The team researched, designed, and economically analyzed a full-scale adsorption column system to be applied in mining processes that leave high amounts of fluoride in their effluent. This system was designed to remove fluoride from water saturated with calcium sulfate, as calcium sulfate is present in high amounts in certain mining processes. Currently, high density sludge (HDS) is commonly employed to reduce fluoride concentrations, but due to solubility limits the sludge treatment cannot lower fluoride below 10 mg/L (ppm). The current enforceable EPA standard for discharged water is at 4 mg/L (ppm), although mining companies anticipate that this standard will soon be lowered to 2 ppm. The team was tasked with designing a process to lower 10 ppm fluoride down to 2 ppm.
The team investigated various methods such as precipitation, ion exchange, and reverse osmosis to remove fluoride from the system. These methods were not cost-effective and did not produce environmentally friendly byproducts. The team ultimately presented the solution of bone char as an adsorbent, with a byproduct that can be safely applied as a soil amendment. A full-scale facility with two adsorption columns was designed to treat 1000 gpm of water

Damian, Adrian

Dopp, Michelle

Golman, Courtney

Johnson, Mary

Le, Kevin

Payne, Jacqueline

Phan, Ethan

English

The process of mining minerals and elements from ores and rocks creates acid rock drainage (ARD). This drainage is water that contains heavy metals and minerals that can be dangerous for human consumption or damaging to the environment. The mining industry has employed various water treatment methods to prevent these metals and minerals from being discharged into water sources such as ponds, lakes, and streams. Currently, the most used treatment process in the mining industry is a cost-effective high-density sludge (HDS) process. This method reduces the concentration of metals and elements with the use of lime/limestone. However, the concentration of fluoride is not reduced to Environmental Protection Agency (EPA) standards, and so it is necessary to design a fluoride removal system. Reverse osmosis (RO) was considered as well as precipitation, ion exchange, and adsorption by media such as biochars, bone char, and activated alumina. Although RO is perhaps the most obvious solution to reducing fluoride concentrations, this method was eliminated due to expensive overhead and maintenance costs. Many metals and compounds present in the mine water will lead to severe scaling and precipitates collecting in the membrane, requiring constant upkeep and high maintenance costs. Precipitation was eliminated because it produced a byproduct only suitable for landfilling, and ion exchange was eliminated due to its high cost and complications with competitive ions. Adsorption was chosen as a viable option for fluoride removal because of its low cost and environmentally friendly byproduct generation. The adsorption media was chosen based on a ranking system designed by our team. This system provided a way for our team to compare the adsorption capacity, rate of adsorption, byproduct application, and price per ton for each adsorbent. From this ranking system, Moo Pig Sooie is presenting a solution of cow bone char as a fluoride adsorbent. This type of biochar can be bought pre-charred and can be land applied as a fertilizer once the char is spent. A full-scale facility was designed to treat 1000 gallons per minute (GPM) of mine water 24 hours a day, seven days a week, for eight months out of the year. To achieve this flowrate and timeline, two packed beds with volumes of 8,900 ft3 each were designed to run in parallel to ensure loading does not occur until the 168-hour mark, the end of the work week. Once the bone char is loaded, the spent bone char will be hauled offsite to be land applied in soil that is naturally slightly acidic. Our experimental results indicate that minimal amounts of fluoride are stripped from bone char in acidic environments. Applying spent bone char to soil presented a desirable environmentally friendly solution for our byproduct. The overall capital cost of a full-scale facility is approximately $750,894 with a yearly operating cost of $4,778,840. Although this is high, the proposed solution will reduce the concentration of fluoride to EPA standards of 2ppm and the process will generate a land-applicable byproduct. Since consuming fluoride in excessive amounts can lead to health issues, public awareness is a necessary aspect of this solution. Citizens affected by the application of fluoride to their soil and water sources should be regularly involved in and aware of the fluoride levels in their environment. From our analysis of bone char adsorption, Moo Pig Sooie believes this type of treatment is a beneficial, cost effective, and sustainable solution for mining facilities that generate high concentrations of fluoride in their water

ScholarWorks@UARK

Removal of Fluoride from Mine Water via Adsorption for Land-Applied Soil Amendment

