Wednesday, November 9, 2022
Technical Sessions
W1: High Recovery RO
IWC Rep: Scott C. Quinlan, P.E., TetraTech, Pittsburgh, PA
Session Chair: Wayne Bates, Hydranautics, Rockton, IL
Discussion Leader: Richard (Rick) L. Stover, Ph.D., Gradiant Corporation
Time: 8:00 AM – 12:00 PM
High Recovery RO is becoming more prevalent as a design goal. MLD and ZLD systems are becoming more popular as the industry is being asked to maximize water recovery and minimize the volume of liquid concentrate (brine) that requires disposal. This session reviews current concentration methods with an emphasis on the use of RO membrane technologies upstream of industrial waste thermal, evaporative and salt precipitation methods and in seawater brine mining for the recovery of valuable minerals.
IWC 22-61: Case Study: 96% Recovery of Power Plant’s Cooling Tower Blowdown with an Advanced Reverse Osmosis Demonstration Plant
Liron Ophek, IDE Water Technologies, Kadima, Israel
The power industry is considered one of the most intensive water consuming industries in the world. However, due to water shortage, growing regulations and related effluent discharge and makeup water costs, power plants require to manage their net water consumption in the most efficient way.
The major water consumer in a power plant are the cooling towers, which are also producing the majority of wastewater as cooling tower blowdown (CTBD).
During the cooling process the water is significantly concentrated inside the cooling towers, resulting in water effluents characterized by high scaling potential arising from Silica, gypsum, hardness and alkalinity, as well as high bio-fouling potential resulting from the open nature of the cooling towers.
The straight-forward way for power plants to save water is to efficiently treat the CTBD and reuse it back to the cooling towers as makeup water. However, due to the challenging water composition of the CTBD, conventional membrane technologies are limited with achieving high water recovery.
IDE developed a membrane-based technology, The MAXH2O DESALTER, that allows achieving high recovery of CTBD and reuse most of it back as makeup, thus reducing the OPEX associated with cooling towers in a power plant.
The technology contains a single stage reverse osmosis system, with an integrated salt precipitation unit. This technology operates by recirculating the CTBD through RO system followed by a fluidized bed reactor in which controlled precipitation of supersaturated sparingly soluble salts is performed.
This cyclic process, which occurs in small and controlled intervals, allows for a continues concentration and precipitation of the salts that are limiting the recovery without increasing the scaling and biofouling potential seen inside the membranes, therefore, enabling extremely high recovery rates beyond 95%.
The produced by-product solids contain over 90% solids, which lead to easy and cost-effective disposal without additional sludge minimization processes.
This paper presents the results of a 48m3/day MaxH2O Desalter demonstration unit in a power plant in Chile which operated for 60 days (24/7) to achieve a 96% recovery of the CTBD.
With conventional technologies, scaling of the membranes would have limited recovery to ~55-60%. At 96% recovery, the theoretical saturation indices reach to LogSI ~3.2, CaSO4 SI ~ 2990% and SiO2 SI ~ 1400% therefore, achieving such a high recovery at these conditions presents a viable and revolutionary solution that can significantly affect the costs and operation associated with CTBD in power plants and in the industry.
IWC 22-62: Mine Water Treatment using Ultrahigh-pressure RO Membrane (UHPRO) system optimizing the size of the downstream Thermal Evaporation System
Mahesh Bhadane, Aquatech International LLC, Canonsburg, PA; M. N. Rao, Aquatech International LLC, Canonsburg, PA; Arun Mittal, Aquatech International LLC, Canonsburg, PA; Charles Desportes, Aquatech ICD, Hartland, WI; Shannon Miko, Niobec, Canada
The Mine Water Desalination Project was awarded by Niobec, Inc. to supply a modularized water treatment system capable of desalinating underground mine water according to the performance specification. The Niobec mine is located in the municipality of Saint-HonorĆ© approximately 200 kilometers north of QuĆ©bec City. It is the only underground niobium mine in the world, and one of three main global producers. The underground operation produces saline water very high in TDS (about 20-40 g/L), total hardness, sulfate, sodium and chloride along with heavy metals. Temperature of the mine water ranges from -2 to 23 Ā°C. Mine water treatment system is provided to treat the highly contaminated mine water to comply with discharge requirement of chloride and TDS.
