Cement Kiln and Waste to Energy Incineration of Spent Media Craig Patterson1, Seyed A. Dastgheib2
1U.S. Environmental Protection Agency, Center for Environmental Solutions and Emergency Response
2Illinois State Geological Survey, University of Illinois at Urbana-Champaign
THERMAL TREATMENT OF PFAS STATE OF THE SCIENCE WORKSHOP
Sponsored by U.S. Environmental Protection Agency's (EPA) Office of Research and Development (ORD) and Department of Defense SERDP/ESTCP Programs Cincinnati, Ohio
February 25, 2020 Project Focus: Incineration of PFAS-laden Ion Exchange Resins with a Lime Sludge Additive
PFAS removal from water by ion exchange resins Management of spent PFAS-laden resins Rotary kilns (e.g., cement kilns) for solid waste and waste to energy incineration Incineration of PFAS-laden resin in rotary kilns . HF capture after incineration is needed . Calcium additive can capture fluorine Lime sludge reuse as a low cost additive for fluorine capture during incineration
Source: Bernard, B., DiPasquale, M.., From Pilot to Full-Scale: A Case Study for the Treatment of PFC’s with Ion Exchange, AWWA ACE, Denver, CO 2019.
2 PFAS Removal from Water Ion exchange and activated carbon adsorption are identified as the most mature and feasible technologies for PFAS removal Anion exchange resins can be used as a stand-alone treatment or in combination with GAC Anion exchange resins have shown excellent performance for PFAS removal at relatively low EBCTs when compared to GAC Sources: 1) I. Ross et al. A review of merging technologies for remediation of PFASs. Remediation 2018, 28, 101-126. 2) Purolite 3 presentation and case study. F. Boodoo et al. Management of Spent PFAS-Laden Resin
Options for Management of the Spent Resins Regeneration with brine solutions: Not recommended due to the fate and liability of concentrated PFAS residuals in wastewater Offsite incineration of single use anion exchange resins . Waste-to-Energy Incinerators . Cement Kiln Incinerators
Source: Paul Chaplin, The Patriot-News/file
4 Source: journal-news.net Case Studies from Resin Manufacturers (Kuraray, Formerly Calgon Carbon)
Spent resin in North Carolina (~70 cubic feet) was sent to a waste-to-energy incinerator in Virginia. Spent resin in Colorado (~425 cubic feet) was sent to a waste-to-energy incinerator in California. New resin water treatment installations are planned in Colorado (14.5 MGD) and New Jersey (3 MGD) in 2020. This equates to ~ 2,700 cubic feet and ~540 cubic feet of spent resin that will be incinerated at the end of their service lives at least two years from now.
5 Case Studies from Resin Manufacturers (Purolite)
Select cement kilns have incinerated waste resins from Purolite’s production plant in Philadelphia. Not all cement kilns are set up to dry feed resins or similar media. Each pound of resin will generate about 12,000 BTUs of energy making resin a useful fuel supplement for the cement kilns. The temperature at which the cement kilns operate (1400°C-2000°C) allows for full destruction of PFAS compounds. The recoverable energy is also helpful from a sustainability standpoint.
6 Rotary Kiln Incinerators
Rotary kilns are used for various Counter-current manufacturing, calcination, thermal processing, and incineration applications including . GAC reactivation . Cement production . Waste incineration Rotary kilns can be operated in co-current or counter-current modes Co-current Source: Gossman. The reuse of petroleum and petrochemical waste in cement kilns. Environmental Progress 1992, 11, (1), 1-6.
