Winchell, Lloyd

Since graduating in 2005 from the University of Minnesota, Lloyd has spent fourteen years with Brown and Caldwell as an environmental engineer. Lloyd's work has focused solely on wastewater treatment projects involving both industrial and municipal clients. His specialties include wastewater liquids and solids process engineering with significant experience addressing whole plant issues and planning efforts. Recent solids process engineering includes PFAS fate, incineration optimization, energy recovery in solids processing, and emissions compliance.

Titles from this speaker

Fate of PFAS through Incineration at Wastewater Reclamation Facilities

Abstract

Introduction Per- and polyfluoroalkyl substances (PFAS) encompass a wide range of compounds, numbering in the thousands. These compounds, because of their properties, have been used in a variety of consumer and industrial products and, consequently, are widely distributed in the environment (Buck et al., 2011). Research focused on understanding the sources of PFAS in drinking water and have identified municipal wastewater reclamation facilities (WRF) as an important pathway (Clara, Scheffknecht, Scharf, Weiss, & Gans, 2008). Because PFAS are concentrated in wastewater solids (Rainey, 2019), WRFs introduce these compounds to the environment through land application of biosolids, potentially allowing PFAS to enter surface water and groundwater (Lindstrom et al., 2011). What has not been well studied is the potential for sewage sludge incinerators (SSI) to introduce PFAS to the environment or destroy it. The extent of PFAS thermal destruction (i.e., thermal degradation by-product formation or complete mineralization) is poorly understood. No published data currently exist on the fate of PFAS through an SSI, although limited information from other industries can be referenced. This paper documents the current understanding on the fate of PFAS through SSIs and the research currently underway to further our understanding. PFAS Thermal Behavior For a combustion process to achieve complete PFAS thermal destruction (mineralization), PFAS compounds would have to be driven to their thermodynamic endpoints of CO2, H2O, HF, or sulfur compounds, if present. Residence time, turbulence (mixing), and stoichiometry (the relative mixture of waste to fuel, oxygen, and other gas-phase constituents) within the flame zone impact the completeness of combustion (Lewis, 2008; Niessen, 2002). Published research and industry guidance indicate that complete destruction of PFAS requires high temperatures (Table 1) which exceeds typical temperatures in SSIs. Notably, this guidance is based on limited conceptual or laboratory-scale experiments and precedence on previous guidance established for hazardous waste incineration. The baseline research for these recommendations stems from USEPA and other international environmental agency activities. Taylor & Yamada (2003) published results of a simulated hazardous waste incineration experiment with limited air to account for non-ideal combustion conditions. Experiments showed less than 0.4% and 0.05% of the PFOS fed to the reactor were detected in the exhaust at tests conducted at 600°C and 900°C, respectively. Yamada, et al., (2005) published a similar laboratory-scale study that considered combustion of PFAS-impregnated textiles. Neither PFOA nor PICs were detected under non-ideal combustion performance. Taylor et al. (2014) found no PFOA emissions after combustion of gasified fluorotelomer-based polymers. Full-Scale Incineration Studies A few full-scale studies have been published on the fate of PFAS through incineration systems with only two considering an SSI. Loganathan et al. (2007) investigated eight PFAS through a wastewater treatment facility. PFAS were measured in dewatered solids fed to the incinerator and in the ash. No mention was made on the operating conditions or whether the bottom or fly ash was sampled. Findings indicated a significant transformation of the measured compounds (26 & 97 percent); however, some PFAS were still detected in the ash. A second study is currently underway at an SSI facility employing an fluidized bed (MacGregor, 2020). Samples were taken at all inputs and outputs of the SSI system and analyzed quantitatively for 28 PFAS. Preliminary results show that mass flows were reduced through the SSI processes for all quantitated PFAS, with the exception of 6:2 fluorotelomer sulfonate. The authors also noted that the inorganic fluoride content of the wet scrubber discharge water was over 10,000 times that of the influent flow plus the measured PFAS fed to the furnace, assuming mineralization. No other studies have been published on SSIs, but limited information can be found in literature investigating incineration in other industries. Lemieux et al. (2007) reported on the USEPA's study of feeding carpet treated with fluorotelomer products into a pilot-scale rotary kiln furnace. The emitted PFAS detected, primarily PFOA and PFHxA, did not change when feeding PFAS contaminated carpet or not. Aleksandrov et al. (2019) investigated emissions from a pilot-scale rotary kiln incinerator. No significant PFAS emissions were detected. Thermal By-Products Bench- and pilot-studies have examined decomposition of specific PFAS congeners and by-product identification; several studies documented thermal PFAS degradation by-products (Table 2). These studies show that PFAS will decompose at temperatures relevant to operating conditions of SSIs although by-product formation will be a concern. Funded Research The USEPA (2021) has recently sampled an SSI as part of a broader sampling program at a WRRF. Samples were taken from all major input and output streams of the multiple hearth for PFAS characterization. The samples are currently being analyzed for targeted, non-targeted, and total organic fluorine. Winchell et al. (2021b) provide a detailed discussion on these analytical techniques. A separate study led by Brown and Caldwell with support from the Water Research Foundation's Tailored Collaboration program will sample two SSIs, one multiple hearth and one fluidized bed. This study mirrors the USEPA from a sampling and analytical standpoint. The full-scale sample will take place during the winter and spring. Initial work has included site selection and workplan development. Including, estimating PFAS emissions at various destruction and removal efficiencies (DREs) based on targeted PFAS measured in initial dewatered cake samples. Figure 1 shows the PFAS emissions from one of the test sites remain above the reporting limits for the analytical method at relatively high DREs. This suggests specific PFAS will be detectable unless achieving high DRE, a question highly sought after by the industry. Conclusions Thermal treatment of PFAS through SSIs represents a potential wastewater solids process for destroying PFAS; although, significant questions remain regarding both the destruction efficiency and potential formation of undesirable by-products. Temperature is only one of the three key operational parameters that should be considered when assessing destruction capacity in combustion systems. The other two important factors include residence time and turbulence. A well-functioning SSI will submit PFAS to greater residence times and mixing (or turbulence) than the laboratory-scale research performed to date, further promoting PFAS destruction.

