Selenate removal is a great challenge in both groundwater remediation & industrial wastewater treatment. A novel porous iron media (named Cleanit^®-LC Plus, LC+) was invented and is manufactured by Höganäs, which has a high reactivity and treatment capacity for selenium (Se) removal. Several laboratory and pilot-scale studies have been conducted for selenate removal. Batch studies showed that the maximum removal capacities of LC+ were 2.70 ± 0.12, 4.90 ± 0.03, 4.74 ± 0.22, and 5.00 ± 0.00 mg Se/g media, for selenate, selenite, selenosulfate, and selenocyanate, respectively. Lab column test on groundwater sample from west coast of the U.S. showed selenate removal from 35.4 ± 3.5 µg/L to 4.0 ± 2 µg/L with an empty bed contact time (EBCT) of 30 min. Another independent pilot column study was performed on industrial wastewater from a battery recycling facility. The selenium concentration was 3.1 ± 1.0 mg/L, which was removed to about 1.6 ± 0.79 mg/L below the treatment target of 2 mg Se/L (EBCT, 20 min). The capacity of LC+ media for selenium was about 3.2 mg Se/g media.

Additional inorganic contaminants (e.g., arsenic, cadmium, lead, antimony, molybdenum and zinc) present in groundwater or industrial wastewater can also be removed ex situ via sorption & reduction processes.

For instance, Pb was removed from 133 ± 14.1 to 18 ± 2.1 mg/L, showing a capacity of 282 mg Pb/g LC+ media. Organic contaminant such as cVOC can be destroyed rather than sorbed using this type of media when a pump & treat system is in operation. The unique composition of the media (99 % iron) allows it to have a sustainable lifecycle as it could be remelted for re-use in other iron powder application or re-activated depending of the type contaminant treated. This limit the cost of disposal for hazardous material and promote a more sustainable environmental approach to the filtration of these type of contaminants.

In summary, this novel iron media demonstrated a significant potential for organic and inorganic contaminant removal for ex situ groundwater remediation and industrial wastewater treatment. Full scale implentation case study demonstrating the system performance and cost will be given during the presentation.

Biography 

Jean Pare, P.Eng., has a degree in Chemical Engineering from Laval University. He has been involved for the last 25 years in the evaluation, development, design, and promotion of both conventional and innovative environmental technologies. As Vice President with Chemco Inc., his responsibilities include the remediation design, technico-economical analysis and technology supply for chemical oxidation and reduction, soil washing, and enhanced bioremediation. Last year, he worked with over 400 sites applying his expertise to various types of organic and inorganic contaminants in soil and groundwater. He is also involved with many environmental organizations such as CLRA, CBN, ESAA, BCEIA and Reseau-Environnement where he is an active technical committee member and regular technical speaker.

Abstract

Ever since researchers at the University of Waterloo observed degradation of halocarbons in cast iron wells, zero valent iron (ZVI) media have been extensively researched and applied in soil/groundwater remediation projects. Typical application of ZVI includes dehalogenation of chlorinated volatile organic carbon (c-VOC), heavy metal removal/stabilization such as hexavalent chromium [Cr(VI)], arsenic (As), selenium (Se), nitrate and nitro-aromatic compound reduction, and uranium (U) reduction and removal. However, there have been several limitations in using conventional ZVI media, including impurities, surface passivation, pH change of groundwater, iron (Fe) leaching, low reactivity of media (caused by low surface area and aging), and low selectivity due to the presence of competing ions. Those issues are largely associated with the intrinsic property and manufacturing processes of the ZVI media.

The ZVI media manufactured from various methods have different characteristics. Testing has been conducted to compare those specific characteristics in more practical application of soil and groundwater remediation, such as iron content, reactivity, longevity, hydraulic conductivity, etc.

The use of NOVEL high surface area high reactivity ZVI allow to deal with specific metals & contaminant in a more diverse and more efficient reactions rate.

A batch kinetic study, using Cleanit^® sponge ZVI media, was conducted with an initial selenium concentration of 10 mg/L (a mix of selenate, selenite, selenosulfate, and selenocyanate) and a loading rate of 0.1 mg Se/g media. Within 24 hours, all four selenium species were removed to below the detection limit (1 µg Se/L). The pseudo first order reaction constants for each selenium species mentioned above were 25.0, 23.7, 11.1, and 1.0 h^-1, respectively. The maximum removal capacities for the four species were 2.70 ± 0.12, 4.90 ± 0.03, 4.74 ± 0.22, 5.00 ± 0.00 mg Se/g media, respectively. Since selenate is the most challenging selenium species to be removed by ZVI, column tests were conducted using three different grades of Cleanit^® media: Cleanit^®-SR.1S, Cleanit^®-SR.2S and Cleanit^®-SR.3S with site soil and the impacted site groundwater. The initial selenium concentration was 2,200 µg/L. With an average retention time of 4.4 hour at a flowrate of 0.5 mL/min, all three Cleanit^® media demonstrated selenate removal efficiencies between 97 and 98%. Among the three Cleanit^® media tested, Cleanit^®-SR.1S showed the highest selenium removal capacity and low pressure build-up in the column. In summary, Cleanit^® media demonstrated a significant potential for organic and inorganic selenium removal for groundwater remediation. Other data for PCE, TCE, chrome and arsenic will also be covered showing cost reduction capability for large scale project implementation.

