Plus 6 Solutions’ Answer to Pollutant Remediation is Using Ferrate

Ferrate (FeO42-)
Ferrate is a supercharged iron molecule, in which iron is in the plus 6 oxidation state (Fe VI or Fe 6+).  Ferrate is extremely powerful, and can deliver multiple treatments from a single application, does not create disinfection byproducts, is environmentally friendly, and solves difficult treatment challenges that other oxidants can’t touch.  Most importantly, Ferrate is often the least expensive and most effective treatment option when compared to water treatment technologies including ozone, hydrogen peroxide, permanganate, or chlorination.

A Laboratory Curiosity … Until Now
Research scientists have been testing Ferrate for the past 50 years.  Previous attempts to commercialize a Ferrate product were unsuccessful due to high costs for synthesis, packaging and transport, which made Ferrate too expensive for broad use. We solved these issues by manufacturing liquid Ferrate onsite, so that it can be applied when its potency is highest.

More Powerful
The relative strength of water treatment chemicals can be measured in volts, similar to an electrical circuit. Scientists compare the oxidation-reduction potential, commonly referred to as “redox” potential or ORP, for different water treatment technologies.  Redox can be used as a gauge of a technology’s ability to gain or donate electrons in a chemical reaction; the higher the redox potential, the more powerful the reaction.  Oxidation potential can be a critical consideration, because oxidation will chemically change a pollutant, rendering the pollutant in less soluble, less biologically active, less toxic, or a combination of these changes. Ferrate is the most powerful common oxidant/disinfectant for water and wastewater treatments, able to achieve the oxidation of various chemicals that are otherwise unchangeable.   Various redox potentials measured in volts are: Ferrate – 2.2, Ozone – 2.08, Hydrogen peroxide  – 1.78, Permanganate – 1.68, Hypochlorite – 1.48, Perchlorate – 1.39, Chlorine – 1.36, Dissolved Oxygen – 1.23, Chlorine Dioxide – 0.95.

 

No Disinfection Byproducts
Ferrate redeploys the power of chlorine for water treatment without producing disinfection byproducts. Chlorination in the presence of organic materials creates carcinogenic disinfection byproducts (DBPs), such as trihalomethanes (THMs), and haloacetic acids (HAAs). Ozone reacts with naturally occurring bromine to form bromates, also a human carcinogen.  Switching to Ferrate from chlorine, chlorine dioxide, or ozone precludes the formation of DBPs. Ferrate is the technology for the future where regulatory compliance will see increasingly difficult permit requirements for total residual chlorine or disinfection byproducts. 

 

Environmentally Friendly
Ferrate is powerful, fast acting, works in small doses, and the final product of Ferrate treatment is ferric hydroxide, Iron (III), a non-toxic, environmentally benign compound.  Ferric hydroxide the same oxidation state of iron as rust.

 

Multiple Treatments from a Single Dose
In a single application, Ferrate can simultaneously perform as an oxidant, coagulant, flocculant, and disinfectant.  Ferrate is more powerful than other oxidants such as ozone and chlorine dioxide. But, the treatment potential of ferrate is further enhanced because the reaction is the byproduct ferric hydroxide (Fe(OH)3 or Fe3+) which can bind to negatively charged particles in water. If allowed to coagulate and flocculate, ferrate residuals are effective at removing ferric chloride, alum and polymers for the removal of metals, non-metals and humic acids.  It can replace coagulant or polymer chemistries that are used to remove contaminants by settling, further improving the economics of water treatment. Ferrate outperforms other disinfectants such as UV, hydrogen peroxide, and chlorine and can kill many chlorine-resistant organisms such as aerobic spore-formers and sulphite-reducing clostridia. Ferrate is a versatile, powerful, multi-use water and wastewater treatment technology.

Oxidation > Disinfection > Coagulation

Solves Difficult Water Treatment Challenges
Ferrate has been demonstrated to treat a wide array of otherwise untreatable chemicals, including: antibiotics, hormones, pesticides, personal care products (PPCPs), metals, carcinogens, that are present in sewers and pass-through municipal treatment plants, but also in industrial waste streams, mine drainage, oil field produced water, ballast tanks, and other extreme or difficult to treat waters.  Industrial wastewater contaminants vary widely across such diverse industries as pulp and paper, mining, food and beverage, pharmaceutical manufacturing, electroplating, metal fabricating, paint production and painting, aquaculture, leather tanning, oil and gas extraction, hazardous waste, and industrial farming. 

