Caliskaner, Onder

Onder Caliskaner is a speaker at WEFTEC 2026.

Titles from this speaker

Description: Domestic Advanced Primary Wastewater Treatment Utilizing Pile Coth Media Filtration...

Domestic Advanced Primary Wastewater Treatment Utilizing Pile Coth Media Filtration for Operational Savings and Increased Biogas Production and Wet Weather Treatment

Abstract

The use of pile cloth media filtration (PCMF) is becoming a new solution to allow treatment facilities to achieve advanced treatment without chemical addition in a dramatically reduced footprint in comparison to conventional primary sedimentation. PCMF brings a high-quality effluent quality which allows the technology to be used, also for the wet weather treatment in dual treatment applications. The study and full-scale installation data has confirmed that PCMF can achieve consistently >80% TSS and >50% BOD/COD removal in primary applications. The has been much testing in documenting the benefits of advanced primary treatment with PCMF. This includes the reduction in aeration requirement for the biological treatment processes and/or more biological treatment capacity without additional basins/tankage. Other benefits such as more primary solids for anaerobic digestion and increased biogas and energy production within the wastewater facility. In wet weather applications, the technology is producing effluent quality that achieves EPA secondary effluent standards or better.

This paper will cover advanced primary treatment utilizing pile cloth media filtration versus conventional treatment. The concept and principles of carbon diversion and how the use of pile cloth media filtration allows WRRF's become more energy efficient and production of biogas. Also, the paper covers the ability to handle wet weather peak flow conditions by providing dual treatment capabilities.

SpeakerDyson, John

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionPrimary Treatment Technologies: Should We Settle for Conventional Primary Sedimentation?

Session locationRoom S501a - Level 5

TopicEnergy Production, Conservation, and Management, Facility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design

Author(s)

Dyson, John

Author(s)J. Dyson 1; T. Reid 2 ; O. Caliskaner 3; J. Dyson 1;

Author affiliation(s)Aqua-Aerobic Systems, Inc. 1; Aqua-Aerobic Systems, Inc. 2 ; Caliskaner Water Technologies 3; Aqua-Aerobic Systems 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159003

Volume / Issue

Content sourceWEFTEC

Word count22

Description: Evaluation and Pilot Testing of Primary Filtration for Upgrade of Silicon Valley...

Evaluation and Pilot Testing of Primary Filtration for Upgrade of Silicon Valley Clean Water Resource Recovery Facility

Abstract

Introduction
Cloth media filters have been traditionally used for tertiary treatment at wastewater resource recovery facilities (WRRF), where effluent limits are less than 10 mg/L or 2 NTU (WEF MOP 8, 2017). When compared to more conventional granular filtration, this technology is attractive because of its lower head requirement (2.5-4 feet), lower backwash ratio (1-3%), and comparable hydraulic loading rates (3.5 gpm/ft2 to 7 gpm/ft2 respectively). Recently, the same cloth media filters have emerged as technologies suitable for primary treatment, offering far greater total suspended solids (TSS) and biochemical oxygen demand (BOD) removals than conventional primary clarification. To date, multiple pilot studies and a few installations have demonstrated TSS and BOD removals of approximately 80% and 50%, respectively (Caliskaner and al., 2020; Caliskaner and al., 2019; Caliskaner, 2022). This corresponds to an approximately 50% increase in removal, which is significant. This process can, therefore, be used to divert more carbon to the anerobic digestion process, leading to an increase biogas production in the order of 20 to 30 %, while, simultaneously, reducing the organic load to the secondary treatment, leading to a reduction in energy demand for aeration in the order of 20-25%. As the cost of electricity continues rising, it is anticipated that this process becomes more and more attractive.

Another significant advantage, when compared to conventional primary clarification, cloth disk primary filtration (CDPF) systems can remove approximately 50% more solids within approximately 20% of the footprint. This alone becomes a valuable tool for WRRFs that require additional secondary treatment capacity due to increased flows and loads, or more stringent discharge limits but have little to no room for expansion using conventional treatment methods and approaches. The later will be the case for San Francisco Bay Area's WRRFs, including Silicon Valley Clean Water's (SVCW) WRRF.

Methodology
SVCW is in Redwood City, CA. It is a Joint Powers Authority serving about 220,000 people living in the communities of Belmont, Redwood City, San Carlos, and the West Bay Sanitary District. The WRRF was designed to treat an average dry weather flow of 29 MGD, however, the current dry weather flow is 13 MGD. Considering the potential benefits of CDPF listed above, SVCW conducted a pilot project between November 2023 and April 2024 to evaluate the CDPF process at its WRRF (supplied by Aqua-Aerobic Systems, Inc.) (Figure 1).

Existing primary treatment consists of rectangular primary clarifiers (PC) that removes approximately 65% of the influent total suspended solids (TSS) concentrations and 35% of the biochemical oxygen demand (cBOD5) loading. Main goal of the project was to investigate the feasibility of replacing the primary clarifiers with CDPF as part of a major upgrade that is planned at the WRRF to meet the upcoming more stringent effluent quality requirements. Specific objectives of the CDPF pilot project were as follows:
1. Monitor the process performance for TSS, Chemical Oxygen Demand (COD) and 5-Day Biochemical Oxygen Demand (BOD5) removal at different hydraulic loading rates and compare this performance with the current plant primary clarification process side by side.
2. Determine the backwash ratio at different hydraulic and solids loading rates, and characterize the backwash water in term of TSS and verify mass balance.
3. Discuss the system operation and maintenance requirements.
4. Determine the number of required filtration units required.

Results and Discussion
Performance of the CDPF system is summarized in Table 1 and 2. The CDPF system achieved TSS removal rates above 80% despite a wide range of hydraulic and solids loading rates, while the TSS removal for the existing PC system ranged between 43 % to 68%. This shows that the CDPF not only significantly improves the primary treatment performance but also improves the consistency of the effluent quality. The pilot effluent TSS concentration ranged from 33.1 to 38.4 mg/L even if the HLR ranged from 1.5 to 5.3 gpm/ft2 and the SLR ranged from 4.6 to 12.4 lbs/ft2. This is a considerable advantage as more consistent effluent quality could lead to improvement in the secondary process. TSS and COD performance data collected during pilot testing are shown in Figure 2 through Figure 4.