This paper was presented at the WEF Residuals and Biosolids Conference in Columbus, Ohio, May 24-27, 2022.

SpeakerWinchell, Lloyd

Presentation time

16:15:00

16:45:00

Session time

13:30:00

17:00:00

Session number03

Session locationGreater Columbus Convention Center, Columbus, Ohio

Topicincineration, PFAS, Residuals

Author(s)

L. Winchell

Author(s)L. Winchell1; J. Ross2; J. Norton3; X. Fonoll Almansa4; M. Khan5; S. Kuplicki6

Author affiliation(s)Brown and Caldwell; 1Brown and Caldwell; 2Great Lakes Water Authority; 3GLWA; 4Great Lakes Water Authority; 5Great Lakes Water Authority; 6

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2022

DOI10.2175/193864718825158449

Volume / Issue

Content sourceResiduals and Biosolids

Word count10

Description: PFAS Fate in Pyrolysis System Reflecting Full-Scale Configurations: Thermal Oxidizer...

PFAS Fate in Pyrolysis System Reflecting Full-Scale Configurations: Thermal Oxidizer Impacts

Abstract

Introduction
Per- and polyfluoroalkyl substances (PFAS) are becoming an increasingly scrutinized and studied class of pollutants due to their widespread use and environmental contamination leading to federal and state health-based guidance and regulatory values. PFAS resist environmental degradation and can accumulate in the urban water cycle, including wastewater systems (Winchell et al., 2021c). Furthermore, various PFAS will migrate to wastewater solids (termed biosolids when stabilized) where conventional treatment technologies have little to no effect on the PFAS content of the solids (Hamid et al., 2016, Yu et al., 2009, Loos et al., 2018, Gallen et al., 2018, Mailler et al., 2017, Kim Lazcano et al., 2019). PFAS in biosolids have the potential to derail beneficial reuse via land application due to the potential impacts to groundwater, and transfer into agricultural crops (Lee et al., 2014, Zhang et al., 2015, Navarro et al., 2017, Ghisi et al., 2019). Thermal treatment is the only process currently identified to reliably destroy PFAS (USEPA, 2020a), but destruction efficiency must be confirmed to avoid worsening atmospheric pollution and deposition (Shafer et al., 2020). While incineration shows promise for PFAS destruction (Winchell et al., 2021a), utilities are looking to thermal treatment alternatives that do not require the same permitting rigor and generate a higher value solid residual. Pyrolysis fits these requirements.
Current Understanding
Pyrolysis systems include more than the reactor thermally processing the feedstock in a reducing atmosphere, see Figure 1. Pyrolytic reactions consume and release heat energy, with an overall heat flow generally considered zero when processing dry feedstocks (Basu, 2013). Dewatered wastewater solids require drying to evaporate water prior to treatment in the pyrolyzer. Contemporary systems recycle heat for drying and pyrolysis by processing the fuel rich off-gas from pyrolysis through a thermal oxidizer. Subsequent processes include removal and handling of the solid residual, biochar, and further cleaning of the flue gas from the thermal oxidizer. The pyrolysis systems offers several opportunities to remove and possibly destroy PFAS. Pollutant destruction and removal efficiency (DRE) in high-temperature thermal processes can generally be benchmarked by the '3 T's' (i.e., time, temperature, and turbulence). Table 1 contains key operating parameters for a recent survey of technology suppliers. The pyrolyzer can reach temperatures up to 950Â°C, depending on the goals of the solid and gas residuals, with several second residence times for the off-gas and 15-20 minutes for the solids. The thermal oxidizer conditions can likewise be tailored, but typically process the off-gas for over two seconds at over 850Â°C. PFAS destruction requirements often quoted only refer to temperature (>1,000Â°C) based on limited data sets designed for hazardous waste incineration (Winchell et al, 2021a) which can lead to premature conclusions about currently available high-temperature processes. The wastewater industry requires a better understanding on the