7 Rotary Kiln Incinerators
Rotary kilns can be operated under different operating conditions . Gas temperature up to ~2,000 ºC . Gas residence times of up to 10 sec . Solid residence time of up to 30 min
Source: D. Gossman. The reuse of petroleum and petrochemical waste in cement kilns. Environmental Progress 1992, 11(1), 1-6. 8 Rotary Kilns for Municipal or Industrial Waste Incineration Solid or liquid waste is injected co-currently with fuel on one side Organic waste combustion provides additional heat, lowering the fuel consumption and energy input A second burner burns the residual organic contaminants in the flue gas Heat is recovered and converted to steam/power Filtration and scrubbing systems clean the flue gas before sending it to the stack
Source: Z. Jegla et al. Secondary combustion chamber with inbuilt heat transfer area – Thermal model for 9 improved waste-to-energy systems modelling, Chemical Engineering Transactions 2010, 21, 859-864. Incineration of PFAS-laden Media Ion exchange resins saturated with PFAS compounds can be incinerated in rotary kilns with gas temperatures of up to ~2,000 ºC PFAS compounds decompose at < 700 ºC and generate different free radicals and unstable fragments of original PFAS molecules, and finally form stable
fluorocarbon compounds such as CF4 and C2F6 Higher temperatures (1,000-1,600 ºC) may be needed to break very stable C-F bonds without a catalyst (e.g., calcium), complete oxidation reactions, and finally form HF that requires post-combustion treatment with a caustic medium
such as Ca(OH)2 A conventional cement kiln with post-combustion treatment unit can effectively incinerate PFAS-laden media and capture HF from combustion flue gas However, there are several research data gaps such as information about optimized temperature and residence time requirements for destruction of various PFAS compounds Sources: Krusic et al. Gas-phase NMR studies of the thermolysis of perfluorooctanoic acid. J. Fluorine Chem. 2005, 126, (11-12), 1510-1516. Watanabe et al. Residual organic fluorinated compounds from thermal treatment of PFOA, PFHxA and PFOS adsorbed onto granular activated carbon (GAC). J. Mater. Cycles Waste Mgt. 2016, 18, 625-630. Wang et al. Effectiveness and Mechanisms of Defluorination of Perfluorinated Alkyl Substances by Calcium Compounds during Waste Thermal Treatment. Environ. Sci. Technol. 2015, 49, (9), 5672-80. Qin et al. Highly Efficient Decomposition of CF4 Gases by Combustion. Conference on Environmental Pollution and Public Health 2010, 126-130. Gossman. The reuse of 10 petroleum and petrochemical waste in cement kilns. Environmental Progress 1992, 11, (1), 1-6. Lime as a Low Cost Additive for Fluorine Capture during PFAS Incineration Several researchers have reported effective PFAS destruction and capture by
using a mixture of PFAS and excess amounts of CaO, CaCO3, or Ca(OH)2 Incineration of a mixture of PFAS-laden media and a calcium sorbent can lower the total energy requirement (by lowering the incineration temperature) Different free radicals and unstable fragments generated during the decomposition stage of PFAS compounds (at < 700 ºC) react with a calcium additive to form stable calcium fluoride mineral before forming stable organic
fluorocarbon compounds (e.g., CF4) that require very high temperature (up to 1,600 ºC) for decomposition
Water Waste 1: Spent PFAS-Laden Spent Anion Exchange Anion Exchange Resin Treatment Incinerator and Energy Plant Waste 2: Water-softening Recovery System lime sludge or lime
Sources: Wang et al. Effectiveness and Mechanisms of Defluorination of Perfluorinated Alkyl Substances by Calcium Compounds during Waste Thermal Treatment. Environ. Sci. Technol. 2015, 49, (9), 5672-80. Wang et al. Influence of calcium hydroxide on the fate of perfluorooctanesulfonate under thermal conditions. J. Hazard. Mater. 2011, 192, (3), 1067-71. Wang et al. Mineralization behavior of fluorine in perfluorooctanesulfonate (PFOS) during thermal treatment of lime-conditioned sludge. Environ. Sci. 11 Technol. 2013, 47, (6), 2621-7. Lime as a Low Cost Additive for Fluorine Capture during PFAS Incineration Similar to conventional incineration of PFAS-laden materials, there are major research gaps in understanding the temperature and residence time requirements for incineration of PFAS-laden media and calcium additive mixtures Utilization of low-cost calcium materials such as lime softening sludge as a replace- ment for CaCO3, CaO, or Ca(OH)2 in PFAS incineration has not been explored
Source: Purolite presentation and case study. F. Boodoo et al. https://ebcne.org/wp-content/uploads/2018/06/Presentations-EBC- 12 Connecticut-Program-Contaminants-of-Emerging-Concern-Update-on-PFAS.pdf Water Treatment Plant Lime Softening Sludge
Lime sludge is precipitated calcium carbonate produced during the lime softening process at water treatment plants Lime sludge is a highly reactive form of calcium carbonate with a BET surface area of up to 12 m2/g, about one order of magnitude higher than the surface
area of limestone or reagent CaCO3 In the US, ~ 3.2 million tons of lime sludge is generated per year with an estimated disposal cost of ~$90 million Generated lime sludge is currently managed by disposal in landfills that may add up to 10% to the overall cost of the water treatment Beneficial reuse of lime sludge can reduce disposal costs and generate revenue
Source: Utilization of water utility lime sludge for flue gas desulfurization in coal-fired power plants: Part 1. Supply-demand 13 evaluation and life cycle assessment. H. Salih, C. Patterson, J. Li, J. Mock, S.A. Dastgheib. Energy & Fuels 2018, 32, 6627-6633. EPA Disclaimer
The U.S. Environmental Protection Agency, through its Office of Research and Development, funded and managed, or partially funded or collaborated in, the research describe herein. It has been subjected to the Agency’s peer and administrative review and has been approved for external release. Any opinions expressed in this presentation are those of the author(s) and do not necessarily reflect the views of the Agency, therefore, no official endorsement should be inferred. Any mention of trade names or commercial products does not constitute endorsement or recommendation for use.
14 Questions?
Craig Patterson at EPA, 513-487-2805, [email protected] Seyed A. Dastgheib at UIUC, 217-265-6274, [email protected]
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Office of Research and Development National Risk Management Research Laboratory – Water Supply and Water Resources Division 15