Subsequent to the pilot testing, a technical evaluation study was conducted to determine the holistic impacts of implementing PF for SVCW. Based on the pilot performance results, the primary filtration process has been analyzed for its effectiveness, efficiency, and overall benefits to the existing and anticipated future processes. Key findings from this technical evaluation are listed below:
- Enhanced Treatment Efficiency: The primary filtration system improved TSS and BOD removal, reducing the loads on secondary treatment processes.
- Energy Optimization: Increased biogas production by 20-30% from enhanced solids capture in primary treatment.
- Footprint: The system requires smaller footprint compared to conventional methods, making it ideal for facilities facing land constraints.
- Wet weather Resilience: The system maintained over 80% TSS removal during extreme wet weather events, improving reliability.
- Regulatory Compliance: Project provided critical insights to meet future stringent Total Inorganic Nitrogen effluent limits.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

13:30:00

14:00:00

Session time

13:30:00

15:00:00

SessionOptimizing the Treatment Train using Advanced Primary Filtration and its impact on Secondary Treatment

Session locationMcCormick Place, Chicago, Illinois, USA

TopicLiquid Stream Treatment Technology - Preliminary, Primary, and Wet Weather Treatment

Author(s)

Miot, Alexandre, Kao, Jane, Ishaya, Robert, Caliskaner, Onder, Dursun, Derya

Author(s)A. Miot1, J. Kao1, R. Ishaya1, O. Caliskaner2, D. Dursun2

Author affiliation(s)Silicon Valley Clean Water1, Caliskaner Water Technologies2, HDR3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825160125

Volume / Issue

Content sourceWEFTEC

Word count18

Evaluation of Advanced Primary Treatment Technologies at Water Resource Recovery Facilities for Carbon Diversion and Management

Abstract

...Introduction Conventional primary treatment (CPT) technologies such as primary clarifier (PC) only remove 20-30% COD and 40-60% TSS, with a large footprint. To improve performance, Advanced Primary Treatment (APT) technologies have emerged. The primary goal of this project (funded by California Energy Commission) is to assess the treatment and hydraulic performances of four APT technologies (Cloth Disk Primary Filter-CDPF, Compressible Medium Biofilter-CMBF, Micro-Screen-MS, and Proteus Filter-PF) (Table 1) over long-term at Linda Water Resource Recovery Facility (WRRF) and is the first to incorporate long-term operation of these technologies in parallel with CPT. Following results will be included in the paper: (1) long-term performance of APT systems; (2) assessment of the improved treatment and hydraulic performances of APT systems; (3) impact of APT effluent on secondary processes; and (4) design and operational criteria. ...Methodology Four APT technologies have been operated at Linda WRRF located in Olivehurst, CA, at 0.06-1.2 MGD (see Figure 1, Tables 1-2). The CDPF and CMBF are in operation since January 2022 while the MS and PF are since April 2023 and July 2023, respectively. To evaluate hydraulic and treatment performance, each APT has inline turbidity/TSS sensors and flow meters to monitor treatment performance in real-time. Inline sensor data are complemented by 24-h composite sampling. Hydraulic performance includes solids loading rate (SLR), hydraulic loading rate (HLR), and backwash reject water (BRW) ratio. APT systems with high HLR, low BRW ratio, and high SLR have lower capital and operational costs. Treatment performances are measured using total COD (tCOD), soluble COD (sCOD), total BOD (tBOD), soluble BOD (sBOD), TSS and total Kjeldahl nitrogen (TKN) removal. ...Results and Discussion ...Treatment Performance of APT systems Cloth Disk Primary Filter: CDPF achieved an average COD and TSS removal of 51 and 78%, respectively, based on 24-hr composite samples (Figure 2). Although influent wastewater TSS concentrations varied greatly (SD = 163 mg/L), effluent TSS remained steady (Figure 2B). Overall, the CDPF performance in the current project is similar to previous projects with 75-85% and 50-60% removal for TSS and COD, respectively (Caliskaner et al., 2018, 2019, 2020, 2021). Influent/effluent turbidity was converted to TSS using TSS-to-Turbidity Ratio based on inline turbidity sensor and laboratory TSS results which is 1.4 for CDPF influent and 1.2 for CDPF effluent and influent and effluent TSS averaged at 188 and 44 mg/L, respectively (Figure 3). CPT achieved average removals of 36% for COD and 62% for TSS while the CDPF achieved removals of 52% for COD and 78% for TSS. Compressible Medium Biofilter: Since the CMBF unit's installation, the project team focused on gathering preliminary information on treatment performance and enhancing hydraulic performance. 24-hr composite samples obtained in October-November 2023 show that the CMBF achieved 63% and 81% in COD and TSS removal efficiency, respectively. Compared to PC, CMBF is able to increase the COD and TSS removal efficiency by 75 and 31%, respectively. Micro-Screen: The MS achieved an average total COD removal of 45% and TSS removal of 65%, based on 24-hr composite samples (Figure 4). The treatment performance was observed to be comparable with CPTs like PC given a footprint reduction of 70-80%. Overall, the MS unit achieved approximately 5 to 10 % increase in removal efficiencies compared to PC. Proteus Filter: The PF achieves an average total COD and TSS removals of 53 and 80%, respectively, based on 24-hr composite samples (Figure 5). When operated in parallel with PC, PF achieved 47 and 27% increase in COD and TSS removals, respectively. The average effluent TSS from the PF's effluent was found to be stabled around 80 mg/L, which is 16% lower than PC's. ...Hydraulic Performance of APT systems The hydraulic performances of APT units are given in Table 3. The CDPF is equipped with 8 discs, each with an effective surface area (SA) of 53.8 ft2. The average HLR is 0.7 gpm/ft2 and SLR is 2.3 lbs TSS/ft2/day. The daily average flow and BWR ratio for the CDPF is shown in Figure 5. The daily average BWR ratio varied from 2 to 11% and averaged 5%. The CMBF is a bed of individual fiber media balls with a total SA of 19.6 ft2. The average flow rate and HLR are 50 gpm and 2.5 gpm/ft2., respectively. The MS is a 5.5-ft diameter unit with a 200 µm stainless steel mesh. The average HLR is 5 gpm/ft2 and BWR is 3%. The PF is a 23.6-inch diameter tower with a layer of expanded polypropylene beads with a total SA of 3.05 ft2. The HLR and SLR of PF averaged at 6 gpm/ft2 and 17 lbs TSS/ft3 of media and the BWR averaged at 13%. ...Impact of APT systems on Secondary Treatment The project aims to compare and evaluate the impact of APT effluent on both activated sludge basins (ASB) and three Advanced Secondary Treatment (AST) technologies [Microvi, Aerobic Granular Sludge (AGS) and Membrane Aerated Biofilm Reactor (MABR)]. To demonstrate the impact of APT on MLE, the two ASBs at Linda were designed to receive either PC or APT effluent. PC and APT effluents are diverted to Conventional ASB and Enhanced ASB, respectively (Figure 8). Using sensors and real time monitoring, energy and treatment performance are measured directly. Parallel simulations are being conducted using SUMO.