fate of PFAS through these systems. Several studies have started looking into the fate of PFAS through pyrolysis systems processing wastewater solids. Kim et al. (2015) observed no significant change of PFAS in the biochar after pyrolysis of wastewater solids at 300 and 700Â°C in a laboratory setup. Kundu et al. (2021), however demonstrated removal of all measured PFAS species in biochar at temperatures ranging from 500 â€“ 600Â°C. Williams et al (2021) detected three PFAS of 28 evaluated in biochar at 500Â°C and none after 700Â°C. Williams et al (2021) also analyzed the off-gas stream and reported a combined mass removal efficiency of 84.4 and 95.6 percent of measured PFAS when including the levels in the biochar at the same two experimental temperatures, respectively. The body of research does not consider the impacts of the thermal oxidizer on the gas-phase outlet.
Experimental Approach
A research consortium partnered to begin evaluating the fate of PFAS through the entire pyrolysis process. The initial phase of the research considers the fate of PFAS through laboratory-scale drying, pyrolysis, and thermal oxidation systems. Collaborative funding of the partners supported construction of a laboratory-scale system at Western University's Institute for Chemicals and Fuels from Alternative Resources (ICFAR). Figure 2 shows the basic configuration of the laboratory system. Dried wastewater solids will be loaded into a 'biomass' feed hopper and metered into the mechanically stirred pyrolyzer. Off-gas can be processed through a condensing system, reflective of historical applications, or through a thermal oxidizer. The system will process roughly one kilogram per hour of dried material under conditions reflecting a currently operating full-scale system at the Silicon Valley Clean Water treatment facility in Redwood City, CA. Construction and commissioning of the laboratory system will be completed in December of 2021. PFAS sampling and analysis poses a significant challenge given the complexity, diversity, and novelty of the target substances (Winchell et al., 2021b). This research will employ the latest standardized and research methods. All streams into and out of the system will be sampled including solid and gas-phases at the laboratory scale. Using targeted, non-targeted analysis (NTA), total organic fluorine (TOF), and Fourier transform infrared spectroscopy (FTIR) this study will aim to close the PFAS mass balance across the system to the extent possible within current analytical constraints. Preliminary assessment of the donor wastewater solids and laboratory system operation suggest specific PFAS can be detected, above the method reporting limits, in the gas emissions at high DREs, see Figure 3. Furthermore, to our knowledge NTA has not been reported yet on wastewater solid pyrolysis systems. NTA identifies PFAS not currently evaluated for in the standardized USEPA Method 537 (2020b). This will help determine what 'other' PFAS are present in wastewater solids, biochar, and gas emissions.
Conclusions
This paper and presentation will provide the WEF audience a detailed summary of the current published literature on the fate of PFAS through pyrolysis systems. This summary identifies the gaps in knowledge and the proposed study takes the first step in evaluating the emissions from the system post thermal oxidation, consistent with existing configurations. An in-depth discussion on the study sampling and analytical procedures will provide the wastewater community a valuable resource on PFAS measurement. Additional value will be provided by way of the available study results.

PFAS partition to the solids generated during wastewater. Pyrolysis systems offer the potential to destroy PFAS, especially when coupled with a thermal oxidizer for off-gas treatment. Limited information can be found on the fate of PFAS through high-temperature process. This paper discusses a collaborative research effort to define PFAS behavior through a laboratory-scale pyrolyzer and thermal oxidizer validated against performance from a full-scale facility.

