Bertoldi, Kathleen

Ms. Bertoldi is a Senior Environmental Scientist at Material Matters Inc. and is responsible for providing support to municipal wastewater clients related to biosolids beneficial use market research analysis, solids management, and regulatory permitting. She has ten years of experience in environmental and/or water resource engineering with eight years as a licensed engineer in training (EIT).Ms. Bertoldi previosuly worked as staff engineer for a county municipal solid waste (MSW) landfill. She also has experience in consulting focused on stormwater managementand water resource engineering,

Titles from this speaker

City of Rock Hill, South Carolina - Biosolids Market Assessment

Abstract

Background and Project Goals: Material Matters conducted a Biosolids Market Study on behalf of the City of Rock Hill (the City), to assist in evaluating biosolids products generated by selected technologies under consideration for the Manchester Creek Wastewater Treatment Facility Plant (MCWWTP). The City initiated the study to better understand the demand for various biosolids products in the region and identify outlet options and associated costs. The MCWWTP generates an average 20,000 wet tons of dewatered solids annually, managed via landfill disposal and incineration. The dependability of the existing solids management options for the City have proven to be a challenge in recent years, with loads turned away during routine and unscheduled outages at the incinerator and trucks turned away at the landfill gate despite having established contracts for disposal. While the incinerator has been cost-effective management option at $40 per wet ton tipping fee, the landfill tipping fees nearly doubled from $34 to $62 per wet ton between 2016 and early 2019. The purpose of the market assessment was to evaluate short-term opportunities and long-term solids handling and management solutions for possible implementation at the treatment plant. Short-term options were identified as alternatives that could be implemented within an 18-month period. Therefore, these options focused on identifying alternate third-party contracts available to the City to provide additional reliability via increased end-use outlets. Long-term options were identified as alternatives that would require more than an 18-month window to implement. Each of the long-term options require significant capital investment. The technologies proposed in the different options: conventional digestion, thermal hydrolysis process (THP), and thermal drying. Project Approach: Potential short-term outlets included landfill disposal, incineration, off-site composting, and land application. Long term outlets considered for the assessment included bulk agriculture, forestry, sod production and soil blending (Figure A-1). Material Matters identified, contacted, and interviewed more than 40 potential outlets including representative of landfills, incinerators, off-site processing facilities, and other outlets within approximately 100 air-mile radius of the MCWWTP. Program costs for biosolids management (transportation and final disposition) were evaluated through two major biosolids distribution pathways: via Full-Service Providers (FSP) and a Self-Managed Program (SMP). FSPs are biosolids management companies (or similar) responsible for processing (e.g., dewatering, composting, etc.) and/or marketing and distribution of the final biosolids product. Figure A-2 illustrates the important components to consider for each type of program: transportation, beneficial use coordination, permitting, marketing, recordkeeping, and regulatory reporting. Interviews were conducted with regional FSP companies to obtain information about product preferences and outside-the-gate program costs (those incurred for transport, final disposition, and product management.) Project Findings: In the short term, maintaining the existing process and producing an unstabilized cake appears to have the greatest flexibility. The City's current management options of landfill disposal (outside-the-gate costs of $54 to $92 per wet ton or $1.1 to $2.0 million per year) and incineration ($40 per wet ton or $880,000 per year) are cost effective; however, they are not always reliable. Material Matters identified a unique opportunity for off-site processing of unstabilized cake, an outlet not explored previously by the City. The outlet is a biosolids composting facility in North Carolina that has capacity to process all the solids generated at MCWWTP. This option offers greater reliability despite a higher outside-the-gate annual cost of $63 to $97 per wet ton or $1.4 to $1.5 million per year (Figure A-3). The City elected to engage with the compost facility and is currently using as a reliable outlet. For long-term options (those requiring processing upgrades and capital investment), the bulk agriculture market appears to be well established within 100 miles of the MCWWTP and is favorable for a low odor product. Both Class B mesophilic anaerobic digested cake and Class A/EQ products (cake, compost and dried) are seen favorably. The market assessment revealed that use in bulk agriculture can be a cost-effective management option through either a Full-Service Provider (FSP) or Self-Managed Program (SMP). For cake products, regardless of meeting Class A/EQ or Class B requirements, the outside-the-gate costs range between $20 and $40 per wet ton or $130,000 to $400, 000 per year. Projected annual management costs for the alternative products and management types is summarized in Figure A-4. Use of biosolids in the local forestry market, topsoil manufacturing, or other specialty markets is not well established and will require effort to educate and market the product. Management of Class A/EQ compost or digested dried products have potential to yield a net revenue of up to $5 per wet ton in if the product is high quality (low odor, consistent, available when needed) and is actively marketed.