Four advanced primary treatment (APT) technologies were evaluated at demonstration to full scale in this technology development project to replace or augment conventional primary treatment (CPT) system of primary clarification. The APT systems are: Cloth Disk Primary Filter, Proteus Primary Filter, Compressible Medium Biofilter, and Micro-Screen. Carbon diversion and management strategies for CPT and APT technologies are evaluated in detail as part of this project.

SpeakerCaliskaner, Onder

Presentation time

13:30:00

13:50:00

Session time

13:30:00

15:00:00

SessionPrimary, Secondary, and Tertiary Applications of Advanced Filtration Technology

Session number411

Session locationRoom 350

TopicFacility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design, Nutrients

Author(s)

Caliskaner, Onder, Dursun, Derya, Wu, Yuanbin, Martinez, Everardo, Tchobanoglous, George, Davis, Brian

Author(s)O.T. Caliskaner1, D. Dursun2, Y. Wu3, E. Martinez3, G. Tchobanoglous4, B. Davis5

Author affiliation(s)1Caliskaner Water Technologies, Inc., CA, 2Hazen and Sawyer, CA, 3Caliskaner Water Technologies, CA, 4George Tchobanoglous, CA, 5Linda County Water District, CA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159633

Volume / Issue

Content sourceWEFTEC

Word count17

Evaluation of Sludge Characteristics from Advanced Primary Treatment Technologies

Abstract

[b]Introduction[/b] Advanced Primary Treatment (APT), which utilizes primary filters (PF) or microscreens (MS), has been increasingly adopted to enhance wastewater treatment. APT improves the capture and diversion of solids and particulate carbon upstream of the secondary treatment process. APT technologies can achieve higher removal rates of total suspended solids (TSS) and total chemical oxygen demand (tCOD) than primary clarifiers (PCs). As a result, APT can reduce the aeration demand in secondary processes and increase energy production from anaerobic digesters. Between 2021 and 2025, in a California Energy Commission funded project, 3 APT technologies were evaluated at the Linda County Water District's (Linda) Water Resources Recovery Facility (WRRF): full-scale Cloth Disk Primary Filter (CDPF, upto 1400 gpm), demonstration-scale Proteus Primary Filter (PF, up to 20 gpm), and full-scale MicroScreen (MS, up to 500 gpm). These systems (Figs. 1, 2, and 3) were operated in parallel with existing PC. Results obtained over 10-36 months of operation showed improved removal rates for TSS and tCOD compared to PC, especially for the PF technologies (i.e., 40-50 % higher compared to PC). The removal rates, as summarized in Fig. 4 for over 200 sampling events, were as follows: the CDPF achieved 84% TSS and 56% tCOD removal; the Proteus PF achieved (operating at 2 gpm/ft²) 85% TSS and 55% tCOD removal; and the MS removed 62% TSS and 40% tCOD. While the treatment performance and energy benefits of APT technologies are well documented[sup]1,2,3,4,5,6[/sup], impacts of APT backwash reject streams (APT sludge) on sludge handling systems (thickening and anaerobic digestion) are less studied. Although increased removal by PF provides significant intensification and energy benefits, it also generates more challenging sludge streams, characterized by higher backwash volumes with low solids concentrations. These impacts must be considered carefully in the design and operation of PF systems to avoid adverse effects on WRRF hydraulic capacity and sludge-handling processes. This project mainly focuses on pretreatment, thickening, and digestion challenges associated with high-volume, low-solids PF sludge. The primary objective is to define design and operational parameters that preserve the energy and intensification benefits of PF, while minimizing adverse impacts on sludge management. Knowledge gaps in the design and operation of sludge-handling systems for APT systems are identified and discussed in this paper. [b]Methods and Results[/b] Sludge from APT systems were evaluated for: (1) filtered and sludge volumes and flows, (2) PF backwash reject ratio (BRR), and (3) PF sludge total solids (TS) concentration across varying hydraulic loading rates (HLR) and solids loading rates (SLR). For CDPF, BRR increased with both HLR and SLR. As shown in Figure 5(A), the average daily BRR was 3.3% at an HLR of 0.20 gpm/ft² and increased to 11.5% at 1.65 gpm/ft², with an average of 5.5% over 3 years of operation. Similarly, as shown in Figure 5(B), the BRR increased from 3.4% at SLRs of 0.50–1.0 lb/day/ft² to 14.6% at an SLR of 11.0 lb/day/ft². For Proteus PF, BRR also increased with HLR and SLR. As illustrated in Figure 6(A), average BRR ranged from 6.9% to 9.7% over an HLR range of 2–9.5 gpm/ft², peaking near the design HLR of 10 gpm/ft². BRR values between 8.2 and 10.3% as SLR increased from 0.7 to 8.6 lb/day/ft² as shown in Figure 6(B). The MS system's performance was evaluated for sludge generation. Figure 7(A) shows that the BRR increased with higher HLR. At low-flow conditions (1.8-3.6 gpm/ft²), the BRR was between 0.7% and 2.0%. In contrast, at higher HLRs (5.8-9.2 gpm/ft²), the average BRR increased to 3.2%. Figure 7(B) illustrates that the BRR also increased with higher SLR. The average BRRs at SLRs of 7.6, 9.5, and 12.4 lbs/day/ft² were 1.7%, 2.0%, and 2.6%, respectively. TS concentrations were also evaluated in the APT reject sludge flow to determine APT's sludge management requirements. The TS value in the backwash stream from the PF system was 0.2%, whereas a TS value of approximately 2% was observed for the backwash (sludge) reject from the MS technology. [b]Conclusions[/b] The impact of different BRRs is a very important consideration in treatment plant design and operation. For example, for a 100 MGD WRRF, different BRRs result in markedly different thickening requirements. A 2% BRR for the MS technology produces a primary sludge flow of 2 MGD, compared to 10 MGD sludge flow for PF with BRR of 10% and 14.6 MGD sludge flow for PF operating at peak HLRs (Figure 9). These PF sludge flow rates are significantly higher than those from PCs. High BRRs combined with low TS increase thickening demands, making MS systems generally more favorable for sludge management. However, PF systems provide greater treatment performance and overall WRRF energy efficiency; therefore, APT system selection and design should be tailored to project-specific conditions and requirements. Specific thickening requirements associated with high BRR values and low TS concentrations are currently being assessed in another ongoing technology demonstration project at the Linda WRRF using the following three sludge thickening technologies: Volute Thickener, Suspended Air Flotation, and Biosolids Filtration Thickener. Specific operational and design criteria for the application of these thickening technologies for APT are evaluated

This paper was presented at WEFTEC 2026 in New Orleans, Louisiana.