SpeakerWinchell, Lloyd

Presentation time

14:00:00

14:15:00

Session time

13:30:00

15:00:00

TopicIntermediate Level, Biosolids and Residuals, PFAS

Author(s)

Winchell, Lloyd

Author(s)Lloyd Winchell1; Franco Berruti2; Alexandre Miot3; John Ross4; Mary L. Romero5; Aren Hansen6

Author affiliation(s)Brown and Caldwell, St. Paul, MN1; Institute for Chemicals and Fuels from Alternative Resources, ON, Canada2; Silicon Valley Clean Water, Redwood City,CA3; Brown and Caldwell, Detroit, MI4; Brown and Caldwell, Walnut Creek, CA5; Brown and Caldwell, Walnut Creek, CA6

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158645

Volume / Issue

Content sourceWEFTEC

Word count12

Pyrolysis, Gasification, and Incineration--How They Compare

Abstract

Introduction Residual solids from wastewater treatment often require further processing prior to end use, beneficially or otherwise. Historically called sewage sludge, the industry refers to these residuals as biosolids if the final product meets specific federal and state requirements (WEF 2021). Historical applications for these materials face mounting pressures from cost and decreasing site options (Collins, 2019; Slaughter, 2013; USEPA, 1994; EREF, 2021). Another pressure emerging in the industry are per- and polyfluoroalkyl substances (PFAS) (Boxall et al., 2012; Kinney et al., 2006; Navarro et al., 2018; Sepulvado et al., 2011; Walters et al., 2010; Winchell, Wells, et al., 2022). Incineration of sludge and biosolids is a widely applied and accepted technology for addressing this suite of challenges because it provides a high level of control for municipalities. However, obtaining and maintaining permits to construct and operate facilities comes at a significant cost and resource commitments in addition to relatively complex operation and maintenance requirements (WEF, 2009). These complications create an opportunity for alternative technologies to enter the industry. Pyrolysis and gasification systems offer incineration alternatives while achieving similar objectives for mass and handling cost reductions. This paper will provide the Water Environment Federation (WEF) audience with an objective comparison of incineration, pyrolysis, and gasification technologies. Basic principles, process outputs, permitting, and equipment capital costs will get covered. The information will largely reflect the recent publication by the authors in WEF's peer-reviewed Water Environment Research journal (Winchell, Ross, et al., 2022). Basic Principles The primary differentiator, outside of temperature and products, between pyrolysis, gasification, and incineration processes is the amount of oxygen introduced into the high-temperature reactor (Figure 1). Pyrolysis thermochemically converts organic feedstock to carbon-rich char and a hydrocarbon-rich off-gas in the absence of oxygen. Gasification processes further refine the char and off-gas from a pyrolysis step using a gasifying medium (such as air, oxygen, or steam). In the presence of adequate oxygen, the primary constituents of sludge and biosolids carbon, hydrogen, oxygen, nitrogen, and sulfur are combusted to thermodynamically stable end products, such is the goal of incineration. The general arrangement of the process train for pyrolysis, gasification, and incineration is similar. Figure 2 depicts the sub-processes for thermally treating sludge or biosolids and indicates the processing train is categorically similar among the three technologies, with a few exceptions. The common input to all three technologies is dewatered sludge or biosolids. Typical outputs include gas-phase emissions from the stack and solid residuals (i.e., char or ash). Table 1 summarizes the fundamental differences among these three processes. Process Outputs Regardless of the thermal technology or site-specific considerations, each process results in solid and gas-phase emissions. The solid ash or char is collected from the thermal reactor or air pollution control equipment, while gas-phase emissions are ultimately emitted to the atmosphere through the process stack. During pyrolysis and gasification, off-gas production increases as temperatures increase, while char yields decrease due to the loss of volatile components (Chen et al., 2014; Yuan et al., 2015). Nearly all carbon is combusted, and volatile components are lost during incineration, resulting in ash comprised of inorganic minerals dominated by silicon, aluminum, iron, and phosphorus oxides along with alkaline earth minerals (Li et al., 2018; Tempest, 2013). Summaries of the ash and char characteristics and air emissions, including examples of allowed levels from operating facilities, from Winchell, Ross, et al (2022) will be presented. Permitting Permitting a gasification or pyrolysis facility differs significantly from an incinerator. The Clean Water Act and Clean Air Act have sections specific to 'incineration' of 'sewage sludge.' Further, both Acts include definitions specifying combustion of the sludge or biosolids as a critical characteristic of incineration, 40 C.F.R. § 60 (USEPA, 2011). However, there are no specific references to pyrolysis, gasification, or associated thermal oxidizers, and permitting requirements are subject to a case-by-case determination (Hambrick, 2021). To date, pyrolysis and gasification facilities have avoided the 'incineration' designation (Aries Clean Technologies, 2021; USEPA, 2013, 2016) and the associated regulatory requirements. Pyrolysis and gasification systems still must undergo an air permitting process similar to that required for an incinerator as outlined in WEF (2009). In general, the current regulatory framework provides pyrolysis and gasification systems a distinct advantage over sewage sludge incinerators if they can continue avoiding the 'incineration' designation. Equipment Capital Costs Several high-temperature equipment suppliers provided planning level capital costs for a single train of equipment from the point of dewatered sludge or biosolids delivery to the stack, including a handling system for residual solids. Figure 3 displays the cost information in cost curve fashion. The pyrolysis and gasification technologies offer a cost-benefit at lower processing capacities but become comparable to incineration at the 110 dry tonnes/day capacity. Given the cost advantages of pyrolysis and gasification technologies in small to mid-size treatment facilities, this is likely where these technologies will enter the wastewater market. Conclusions Primary advantages of pyrolysis and gasification systems versus a contemporary incinerator identified include operating characteristics, equipment sizing, air emissions, emissions regulations, potential char applications, and equipment costs. These advantages need to be weighed against the added complexity of equipment required for these processes. These advantages and disadvantages will be discussed and detailed in the full paper. Altogether, pyrolysis and gasification show promise as alternatives to incineration for some facilities, particularly small to mid-sized facilities, and the current and contracted-to-build installations will, over time, provide valuable information on real-world operating and maintenance requirements.

