Bullard, C

Mr. Bullard is a Vice President with Hazen and Sawyer and has over 35-years of experience in design, operation, maintenance, and process optimization...

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About Bullard, C

Mr. Bullard is a Vice President with Hazen and Sawyer and has over 35-years of experience in design, operation, maintenance, and process optimization of municipal and industrial wastewater treatment plants. He is a registered professional engineer in several states and previously had been a licensed Wastewater Treatment Plant Operator and he is currently Hazen and Sawyers National Practice Leader for Residuals and Biosolids Processes Design.

Bullard, C

Titles from this speaker

Preparing for the Future: WAS Only Indirect Thermal Drying at Manchester Creek WWTP

Abstract

Summary This paper and presentation will discuss the planning that went into the design of a new solids processing facility at the City of Rock Hill's wastewater treatment plant, the Manchester Creek WWTP (MCWWTP), to accommodate a future secondary treatment process change and plant expansion. Specifically, the paper will discuss the accommodations that were made in design for existing and future feedstocks to the solids train. The pre-selection process for the belt filter presses (BFPs) and the indirect thermal dryer will be discussed including details on the manufacturer coordination and selection parameters. The benefits of thermal drying and flexibility inherent to the design of the MCWWTP's biosolids facilities will also be explored. Background The Manchester Creek WWTP (MCWWTP) treats wastewater for the City of Rock Hill, South Carolina. The MCWWTP has a currently permitted maximum month capacity of 20 million gallons per day (MGD). Final treated effluent is discharged directly to the Catawba River upstream of its confluence with Manchester Creek. A liquid train expansion and improvement project is currently under design to expand the plant to a maximum month capacity of 30 MGD, with an ultimate buildout capacity of 50 MGD. In the existing solids handling process, solids from primary and secondary clarifiers are currently blended and dewatered with two 2.0-meter width belt filer presses (BFPs) to approximately 22% total solids (%TS). Dewatered cake is transported to either the Water and Sewer Authority of Cabarrus County's (WSACC) sewage sludge incinerator to be incinerated; to the Anson County landfill for disposal; or to the McGill Environmental New Hill (NC) Facility for composting. The MCWWTP contracts dewatering operations, dewatered cake transportation, and dewatered cake disposal services to a contract service provider. In accordance with the latest MCWWTP Biosolids Master Plan, the City of Rock Hill is pursuing improvements at MCWWTP that will improve the dependability of the existing solids management options and expand the plant's biosolids facilities to handle the load associated with the plant expansion. Following the completion of the 30 MGD expansion, the MCWWTP will eliminate the primary clarifiers and utilize an aerobic granular sludge process leading to a change in solids feedstock to the solids train. The solids project will be constructed prior to the 30 MGD expansion and therefore must accommodate both the existing and future solids feedstocks as a part of the design. The updated biosolids facilities will improve plant operation, provide multiple outlet options (potential for Class A Biosolids), and provide improvements to outdated facilities. The project includes the following facilities: -WAS Storage - BFP Dewatering - Indirect Thermal Drying - All Ancillary Equipment The new Thermal Dryer Facility will be designed for WAS only thermal drying. By eliminating primary sludge (PS) in the dryer feedstock, the heat transfer efficiency (lb-water/hour per square foot heat transfer surface area) of the thermal dryers is significantly increased in comparison to PS + WAS solids, due to the recalcitrant nature of the blend. Furthermore, undigested PS does not form a granular product but tends to be more fibrous in nature, whereas undigested WAS typically forms a granular product with higher bulk density more suitable for land application, storage, and handling. Because the solids project will be completed in advance of the liquid train expansion there will be an approximately five-year period when primary solids will be produced at the MCWWTP and will still need to be processed, but not dried. Therefore, the new solids facilities include the provision to process PS and WAS separately during the five-year period prior to the expansion and process change completion. See Figure 1 for the initial process flow diagram with two separate treatment trains for PS and WAS and Figure 2 for the ultimate planned solids process flow diagram. Flexibility in Solids Facility Design Because all new infrastructure associated with the primary solids management train will be for a short period of time the overall project goal was to minimize capital expenditures on PS only equipment that could not be used following the process change. For solids storage, a small, bolted steel tank (25,000 gal) with a vertical turbine mixer was proposed for PS storage. Following the liquid train conversion, the PS tank would be taken out of service and could be repurposed elsewhere onsite or demolished. The capital expenditure associated with the PS tank was considered necessary for operator flexibility, but tank size was reduced to keep costs minimal. A new, larger WAS storage tanks was proposed to support the long-term plan for a conversion to a WAS only process and a new dryer operational schedule of 24 hours per day, 4 days per week at annual average conditions. The larger WAS storage allows the facility to practice continuous wasting and decouple the liquid train operations from the solids operations by providing a wide spot in the line as well as provide a homogenous feed to the BFPs. The proposed Dewatering Facility is designed to house up to four (4) belt filter presses to meet long-term buildout. Initially three BFPs will be installed in the building and PS and WAS will be dewatered on separate BFPs. Piping and valving interconnections will allow the two streams to remain completely separate but provide needed equipment flexibility and redundancy to have a shared standby machine. The WAS dewatered cake will be conveyed to the thermal dryer facility while the PS dewatered cake will be hauled offsite for processing. The dewatering building should see a seamless transition to all BFPs dewatering the same feedstock from the WAS Storage Tanks following the process conversion. Because the Thermal Dryer Facility will only be designed for a WAS only stream the facility should transition easily with the liquid train process upgrades. Future planning discussions with the paddle/screw dryer manufacturers revolved around the impact of the liquid train process change on solids dewaterability and solids loading to the dryer. Overall, the thermal dryer facility will significantly decrease the water content of the biosolids, which will reduce both the volume and wet mass to be transported and final product to be managed by Rock Hill and increase their product end use alternatives. Equipment Selection Two requests for proposals (RFP) were developed for pre-selection of the belt filter press manufacturer and thermal dryer system supplier to help expedite the design process. Pre-selection of the thermal dryer system supplier was an important step as each manufacturer has their own intricacies and design details. Working with only one dryer manufacturer following preliminary design allowed manufacturer specific details and requirements to be coordinated in advance of construction. Manufacturer coordination prior to issuing the RFPs included: bench scale testing across a range of primary and secondary sludge blends to understand the impact of the PS only, WAS only and PS/WAS blend on dewatering equipment throughput, polymer usage and dewatered cake concentrations and thermal dryer performance (fouling potential, heat transfer, final product quality). In addition, potential technology suppliers were invited to meet with Rock Hill to discuss their technology offerings and differentiators from their competitors. Manufacturers were given the opportunity to review the equipment specifications that were a part of the RFP package. RFPs were evaluated using the methodology shown in Tables 1 and 2. The paper and presentation will detail the selection process.

