Metch, Jacob

Jacob Metch is a wastewater process engineer with HDR. He received his Bachelor’s degree in Civil Engineering from Texas Tech University and his...

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About Metch, Jacob

Jacob Metch is a wastewater process engineer with HDR. He received his Bachelor’s degree in Civil Engineering from Texas Tech University and his PhD in Civil Engineering from Virginia Tech. He has extensive research experience using cutting-edge analytical techniques to study contaminants of emerging concern, activated sludge microbial communities, pathogen removal in wastewater treatment, and evaluating emerging wastewater technologies. His current work focuses primarily on wastewater facility planning, emerging technology evaluation, and wastewater process modeling.

Metch, Jacob

Titles from this speaker

Doing More with Less: Enhanced Biological Phosphorous Removal in a Small System

Abstract

Small utilities often turn to chemical phosphorous removal when needing to meet stringent phosphorous limits, however, operators at a water resource reclamation facility (WRRF) in New Hampshire are showing that creative aeration can be an attractive alternative. This small WRRF, not designed for biological nutrient removal, achieved greater than 90% phosphorous removal by implementing cyclic aeration in their aeration basins. With needed facility and collection system upgrades in the near future, a better understanding of the process was needed to ensure future performance. Historical process data, additional sampling, and process modeling were used to determine that the aeration strategy used leads to low-DO and anaerobic zones in the aeration basin, thus sustaining enhanced biological phosphorous removal (EBPR).
Introduction
Wolfeboro is a popular vacation destination with a population of approximately 6,400 on Lake Winnipesaukee in New Hampshire. The Town of Wolfeboro's WRRF was built in the 1970's and was designed as an extended aeration activated sludge process. Figure 1 shows an aerial photo of the WRRF which has a design capacity of 0.6 mgd and receives an average daily flow of 0.28 mgd. In 2007 the facility started utilizing cyclic aeration in their aeration tanks in response to tighter effluent nitrogen limits of 10 mg/L TN and 5 mg/L Ammonia as N. While this process change was successful in meeting nitrogen limits, unexpectedly, luxury uptake of phosphorous was also observed as a result. The Town suspected that the luxury uptake of phosphorus in the process was due to EBPR which requires anaerobic and anoxic/aerobic sequential zones and a source of volatile fatty acids (VFAs). In anaerobic zones, phosphorus accumulating organisms (PAOs) consume VFAs and release orthophosphate, then in subsequent anoxic/aerobic zones PAOs store phosphorous in excess of what is required for growth, thus removing dissolved phosphorus across the system. VFAs are typically a product of fermentation in EBPR processes however if the conditions are right VFAs can form in collection systems. Not fully understanding the mechanisms under which luxury phosphorus uptake is occurring, Town staff feared modifying any parameters of their treatment process or lift station operations should they inadvertently interfere with the EBPR process.
Objectives
This evaluation sought to understand the mechanism of phosphorous removal in the Wolfeboro WRRF to support future optimization and planning efforts. Approach Our approach included historic data review, additional sampling, and modeling. Ten years' of process data were evaluated to determine long term wastewater characteristics and establish process performance. Supplemental sampling was conducted to further characterize influent wastewater and the treatment process. A full plant model was developed and calibrated using the data. The model was subsequently used to identify potential explanations for the EBPR found at this plant.
Results
The historical data evaluation confirmed luxury phosphorous uptake with influent total phosphorous (TP) averaging 9.9 mg/L and effluent TP averaging 0.8 mg/L. Daily influent wastewater was sampled for five days and showed an influent VFA concentration of approximately 50 mg COD/L which indicates a significant VFA source in the collection system. Supplemental sampling also included monitoring of key process parameters within the basin to better understand the environmental conditions created by the cyclic aeration in the flow-through basins. Twice daily for one-week, dissolved oxygen (DO), pH, oxidation-reduction potential, nitrate concentration, and orthophosphate concentration were measured along the length of the basin during air on and air off cycles. The process model was developed in BioWin using annual average influent characterization and each of the narrow aeration basins of the WRRF were modeled as six aeration zones in series (AER1 through AER6). The facility controls DO in the aeration basins using DO probes at the effluent end of the basin and a DO set-point of 2 mg/L during air-on cycles. This aeration strategy was modeled by using a DO set-point of 2 mg/L for AER 6, and a controller was used to set the airflow of AER1 through AER5 equal to that of AER6. The process flow diagram and aeration strategy is presented in Figure 2. A controller was also used to adjust the waste activated sludge (WAS) wasting rate to maintain a mixed liquor suspended solids (MLSS) of approximately 4,500 mg/L (the observed annual average MLSS). This resulted in a modelled solids retention time of approximately 10.5 days. WAS is stored in two aerated storage basins and occasionally polymer is added, sludge settled, supernatant decanted and returned to the head of the plant, then thickened solids are hauled to an incineration facility. These storage basins were modeled as aerated digesters with a low DO set-point. While the influent VFAs would decrease the required anaerobic retention time for EBPR, an anaerobic zone is still required for selection of PAOs. As shown in Figure 3, the model predicted that the aeration strategy used by the WRRF would lead to low DO conditions on the influent end (approximately 0.25 mg/L in AER1 during air-on cycles) of the basin and increasing DO concentration along the basin meeting the DO target at the effluent end of the basin (where the DO probe is located). This occurs because the airflow is set for the entire basin based on where the oxygen demand is the lowest (the effluent end of the basin). This low DO environment limits nitrification and therefore allows for an anaerobic zone to quickly develop during air-off cycles due to high BOD loads in the influent and denitrification. This anaerobic zone was confirmed by the orthophosphate results of the supplemental sampling shown in Figure 4 which demonstrates an anaerobic gradient in the basin through PAOs releasing more orthophosphate at the influent end of the basin, and decreased release along the basin.
Conclusions
This evaluation of the Wolfeboro WRRF luxury phosphorous uptake determined: - The flow-through cyclic-aeration strategy applied here can sustain both biological nitrogen reduction and EBPR. - A DO gradient and development of anaerobic zones at the influent end of aeration basins were predicted by the process model because of aeration control using a DO probe at the effluent end of the basin. - Supplemental sampling results indicated high influent VFA concentrations which likely bolstered EBPR at this WRRF. Utilization of the process described here may make EBPR a more attractive, cost effective option for similar small WRRFs that are required to meet nitrogen and phosphorous effluent limits.