Presentation time

09:00:00

09:30:00

Session time

8:30:00

10:00:00

SessionAdvanced Primary Treatment Pathways: High-rate Filtration and Sludge Process Integration

Session locationErnest N. Morial Convention Center

TopicFacility Operations and Maintenance, Municipal Wastewater Treatment Design

Author(s)

Caliskaner, Onder, Wu, Yuanbin, Dursun, Derya, Khuntia, Himanshu Kumar, Martinez, Everardo, Tchobanoglous, George, Davis, Brian

Author(s)O. Caliskaner1, Y. Wu1, D. Dursun1, H. Khuntia4, E. Martinez1, G. Tchobanoglous6, B. Davis2

Author affiliation(s)Caliskaner Water Technologies, 1Caliskaner Water Technologies, 1Caliskaner Water Technologies, 1Caliskaner Water Technologies, 1Linda County Water District, 2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Sep 2026

DOI10.2175/193864718825160499

Volume / Issue

Content sourceWEFTEC

Word count10

Description: Evaluation of the Impacts of Three Advanced Primary Treatment Technologies on...

Evaluation of the Impacts of Three Advanced Primary Treatment Technologies on Performance of Water Resource Recovery Facilities

Abstract

INTRODUCTION
Several filtration and micro-screen technologies have been developed to provide advanced primary treatment (APT) to replace conventional primary treatment (CPT). Primary filtration [e.g., cloth disc primary filter (CDPF)] provides improved removal of particulate material compared to CPT with a significantly smaller treatment footprint and modified effluent particle size distribution. Primary biofiltration [e.g., compressible medium biofilter (CMBF)] provides additional removal of soluble material compared to CPT. When a screening technology is used with pore size between 100 and 300 microns to replace CPT, the process application is known as micro-screening (MS). Performance data from full-, demonstration-, and pilot-scale CDPF, CMBF, and MS projects have demonstrated the feasibility of these technologies for APT. APT effluent has significantly lower concentrations of total suspended solids (TSS) and biochemical oxygen demand (BOD) compared to CPT, which results in reduced secondary treatment aeration energy requirements and increased secondary treatment capacity. APT diverts carbon from the energy-intensive secondary process towards energy-recovering anaerobic digestion.
METHODOLOGY
The results presented in this paper are from CDPF, CMBF, and MS projects since 2012, including an on-going comprehensive APT demonstration project. The evaluation of APT technologies is focused on hydraulic performance in addition to treatment performance. The hydraulic performance can be evaluated by monitoring solids loading rate (SLR), hydraulic loading rate (HLR), and the ratio of reject streams (backwash water, settled sludge, and scum) to applied wastewater. The backwash reject water (BRW) ratio, defined as the amount of backwash flow relative to the amount of wastewater filtered, is an important consideration to evaluate and optimize the performance of APT technologies. For APT systems, high HLR, low BRW ratio, and high SLR correlate to lower capital and operational costs. Treatment and hydraulic performances of APT systems are evaluated with respect to subsequent overall energy and capacity impacts for water resource recovery facilities (WRRFs).
RESULTS
CDPF. In a CPDF system (Aqua-Aerobics Systems, Inc.), cloth media (via small pore sizes of 5 Âµm) provides a physical barrier for filtration while floatable and settable materials are removed separately. As shown on Figure 1, the hydraulic and treatment performance across CDPF units installed at Linda WRRF (full-scale), Manteca WRRF, and Lancaster WRRF was consistent, achieving removals of 80â€“85% for TSS and 45â€“60% for organics (Table 1). The demonstration-scale filters in Lancaster and Manteca were found to have BRW ratio between 12â€“15%, while the Linda full-scale filter had an average BRW ratio of 10%. Figure 2 summarizes TSS removal performance for the full-scale CDPF based on 3-year operation; effluent TSS concentration remained relatively constant over a wide range of influent TSS concentrations (influent and effluent TSS averaged 300 and 55 mg/L, respectively).
CMBF. In a CMBF system (WesTech Engineering, Inc.), liquid passes through a bed of compressible filter media and creates a pore size gradient (smaller particles are captured by increasingly smaller pores). Biofiltration is promoted by allowing controlled biofilm growth within the filter media. A two-year demonstration-scale project was conducted at Linda WRRF to evaluate primary biofiltration using CMBF (Figure 3). Consistent removal of soluble material was observed. Test results for the removal of soluble BOD (sBOD), seen on Figure 4, and soluble chemical oxygen demand (sCOD) were 22 and 25%, respectively. Based on the analysis of forty samples, TSS, BOD, and COD removals were 70, 52, and 50%, respectively.
Micro-Screen. A MS (Huber, Inc.) system utilizes a horizontally installed screen basket that wastewater flows through from inside to outside. A filter carpet develops on the filter mesh that helps to retain particles that are much smaller than the nominal aperture size of the mesh. A fixed spray bar cleans the basket surface and fine screenings (primary sludge). In pilot testing of a MS (Huber Drum Screen Liquid) at Sand Island WRRF, reductions of 60â€“70% TSS and 25â€“35% BOD were achieved. These APT systems have demonstrated consistent high effluent quality across a wide range of influent raw wastewater conditions at a lower treatment footprint than CPT (Table 2). APT technologies can treat a larger volume of raw wastewater per square foot of land. For example, at Linda WRRF, the primary clarifier requires 220 m2 (2,400 ft2) to treat 11,000 m3/day (2.5 MGD), while the CDPF or MS (if scaled up to the primary clarifier) would require less than 50 m2 (500 ft2) to treat 11,000 m3/day (2.5 MGD). This significant reduction in primary treatment footprint translates to significant cost savings, particularly for WRRFs with limited land availability. DISCUSSION/CONCLUSIONS APT technologies can significantly improve the efficiency of WRRFs with respect to energy and treatment performance, capacity, and footprint. A summary of APT and CPT technologies is provided in Table 2. The following conclusions have been observed from the demonstration projects reviewed in this paper: - BOD and COD removal for APT technologies is 25â€“40% higher compared to CPT. - The overall WRRF energy savings possible with APT are significant and can be as high as 40â€“50%, depending on system specifics. Energy cost savings result from: (1) a reduction in the primary effluent organic load which, in turn, results in a 20â€“40% decrease in the aeration energy requirement in secondary treatment and (2) the high energy content of the captured VSS in filter BRW and the increased volume of primary sludge increases gas energy production in the anaerobic digester. - The increase in biogas energy production with APT has been estimated to be between 15 and 35%, depending on specific WRRF conditions. - APT enhances the particle size characteristics of primary effluent which allows secondary treatment processes to operate more efficiently. As shown on Figure 5, the effluent particle size distribution obtained with APT is superior compared to CPT effluent; for example, average removal for a 10-micron particle was 76, 64, and 56% for the CDPF, CMBF, and primary clarifier, respectively. - Effluent TSS concentration from APT systems remained relatively constant (Figure 2), thus providing an improved/constant mass loading to the secondary treatment process. - APT can reduce the footprint of CPT up to 80%.
ONGOING PROJECT
A technology research, demonstration, and development project is underway to further demonstrate the increased performance and economic benefits of advanced wastewater treatment technologies (Figure 6) compared to conventional treatment. The three APT technologies shown in Table 2 [CDPF (full-scale), MS (full-scale), CMBF (demonstration-scale)] are deployed at Linda WRRF. Main objectives include: (1) evaluate the performance of APT compared against CPT, (2) improve the economic feasibility and capacity of APT by reducing the BRW ratio and increasing the hydraulic performances, and (3) evaluate the performance and benefits of combined APT and advanced secondary treatment systems [supply APT effluent to a full-scale membrane aerated bioreactor and demonstration-scale aerobic granular sludge and Micro-Vi systems].