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

SpeakerBertoldi, Kathleen

Presentation time

9:00:00

9:30:00

Session time

8:30:00

11:15:00

Session number17

Session locationGreater Columbus Convention Center, Columbus, Ohio

TopicOff-Site Processing

Author(s)

K. Bertoldi

Author(s)K. Bertoldi1; L. Challenger2

Author affiliation(s)Residuals and Biosolids Speaker; 1Material Matters; 2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May, 2022

DOI10.2175/193864718825158390

Volume / Issue

Content sourceResiduals and Biosolids

Word count11

Landfill Challenges & Biosolids Disposal Trends Analysis

Abstract

Background and Project Goals Reduced acceptance of wastewater solids at landfills, paired with increased disposal tip fees, are a problem noted by wastewater utilities across the nation and one that has worsened in the past two years throughout the Mid-Atlantic and Northeast. A biosolids landfill study was conducted for a wastewater utility that treats 220 million gallons of wastewater per day, generates 105,000 wet tons of solids per year, and covers a service area with a population of nearly 900,000 residents. Approximately 18% of production is managed through landfill disposal. Regional landfills have enacted limitations on the utility over a two-year period that range from reduced tonnage and disposal times to complete cessation of acceptance. In response, a biosolids trends analysis project was initiated with a focus on landfill challenges and subsequent disposal policies. The primary purpose of the project was to establish the sustainability of landfill as a routine outlet for the utility's solids, and if regional capacity exists for potential emergency situations. A secondary goal was to provide understanding of the causes of extreme landfill heating (subsurface internal temperatures 250 °F up to 1500 °F) and slope failures at landfills — challenges that landfills reported as the main cause of biosolids volume restrictions. The project included interviews with industry experts to investigate causes of extreme landfill heating and slope failure, and surveys of regional landfills to understand limitation policies and identify potential disposal opportunities. Project Findings The most noteworthy finding of the project is that 'existing' approved landfill capacity can change from week to week. Verbal reports regarding capacity and acceptance by landfill representatives is unreliable. Figure 1 shows the monthly solids production volume that would go to landfills if other management programs failed in comparison to the ever-changing 'available' and 'approved' capacity reported by regional landfill representatives. The graphic shows approved capacity at the start of the project in January 2020 (6,380 wet tons per month) compared to approved capacity in August 2020 (2,910 wet tons per month). Also displayed is the available capacity reported during project interviews conducted from March to June 2020 (11,815 wet tons per month) versus capacity landfills were willing to accept post-completion of the project in October 2020 (4,190 wet tons per month). Total approved monthly landfill capacity dropped by 54% over the course of eight months and actual capacity secured at regional landfills post-project was 65% lower than what was indicated by representatives during project surveys. When interviewed for the project, representatives from six landfills reported available capacity but only one provided an approval to the utility beyond one load per day. Additionally, four landfills reduced existing approvals to 'emergency use only' though this was not indicated during landfill interviews. Even more surprising was three of those same landfills had also reported an abundance of available capacity to the County the year prior in a pledged long term 10-year plan submission. The reasons cited to the utility consistently involved wet waste restrictions and alleged connection between biosolids and extreme landfill heating and/or slope instability. In fact, all sixteen landfills participating in surveys noted operational changes and disposal restrictions based on those issues — with only two experiencing either challenge at their site. Another key finding from the project, based on interviews with industry experts, is that biosolids are not a direct standalone cause of either of these landfill challenges. Industry experts reported that extreme landfill heating and slope instability challenges are both caused by a combination of operational, biological, and chemical factors. Saturated waste masses do increase the chances of both landfill challenges — a primary reason the landfill limits are targeting reduction of 'wet wastes' as a preventative measure. While biosolids do add to the wet waste ratio, experts reported that a ratio of 20% wet waste to 80% municipal solid waste (MSW) is acceptable as long as sound operational practices are in place. Despite this, Waste Management is enforcing a strict 5% wet waste limit as a company policy and others (i.e., Republic, Advanced Disposal) are set at 10 - 15% in a conservative effort to avoid either challenge. Although the exact mechanisms are still under investigation, primary contributors to extreme landfill heating include poor liquid management, inefficient landfill gas collection systems, and exothermic reactions between wastestreams. Elevated temperatures can lead to drastic operational challenges including melting of leachate and landfill gas collection system piping, rapid decomposition and settling within the waste mass, and geysers of leachate due to pressure built up (Figure 2). One of the most interesting findings about extreme landfill heating is that one cause is the reaction between ash (i.e., fly ash, MSW incinerator ash) and organic wastes. The oxides in the ash mixed with organic material (including biosolids) can cause exothermic reaction over time — and lead to pockets of subsurface trapped heat. In other cases, subsurface extreme heating is occurring at landfills that used mixtures of ash and organics as an alternative daily or intermediate landfill cover, leading to a disproportionate ratio of reactive wastestreams in the deep waste mass. Extreme landfill temperatures can lead to slope instability and/or failure but are only one of the reported causes. Figure 3 shows a portion of a 12-acre slope failure at a landfill due primarily to inadequate design and stability analysis. As in the case of elevated temperatures, limiting biosolids acceptance is not the key answer to assuring slope stability. Sound operational handling practices including mixing wet wastes with solid wastes, spreading wet wastes out, and avoiding wet waste disposal at the toe of slope or at the interface of two landfill cells — can help to ensure safe disposal of wet wastes including biosolids. Conclusion As more is discovered about the mechanisms of the reactions leading to extreme heating and root causes of massive slope failures are identified — the industry is shifting recommendations away from over-saturating landfills, encouraging more focus on segregation of wastestreams that could lead to exothermic reactions, and homing in on how important it is to properly mix and spread out wet wastestreams. As a result, landfills are taking precautions by setting even stricter than recommended wet waste ratio limits and in some cases ceasing acceptance altogether. The utility is bearing the results of this with the most recent restrictions effectively reducing the approved disposal sites from eight to three sites over a period of three months. The main takeaway is that even a large utility, one with 900,000 resident's dependent on their facility, can essentially be refused disposal of solids, and landfill approvals can change at any moment — making landfill disposal an unreliable long-term biosolids management plan.