This paper was presented at the WEF Residuals and Biosolids Conference, June 18-21, 2024.

SpeakerBorgmann, Ruth

Presentation time

08:30:00

11:15:00

Session time

08:30:00

11:15:00

SessionCase Studies & Lessons Learned

Session number27

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicDewatering, Drying, Flexibility

Author(s)

Borgmann, Ruth

Author(s)R. Borgmann1, C. Bullard1, M. Bridwell1, A. Young1

Author affiliation(s)Hazen and Sawyer 1; Hazen and Sawyer 1; Hazen and Sawyer 1; Hazen and Sawyer 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Jun 2024

DOI10.2175/193864718825159450

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count14

Description: Rapid Digester Start-up for the Lower Reedy WRF Anaerobic Digesters - Taking a...

Rapid Digester Start-up for the Lower Reedy WRF Anaerobic Digesters - Taking a Last-Minute Detour

Abstract

Renewable Water (ReWa) operates a number of treatment facilities in the upstate region of South Carolina. The Lower Reedy WRF facility consists of primary and secondary treatment and has used anaerobic digestion for residuals stabilization for approximately two decades. The existing anaerobic digestion facility consisted of a single digester tank of approximately 1.5 million gallons volume and did not have any a process redundancy. ReWa recently undertook a capital project to construct a new second anaerobic digester tank at the facility to provide process redundancy and provide additional capacity to handle increased residuals production from the treatment facility. The new anaerobic digestion tankage has an operating volume of approximately 1.5 million gallons volume and consists of a post-tensioned concrete tan with a fixed concrete dome cover and linear motion style mixing. The new digestion complex also includes a new digester control house, hot water boiler and digester heating system, membrane digester gas storage facilities and a new enclosed waste digester gas flare. Future work, Phase II with design currently underway, includes rehabilitation of the existing digester complex to extend operating life and improve digester heating and mixing systems. However, late in the construction phase as start-up and commissioning activities for the new facility were nearing completion the existing digester experienced a process failure and had to be removed from digestion service. This process failure resulted in the inability to seed the new digester from the existing on-site digester using an indigenous sludge seed. As a result, the start-up and commissioning team, consisting of representatives from ReWa, the construction contractor, and the design engineer had to make a 'last-minute detour' from the initial start-up plan and import anaerobically digested seed sludge from another ReWa facility. The team was able to rapidly pivot to an imported seed sludge approach and develop a new start-up plan, including revised process control monitoring and measurement tools, to successfully start the anaerobic digestion facilities and restore on-site stabilization activities. The new digester seeding plan utilized approximately 525,000 gallons of imported seed sludge from the ReWA Mauldin Road WRF and represented a total imported seed mass of approximately 250,000 pounds total solids. Seeding was accomplished over a period twelve (12) days from 04/05/2021 to 04/16/2021. During seeding activities, the digester was also fed some indigenous primary and secondary seed sludge from the Lower Reedy WRF. After sixteen (16) days on 04/20/2021 the digester reached its full operating volume and began to overflow and was able to receive 100% of the indigenous Lower Reedy volume and mass and off-site management of these materials was able to cease. Included as figures are the following: Figure 1 & Digester Total and Volatile Suspended Solids Figure 2 & Digester In-Tank VSS/TSS Fraction Figure 3 & Digester In-Tank pH Figure 4 & Digester In-Tank sVFA/sALK Ratio Figure 5 & Digester Daily Feed Volume

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

SpeakerBullard, C

Presentation time

10:45:00

11:15:00

Session time

8:30:00

11:15:00

Session number19

Session locationGreater Columbus Convention Center, Columbus, Ohio

TopicAnaerobic Digestion

Author(s)

C. Bullard

Author(s)C. Bullard1; A. Allen2; R. Borgmann3; M. Bridwell4

Author affiliation(s)Hazen and Sawyer; 1Renewable Water Resources; 2Hazen and Sawyer; 3Residuals and Biosolids Speaker; 4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May, 2022