The performance of three advanced primary treatment (APT) technologies including Cloth Disk Primary Filter (CDPF), Compressible Medium Biofilter (CMBF) and Micro-Screen (MS) was evaluated. Compared to primary clarifier, APT technologies demonstrated significant benefits for energy and capital cost savings. To maximize the benefits of APT, a 3-year comprehensive research and demonstration project is underway to quantify performance of APT combined with advanced secondary treatment technologies.

SpeakerCaliskaner, Onder

Presentation time

16:30:00

16:55:00

Session time

15:30:00

17:00:00

TopicIntermediate Level, Municipal Wastewater Treatment Design

Author(s)

Caliskaner, Onder

Author(s)Onder Caliskaner1; Yihan Zhang1; Yuanbin Wu1; George Tchobanoglous2; Brian Davis3

Author affiliation(s)Caliskaner Water Technologies, Woodland, CA1; University of California Davis, Davis, CA2; Linda County Water District, Olivehurst, CA3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158732

Volume / Issue

Content sourceWEFTEC

Word count18

Description: Impacts of Advanced Primary Treatment on Advanced Secondary Treatment and MLE...

Impacts of Advanced Primary Treatment on Advanced Secondary Treatment and MLE Processes

Abstract

The performances of four advanced primary treatment (APT) technologies including Cloth Disk Primary Filter (CDPF), Compressible Medium Biofilter (CMBF), Micro-Screen (MS) and Proteus Filter were evaluated. Compared to primary clarifier which achieved 58% removal for total suspended solids (TSS) and 32% removal for chemical oxygen demand (COD), both CDPF and CMBF demonstrated a significantly higher removal performance. The CDPF achieved 76% removal for total suspended solids (TSS) and 49% removal for COD, while the CMBF achieved 70% removal for TSS and 52% removal for BOD. The performance of the MS was comparable to primary clarifier at a footprint of only 20-30% of primary clarifier. The CDPF and Proteus filter also showed similar significant footprint reduction compared to primary clarifier. To demonstrate the full benefits of advanced wastewater treatment, the impacts of APT on advanced secondary treatment (AST) and conventional MLE process is evaluated as part of the ongoing technology research and demonstration project at Linda Water Resource Recovery Facility

The performances of four advanced primary treatment (APT) technologies including Cloth Disk Primary Filter, Compressible Medium Biofilter, Micro-screen and Proteus Filter were evaluated in this long-term and comprehensive technology development and demonstration project. Compared to primary clarifier, APT technologies demonstrated higher treatment performances also resulting in significant energy savings, secondary treatment capacity increase, and footprint reduction in primary treatment.

SpeakerCaliskaner, Onder

Presentation time

14:30:00

15:00:00

Session time

13:30:00

15:00:00

SessionPrimary Treatment Technologies: Should We Settle for Conventional Primary Sedimentation?

Session locationRoom S501a - Level 5

TopicEnergy Production, Conservation, and Management, Facility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design

Author(s)

Caliskaner, Onder

Author(s)O. Caliskaner 1; Y. Zhang 2 ; O. Caliskaner 1; Y. Wu 3; E. Martinez 4; G. Tchobanoglous 5; B. Davis 6;

Author affiliation(s)Caliskaner Water Technologies, Inc. 1; Caliskaner Water Technologies, Inc. 2 ; Caliskaner Water Technologies, Inc. 1; Caliskaner Water Technologies, Inc. 3; Caliskaner Water Technologies, Inc. 4; University of California at Davis 5; Linda County Water District 6;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159004

Volume / Issue

Content sourceWEFTEC

Word count13

Description: Impacts of Primary Effluent Filtration and Primary Filtration Technologies on...

Impacts of Primary Effluent Filtration and Primary Filtration Technologies on Performance of Water Resource Recovery Facilities Compared to Conventional Primary Treatment

Abstract

Several filter technologies have been developed over the past 20 years that can be used to
- enhance the performance of or
- replace conventional primary treatment facilities. To enhance primary treatment performance, primary sedimentation (PS) tank effluent can be filtered to further reduce the constituent concentrations discharged to the secondary treatment facilities. This form of primary enhancement is known as primary effluent filtration (PEF). When a filter technology is used to replace primary sedimentation, the process application is known as primary filtration (PF). The principal focus of this paper is to compare the performance of PEF and PF technologies against conventional primary treatment. The comparison will focus on treatment and hydraulic performance impacts on Water Resource Recovery Facilities (WRRF). Carbon management and energy impacts are also addressed. Performance data from full-, demonstration- and pilot-scale projects are included, based on a review and analysis of several projects conducted between 2008 and 2020.

The following conference paper was presented at WEFTEC 2021, October 16-20, 2021. To read the full abstract, see "Abstract" tab below.