Biography - JEAN PARE

Jean Pare, P.Eng., has a degree in Chemical Engineering from Laval University. He has been involved for the last 25 years in the evaluation, development, design, and promotion of both conventional and innovative environmental technologies. As Vice President with Chemco Inc., his responsibilities include the remediation design, technico-economical analysis and technology supply for chemical oxidation and reduction, soil washing, and enhanced bioremediation. Last year, he worked with over 400 sites applying his expertise to various types of organic and inorganic contaminants in soil and groundwater. He is also involved with many environmental organizations such as CLRA, CBN, ESAA, BCEIA and Reseau-Environnement where he is an active technical committee member and regular technical speaker.

Abstract

Over 65 percent of North American communities obtain their drinking water from lakes, rivers or other surface water. Protecting these sources from outside contaminants is an ongoing struggle for many public water systems. Climate change coupled with fertilizer and manure washing off farm fields during heavier and more frequent rains accelerates the frequency and intensity of harmful algal blooms (HAB) in freshwater. Phosphorus, nitrogen and suspended substances (BOD) are the main sources for blue-green algae causing HABs.

Currently, microcystins and other cyanotoxins that develop from blue-green algae are not regulated under the Safe Drinking Water Act, but they are on the EPA’s Contaminant Candidate List. The World Health Organization has established an advisory guideline of 1 µg/L for microcystin in drinking water. Microcystin is a common and very potent toxin created by blooms of cyanobacteria, also known as blue-green algae. As with other contaminants of emerging concern, most countries have placed different guidance on cyanotoxins, ranging from 0.7 to 3 µg/l. Very low amounts of microcystins in drinking water have been linked to an increased liver and kidney failure and nervous system health problems. EPA monitoring has shown levels well in excess of any guidance level.

Management options include source controls (reduced nutrient load, chemical phosphorus precipitation, aeration, bioremediation), intake modifications (inlet filtration) and treatment modifications (chlorine, DAF, ozone-AOP, UV-AOP, activated carbon, dissolved air flotation). However, these technologies are generally limited by their harsh treatment conditions, complicated operation (two or more coupled technologies), chemical additives, inapplicability to small or large water bodies, high capex/footprint, low energy efficiency, or high operation costs. In addition, the application of many of these technologies to treat large volumes of algae laden waters is not technically and economically feasible as they may release toxins by rupturing the cell membrane.

In this paper we present the application of a high efficiency electrochemical advanced coagulation process (EACPs) for the treatment of wastewater from a waste water treatment facility into a community lake used as the drinking water source. Considerable validation of the technology had been performed at both the bench-scale and pilot-scale, which facilitated the on-site application. The key success criteria of the technology was its ability to rapidly mineralize ammonia and phosphate to struvite, thus eliminating the source of the HAB. Conditions studied were (1) EACP electrode types, (2) EACP reactor design and operation and sample treatment conditions. Results of the full-scale application at the lake site treated with the EACP showed a >98.5% removal of the phosphorus and nitrogen after one pass through the system. Lake water levels of phosphate have been effectively maintained below HAB threshold levels.

Biography - Marco Polverari

Marco Polverari is the Vice President of Business Strategy and Business Development for E2Metrix, a Canadian company which has developed ECOTHOR™, an electrolysis technology platform for removing or destroying pollutants in wastewater and process water streams. Dr. Polverari has over 30 years experience in the field of water and waste water treatment. Dr. Polverari oversees all strategy and business development with a strong focus on market development and technology implementation. Dr. Polverari holds an undergraduate degree in Chemistry (Concordia, 1990), a PhD in polymer chemistry (McGill, 1994) and an MBA (John Molson School of Business, 2006).

Abstract

Aquatic environments on many military bases have the potential to be impacted by military training activities through alterations of water quality, aquatic habitat, and rate of flow. Potential stressors include the addition of inorganic elements and energetic compounds from munitions constituents associated with firing activities. Increases in total suspended solids (TSS) may also occur as a result of intensified soil erosion due to vegetation loss and manoeuvre training. Environmental monitoring programs at military installations typically evaluate surface water quality, but water chemistry can be highly variable with low statistical power to detect long-term trends. Exceedances of water quality guidelines also do not always correlate well with biological effects. A direct risk-based measure of aquatic ecosystem health, such as the benthic invertebrate community composition, provides an assessment of long term exposure and effects that can be difficult to evaluate using physical and/or chemical data alone. Benthic monitoring programs are particularly useful when water quality impacts are episodic and likely to be missed by water sampling, and for determining whether guideline exceedances in water and sediment are indicative of actual ecological effects.