The mine water treatment solution provided with the lowest life cycle cost (CAPEX and OPEX) includes two (2) advanced technologies, an ultra-high pressure reverse osmosis units (UHP-RO) followed by a forced circulation thermal evaporators. RO systems use both seawater (SWRO) and ultrahigh-pressure (UHP-RO) membranes specifically designed to minimize the brine flow to the downstream thermal evaporation system (TES). UHP-RO unit is designed to operate at pressures range from 110 bar to 118 bar. Concentrate TDS concentrations in the UHP-RO reject stream feeding the thermal system range from 90 g/l to 105 g/l. This is the first full-scale industrial application in North America where an ultrahigh-pressure RO membrane system is being used. The TES system designed to concentrate the UHP-RO Reject produced by the MWTS into a concentrated brine.
This paper demonstrates, how advanced membrane technology, combined with thermal evaporators can successfully process challenging highly contaminated mine waters while respecting effluent disposal limits and customer goals and objectives.
Discusser: Ryan Schipper, Barr Engineering, Leo, IN
IWC 22-63: Case Study: High Recovery PFRO for Brine Minimization in a Semiconductor FAB
Tomer Efrat, IDE Technologies, Kadima, Israel; Vitaly Levitin, IDE Technologies, Kadima, Israel; Marina Shulman, IDE technologies, Kadima, Israel; Gal Greenberg, IDE Technologies, Kadima, Israel; Avi Hamu, IDE Technologies, Kadima, Israel
The presented case study refers to a brine minimization solution implemented in a semiconductor FAB in Israel using 2 x 360gpm PFRO units, in order to treat and minimize the end brine of the FAB wastewater treatment plant while maximizing the water reuse back to the process.
The feed water to the PFRO system is a blend of BWRO brine, after treating MBR water, and cooling tower blowdownā both with high scaling potential and high risk for biofouling. The objective of the project was to treat the brine blend and to achieve recovery rate of 50% while maintaining high availability and permeate water quality.
During XX 2021 2 x 360gpm PFRO units were commissioned in the semiconductors FAB and are in continues operation ever since while meeting all guaranteed parameters.
In this case study, we will present the project, its objectives, and challenges and analyzed performance data from the first months of operation.
Discusser: Alison Ling, Ph.D., P.E., Barr Engineering, Minneapolis, MN
IWC 22-64: Towards Membrane-Based ZLD: Using Turbochargers to Maximise Recovery in Multi-Stage RO Systems
Rory Weaver, MLitt, FEDCO, Monroe, MI; Eli Oklejas, MLitt, FEDCO, Monroe, MI; Craig Bartels, Hydranautics, Oceanside, CA
This paper demonstrates the use of turbochargers for pressure management in a pilot facility extracting minerals from seawater in Saudi Arabia. Located in Jubail, this facility uses a two-stage RO array incorporating multiple turbochargers to concentrate pretreated seawater from 47,000 ppm to 120,000 ppm. Effective pressure management is key to enhancing the RO membrane performance in this multi-stage, high pressure, high recovery operating environment.