The process of mining minerals and elements from ores and rocks creates acid rock drainage (ARD). This drainage is water that contains heavy metals and minerals that can be dangerous for human consumption or damaging to the environment. The mining industry has employed various water treatment methods to prevent these metals and minerals from being discharged into water sources such as ponds, lakes, and streams. Currently, the most used treatment process in the mining industry is a cost-effective highdensity sludge (HDS) process. This method reduces the concentration of metals and elements with the use of lime/limestone. However, the concentration of fluoride is not reduced to Environmental Protection Agency (EPA) standards, and so it is necessary to design a fluoride removal system. Reverse osmosis (RO) was considered as well as precipitation, ion exchange, and adsorption by media such as biochars, bone char, and activated alumina. Although RO is perhaps the most obvious solution to reducing fluoride concentrations, this method was eliminated due to expensive overhead and maintenance costs. Many metals and compounds present in the mine water will lead to severe scaling and precipitates collecting in the membrane, requiring constant upkeep and high maintenance costs. Precipitation was eliminated because it produced a byproduct only suitable for landfilling, and ion exchange was eliminated due to its high cost and complications with competitive ions. Adsorption was chosen as a viable option for fluoride removal because of its low cost and environmentally friendly byproduct generation. The adsorption media was chosen based on a ranking system designed by our team. This system provided a way for our team to compare the adsorption capacity, rate of adsorption, byproduct application, and price per ton for each adsorbent. From this ranking system, Moo Pig Sooie is presenting a solution of cow bone char as a fluoride adsorbent. This type of biochar can be bought pre-charred and can be land applied as a fertilizer once the char is spent. A full-scale facility was designed to treat 1000 gallons per minute (GPM) of mine water 24 hours a day, seven days a week, for eight months out of the year. To achieve this flowrate and timeline, two packed beds with volumes of 8,900 ft3 each were designed to run in parallel to ensure loading does not occur until the 168-hour mark, the end of the work week. Once the bone char is loaded, the spent bone char will be hauled offsite to be land applied in soil that is naturally slightly acidic. Our experimental results indicate that minimal amounts of fluoride are stripped from bone char in acidic environments. Applying spent bone char to soil presented a desirable environmentally friendly solution for our byproduct. The overall capital cost of a full-scale facility is approximately $750,894 with a yearly operating cost of $4,778,840. Although this is high, the proposed solution will reduce the concentration of fluoride to EPA standards of 2ppm and the process will generate a land-applicable byproduct. Since consuming fluoride in excessive amounts can lead to health issues, public awareness is a necessary aspect of this solution. Citizens affected by the application of fluoride to their soil and water sources should be regularly involved in and aware of the fluoride levels in their environment. From our analysis of bone char adsorption, Moo Pig Sooie believes this type of treatment is a beneficial, cost effective, and sustainable solution for mining facilities that generate high concentrations of fluoride in their water

UARK (University of Arkansas )

Personal Introduction to Honors Thesis Courtney Golman Honors Chemical Engineering Removal of Fluoride from Mine Water via Adsorption for Land-Applied Soil Amendment   As a part of Moo Pig Sooie, I worked on the overall development of our proposal for a secondary system to remove fluorine from mine water discharge. My specific role on the team was Purchasing Coordinator, which required me to function as the liaison between my team members and the appropriate University of Arkansas staff to purchase and obtain the tools needed for our laboratory experience. Initially, I was in charge of ordering our first chemicals, sodium fluoride and calcium sulfate, known as gypsum. I also got my team the laboratory equipment needed that was not already available in one of the chemical engineering department’s labs, such as rice hulls, bone char, multiple kinds of activated alumina, our own disposable pipettes, weighing boats, and material scoops, as well as a scale that was able to function at the milligram level as needed by our sodium fluoride content in the synthetic water. After these initial purchases, I was in charge of keeping the chemicals and adsorbents stocked as well as ordering any additional equipment we deemed necessary as our experiments progressed, such as syringes to better filter our batch scale samples and 30-gallon drums for our bench scale experiments.   Another responsibility I had as the Purchasing Coordinator for Moo Pig Sooie was to set up our relationship with the Water Quality Lab and facilitate the testing of our samples, sometimes up to one hundred delivered in a day. We understood that this was a large burden on the Water Quality Lab and its staff, so I strived to maintain a cooperative relationship that would allow them to complete their work in detail while also relaying the data to my team members in a timely manner as they relied on me heavily to deliver the results in order to compute the models and interpret our data. This role was crucial because if the data were received too late, decisions could have been made that would have been found to be inappropriate had the values been seen sooner. One example of this was when we tested our bio chars, rice hull and orange peel, as normal batch tests. They were placed into a beaker with one liter of our synthetic water, stirred with an impeller and baffles, and samples were taken in different time intervals, running for up to four hours. We continued to test different masses of these adsorbents, as was done with bone char and activated alumina, until the data came back showing us that they increased the fluorine concentration in the water. Had we known this before, we would have begun the tests with only the pyrolyzed chars in deionized water, which also showed to increase the fluorine concentration in the water. This would have preventing the extra unnecessary testing of different masses of the adsorbents and would have allowed us to focus our time and resources elsewhere into a more promising solution.  Finally, as a member of Moo Pig Sooie, I had the responsibility of helping with both research and laboratory experiments to progress our work on the task laid out. I spent many hours in the lab along with my team members, running the batch tests that often lasted four hours, pyrolyzing our chars, bench testing our column at different flow rates, and producing synthetic water and more realistic mine water at the correct pH. I learned a great deal in this laboratory setting from the experiences I had and from my advisors and peers. We worked beginning to end on the design of a secondary fluorine removal system for mine water discharge, encompassing economics, full scale design, and health and environmental regulations.  