DOI10.2175/193864718825158409

Volume / Issue

Content sourceResiduals and Biosolids

Word count16

Taking a Late Phase Detour: Dewatering System Redesign for the Plum Island WPCP

Abstract

Summary This paper and presentation will discuss the in-plant operating conditions leading to a late-in-the-design-process dewatering technology selection reevaluation for the Charleston Water System's (CWS) main wastewater treatment facility, the Plum Island Water Pollution Control Plant (PIWPCP). Specifically, the paper will discuss the steps taken to reevaluate the solids dewatering design after 90% design completion by transitioning the selected dewatering technology and making this change while minimizing impacts to the construction schedule already underway. The efficient and timely redesign around a new dewatering technology was achieved by leveraging onsite pilots, solids sampling and off-site assessments, as well as manufacturer presentations to assist CWS in reviewing the preferred technology vendor options. Ultimately, CWS selected centrifuges to replace the originally selected rotary fan press technology to ensure improved dewaterability across a wide range of influent characteristics. Furthermore, the paper will discuss the design challenges associated with accommodating a dewatering technology change while concurrently minimizing impacts to the building footprint and structural design in order to curtail construction sequencing design delays and allowing the Construction Manager At Risk (CMAR) contractor to begin pile driving and sub-surface foundation work as originally scheduled. Background The Plum Island Water Pollution Control Plant (PIWPCP) is the main wastewater treatment facility for Charleston Water System (CWS), providing wastewater treatment for the City of Charleston, Daniel Island, James Island, and several surrounding municipalities. The facility is positioned on a 22-acre island surrounded by salt marsh and discharges to the tidally influenced Charleston Harbor at a rated capacity of 36-MGD. This location causes significant constructability issues due to high ground water from tidal influences and local major rain events coupled with challenging subsurface issues and seismic codes requiring major structures to be built on pile supported foundations. Prior to design, a long-term facility master plan had been completed for the PIWPCP identifying facilities required to accommodate currently permitted flows of 36-MGD with expansion up to an ultimate facility capacity of 54-MGD on both the liquid and solids treatment trains. In accordance with the master plan recommended improvements, new solids handling facilities were included as part of the Phase 4 Capital Improvements Project. These capital improvements included the following new solids handling processes: - New Solids Handling and Dewatering Building with Rotary Fan Press dewatering technology - Three (3) Sludge Storage Tanks with Blending Pumps - Dewatered Cake Storage Sludge Hopper and Loadout Facility The existing dewatering unit process equipment at the facility includes three (3) rotary fan press dewatering units which dewater a blend of undigested primary and secondary solids resulting from the liquid treatment process. Secondary solids are gravity thickened prior to blending with the primary sludge solids immediately upstream of dewatering in a blending tank. CWS had many years of acceptable operating experience (See Figure 1, January 2017 through October 2021) with the existing rotary fan press technology entering the detailed design phase of the upgrade and had thus selected the same technology to utilize in the new dewatering facilities to be constructed during the Phase 4 Capital Improvements Project. The originally proposed Phase 4 Solids Handling Building was designed to hold up to seven (7) 8-channel rotary fan presses with ancillary feed, polymer makeup, and conveyance equipment to meet long-term buildout solids handling needs and accommodate facility expansion up to a 54-MGD ultimate treatment capacity. However, during the later stages of the facility design, CWS identified insurmountable issues with the existing rotary fan press technology used for dewatering (See Figure 1, After October 2021). Steep declines in dewatered cake solids content resulted in increased wet cake mass and volumes for transportation and disposal at a