Discusser: Ken Robinson, Avista Technologies, San Marcos, CA
W2: Whatās Hot in Cooling Water Monitoring and Treatment
IWC Rep: Jeff Easton, WesTech, Inc., Salt Lake City, UT
Session Chair: Michael Bluemle, Ph.D., Solenis LLC, Wilmington, DE
Discussion Leader: Mary Jane Felipe, Baker Hughes, Sugar Land, TX
Time: 8:00 AM – 12:00 PM
Cost-effective mitigation of mineral scaling, fouling, corrosion and microbial growth is the fundamental objective of treatment of once through and recirculating cooling water systems. Management of these interrelated processes has become progressively more challenging due to increasingly stringent discharge limits and expanding water scarcity. The four presentations in this session describe the application of innovative phosphorus-free treatment technologies, an online Legionella monitoring system and the development of new corrosion inhibitor dosage models.
IWC 22-65: Field Experiences Using a Novel Non-Phosphorus Cooling Water Treatment
Timothy Eggert, Portland, OR; Robin Wright, SUEZ Water Technology & Solutions, Ponte Verde, FL; Robert Hendel, SUEZ Water Technology & Solutions, Trevose, PA; Paul DiFranco, SUEZ Water Technology & Solutions, Trevose, PA
For decades, cooling water chemical treatment programs have relied mainly on organic and/or inorganic phosphorus-containing compounds. In recent years, phosphorus has become the target of increasing environmental scrutiny resulting in environmental regulators requiring many industrial facilities to drastically reduce the amount of phosphorus in their discharge streams. These environmental pressures and other drawbacks associated with phosphorus-based treatment programs have driven chemical providers in developing substitute cooling water treatment programs that contain less or no phosphorus at all. The non-phosphorus treatment technologies had to not only eliminate phosphorus, but also deliver equivalent or better corrosion and deposit control at an acceptable cost when compared to phosphate-based programs. In addition to this challenging design task, developers needed to provide treatment technologies flexible enough to meet sustainability goals and individual needs of users in various industries. For example, oil refinery and chemical plant users may be focused primarily on phosphate deposition on heat transfer equipment; while an electric power producer may be most concerned about excessive algae growth caused by phosphorus which can negatively impact the cooling tower and downstream water bodies. Several of the programs that have been implemented thus far are adaptations of existing technologies and some utilize chemistries that are less environmentally acceptable than phosphorus itself. This paper describes a novel, non-phosphorus cooling water treatment technology that has shown equivalent or improved performance over a wide range of operating conditions and in different industrial environments. Case studies are presented that describe how the new technology was able to provide transformational improvements that met the unique needs of individual users. Application lessons learned are also reviewed.
IWC 22-66: Use of Polymers for Deposit Control in Once Through Utility Systems
Michael Standish, Radical Polymers, LLC, Chattanooga, TN
For decades, polymers have been used in conjunction with phosphonates to control mineral scale and deposits in a wide range of applications. With the recent supply shortages and logistics issues for phosphonates along with the drive for zero phosphorous, polymers are being used as stand-alone treatments for this purpose. One critical use of phosphonates in the water industry is the control of mineral deposition in once through utility systems. Unlike recirculating cooling water systems, once through systems, are unique in that the scale inhibitor is only required to delay the onset of precipitation (induction time) for a few seconds to effectively control deposition onto condenser tubing. As such, the dosage of scale inhibitor is typically fed in parts per billion levels. This paper covers the methods development and use of a Quartz Crystal Microbalance (QCM) to evaluate a combination of an Enhanced Polymaleic Acid (EPMA) and a high purity sulfonated polymer (HPSP) versus phosphonates and untreated blank samples in synthetic waters representing three separate once through systems in the USA. The data show that the EPMA + HPSP treatment has comparable performance to traditional phosphonate treatments and demonstrates the utility of the use of QCM for evaluating scale inhibitors in ultra-low induction time applications.