This paper was presented at the WEF/IWA Residuals and Biosolids Conference, May 16-19, 2023.

SpeakerWinchell, Lloyd

Presentation time

13:30:00

14:00:00

Session time

13:30:00

16:45:00

SessionSession 16: Advances and Innovations in Thermal Processes I

Session number16

Session locationCharlotte Convention Center, Charlotte, North Carolina, USA

TopicResearch & Innovations

Author(s)

L. Winchell

Author(s)L. Winchell1, J. Ross2, D. Brose3, T. Bremm Pluth4, X. Fonoll Almansa5, J. Norton6,

Author affiliation(s)Brown and Caldwell1; Metropolitan Water Reclamation District of Greater Chicago2; Great Lakes Water Authority3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2023

DOI10.2175/193864718825158826

Volume / Issue

Content sourceResiduals and Biosolids

Word count7

Update - NEORSD Southerly WWTC Biosolids Combustion Optimization

Abstract

Problem Since the startup of the three fluidized bed incinerators (FBIs) at the Northeast Ohio Regional Sewer District (NEORSD) Southerly Wastewater Treatment Center (Southerly WWTC) in 2014 greater than expected auxiliary fuel, that is natural gas, usage has been observed. The original FBI design assumed no auxiliary fuel would be necessary during typical operations. This abstract updates the paper submitted for the 2020 RBC, which was unfortunately cancelled due to the pandemic, with additional data obtained during the interim. Background The NEORSD owns and operates three FBIs at the Southerly WWTC, each design to process 100 dry tons per day (dtpd) at 28 percent solids and 68 percent volatile solids. The FBIs are fed dewatered sludge cake consisting of primary and waste activated sludges generated at the Southerly WWTC. Sludge from the Easterly WWTC managed by NEORSD, discharges into the headworks at the Southerly WWTC for ultimate processing by the FBIs. Typically, FBIs do not require auxiliary fuel when operated near the design condition. Auxiliary fuel is required during startup and sometimes during shutdown operations. Continued use of auxiliary fuel throughout all operations indicates the system is not operating as designed. Objective This study evaluated the existing conditions the FBIs operate under to determine which parameters might be adjusted for more efficient operation. NEORSD can then adjust, as possible, to reduce auxiliary fuel use. Historical Operation Evaluation NEORSD originally provided one year of hourly (average) data from April 2016 to March 2017, see Table 1 for the operational averages. The data was evaluated to determine which parameters impact autogenous operation. The screened parameter set included the following six which were likely to have the greatest impact on autogenous operation. Sludge feed Sludge percent solids Sludge percent volatiles Windbox temperature (preheated air from heat exchanger) Bed temperature Fluidizing airflow All these parameters statistically correlated with autogenous operations at specific levels per the t-test results in Figure 1. So, BC further evaluated this list using NEORSD's existing operating strategy as a guideline. In the end, BC determined the sludge feed rate was the most readily adjustable parameter to achieve more reliable autogenous operation. The sludge feed provides all the heat, when operated close to design values, to heat the combustion air and evaporate the water from the sludge without natural gas addition. When averaging all three FBIs the average sludge feed rate is 1.2 wet tons per hour (wtph) higher during autogenous conditions. It should be noted that the average sludge feed rate, during these autogenous conditions, was roughly 64 percent of the incinerator capacity (13.9 wet tons per hour at 30 percent total solids [TS]). The data suggests that operating the FBIs at higher feed rates will result in autogenous conditions more often. Operational Alternatives Two distinct operational changes could increase the sludge feed rate per FBI. Each option increases the number of thermal cycles, that is the frequency the system goes from operating temperatures to a significantly cooler level. Revised Operations — Option 1 - The first option utilizes storage capacity to provide consistent incinerator operations. Each storage tank holds approximately 1.5 days' solids processing capacity of one incinerator. There are three storage tanks available