SpeakerCaliskaner, Onder

Presentation time

11:20:00

11:40:00

Session time

11:00:00

12:00:00

SessionAdvancements in Primary Treatment: Going Beyond the Conventional

Session number204

TopicAdvanced Level, Facility Operations and Maintenance, Municipal Wastewater Treatment Design

Author(s)

Onder Caliskaner

Author(s)O. Caliskaner1; G. Tchobanoglous2; L. Imani1; B. Davis3;

Author affiliation(s)Caliskaner Water Technologies, Inc., CA1University of California at Davis, CA2Linda County Water District, CA3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2021

DOI10.2175/193864718825158028

Volume / Issue

Content sourceWEFTEC

Word count22

Integrating Advanced Primary Treatment with Aerobic Granular Sludge

Abstract

[b]Introduction:[/b] Wastewater treatment plants (WWTP) are facing increasing demands to reduce energy consumption and footprint requirements while maintaining compliance with stringent nutrient discharge limits. Aerobic Granular Sludge (AGS) has emerged as an innovative treatment technology capable of effective nutrient removal with greatly reduced aeration and footprint requirements when compared to conventional activated sludge systems (CAS). Advanced Primary Treatment (APT) is another innovative technology that replaces conventional primary treatment (CPT) with compact cloth disk filters. APT has been shown to have superior total suspended solids (TSS) and chemical oxygen demand (COD) removal than CPT, have a smaller footprint, and potentially reduce aeration requirements in the subsequent biological treatment due to reduced organic loading. While both technologies have been demonstrated to be effective at the pilot and full-scale (Caliskaner et al. 2021; Ekholm et al. 2023), combining these two intensification processes and their holistic impact on each other has not been explored. As a result, this paper aimed to evaluate and model the performance, aeration savings, and footprint savings of integrating APT prior to AGS. [b]Methods:[/b] In this study, two Aqua-Nereda AGS pilot reactors were operated over a year and were fed with either CPT (Reactor B) or APT (Reactor A) effluent. Both reactors ran with 4-hour cycle including: 1-hour simultaneous feed and decant, 2.5-hour reaction, and 0.5 hour settling periods. The reactors were operated under low DO conditions and utilized an ammonia setpoint to distinguish between aerobic and anoxic reaction periods. Several oxygen transfer efficiency tests were conducted to determine the alpha value associated with each reactor. The removal performance and aeration requirements were used to calibrate two computer models built in the software SUMO (Dynamita). The calibrated pilot-scale models were then used to predict aeration and footprint savings if the proposed CPT + AGS or APT + AGS treatment trains were implemented at the Linda County WWTP (CA, U.S.), where the pilot study was conducted. A previously built full capacity (10 MGD) model of the Linda County WWTP was used for comparison. [b]Results:[/b] The performance of the cloth disk filter was consistent with other full-scale studies that utilized the same treatment system (Caliskaner et al. 2021). The average TSS and VSS effluent concentrations of the APT system were 46 mg/L (43% lower than CPT) and 38 mg/L (47% lower than CPT), respectively. The performance between Reactor's A and B showed no significant differences in nitrogen removal. Inhibited denitrification activity is often a concern for APT effluent due to the enhanced organic carbon removal. However, no significant variation in NO[sub]3[/sub] removal was observed. Additionally, the APT effluent-fed AGS reactor only used a cumulative daily average air flow of 18 m[sup]3[/sup]/d, compared to 27 m[sup]3[/sup]/d for the CPT effluent-fed reactor. Both reactors achieved the same level of ammonia removal. The average alpha value for both reactors was 0.45, lower than what is typically seen in full-scale applications. Calibration of the pilot-scale systems in SUMO was mainly related to NO[sub]3[/sub] performance, as the default kinetic parameters had good agreement with COD, NH[sub]3[/sub], and TSS concentrations. The reduction factor for ordinary heterotrophs growth under anoxic conditions was adjusted to match the measured NO[sub]x[/sub] concentrations. Phosphorus species were not calibrated and considered to beyond the scope of this paper. The model revealed more insight into the aeration savings seen in the pilot study. By lowering the organic loading, nitrification occurred faster in Reactor A, and the ammonia threshold was reached sooner. As a result, the air requirement was lower, and the subsequent anoxic phase was longer. Better NO[sub]3[/sub] removal was achieved. The low alpha value was used for model calibration, but it should be noted that the modeled aeration savings seen by the addition of AGS could be much higher based upon full-scale AGS testing (de los Santos, et al., 2020). For the full-scale simulations, the applications of CPT + AGS and APT + AGS showed a 7% and 12% decrease in aeration requirements when compared to the modeled CAS system with similar performance. Other full-scale AGS applications have seen higher aeration savings (Pronk et al. 2015), and the difference can be attributed to the conservative alpha value determined from the pilot testing. Beyond aeration, the AGS + APT treatment trains also reduced the footprint requirements by 42% when compared to CAS. [b]Significance:[/b] The results of the study demonstrate the benefits of combining APT with AGS, and the treatment train may be considered by practitioners facing extreme footprint and effluent quality restrictions. Neither the oxygen transfer efficiency nor denitrification rate of the AGS reactor was negatively affected by upstream primary filtration which removes more organics prior to the secondary treatment. At the pilot scale, the AGS reactor that was fed APT used nearly 50% less air than its counterpart. The full-scale model of APT + AGS resulted in a reduction of 11% and 42% for aeration and footprint respectively when compared to CAS. Aeration savings were less than seen in full-scale implementations due to the conservative alpha.

This paper was presented at WEFTEC 2026 in New Orleans, Louisiana.

Presentation time

16:00:00

16:30:00

Session time

15:30:00

17:00:00

SessionAerobic Granular Sludge: Design, Integration, and Water Quality

Session locationErnest N. Morial Convention Center

TopicMicroconstituents and Contaminants of Emerging Concern (Non-PFAS), Municipal Wastewater Treatment Design, Nutrients, Research and Innovation

Author(s)

Dursun, Derya, Jang, Ziya, Okan, Bora, Wu, Yuanbin, Dorn, Paula, Gravagno, Darryl, Reid, Terry, Dursun, Derya, Caliskaner, Onder

Author(s)D. Dursun1, Z. Jang1, B. Okan1, Y. Wu1, P. Dorn4, D. Gravagno2, T. Reid2, D. Dursun1, O. Caliskaner1

Author affiliation(s)Caliskaner Water Technologies, 1Caliskaner Water Technologies, 1Caliskaner Water Technologies, 1Caliskaner Water Technologies, 1Aqua Aerobic Systems Inc, 2Aqua-Aerobic Systems Inc., 2Caliskaner Water Technologies, 1Caliskaner Water Technologies, 1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Sep 2026