IWC 22-67: An Innovative, On-line, Automated Field qPCR Legionella Test Device
Loraine Huchler, MarTech Systems, Inc., Exmore, VA; Etienne Lemieux Ph.D., MBA, BioAlert Solutions
The use of an innovative, on-line, automated field qPCR legionella test device provides the most robust approach to manage the risk of Legionellosis infections. This paper describes the simple operation of this technology, including routine replacement of reagents, maintenance and remote programming, operation and data management. This system has provisions for a maximum of four on-line samples and/or multiple bottles containing grab samples . This paper also documents the results of a field study for an evaporative cooling water system serving a comfort cooling application at the headquarters of a medical device company on the East Coast of the United States. This study compares the automated, on-line field qPCR test results with manual field qPCR test results and laboratory legionella culture test results. This study confirms that very frequent qPCR testing for legionella in evaporative cooling water systems provided important information about the effect of operating and environmental changes.
IWC 22-68: Developing Corrosion Models That Include the Impact of Inhibitors
Robert Ferguson, French Creek Software, Valley Forge, PA; Kaylie Young, ChampionX, Sugar Land, TX
Volumes of information are available in the literature for the computer modeling of scale formation and its control, but few studies have been published on the modeling of corrosion and its inhibition in aerated cooling water systems. Frequent questions from users of water chemistry modeling software include:
What corrosion rates can be expected for carbon steel and common alloys as a functions of water chemistry, temperature, pH, and inhibitor dosage?
What inhibitor dosage will be required to achieve a target corrosion rate?
Can you profile corrosion rate as a function of water chemistry parameters and inhibitor dosage?
What are the relative costs projected to achieve different degrees of corrosion control?
This paper describes experimental designs for the development of the data required to develop models for relative corrosion rates, and the models used to correlate water chemistry to corrosion rates and inhibitor dosage. The model projections are validated through comparison to field observations in the wild. Significance levels for various parameters tested for inclusion in the correlations are discussed.
The models are directed towards aerated cooling water systems.
W2-Reserve: Selecting Cost Effective and Sustainable Industrial Water Treatment Based On an Holistic Approach
Jasbir Gill, Water Energy Solutions, Naperville, IL
Water treatment for any system should not be viewed simply as the addition of scale and corrosion inhibitors, dispersants, or biocides. It requires a thorough knowledge of many simultaneous processes responsible for scale corrosion and biofouling. These processes have a great deal of dependency on each other. The use of impaired waters is increasing due to the shortage of good quality water and for such systems the best solution may require a combination of chemical and non-chemical approaches. Achieving higher cycles of concentration or ZLD may not be the most cost effective and environmentally sustainable due to deploying technologies to clean water that require high consumption of energy or produces green-house gasses in the process. Balancing scaling and corrosion potential along with cycles of concentration may help lower chemical use or no P inhibitors for the treatment The paper discusses a systematic approach to developing a water treatment program by evaluating mechanical, operational, and chemicals parameters and their impact on each other.
W3: PFAS 2: PFAS ā Prescription For Annoying Situations
IWC Rep: Derek Henderson, Duke Energy, Raleigh, NC
Session Chair: Brandon Kern, DuPont, Midland, MI
Discussion Leader: Kristen Jenkins, Brown and Caldwell, Atlanta, GA
Time: 8:00 AM – 12:00 PM
Per- and polyfluoroalkyl substances (PFAS) are long lasting chemicals that break own very slowly over time. They have been widely used and have become quite persistent in the environment. Papers in this session will dive into treatment technologies reviewed and installed to address this growing concern, with a focus on destruction technologies having the potential to make PFAS no longer āforever chemicalsā.
IWC 22-69: Treatment of PFAS, A Review of the Process Lifecycle:Ā Pretreatment, Membranes, Medias, Handling, and Final Disposal or Destruction
Chris Scott, SUEZ Water Technologies & Solutions, Trevose, PA; Elaine Towe, P.Eng., SUEZ Water Technologies & Solutions, Oakville, ON, Canada
The nation and world have become aware that PFAS is in our drinking water, and that its prevalence and impact are growing. Discharge, drinking, handling, and disposal regulations are on the rise globally, and are expected to be issued by central government authorities, such as the US EPA, in more comprehensive forms, within a few short years. The challenge involves both the remediation of spill sites and the augmentation of many existing drinking water facilities.