  • Iron VI as an oxidant can treat a multitude of chemicals that can adversely impact human health. Fe6+ can improve water quality by de-coloring 1 and deodorizing water 2, 3, attributed to oxidation of compounds such as fluvic acid 4, mercaptans 3, and hydrogen sulfide 3. Ferrate will also deactivate water toxins, such as microcystins 5, which cannot be removed by conventional water treatment methods.
  • Low doses of Ferrate have been shown to biologically inactivate those EDCs and PPCPs 6. EDCs and PPCPs are compounds that can disrupt normal endocrine signaling of the human body and can exert a biological effect in very miniscule quantities. Oxidation of these compounds can render the compound ineffective at disrupting the hormonal pathways, particularly for the estrogenic steroids 17-α ethynyl estradiol (EE2), estrone (E1), β-estradiol (E2), and estriol (E3).
  • Removal of metals is very effective by ferrates, including copper, cadmium, chromium, cobalt, manganese, zinc, and antimony 7, 8, 9. Ferrate works by oxidizing soluble metal, forms complexes with the oxidized metals and the ferric residual, and then precipitates a residual. No other treatment technology can address a broad spectrum of metals in a single process.
  • Similarly, ferrates can also facilitate the removal of arsenic, a potent toxic semi-metal that has both acute toxicity and can cause cancer as a result of exposure 9, 10, 11. Arsenic is problematic in groundwater in developing countries in Asia and as a component of industrial wastes, such as paints. Ferrate has great promise for meeting revised Safe Drinking Water Act regulations, which reduced the maximum concentration in water from 50 to 10 µg of arsenic per liter.
  • The degradation of cyanide-contaminated water has also been extensively researched, with ferrate being a robust and effective treatment of industrial wastes, groundwater, and surface waters contaminated with toxic cyanide 8, 12, 11, 13, 14, 15, 16, 17, 18.
  • Ferrate can also remove difficult to treat chlorinated compounds, which can persist in the environment for substantial lengths of time 17, 19, including monochlorinated benzene, chlorophenols, dechlorinated benzene, and polychlorinated benzenes (PCBs). These chemicals have been found to largely be recalcitrant to biological degradation and can persist for decades in industrially contaminated soils and groundwater.

Solves Difficult Biosolids Treatment Challenges
Ferrate has been proven to be a key ingredient in a new biosolids-to-fertilizer process.  It disinfects and stabilizes biosolids to inhibit putrefaction, destroys odors, and adds iron as a vital micronutrient. Ferrate also helps bind phosphorus and nitrogen to the organic matter to create a “slow-release” fertilizer, which prolongs its availability, increases uptake in the root zone, and reduces nutrient runoff into local streams and rivers 20.

Works Cited

(1) Liyanage, L. R. J.; Finch, G. R.; Belosevic, M. Effect of aqueous chlorine and oxychlorine compounds on Cryptosporidium parvum oocysts. Environmental Science & Technology 1997, 31 (7), 1992-1994.

(2) Jiang, J. Q.; Panagouopoulos, A.; Bauer, M.; Pearce, P. The application of potassium ferrate for sewage treatment. Journal of Environmental Management 2006, 79 (2), 215-220.

(3) Sharma, V. K. Potassium ferrate(VI): an environmentally friendly oxidant. Advances in Environmental Research 2002, 6 (2), 143-156.

(4) Tuncsiper, B. Removal of nutrient and bacteria in pilot-scale constructed wetlands. Journal of Environmental Science and Health Part a-Toxic/Hazardous Substances & Environmental Engineering 2007, 42 (8), 1117-1124.

(5) Sobsey, M. D. Inactivation of health-related microorganisms in water by disinfection processes. Water Science and Technology 1989, 21 (3), 179-195.

(6) Jiang, J. Q.; Yin, Q.; Zhou, J. L.; Pearce, P. Occurance and treatment trials of endocrine disrupting chemicals (EDCs) in wastewaters. Chemosphere 2005, 61 (4), 544 – 550. Li, C.; Li, X. Z.; Graham, N.; Gao, N. Y. The aqueous degradation of bisphenol A and steroid estrogens by ferrate. Water Research 2008, 42 (1-2), 109-120. Lee, Y.; Escher, B. I.; Von Gunten, U. Efficient removal of estrogenic activity during oxidative treatment of waters containing steroid estrogens. Environmental Science & Technology 2008, 42 (17), 6333-6339. DOI: 10.1021/es7023302.

(7) Farooq, S.; Bari, A. High Level Disinfection of Wastewaters for Reuse. Environmental Technology 1988, 9 (5), 379 – 390. Lim, M.; Kim, M.-J. Effectiveness of Potassium Ferrate (K2FeO4) for simultaneous removal of heavy metals and natural organic matters from river water. Water Air and Soil Pollution 2010, 211 (1-4), 313-322. Prucek, R.; Tuček, J.; Kolařík, J.; Hušková, I.; Filip, J.; Varma, R. S.; Sharma, V. K.; Zbořil, R. Ferrate(VI)-Prompted Removal of Metals in Aqueous Media: Mechanistic Delineation of Enhanced Efficiency via Metal Entrenchment in Magnetic Oxides. Environmental Science & Technology 2015, 49 (4), 2319-2327. DOI: 10.1021/es5048683. Johnson, M. D.; Lorenz, B. B. Antimony Remediation Using Ferrate(VI). Separation Science and Technology 2015, 50 (11), 1611-1615. DOI: 10.1080/01496395.2014.982294.