DOI10.2175/193864718825160343

Volume / Issue

Content sourceWEFTEC

Word count9

Integrating Fixed-Film Biofiltration into Primary Treatment Processes

Abstract

As wastewater treatment facilities face increasing constraints on footprint, energy consumption, and capital expansion, there is growing interest in treatment technologies that intensify performance within existing process boundaries. Conventional primary clarification is largely limited to gravity-driven particulate solids removal and provides minimal attenuation of soluble organic matter, thereby placing the full burden of biological oxidation on downstream secondary treatment processes. This conventional separation of physical and biological treatment functions results in large reactor volumes, high aeration demand, and limited operational flexibility. This study evaluates an integrated primary biofiltration approach that introduces fixed-film biological activity into a primary treatment configuration, effectively redefining primary treatment as an intensified, multifunctional unit process capable of combining physical filtration and biological oxidation. An up-flow floating media biofiltration pilot system was designed and operated over a seven-month period (August 2024-March 2025) at the Linda County Water District municipal wastewater treatment plant in Northern California. The reactor consisted of two vertically stacked floating media zones: a lower, unaerated filtration zone providing physical capture of suspended solids, and an upper, aerated zone supporting attached biofilm growth and biological oxidation. This configuration enabled concurrent solids removal and biological treatment within a single vessel, while maintaining short hydraulic retention times compatible with primary treatment applications. Pilot testing was conducted at empty bed contact times (EBCTs) of 20, 30, 60, and 120 minutes to evaluate system performance across a range of hydraulic and organic loading conditions representative of both high-rate and extended-contact operation. Treatment performance was assessed using total suspended solids (TSS), five-day biochemical oxygen demand (BOD), and soluble chemical oxygen demand (sCOD) as key indicators of physical and biological treatment efficacy. Results demonstrate that integrating fixed-film biological activity into a primary treatment configuration can substantially intensify organic removal at hydraulic retention times far shorter than those required for conventional secondary treatment. At EBCTs of 20-30 minutes, the system consistently achieved TSS removals on the order of 80%, exceeding values typically reported for conventional primary clarification, while simultaneously achieving measurable reductions in soluble organics (50-59% sCOD removal). These results indicate that the system provided meaningful attenuation of both particulate and soluble organic loading under short-contact conditions relevant to high-rate treatment. At an EBCT of 60 minutes, average BOD removal exceeded 80% and sCOD removal exceeded 70%, demonstrating that a significant fraction of biological oxidation typically assigned to secondary treatment could be achieved upstream within a compact primary-scale reactor. Analysis of effluent sCOD:BOD ratios revealed a progressive shift toward more stabilized organic fractions with increasing EBCT, confirming that soluble organic removal was driven by biological oxidation within the attached biofilm rather than physical filtration alone. Importantly, solids removal performance remained stable across all tested EBCTs, indicating that biological activity did not compromise filtration performance and that the integrated system was resilient to hydraulic variability. These findings suggest that the combined physical-biological configuration can decouple solids capture from biological kinetics while maintaining consistent treatment performance. High oxygen transfer performance was observed within the aerated biofiltration zone, sustaining biofilm growth and enabling biological oxidation at elevated areal and volumetric rates. Measured oxygen transfer efficiencies per unit depth ranged from 1.10 to 1.69% OTE·ft⁻¹ exceeding values commonly reported for conventional activated sludge systems, including those equipped with fine-pore diffusers. These elevated oxygen transfer efficiencies are notable given the relatively shallow reactor depth and primary-scale configuration, and they suggest favorable gas-liquid mass transfer conditions associated with the floating media architecture and internal hydraulics. At extended EBCTs, partial nitrification was observed, further confirming the biological functionality of the integrated system and indicating that the reactor environment supported both heterotrophic and autotrophic microbial activity. Similar performance trends were independently documented at a separate facility in Ohio in 2025, supporting the broader applicability of the observed mechanisms. Collectively, these results demonstrate that biologically active primary biofiltration can shift a meaningful portion of organic oxidation upstream of secondary treatment, thereby reducing the biological load imposed on downstream processes. From a treatment-train perspective, this redistribution of treatment functions has implications for secondary reactor sizing, aeration demand, and solids production dynamics. By consolidating physical filtration and biological oxidation within a single intensified unit process, integrated primary biofiltration offers a pathway toward more compact, energy-efficient, and adaptable wastewater treatment configurations. This work reframes primary treatment not as a passive, gravity-driven step, but as an active and biologically relevant process with the potential to simplify treatment trains and enhance overall system performance.

This paper was presented at the WEF Residuals, Biosolids, and Treatment Technology Conference in Kansas City, MO, May 11-14, 2026.

Presentation time

08:30:00

09:00:00

Session time

08:30:00

10:00:00

SessionUnderstanding a Variety of Biofilm Applications

Session locationKansas City Convention Center

TopicInnovative and Advanced Treatment for Achieving Limit-of-Technology Performance

Author(s)

Dsane, Victory Fiifi, Rhu, Daehwan, Kang, Shin Joh, Dursun, Derya, Caliskaner, Onder, Daigger, Glen, Wu, Yuanbin

Author(s)V. Dsane1, D. Rhu1, S. Kang, D. Dursun2, O. Caliskaner2, G. Daigger3, Y. Wu2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2026

DOI10.2175/193864718825160224

Volume / Issue

Content sourceResiduals, Biosolids and Treatment Technology Conference

Word count8

Description: Optimization of Advanced Primary Treatment Technologies for Carbon Diversion and...

Optimization of Advanced Primary Treatment Technologies for Carbon Diversion and Management at Water Resource Recovery Facilities