This paper presentation will provide a comprehensive examination of the traditional and new treatment steps and technologies to achieve complete removal. The key action categories are: Test, Pilot, Treat, Concentrate, Destroy. Best available technologies (BAT) will be reviewed for each step in the process, with an emphasis on efficiency, cost/benefit analysis, and new technologies to enable superior economics. Promising new technologies now under study will be described with some evaluation of their utility and breadth of practical application. Process steps with case studies will also be included, covering the spectrum of influent PFAS concentrations, from lower concentrations, such as in drinking water, to higher concentrations, such as at an air base.
Some technologies that will be explored are: 1) state of the art laboratory testing & identification, 2) concentration of PFAS via ion exchange, reverse osmosis, carbon adsorption; 3) required adjunct technologies such as coagulation, ultrafiltration, chemistry management, and zero liquid discharge.
Discusser: Cathy Swanson, Purolite, Fullerton, CA
IWC 22-70: Destructive Treatment Technologies for Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous Media
Jim Claffey, Ph.D., P.E., Brown and Caldwell, Ramsey, NJ; Kevin Torrens, BCEEM, Brown and Caldwell, Ramsey, NJ; Krystal Perez, P.E., Brown and Caldwell, Seattle, WA; Andrew Safulko, P.E., Brown and Caldwell, Lakewood, CO
A major challenge associated with PFAS propagating through the environment, largely as part of the water cycle, is their high recalcitrance to conventional water treatment processes, including coagulation, media filtration, biological or chemical oxidation. Current best available technologies for PFAS treatment are mainly based on adsorption and separation, including granular activated carbon, anion exchange resins, other novel adsorbents, and reverse osmosis. However, these processes do not destroy PFAS, but instead concentrate them in the form of residual wastes (e.g., exhausted adsorbents, RO concentrate). These wastes require additional management and treatment, which is often costly and not without risk.
In order to break PFAS cycling to the environment, PFAS must be either sequestered or destroyed. Placement of separated PFAS in secure landfills that incorporate PFAS removal from leachate is one approach for sequestration but the PFAS compounds remain in their original form. For this reason, there is an urgent need to develop destructive treatment technologies that can disrupt the movement of these contaminants in the water cycle by breaking PFAS down into less toxic, potentially biodegradable products, and ultimately mineralizing them into water, hydrofluoric acid, and carbon dioxide.
Numerous destructive treatment approaches have been proposed in recent years. However, their mechanisms, effectiveness, and applicability are not yet well understood. Performance demonstration projects to date have been limited and continue to be of interest to regulated and potentially regulated parties. Further, the economics of these technologies are largely expected to be driven by power requirements since the processes required to break the powerful carbon-fluorine bonds in all PFAS compounds are generally energy intensive, but economic demands are currently an afterthought. Quantitative comparison of energy demands is warranted.
This presentation will highlight the progress on the efficacy of various emerging PFAS-destructive treatment technologies. Additional information on new technologies that are or could soon be available for PFAS treatment and that will reflect consideration of site-specific treatment conditions, including PFAS concentrations, matrix effects, and treatment objectives, will be provided. New insights regarding treatment mechanisms, kinetics, and factors that impact treatment performance of each process will be discussed based on our experience leading recent performance demonstration projects. Weāll share insights on pretreatment that may be required to couple destructive treatment processes with conventional adsorptive or separative treatment processes. Additionally, information on the scalability, economic feasibility, and market readiness of each treatment technology will be provided.
IWC 22-71: PFAS Destruction in Water using BDD Electrodes Electrooxidation: Cost-Effective? In Which Conditions?