(8) Filip, J.; Yngard, R. A.; Siskova, K.; Marusak, Z.; Ettler, V.; Sajdl, P.; Sharma, V. K.; Zboril, R. Mechanisms and Efficiency of the Simultaneous Removal of Metals and Cyanides by Using Ferrate(VI): Crucial Roles of Nanocrystalline Iron(III) Oxyhydroxides and Metal Carbonates. Chemistry-a European Journal 2011, 17 (36), 10097-10105, Article. DOI: 10.1002/chem.201100711.

(9) Lim, M.; Kim, M. J. Effectiveness of Potassium Ferrate (K2FeO4) for Simultaneous Removal of Heavy Metals and Natural Organic Matters from River Water. Water Air and Soil Pollution 2010, 211 (1-4), 313-322, Article. DOI: 10.1007/s11270-009-0302-7.

(10) Fan, M. H.; Brown, R. C.; Huang, C. P. Preliminary studies of the oxidation of arsenic(III) by potassium ferrate. International Journal of Environment and Pollution 2002, 18 (1), 91-96. Lee, Y.; Um, I. H.; Yoon, J. Arsenic(III) oxidation by iron(VI) (ferrate) and subsequent removal of arsenic(V) by iron(III) coagulation. Environmental Science & Technology 2003, 37 (24), 5750-5756. DOI: 10.1021/es034203+.

(11) Sharma, V. K. Oxidation of inorganic compounds by ferrate(VI) and ferrate(V): one-electron and two-electron transfer steps. Environmental Science & Technology 2010, 44 (13), 5148 – 5152.

(12) Seung-Mok, L.; Diwakar, T. Application of ferrate (VI) in the treatment of industrial wastes containing metal-complexed cyanides: A green treatment. Journal of Environmental Sciences 2009, 21 (10), 1347 – 1352.

(13) Yngard, R.; Damrongsiri, S.; Osathaphan, K.; Sharma, V. K. Ferrate(VI) oxidation of zinc-cyanide complex. Chemosphere 2007, 69 (5), 729-735. DOI: 10.1016/j.chemosphere.2007.05.017.

(14) Yngard, R. A.; Sharma, V. K.; Filip, J.; Zboril, R. Ferrate(VI) oxidation of weak-acid dissociable cyanides. Environmental Science & Technology 2008, 42 (8), 3005-3010. DOI: 10.1021/es0720816.

(15) Sharma, V. K.; Yngard, R. A.; Cabelli, D. E.; Baum, J. C. Ferrate(VI) and ferrate(V) oxidation of cyanide, thiocyanate, and copper(I) cyanide. Radiation Physics and Chemistry 2008, 77 (6), 761-767. DOI: 10.1016/j.r,idphyscliezii.2007.11.004.

(16) Hari Krishna, S.; Prasanthi, K.; Chowdary, G. V.; Ayyanna, C. Simultaneous saccharification and fermentation of pretreated sugar cane leaves to ethanol. Process Biochem. 1998, 33 (8), 825-830.

(17) Graham, N.; Jiang, C. C.; Li, X. Z.; Jiang, J. Q.; Ma, J. The influence of pH on the degradation of phenol and chlorophenols by potassium ferrate. Chemosphere 2004, 56 (10), 949-956.

(18) Sharma, V. K.; O’Connor, D. B.; Cabelli, D. E. Sequential one-electron reduction of Fe(V) to Fe(III) by cyanide in alkaline medium. Journal of Physical Chemistry B 2001, 105 (46), 11529-11532. DOI: 10.1021/jp012223x.

(19) Vizsolyi, E. C.; Katona, K.; Lang, G. G.; Varga, J.; Zaray, G. Effect of cations and ferric-oxide/hydroxide precipitation on the removal of chlorobenzene compounds from model solutions applying ferrate treatment. Desalination and Water Treatment 2020, 193, 352-358. DOI: 10.5004/dwt.2020.25802. Monfort, O.; Usman, M.; Soutrel, I.; Hanna, K. Ferrate(VI) based chemical oxidation for the remediation of aged PCB contaminated soil: Comparison with conventional oxidants and study of limiting factors. Chemical Engineering Journal 2019, 355, 109-117. DOI: 10.1016/j.cej.2018.08.116.

(20) DeLuca, S. J.; Idle, C. N.; Chao, A. C. Quality improvement of biosolids by ferrate(VI) oxidation of offensive odour compounds. Water Science and Technology 1996, 33 (3), 119-130. Reimers, R. S.; Sharma, V. K.; Pillai, S. D.; Reinhart, D. R.; Boyd, G. R.; Fitzmorris, K. B. Application of Ferrates in Biosolids and Manures Management with respect to Disinfection and Stabilization. In Joint Residuals and Biosolids Mangement Conference 2005 – Advancing the State of Technology, Alexandria, VA; 2005.