for operational storage with a fourth one for emergency storage. This option uses one sludge storage tank with one FBI to handle the solids with excess flowing into a second sludge storage tank. When the second sludge storage tank becomes half full and climbing a second FBI can be brought on line to help deplete the incoming and stored solids until one FBI can again handle the solids production. This option includes some concerns about placing additional thermal cycles on the equipment. Revised Operations - Option 2 - The second option operates two FBIs at a higher capacity. This is accomplished by placing one of the operating FBIs in hot standby mode for 6 to 8 hours every day. Though the FBI internals would likely see a relatively small thermal cycle, downstream equipment will undergo a larger cycle or temperature range. Option 2 would also likely not yield the same natural gas savings due to heating if the standby FBI required intermittent heating during downtime. Revised Operation Implementation An industry survey was conducted to better understand thermal cycling on sewage sludge incineration systems and impacts on equipment. Based on the survey Option 1 would likely result in less thermal cycle impacts due to relative infrequency compared to Option 2. Furthermore, discussions with the key equipment supplier (primary heat exchanger and waste heat boiler) indicated the equipment was designed for far more thermal cycles than practical over the anticipated service life of the equipment. After reviewing the two options NEORSD selected and began planning to implement Option 1. NEORSD operates three sludge storage tanks, two are normally used with a third for peak demands. At an assumed 5 percent solids concentration each tank holds roughly 230 dry tons of solids. Each cycle from 1 FBI to 2 FBIs and then back to 1 FBI should take approximately 30 to 40 days, depending on the sludge generation rate, the sludge incineration rate, and the sludge solids concentration achieved in thickening and storage. Based on this approach the FBI sludge feed rate will exceed 80 percent of the design capacity, greatly increasing the chances for autogenous operation. NEORSD conducted multiple full-scale trails, with a month-long campaign in April of 2019 providing the most representative operations of the selected option. Other trials in May 2019, September/October 2019, and August 2020 resulted in shorter durations and experienced other complications resulting in higher energy consumption. Table 2 presents the comparison between the trials and historical costs spanning 2016 through 2018. Costs in the table represent annual values. The trial values were projected to annual operations for comparison. The results of the trials indicate energy and economic savings will result from the revised operating strategy. The April 2019 trial most represents the anticipated revised operating strategy and would result in an annual savings of $390,000. Conclusions This study initially investigated the alternatives to minimize the use of auxiliary fuel during normal operations. This effort identified that recommended increasing the sludge feed rate reduces auxiliary fuel demand and presented two options to achieve a higher FBI throughput. NEORSD opted to manage the sludge in the SSTs to operate the FBIs at a higher sludge feed rate which requires alternating between one and two FBIs in service. The recent April 2019 full-scale trial showed significant energy reductions from the revised operating strategy. Based on this effort NEORSD will continue to pursue operating in the revised manner full time. NEORSD will also continue to closely monitor equipment condition to prevent unplanned outages and whether the slight increase in thermal cycles have any effect. Status NEORSD continues to test the revised operating strategy to verify the operational savings and gain experience. Ultimately the strategy will be implemented as the standard operating procedure.

The following conference paper was presented at Residuals and Biosolids 2021: A Virtual Event, May 11-13, 2021.

SpeakerWinchell, Lloyd

Presentation time

11:15:00

11:30:00

Session time

11:00:00

11:45:00

SessionThermal Process Optimization

Session number6

Session locationSimu-Live

TopicEnergy recovery, Operations And Maintenance, Thermal Processes