SpeakerMetch, Jacob

Presentation time

08:30:00

08:55:00

Session time

08:30:00

10:00:00

TopicFundamental Level, Small Communities and Decentralized Systems, Utility Management and Leadership

Author(s)

Metch, Jacob

Author(s)Jacob Metch1; Rebecca A. Elwood1; Mario Benisch1; Dave Ford2

Author affiliation(s)HDR, Manchester, NH 1; Town of Wolfeboro, Wolfeboro, NH2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158488

Volume / Issue

Content sourceWEFTEC

Word count13

Description: Technology Evaluation Framework Opens Pathway to Adoption of Emerging and Innovative...

Technology Evaluation Framework Opens Pathway to Adoption of Emerging and Innovative Technologies

Abstract

This paper describes the technology evaluation framework developed by the Philadelphia Water Department (PWD). The framework was developed to create a feasible pathway for realizing potential benefits of new technologies, allowing them to be considered as viable alternatives to conventional technologies for a generally conservative utility. A case study applying the framework to address anticipated effluent ammonia limits for PWD’s water pollution control plants (WPCPs) is also presented. One promising high-impact technology for ammonia removal, Nuvoda mobile organic biofilm (MOBTM; hereafter “MOB”), was fast-tracked. It shows potential to substantially reduce lifecycle costs for ammonia removal compliance and is currently in the execution phase of testing. In parallel, PWD is also in the discovery phase of identifying and screening other potentially viable technologies and innovative approaches to diversify its portfolio of cost-saving ammonia removal alternatives.

A technology evaluation framework can be used to create a feasible pathway for realizing benefits of new technologies, allowing them to be considered as viable alternatives and avoid being constrained to established technologies or ad-hoc selection of new technologies. This case study presents Philadelphia Water Department's efforts to evaluate innovative nutrient removal technologies that have potential for substantial capital and operational cost savings over conventional treatment methods.

SpeakerMetch, Jacob

Presentation time

11:30:00

11:50:00

Session time

10:30:00

12:00:00

SessionStrategies for Transformational Change, Innovation, and Operational Efficiency

Session locationRoom S405 - Level 4

TopicFacility Operations and Maintenance, Intermediate Level, Research and Innovation, Utility Management and Leadership

Author(s)

Metch, Jacob

Author(s)J. Metch 1; B. Figdore 2 ; S. McKelvey 3; A. Hendricks 3; J. Metch 1;

Author affiliation(s)HDR, Philadelphia, PA 1; HDR, Philadelphia, PA 2 ; Philadelphia Water Department, Philadelphia, PA 3; Philadelphia Water Department 3; HDR 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159200

Volume / Issue

Content sourceWEFTEC

Word count13

Description: What Goes in Must Come Out: An Approach to Developing a Mass Balance Tool...