The process of mining minerals and elements from ores and rocks creates acid rock drainage (ARD). This drainage is water that contains heavy metals and minerals that can be dangerous for human consumption or damaging to the environment. The mining industry has employed various water treatment methods to prevent these metals and minerals from being discharged into water sources such as ponds, lakes, and streams. Currently, the most used treatment process in the mining industry is a cost-effective highdensity sludge (HDS) process. This method reduces the concentration of metals and elements with the use of lime/limestone. However, the concentration of fluoride is not reduced to Environmental Protection Agency (EPA) standards, and so it is necessary to design a fluoride removal system. Reverse osmosis (RO) was considered as well as precipitation, ion exchange, and adsorption by media such as biochars, bone char, and activated alumina. Although RO is perhaps the most obvious solution to reducing fluoride concentrations, this method was eliminated due to expensive overhead and maintenance costs. Many metals and compounds present in the mine water will lead to severe scaling and precipitates collecting in the membrane, requiring constant upkeep and high maintenance costs. Precipitation was eliminated because it produced a byproduct only suitable for landfilling, and ion exchange was eliminated due to its high cost and complications with competitive ions. Adsorption was chosen as a viable option for fluoride removal because of its low cost and environmentally friendly byproduct generation. The adsorption media was chosen based on a ranking system designed by our team. This system provided a way for our team to compare the adsorption capacity, rate of adsorption, byproduct application, and price per ton for each adsorbent. From this ranking system, Moo Pig Sooie is presenting a solution of cow bone char as a fluoride adsorbent. This type of biochar can be bought pre-charred and can be land applied as a fertilizer once the char is spent. A full-scale facility was designed to treat 1000 gallons per minute (GPM) of mine water 24 hours a day, seven days a week, for eight months out of the year. To achieve this flowrate and timeline, two packed beds with volumes of 8,900 ft3 each were designed to run in parallel to ensure loading does not occur until the 168-hour mark, the end of the work week. Once the bone char is loaded, the spent bone char will be hauled offsite to be land applied in soil that is naturally slightly acidic. Our experimental results indicate that minimal amounts of fluoride are stripped from bone char in acidic environments. Applying spent bone char to soil presented a desirable environmentally friendly solution for our byproduct. The overall capital cost of a full-scale facility is approximately $750,894 with a yearly operating cost of $4,778,840. Although this is high, the proposed solution will reduce the concentration of fluoride to EPA standards of 2ppm and the process will generate a land-applicable byproduct. Since consuming fluoride in excessive amounts can lead to health issues, public awareness is a necessary aspect of this solution. Citizens affected by the application of fluoride to their soil and water sources should be regularly involved in and aware of the fluoride levels in their environment. From our analysis of bone char adsorption, Moo Pig Sooie believes this type of treatment is a beneficial, cost effective, and sustainable solution for mining facilities that generate high concentrations of fluoride in their wate

The Moo Pig Sooie’s researched, designed, and economically analyzed a full-scale adsorption column system to be applied in mining processes that leave high amounts of fluoride in their effluent. This system was designed to remove fluoride from water saturated with calcium sulfate, as calcium sulfate is present in high amounts in certain mining processes. Currently, high density sludge (HDS) is commonly employed to reduce fluoride concentrations, but due to solubility limits the sludge treatment cannot lower fluoride below 10 mg/L (ppm). The current enforceable EPA standard for discharged water is at 4 mg/L (ppm), although mining companies anticipate that this standard will soon be lowered to 2 ppm. The Moo Pig Sooie’s were tasked with designing a process to lower 10 ppm fluoride down to 2 ppm.
Moo Pig Sooie investigated various methods such as precipitation, ion exchange, and reverse osmosis to remove fluoride from the system. These methods were not cost-effective and did not produce environmentally friendly byproducts. The team ultimately presented the solution of bone char as an adsorbent, with a byproduct that can be safely applied as a soil amendment. A full-scale facility with two adsorption columns was designed to treat 1000 gpm of water

https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=1166&context=cheguht

Removal of Fluoride from Mine Water via Adsorption for Land-Applied Soil Amendment

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