local landfill facility, significantly increasing downstream disposal costs. Concurrently, the local landfill was significantly increasing tipping fees for 'wet waste', further exacerbating solids disposal costs for CWS. In addition to reduced dewatered cake solids content, the rotary fan press solids and hydraulic loading rate performance declined which would require increased numbers of dewatering units to process the anticipated solids loadings under current and future operating conditions. This combination of impacts, decreased dewatered cake solids, increased downstream management costs, and reduced rotary fan press performance, caused CWS to investigate and reconsider the dewatering technology selection and basis of design for the new facility after the rotary fan press design had advanced to the 90% completion level. Upon further investigation, it was determined that influent characteristics at the plant had changed since the initial assessments, causing a detrimental impact on the proposed dewatering equipment performance. Some of the impacts were due to a new influent conveyance tunnel system and collection system behavior between wet and dry periods, new headworks facilities with increased grit removal capability, and new primary and secondary treatment facilities which were included with recently completed capital improvements projects (Phase 2 and Phase 3 projects). Following this initial investigation, CWS approved reconsideration of the dewatering technology selection to include other dewatering technologies (e.g., belt presses, centrifuges). Alternative Technology Selection Immediately following the decision to reconsider the dewatering technology selection, work began to conduct on-site pilot and demonstration testing of belt filter presses and centrifuges. Concurrent demonstration testing was conducted on the same feed sludge for the existing rotary fan presses, a trailer-mounted belt filter press, and a trailer-mounted centrifuge to assess dewatered cake performance and other design parameters for each technology. Table 1 and Figure 2 show the results of the concurrent dewatering technology testing. On-site testing was coupled with off-site and bench scale testing across a range of primary and secondary sludge blends to understand the impact of the primary to secondary sludge (PS/WAS) ratio on anticipated dewatering unit performance to inform operational decision making. Lastly, potential technology suppliers were invited to make presentations to CWS regarding their technology offerings. Ultimately, CWS selected high solids, horizontal decanting centrifuges to replace the rotary fan presses to ensure improved dewaterability across a wide range of influent characteristics and PS/WAS ratios. Following the updated technology selection, the planned dewatering facility had to be redesigned on an accelerated schedule for the new technology while staying within the same building envelope to retain as much of the prior design structural framing and layout as possible to expedite the design and permitting processes. This paper will share some of the design challenges associated with and overcome with the conversion from rotary fan press to centrifuge dewatering technology across the various engineering disciplines (e.g., process mechanical, structural / architectural, and electrical and control systems). Updated design of the new dewatering facility has since been completed with centrifuges (See Figure 3 for a rendering comparison) and construction is currently progressing on the facility.

This paper was presented at the WEF Residuals and Biosolids Conference, June 18-21, 2024.

SpeakerYeh, Jacqueline

Presentation time

15:45:00

16:15:00

Session time

13:30:00

16:45:00

SessionDewatering

Session number05

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicBiosolids, Dewaterability, Process Design

Author(s)

Yeh, Jacqueline

Author(s)J. Yeh1, R. Borgmann1, C. Bullard1, J. Hartwig J. Walker2, G. Hider2

Author affiliation(s)Hazen and Sawyer 1; Hazen and Sawyer 1; Hazen and Sawyer 1; Hazen and Sawyer 1; Charleston Water System 2; Charleston Water System 2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Jun 2024

DOI10.2175/193864718825159439

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count14

Thermal Dryer Selection and Procurement Approaches in Athens-Clarke County Georgia