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

SpeakerBertoldi, Kathleen

Presentation time

15:00:00

16:00:00

Session time

15:00:00

16:00:00

SessionLand Application and Surface Disposal Benefits and Challenges

Session number5

Session locationLive on Zoom

TopicAsh Management, Biosolids, Landfill

Author(s)

K. BertoldiT. Johnston

Author(s)K. Bertoldi1; T. Johnston2

Author affiliation(s)Material Matters; Inc 1; Material Matters Inc. 2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2021

DOI10.2175/193864718825157950

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count8

Milorganite Operational Risk Register Market Assessment

Abstract

Background and Project Goals: Material Matters supported the Applied Technologies Inc Team (Applied Technologies, Inc. GHD Group, and Veolia Water Milwaukee) in developing an Advanced Biosolids Facilities Plan for the Milwaukee Metropolitan Sewerage District (the District). The Advanced Biosolids Facilities Plan will identify and evaluate a variety of biosolids treatment alternatives that the District will consider, adopt, and implement. The project sought to answer the following three questions: 1. What is the best way to make Milorganite®? 2. What drivers influence the long-term viability of Milorganite®? 3. How can the District adapt to changing drivers? To answer the project questions, Material Matters developed an Operational Risk Register, with the support of the project team, to identify market risks most critical to maintaining the District's nationally acclaimed and distributed dried biosolids product - Milorganite®. Project Approach: The Operational Risk Register was developed to identify regulatory and market-based risk events associated with the Milorganite program. A risk register is a risk management tool that identifies potential risk events, assigns the probability of the risk event occurring (likelihood of failure [LOF]), and quantifies the resulting consequence if the risk event occurs (consequence of failure [COF]). Risk events include internal risk events (i.e., risk events that can be controlled by the operating entity), as well as external risk events (i.e., risk events that are outside of the control of the controlling entity). A risk register is a unique and innovative tool for evaluating a biosolids management program because it is dynamic and can be updated to match any changes in program goals or to reflect known changes in the market. Ultimately, over 60 potential risk events were identified and evaluated resulting from changes to District's biosolids processing (internal risks) or changes in the market or regulatory climate (external risks). The risk evaluation was based on existing customer purchase data, interviews with a representative sampling of Milorganite direct customers, and interviews with regulators from the top distribution states (Figure A-1). Information collected was summarized and used to evaluate the likelihood of the risk events occurring, and the corresponding level of consequence to the District should the risk occur. The scoring matrix and risk rating used for the risk register is shown in Table A-1 and based on scoring methods developed with the District as part of the 2050 Facilities Plan. Project Findings: Project findings revealed five key market-based risks critical to consider for the ongoing dominance of Milorganite® in the natural fertilizer market space, including: 1. Changing the physical characteristics of the Milorganite product (Figure A-2), 2. Reducing the production of Milorganite®, 3. Change in nutrient content or ratios, 4. Change in product odor, and 5. Regulatory changes related to contaminants of emerging concern (CEC) including per- and polyfluoroalkyl substances (PFAS). Mitigation measures and future consideration were provided to the District for operational risks identified as Medium or High overall risk. The risk register results will be used by MMSD to guide selection of process changes and technology choices for the remainder of the project. The outcome of the risk analysis concluded that technology decisions for wet-side treatment processes, digestion, thermal drying technology, and product diversification must be carefully considered in the next phase of the Advanced Biosolids Facilities Plan to avoid the highest rated operational risk. This paper will describe the risk register development process, including data gathering approach, scoring, and ranking process. The paper will also discuss the overall outcome, including mitigation measures to be used by the District to reduce risk impact on the program & and to preserve the Milorganite's unique position in the national fertilizer marketplace.

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

SpeakerBertoldi, Kathleen

Presentation time

13:30:00

14:00:00

Session time

13:30:00

15:00:00

Session number04

Session locationGreater Columbus Convention Center, Columbus, Ohio

TopicBiosolids Management, Market Analysis, Risk Assessment

Author(s)