ValĆ©rie LĆ©veillĆ©, Golder, MontrĆ©al, QuĆ©bec Canada; Ćric Bergeron, Golder, MontrĆ©al, QuĆ©bec, Canada; Giovanna Llamosas, Golder, MontrĆ©al, QuĆ©bec, Canada; Imad Touahar, Golder, MontrĆ©al, QuĆ©bec, Canada; Jinxia Liu, McGill University, MontrĆ©al, QuĆ©bec, Canada
This paper will discuss lab-scale treatment results of ground and industrial waters using a novel electrochemical oxidation (EO) process employing long-lasting boron-doped diamond (BDD) electrodes. The goal is to present the water matrix dependent treatment efficiency and capital and operating costs of this process on Per- and Polyfluoroalkyl substances (PFAS), assess its effects on PFAS precursors, perchlorate generation, and water pH and temperature.
IWC 22-72: Electrochemical Destruction of PFAS in Concentrated Waste Streams
Orren Schneider, Aclarity, LLC, Plainsboro, NJ
PFAS contamination of water streams has become ubiquitous. In order to deal with this contamination, treatment has been focused on removal of these pollutants, chiefly by granular activated carbon or anion exchange. When exhausted, the spent media is sent to landfills or incinerators. With changing regulations pending, there is ongoing development of destructive technologies that can actually degrade or even mineralize these persistent compounds rather than transferring them from water to another phase.
While several different types of destructive technologies are being developed, electrochemical oxidation has begun to emerge from labs to become commercially available. Both academic and commercial research has shown that these systems can degrade these compounds to below detection limits. While electrochemical treatment for low concentration streams is not yet cost effective, treatment of high concentrations in waste brine or landfill leachates can be a cost-effective solution. This paper will present lab and field data showing destruction of a variety of PFAS compounds in several different water matrices and present economics for these systems relative to existing removal solutions.
W3-Reserve: PFAS Treatment – Lessons Learned in Design, Implementation & Operation
John Peichel, SUEZ Water Technologies & Solutions, Minnetonka, MN
The PFAS market is experiencing rapid change due to evolving regulations and more frequent sampling and testing leading many municipal and industrial customers to implement full scale treatment of PFAS .Ā For many customers, the specific PFAS solution must address constraints such as specific treatment targets, source knowledge/variability, time pressure and final PFAS disposition.Ā This paper will summarize design and performance aspects of PFAS applications running for 1-3 years using technologies of GAC, IX and RO in drinking water and industrial wastewater treatment.Ā Where applicable, lab testing and pilot study learnings that impacted full scale implementation decisions will also be included.Ā Customer specific information covered under confidentiality will be protected and only high level learnings will be discussed.Ā Details included will be key flowsheet components, treatment targets, design constraints and performance data.Ā Key learnings summarized from these experiences should allow readers to apply these experiences to their own PFAS treatment project.
W4: Wastewater 2: Wastewater Treatment Innovations, Improvements, and Optimizations
IWC Rep: Max Brefeld, Toyota Motors North America, Georgetown, KY
Session Chair: Julie Horan, HDR, Inc., St. Louis, MO
Discussion Leader: Jaron Stanley, WesTech, Salt Lake City, UT
Time: 8:00 AM – 12:00 PM
Whatās new in wastewater? Innovation and optimization of treatment technologies is necessary to address water scarcity, improve treatment economics, and comply with new and tightening quality requirements. This sessionās papers will discuss innovative technologies and improvements to existing technologies for wastewater treatment. The papers in this session will focus on case studies from recent projects. Treatment technologies covered in this sessionās papers include membrane bioreactors, high recovery membrane desalination, advanced oxidation processes, and bioaugmentation.
IWC 22-73: 15 Years of Membrane Bioreactor (MBR) Experience for Industrial Wastewater
Sara Arabi, Ph.D., P.E., BCEE, MBA, Stantec, Fort Collins, CO
In the last 15 years, Membrane Bioreactors (MBRs) have become common for industrial wastewater treatment. This paper presents the progress and applications of MBRs which provides the benefit of biological treatment process in a compact footprint and solids liquid separation for a high-quality effluent. In this paper, lessons learned and challenges from design and operation of MBR plants for industrial wastewaters are presented. MBRs provide the pretreatment required for other treatment technologies such as Reverse Osmosis (RO) where wastewater reuse and recycle or PFAS removal is targeted.