Over the past decade, the Environmental Sciences Group (ESG) has established benthic monitoring programs for several Canadian military bases to evaluate the sustainability of range training activities with respect to aquatic environments. ESG developed a prioritization tool to evaluate military sites according to the need for a benthic monitoring program and feasibility of program implementation using available information for most bases. Sites were ranked as high priority for the establishment of a benthic monitoring program when there were extensive range training activities located in close proximity to water features; documented exceedances of relevant surface water and sediment quality guidelines; greater potential for off-site migration of contaminants; and when sensitive aquatic habitat or documented aquatic Species at Risk were present. The feasibility and cost-effectiveness of establishing a benthic monitoring program were evaluated based on the types of water features present; the number and accessibility of potential monitoring locations sensitive to impacts; and the availability of existing regional benthic community reference data. To date, benthic monitoring programs have been established at four Canadian military sites ranked as high priority for establishment of an aquatic biomonitoring program.

Development of a nationally consistent approach for benthic monitoring programs on Canadian military sites presents several design challenges. For example, munitions constituents typically enter waterways as diffuse inputs rather than as a defined point source. Biomonitoring programs must also account for the influence of natural factors (e.g., bedrock geology, climate, hydrology) and off-base human activities in structuring benthic communities. This presentation will provide case study examples and an overview of the approach taken to address these challenges, including a GIS-based land use analysis; the development of quantitative benchmarks and statistical approaches for the evaluation of benthic monitoring results compared to reference condition; and the establishment of frameworks to guide decision-making based on the monitoring results. Overall, results from established programs to date indicate that minor exceedances of surface water and sediment quality guidelines are typically not associated with adverse effects on benthic community health. However, aquatic biomonitoring programs can be useful to pinpoint areas of watercourses where consistent ecological effects have been noted and where mitigation measures could be implemented to improve aquatic health.

Biography - Tamsin Laing

Tamsin holds a Ph.D. in aquatic biology from Queen’s University and is an adjunct professor in the Chemistry & Chemical Engineering Department at RMC. She is currently the scientific advisor and project leader for aquatic contaminated site programs at the Environmental Sciences Group, RMC. Over the past 15 years, she has worked on a variety of projects including the assessment and management/remediation of contaminated sediments, ecological risk assessment, and long-term monitoring. Her work has taken her to sites across Canada and the Arctic, as well as northern Russia. Recent projects include designing aquatic monitoring programs, as well as developing scientific guidance for federal aquatic contaminated sites.

The Canadian federal contaminated sites decision-making framework was used to assess remedial options for the Boat Harbour site in Nova Scotia, Canada. Boat Harbour was originally a tidal estuary connected to the Northumberland Strait in Pictou County, Nova Scotia. The Province constructed the Boat Harbour Effluent Treatment Facility (BHETF) in 1967 to treat effluent from industrial sources; this reconstruction converted the natural tidal estuary into a closed effluent stabilization lagoon. The Province has committed to ceasing the reception and treatment of new effluent to the BHETF by January 31, 2020, and the subsequent remediation of Boat Harbour to restore the tidal estuary. At the core of the remediation will be removal of impacted sludge/sediment and managing all associated effluents.

As specified in Step 7 of the federal contaminated sites decision-making framework, a remediation strategy was developed. This strategy had several key elements which included waste management, wetland management, infrastructure decommissioning, sediment treatment, water management, dewatering effluent management, and leachate management. For each element active remediation versus risk management approaches were considered and filtered to ensure only approaches conforming to the project goals were evaluated further. The components and methods for each approach were then evaluated for technical applicability and feasibility. The feasible remedial options were defined and decisions were made taking into account sustainability, environmental impact, end use, regulatory levels and public acceptance.

Key challenges for the site were the high profile nature of the site and the need to develop alternatives that would be acceptable to the public while still being technically sound. The end use of the site by the Pictou Landing First Nation was also a key driver of the decision-making process as the remediated site will need to be suitable for traditional uses.

Based on the options selected and the information requirements for these options a bench scale study and a pilot study were performed to test the most promising options for waste, water, and leachate management and sediment treatment. These studies further refined the options under consideration.

The selected alternatives included the use of an on-site disposal cell for waste management, sediment removal in the wet with geotube dewatering for sediment treatment, a combination of natural attenuation and active remediation for wetland management based on a risk assessment, natural attenuation for bulk water and dewatering effluent management, and off-site disposal for long-term leachate management. Different options were selected for the different types of infrastructure to be decommissioned such as replacement of the causeway at Highway 348 with a concrete girder bridge; cleaning, inspecting and abandoning pipelines in place; removing berms and a dam to return Boat Harbour to natural tidal conditions; and upgrading and utilizing existing road networks.

The implementation of the selected alternatives is currently in progress.

Biography - Sophia Dore

Sophia Dore is a member of the GHD Innovative Technology Group. She has 17 years of experience in environmental remediation. Sophia assists project managers by providing technical expertise in the areas of biology, chemistry, and remedial design. Sophia manages the treatability study laboratory and is responsible for designing, conducting, performing data analysis, and reporting on treatability studies including chemical and biological treatments of contaminated soils and waters. She then assists project managers with the use of the treatability study data in implementing the full scale treatment. She also performs remedial technology assessments, which include a review of site data in order to assess remedial options and make recommendations and develop dosing and cost estimates for in situ treatment. Sophia also performs assessments of existing treatment systems and pilot studies and evaluates the data in order to make recommendations for treatment optimization.