What Goes in Must Come Out: An Approach to Developing a Mass Balance Tool Encompassing Three WRRFs and a Biosolids Processing Facility

Abstract

Issue: While managing solids is integral to all Water Resource Recovery Facilities (WRRFs), evaluating whole facilities and systems from a mass balance perspective is often challenging. All WRRFs must manage their biosolids whether it be for treatment or processing/handling at the end of the treatment process. To understand the quantity of biosolids that must be managed, utilities need a proper biosolids inventory. To further enhance the understanding of a biosolids inventory, a biosolids mass balance tool can be developed and applied to monitor performance. However, quality biosolids data is often not available at utilities through all process points, rendering a mass balance tool difficult to develop and calibrate. Objectives: This presentation will provide an approach to developing a biosolids mass balance tool to identify potential process limitations, support solids processing optimization and capital planning, and to evaluate data improvements. This approach will be demonstrated with a case study of a biosolids mass balance tool that was developed for the Philadelphia Water Department's (PWD's) three WRRFs and centralized biosolids processing facility. Utilization of PWD and its facilities within this case study provides a unique opportunity to address not only the benefits, but the challenges that present when constructing a biosolids mass balance tool for a large, public utility. Lessons learned throughout the process will be included for application to any utility seeking to develop a similar tool. Approach for Developing a Biosolids Mass Balance Tool: The development of an informative solids mass balance requires data gathering, quality assurance/quality control (QA/QC) of data, and annotation of assumptions. First a request for information is generated based on the unit processes utilized at the facilities of interest. Primary and secondary treatment data is gathered and reviewed by plant staff and engineers. This request is prioritized by grouping parameters into categories (e.g., 'must have', 'nice to have', etc.). QA/QC of the data is done by evaluating historic data trends to identify outliers or possible analytical errors. Following the initial data screening, a mass balance is built for each process based on the data received. When the mass balances around a process do not close (i.e., solids in does not equal solids out), further investigation is required to identify potential reason(s) for the error. Reasons may include metering errors, analytical errors, an indication of process inefficiency, etc. Assumptions must be made using engineering judgment and industry standards to calibrate the model based on observed data, fill in knowledge gaps, or resolve issues discovered during data analysis. Assumptions must be well documented to inform the mass balance user for current and future applications as more data/information becomes available. Once the mass balance is developed, key process metrics of the unit processes of interest can be compared to industry standards to determine process capacity/limitations. The mass balance can also be used to evaluate optimization/upgrade alternatives for planning purposes in a timely manner. Case Study: PWD, established in 1801, is a public water utility, providing integrated drinking water, wastewater, and stormwater services to the City of Philadelphia and several neighboring communities. PWD owns and operates three WRRFs with a combined permitted maximum daily average flow capacity of 783 MGD. Biosolids from PWD's WRRFs are anaerobically digested and sent to a central biosolids recycling center (BRC). The BRC is located on PWD property but operated by an outside entity. The BRC produces Class A pellets that are land applied throughout the east coast. To better characterize PWD's biosolids handling, understand system limitations, and support planning efforts, PWD collaborated with consulting teams HDR and AECOM on the development of a biosolids mass balance tool. The tool was developed to assess the individual WRRFs as well as the overall solids strategy among the three WRRFs and the BRC. Figure 1 presents a process flow diagram of the three WRRFs and the solids flows among facilities. As shown, this system is complex with respect to solids processing in that one of the three plants sends their sludges to another plant for processing, and the third plant conveys solids via barge to the processing facility. Like other utilities of its age and size, PWD faces the challenges of aging infrastructure and a changing regulatory environment that drives optimization of existing processes and adoption of new processes. These forces, coupled with the ever-present requirement of meeting NPDES permits, can make the prioritization of biosolids data collection and system optimization difficult. PWD and HDR employed creative collaboration strategies to secure the support and cooperation of PWD stakeholders as well as the data required to develop the biosolids mass balance tool. Within Figure 2 is the preliminary output from the mass balance tool calibration that tracks solids production, transport, and destruction across PWD WRRFs. During calibration, several processes were identified for further evaluation due to the mass balance not closing. Further investigation of these processes may lead to important improvements in process performance or process monitoring. Observed key process parameters were also compared to industry standards to identify system limitations and identify optimization opportunities. In doing this, potential inefficiencies were identified such as anaerobic digesters being organically underloaded but hydraulically limited, indicating potential improvement in performance and energy efficiency through further digester feed thickening. This presentation will discuss a process for developing and utilizing a biosolids mass balance to evaluate WRRF biosolids management, as well as present lessons learned from PWD's biosolids mass balance development and evaluation.

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

SpeakerMetch, Jacob

Presentation time

15:45:00

16:15:00

Session time

13:30:00

17:00:00

Session number02

Session locationGreater Columbus Convention Center, Columbus, Ohio

TopicBiosolids, Data Management, Master Planning

Author(s)

J. Metch

Author(s)S. Burke1; J. Metch2; M. Falk3; M. Murphy4; N. Brown5

Author affiliation(s)Philadelphia Water Department; 1Residuals and Biosolids Speaker; 2HDR Inc; 3Philadelphia Water Department; 4AECOM; 5

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2022

DOI10.2175/193864718825158439

Volume / Issue

Content sourceResiduals and Biosolids

Word count23

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Metch, Jacob

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