The key design considerations for MBR include selection of membrane flux rates for cold temperature operations, influent characterization, and design of equalization basins. Some of the key operational considerations for MBR plants are nutrient balance for macro-nutrients (where nitrogen or phosphorus are limiting the biological growth) and micro-nutrients, membrane fouling mitigation, and foaming issues. Short case studies for MBR operation for landfill leachate and pharmaceutical wastewater are presented.
Discusser: Srikanth Muddasani, Civil & Environmental Consultants, Inc., McDonald, PA
IWC 22-74: High Recovery Electrochemical Desalination for Tertiary Wastewater Treatment
Chad Unrau, MI Systems, Houston, TX; Sunil Mehta, MI Systems, Houston, TX
Minimum and Zero Liquid Discharge applications often require high recovery membrane desalination to make treatment and performance targets economically feasible. Water recovery in membrane desalination is typically limited by scale formation from silica and partially soluble salts such as calcium sulfate. In addition, chemical and energy consumption can often make the operating cost of a project prohibitive. The latest evolution of electrodialysis reversal enables high recovery desalination of brackish waters without concentrating silica due to its neutral charge. Polarity reversal naturally mitigates scaling from partially soluble salts and energy consumption is minimized with the lastest innovations of the technology. Finally, electrodialysis reversal enables the tuning of the product output to deliver the required user treatment level. This feature minimizes over-treatment of the water which in turn minimizes energy consumption and it minimizes the amount of scaling ions transferred to the brine. As such, higher recoveries can be achieved with lower risk of scale formation.
An exemplary project that highlights the capabilities of the latest advancements in electrodialysis reversal is a pilot project conducted by MI Systems for tertiary treatment of a California WWTP effluent. The water quality for the plant is 1600 ppm TDS, 187 – 200 ppm chloride and ~30 ppm silica. The objective of the pilot study was to reduce chloride concentrations to meet effluent discharge limits <100 ppm chloride and to demonstrate 95% water recovery. Water recovery is critical for this client as opex limitations necessitated the need for onsite handling of the brine with minimal space available to do so. The system operated at an average water recovery of 95% and an average SEC of 0.5 kWh/m3. The system was able to consistently meet target chloride concentrations < 100 ppm within the pilot study period by tuning the applied voltage without over-treating the water. The concentration of silica remained unchanged in the influent and effluent streams of the system due to its neutral charge. As a comparison, for this type of water, a typical RO system would operate at a maximum of ~90% recovery due to high silica concentrations and would require the use of antiscalant. Demonstrating 95% water recovery was critical for this client as this level of recovery enables the use of small onsite evaporation ponds to handle the minimal brine production at full scale. A 200 gpm system is currently be constructed and installed for this client in 2022.
IWC 22-75: Ultraviolet Advanced Oxidation Processes for 1,4-Dioxane Destruction In Bench-Scale and Pilot-Scale Units
Roberto Silva De Faria, Evoqua Water Technologies LLC, Pittsburgh, PA; Mohsen Ghafari, Evoqua Water Technologies LLC, Pittsburgh, PA; Simon Dukes, Evoqua Water Technologies LLC, Tewksbury, MA
The identification of sustainable water treatment processes becomes urgent as the quality and quantity of available water sources reduces. Increased attention is given to those alternatives that promise a scalable, cost-effective solution to our water problems while meeting public health demands. Advanced oxidation processes (AOPs) have proven to be effective for toxic contaminant removal when compared to more conventional treatment processes. AOP has been applied successfully to degrade or remove toxic pollutants of emerging concern such as 1,4-dioxane, a major recalcitrant and toxic contaminant.