Abstract

Summary This paper will share the progressive evaluation and selection of a thermal drying technology for application at the Athens-Clarke County Public Utilities Department (ACCPUD) North Oconee Water Reclamation Facility (NOWRF). The progressive evaluation and selection process was conducted in multiple phases and included: - Confirmation of Sizing Criteria - Evaluation of the 'World of Options' for Thermal Dryers - Screened Technology Assessment Site Visits - Technology Type Selection and Competitive Pre-Procurement Process - Detailed Design and Bidding This paper and presentation will share the progressive process utilized by ACCPUD for the selection of a dryer technology and a technology provider using a combination of cost and non-cost evaluation factors in a multi-criteria procurement process. Confirmation of Sizing Criteria The current plant is permitted for a 14-MGD capacity and uses an advanced activated sludge process for treatment coupled with high solids centrifuge dewatering to produce a cake for landfill disposal. Future plans are to expand the plant by adding primary treatment and anaerobic digestion. Dryer sizing was confirmed against current and future residuals production rate scenarios and a design evaporation of of 4,500 lb-water per hour was selected. Evaluation of the 'World of Options' for Thermal Dryers The first phase assessment included a preliminary screening of the following thermal dryer technologies for possible application of at NOWRF: - Belt Dryers, - Rotary Drum Dryers, - Indirect Paddle Dryers; and - Fluid Bed Dryers Based on the preliminary screening of technologies the belt dryers and indirect paddle dryer technologies were selected for additional screening assessment. Screened Technology Assessment Site Visits Following the preliminary screening site visits were arranged for plant operating and maintenance staff to visit operating installations of the belt and paddle dryer technologies. Site visits were conducted in Pennsylvania, North Carolina and Tennessee to view operating installations and have discussions with facility operators. Results of these site visits will be summarized in the paper and presentation. Technology Type Selection and Competitive Pre-Procurement Process Following the site visits and discussions with facility operators of belt and paddle dryers ACCPUD operations and maintenance staff selected the indirect paddle dryer technology as the most appropriate technology for application at the NOWRF. Based on the preliminary screening of technology suppliers a competitive procurement process was designed that would consider both cost and non-cost factors in the final selection of a technology vendor. The competitive procurement was conducted between the Komline-Sanderson Paddle Dryer and the Andritz-Gouda Paddle Dryer systems based on development of a detailed technical specification describing the system and the minimum required system elements coupled with a preliminary general arrangement drawing for location of the facility on the plant site and integration with the existing dewatering system. The competitive procurement scoring allocated 25% of the scoring points to cost factors and 75% of the scoring points to non-cost factors. Cost based scoring criteria considered the following: (1) equipment capital costs, (2) estimated building costs to house the equipment, and (3) system operating and maintenance costs based on power consumption and thermal energy efficiency of the dryer system. The non-cost factors were allocated to the following major criteria: (1) manufacturer experience; (2) operability and maintainability; (3) air permitting and air emissions rates; and (4) process safety. The paper and presentation will share the results of the cost and non-cost scoring for the selection of the technology supplier. Detailed Design and Bidding Following selection of the technology supplier detailed design activities were initiated for the project. Preliminary design activities included sending a large sample (~ 15 cubic feet) of dewatered cake to the selected technology supplier to test in their pilot plant to confirm heat transfer coefficients and the minimum ignition temperature (MIT) for the paddle dryer. The sludge-specific heat transfer coefficient was utilized to confirm adequacy of the proposed heat transfer surface area. The minimum ignition temperature was used to confirm the paddle dryer thermal oil operating temperature. Results of the pilot testing will be shared in the paper and presentation. Detailed design has progressed through the 'bid ready' stage and the project has been bid and will begin construction in late 2021 / early 2022.

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

SpeakerBullard, C

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

Session number04

Session locationGreater Columbus Convention Center, Columbus, Ohio

TopicDrying, Thermal drying, Thermal Processes

Author(s)

C. Bullard

Author(s)C. Bullard1; A. Bowling2; E. Mccallum3; H. Terry4; M. Hughes5

Author affiliation(s)Hazen and Sawyer; 1Residuals and Biosolids Speaker; 2Residuals and Biosolids Speaker; 3Athens-clarke County; 4Athens-Clarke County Government; 5

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2022

DOI10.2175/193864718825158426

Volume / Issue

Content sourceResiduals and Biosolids

Word count11

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Bullard, C

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