgrades including the implementation of enhanced biological phosphorus removal. The project involved the development of a calibrated model and the implementation of this model to investigate current operational problems as well as their resolution. A second objective involved the investigation of future expansions to improve effluent quality and be able to meet future TN and TP effluent standards. The project is currently in progress.

Project: Modelling the Shawville Wastewater Treatment Plant
Plant location: Québec, Canada
Client: CIMA Engineering Consultants
A model of the Shawville wastewater treatment plant was developed and calibrated for CIMA Engineering Consultants. The calibrated model was used to evaluate plant capacity and suggest future plant expansions. These alterations would be necessary if the plant was required to treat additional flow resulting from future domestic and industrial development (abattoir waste). In particular, the model was used to evaluate how much of the projected future flow and load could the plant treat without alterations and what would be the most immediate upgrades required in order for the plant to be able to treat all of the expected future flow and load.
Model results suggested that the existing aeration tank volume could provide adequate sludge retention time to treat the expected future flows and loads to the current effluent standards as well as to the anticipated future ammonia effluent standard, provided no inhibitory substances were present in the wastewater. Furthermore, the calibration and evaluation work highlighted several areas requiring attention prior to the plant accepting increased flows. These areas were the aeration system and the final tank surface area. Further evaluation of the impact of the oil and grease fraction of the abattoir wastewater on the sludge settling properties, the impact of the pH variations of the abattoir wastewater on nitrification and the influent stoichiometry of the abattoir waste were also recommended.

Project: Modelling the Clay Mills Pilot Plant and New ASP
Plant location: England, UK
Client: Severn Trent Water (STW)
Clay Mills STW serves the town of Burton-upon-Trent and takes trade waste discharges from numerous industrial traders including breweries and food manufacturing. The existing biological filters were to be replaced with a diffused air ASP plant to be operated in BNR mode. A pilot plant was set-up and operated in BNR mode to provide Severn Trent Water information for undertaking ASP modelling work. Severn Trent Water’s goal for this project was to investigate, using a mathematical model, the impact of load and temperature changes on the performance of the new Clay Mills ASPs.
A calibrated model of the Clay Mills pilot plant was developed using data from the pilot plant. In calibrating the model several aspects were addressed including settling behaviour of the flocs, influent fractionation / characterisation, pH, temperature and peroxide impacts on the default autotrophic growth rate, nitrogen removal mechanisms in the un-aerated stage and model parameter adjustments. During the calibration process several conflicting issues with respect to nutrient levels within the process train were observed. After consultation with STW and a visit to the Clay Mills pilot plant, it was concluded that the most likely explanation for the measured data was unintentional back-mixing due to a large gap at the base of the pilot plant weirs.
The aim of developing the calibrated pilot plant model was to use that model as a means to estimate the behaviour of a yet-to-be-built full-scale facility. In this regard, the calibrated pilot plant model was subjected to proportionally-scaled flows and used to investigate the impact of BOD load and aerobic SRT on effluent quality parameters, sludge production and ASP volumes. Another goal of this project was to investigate the impact of the Coors brewery wastewater on plant behaviour. The influent was split into three components (domestic wastewater; Coors and other traders), the model predicted that load had little impact on the effluent quality, but did have a significant impact on the required airflows and aeration system taper.

Project: Modelling the Bridgeport East Side WWTP
Plant location: Bridgeport, Connecticut, USA
Client: Stearns and Wheler
Bridgeport United Recycling, Inc. (BUR) processes waste oil and other petroleum products and discharges its wastewater to the Bridgeport East Side Wastewater Treatment Plant (WWTP).  The objective of this study was to model the Bridgeport East Side (BES) WWTP and evaluate the impact of the BUR discharge on the nitrogen removal capabilities of the plant at low temperatures. The detailed project objectives were to develop a calibrated model for BES and to use the model to predict plant performance for several load conditions with and without the BUR contribution. The plant nitrification and denitrification capacity for each of these loads as predicted by the model was recorded. The model highlighted the need for several critical site evaluations such as aeration system upgrades, final clarifier hydraulic evaluations as well as determination of the variability of the BUR influent stoichiometry.