1,4-dioxane has been detected in many water resources and municipal wastewater influents due to discharge from chemical industries. Given that several US states have established drinking water guidelines as low as 0.3 ppb, it is imperative to develop efficient and sustainable technologies for its destruction. Currently, municipalities are expanding their treatment capabilities for indirect potable water reuse by implementing conventional and advanced technologies. Specifically, Evoqua partnered with a municipality in Maryland, USA to implement an improved AOP technology with onsite hydrogen peroxide generation.
In this study, UV-activated AOPs were investigated for the destruction of 1,4-dioxane in both laboratory scale and pilot scale systems. At the laboratory scale, hydrogen peroxide (H2O2) and sodium hypochlorite (NaOCl) were used as oxidants. Results showed increased reduction of 1,4-dioxane when using H2O2 over NaOCl. At the pilot scale, 1,4-dioxane destruction was tested in a reactor equipped with 0.8 kW low pressure UV lamp. An onsite H2O2 generation unit was used for introduction of oxidant to the reactor influent water. The results showed complete destruction of 1,4-dioxane when H2O2 to 1,4-dioxane mass ratio greater than 10 was used. This study demonstrates the potential of UV-H2O2 for destruction of recalcitrant compounds for safe indirect potable reuse.
Discusser: Harley Schreiber, WesTech Engineering, Salt Lake City, UT
IWC 22-76: Improved Biological Nutrient Removal by integrating bioaugmentation in the wastewater collection system
Dimitris Chrysochoou, Tradeworks Environmental, Mississauga, ON Canada
A Rotating Biological Contactor [RBC] wastewater treatment plant was facing challenges with meeting the effluent ammonia criteria. It is a 1.2 MGD wastewater treatment plant located in a residential area in Nova Scotia region. It utilizes screening, primary clarification, 2 parallel RBC trains, secondary clarification, and disinfection prior to discharge. The wasted sludge from the system is co-thickened in the primary clarifier and pumped into the anaerobic digester. Waste sludge from the anaerobic digester is hauled away for further processing and disposal. Due to the challenges, the facility was scheduled to be decommissioned and be used as a lift station to divert the flow to another facility nearby. The facility has different effluent ammonia criteria for the winter and summer seasons [5mg/l and 3mg/l respectively].
For this project it was suggested to apply the bioaugmentation in the wastewater collection system. This way, the sewage conveyance system is leveraged to precondition the wastewater prior to its introduction into the treatment plant, which is also enhanced by the microbial addition. The project started in August 2020 and is still undergoing today as part of the standard operations. The primary objective of this project was to enhance nitrification.
During the first year of application, it was demonstrated that the bioaugmentation assisted with enhancing the nitrification process, which was able to meet the ammonia effluent criteria and have the primary objective satisfied. As the system has different effluent criteria for winter and summer seasons, for the period of November 1st, 2019, to April 30th, 2020 [before the bioaugmentation] the average effluent ammonia values were 4 ppm, while for the period of November 1st, 2020, to April 30th, 2021 [after bioaugmentation] the average ammonia effluent values were 1.75 mg/l. Furthermore, for the period of May 1st, 2020, to August 31st, 2020 [before bioaugmentation] the average effluent ammonia was 2.92mg/l, and for the period of May 1st, 2021, to August 31st, 2021 [after bioaugmentation] the average effluent ammonia values were 1.38 mg/l. The daily ammonia removal rate increased by 28%.
Secondary objectives included optimization of the system in various stages. It was shown, that after bioaugmentation application the biogas production was increased compared to the same months the year prior to the application, by 20-50% and the sludge hauling reduced by 15%.
This application in the collection system was able to provide a sustainable solution to the wastewater authority saving the facility from being decommissioned.
Discusser: Bridget Finnegan, P.E., CDT, ENV SP, GHD, Allison Park, PA