Project: Modelling the Tadcaster Trade Wastewater Treatment Facility
Plant location: England, UK
Client: Hydromantis Inc. and Yorkshire Water
The Tadcaster Trade Wastewater Treatment Facility (TWTF) treats waste from three Tadcaster breweries and occasionally suffers from poor settling.  The goal of this project was to investigate the reasons for this poor settling and the conditions that encourage filamentous bacteria proliferation in this facility, using a process model. The main objectives of this project were to analyse the operational strategies, wastewater quality, process, operational and decision making data from the Tadcaster facility to develop a calibrated GPS-X model of the Tadcaster TWTF and to correlate, if possible, operational and/or process issues at the facility to filament proliferation with an aim to provide Yorkshire Water with insight into settling issues at the plant.
By using the calibrated model, several aspects of plant operations were identified as potentially contributing to the growth of the filamentous microorganisms. In particular, the DO levels in the aeration basins, sulphide and volatile fatty acid concentrations leaving the balancing tanks and the TKN content of the biomass. More specifically, model results pointed to the need to further evaluate the aeration system and whether it was able to supply sufficient DO to discourage low DO filamentous growth. A further investigation into the operation of the balancing tanks was also recommended. The presence of Thiothrix and of sulphur granules in the filament cells indicated that waste septicity may have been an issue. Lastly, the model identified that nitrogen levels may have been limiting within the system as nutrient limitations are not uncommon in industrial facilities.

Project: Washington Suburban Sanitary Commission: Western Branch WTP Enhanced Nutrient Removal Evaluation
Plant location: Washington DC, USA
Client: Metcalf & Eddy / AECOM (M&E)
The Western Branch Wastewater Treatment Plant (WTP) services a population of approximately 160,000. The plant is a three-sludge system with high rate, nitrifying, and denitrifying/nitrogen stripping sections. The plant owners have embarked on a plan to investigate upgrade options that would enable the plant to meet new effluent standards under current and future loading conditions. In an effort to better understand the current process behaviour, Metcalf & Eddy / AECOM (M&E) has developed a mathematical wastewater treatment model of the facility. Primodal’s task in this project was two-fold: i) to check the model calibration developed by M&E and supplied to Primodal; and ii) to calibrate a separate model using a different customised model approach.
During the calibration task several model adjustments were made to allow for the production of soluble organic nitrogen in un-aerated basins. It was also found that the modeled rate of aerobic hydrolysis of particulate organic material had to be reduced to limit the demand for nutrients in the high rate and nitrifying sections of the plant. The model calibration step also highlighted the atypical composition of the wastewater which included a very high inert content.

Project: Development of two customized operator interfaces for the Roger Road WWTP and Ina Road WWTP
Plant location: Tucson, Arizona, USA
Client: PIMA County
The objective of the project was to develop two operator interfaces for the GPS-X layouts developed for the Roger and Ina Road sites. The operator interfaces were developed in the Java programming language and had fully customized functionality and appearance. The actual layouts and scenarios used by the interfaces and the functionality and appearance of the interfaces were specified during on-site scoping exercises. Following layout updates and interface development, site meetings were conducted to receive feed back from operations staff. Site staff suggestions were incorporated and a final training session was organized at the time of the installation of the software.

Project: Modelling the Minworth Wastewater Treatment Facility
Plant location: England, UK
Client: Severn Trent Water (STW)
Minworth STW is Severn Trent’s largest sewage treatment works, serving a population equivalent of approximately 1.8 million people and also treating sludge for approximately 2.5 million people. The load to the facility is mostly domestic but there are various trade inputs. Severn Trent Water (Technology and Development) wanted to investigate options for upgrading the Minworth Wastewater Treatment Facility from its current treatment with an aim to improve final effluent ammonia. As one step in this process, Severn Trent Water wanted to use a process simulation model to investigate possible process changes that will help achieve this goal.
The aim of this project was to investigate expansion possibilities for the Minworth facility. A previously calibrated model (2003) of the Minworth Wastewater Treatment Facility formed the basis for the work on this project. Several things were updated in the 2005 version including several model default parameter values and aeration information. The model was subjected to various full-scale flow, load and storm scenarios and used to investigate the impact of aeration, expansion volume and temperature on several process quantities including effluent quality, sludge production and oxygen requirements.