Abstract

Introduction Advanced Primary Treatment (APT) is a process in which filtration or micro-screening technology is used to replace or supplement Conventional Primary Treatment (CPT). In this project, the Cloth Disc Primary Filter (CDPF) and Proteus Primary Filter (Proteus PF) have been demonstrated for 3 and 1.5 years, respectively. Significantly higher treatment performance values (i.e., 40 to 50 % higher) were observed with both primary filtration (PF) technologies compared to CPT. PF increases capacities of primary and secondary treatment systems minimizing (or sometimes even eliminating) expansion requirements for existing installations or reduce the required footprint for new installations. Primary filtration is also the most effective carbon diversion strategy at Water Resource Recovery Facilities (WRRFs). Carbon diversion involves reducing the organic load on secondary systems by redirecting more biochemical oxygen demand towards the solids line at the primary treatment stage, which reduces the aeration requirements for aerobic biological processes downstream. Resultant benefits of PF are: (1) savings in aeration energy costs, (2) increase in digester gas energy production, and (3) reduction in primary and secondary treatment footprint and volume requirements. Significant CAPEX and OPEX savings are realized because of these benefits. One important design and operational challenge for PF is the high primary sludge volume produced during backwash operation. Sludge produced from PF backwash is also thinner (i.e., 0.2 to 0.4 %) compared to CPT sludge. Thickening is an essential process component of PF systems and its design conditions are quite different due to high sludge volumes, low solids concentrations, and significant differences in sludge characteristics. Optimization of PF systems to minimize backwash sludge volumes and still achieving high treatment efficiencies is one of the main objectives of this on-going technology research and demonstration project. Methodology Funded by California Energy Commission, the focus of this project is to evaluate the treatment and hydraulic performance of several PF technologies at Linda County Water District's (Linda) WRRF located in Olivehurst, CA (Fig. 1). General information for the Proteus PF and CDPF systems are provided in Table 1. The Proteus PF and CDPF units are shown in Figs. 2 and 3, respectively. CDPF unit has been in operation since January 2022 and Proteus PF has been in operation since July 2023. The specific objectives of the project include: (1) Evaluate the performance of PF technologies; (2) Improve the treatment and hydraulic performances; (3) Optimize the design & operational criteria including sludge treatment system, and (4) Evaluate impacts on downstream secondary process. Inline turbidity/TSS sensors and flow meters have been installed at each PF system and sensor data are synchronized to provide real-time monitoring of treatment performance. Inline sensor data are complemented by lab analysis of 24-h composite samples from influent and effluent channels of each unit. Overall, the evaluation is based on hydraulic and treatment performances. The hydraulic performance was assessed using solids loading rate (SLR), hydraulic loading rate (HLR), and backwash reject ratios (BRR) of both PF systems. High HLR, low BRR, and high SLR typically correlate to lower capital and operational costs. The key parameters impacting BRR include: HLR, SLR, pressure build-up rate, backwash flowrate, and backwash frequency and duration. The treatment performance was evaluated based on total COD (tCOD), soluble COD (sCOD), total BOD (tBOD), soluble BOD (sBOD), TSS and total Kjeldahl nitrogen (TKN) removal. Treatment Performance of APT systems The performance of the Proteus Filter and Cloth Disk Primary Filter are reported and compared to conventional primary sedimentation. Proteus Filter: The TSS and COD removal performances of the Proteus Filter are shown in Fig. 4 and Fig. 5, respectively. Results were obtained based on 24-hr composite samples collected between July 2023 and September 2024. More than 100 samples were used to evaluate the removal performances. As shown in Fig. 4, influent and effluent TSS concentrations averaged at 471 and 100 mg/L, respectively, when the unit was operated between its average and peak flow design conditions. Influent and effluent COD, as reported in Fig. 5, averaged 981 and 419 mg/L, respectively. Cloth Disk Primary Filter: The TSS and COD removal performances of the full-scale CDPF system are shown in Fig. 6 and 7, respectively. Results were obtained based on 24-hr composite samples collected between May 2022 and September 2024. More than 150 samples were used to evaluate the removal performances. As shown in Fig. 6, influent and effluent TSS concentrations averaged at 421 and 56 mg/L, respectively. It should be noted that even though influent wastewater TSS concentrations varied significantly, a relatively stable effluent TSS between 50 to 70 mg/L was observed. Influent and effluent COD, as reported in Fig. 7, averaged 805 and 335 mg/L, respectively. Overall, the CDPF performance has been observed to be similar to the results obtained from previous demonstrations where 75-85% and 50-60% removal for TSS and COD were observed, respectively (Caliskaner et al., 2018, 2019, 2020, 2021, 2022). Performance Comparison versus Primary Sedimentation: Both PF systems were operated in parallel with the existing primary clarifiers at the Linda WRRF, and performance comparisons were conducted using samples taken during the same 24-hr sampling intervals. As seen in Fig. 8, primary clarifier (PC) achieved average removals of 38% for COD and 66% for TSS. As seen in Fig. 8, the Proteus PF unit achieved average removals of 65% for COD and 85% for TSS when operated at 2 gpm/ft2, which are 40 to 50 % higher compared to PC removal efficiencies. Similar high treatment performances were also obtained with the CDPF system when compared to primary clarifier. Average removals of 56% for COD and 85% for TSS were achieved with the CDPF system. Hydraulic Performance of APT systems The optimum design and operational conditions are investigated in this project considering HLR, SLR, headloss development (across the filter media), and BRR ratios. Summary of hydraulic values observed for both PF systems are presented in Table 2. PF backwash is triggered by preset filtration time or maximum headloss development , whichever comes first. Headloss development is measured by pressure transducers. Headloss development rates were observed to change with changes in HLRs. Proteus PF: As illustrated in Fig. 9, headloss development increases as the HLR increases resulting in higher BRRs. The daily average headloss development under HLR of 2 gpm/ft2 and 6 gpm/ft2 were 5.2 and 6.2 psig, respectively. The increased flowrate and HLR caused increased accumulation of particulate material within the filter media resulting in larger headloss values and hence higher BRR values. The HLR and BRR values with respect to time are summarized in Fig. 10. The Proteus PF system has been operated between 2 and 9 gpm/ft2 most of the demonstration resulting in an average BRR of 9.4%. Daily average HLR and SLR for the Proteus PF System during the demonstration is shown on Fig. 11. Based on an analysis of HLR and BRR values, HLR ranging from 2 to 2.5 gpm/ft2 are considered for optimum average flow design conditions and 5 to 6 gpm/ft2 are considered for peak flow design conditions. Cloth Disk Primary Filter: The volumes of filtered effluent, backwash reject, and sludge wasting are all monitored along with HLR and SLR values. Recorded HLR and BRR values are shown in Fig. 12. Similar to Proteus PF system, headloss development and BRR increase as the HLR increases. Average daily BRR values were observed to be approximately 10 percent under average design flow/loading conditions. Based on an analysis of HLR and BRR values, HLR value of approximately 2 gpm/ft2 is considered for optimum average flow design conditions and 4 to 4.5 gpm/ft2 are considered for peak flow design conditions. Impact of Primary Filtration Systems on Energy Consumption and Recovery One major project objective is to demonstrate the energy and capacity impacts of PF on WRRFs. Specifically, impacts of PF on MLE process and three Advanced Secondary Treatment technologies including Microvi, AGS and MABR were evaluated. Energy savings and footprint reductions are measured directly in addition to the process modeling studies to further investigate the impacts on BNR kinetics. The impacts of PF on secondary treatment and anaerobic digestion were predicted with SUMO process modeling using the obtained PF demonstration data. PF results in 25% in aeration energy savings and 35% increase in digester gas production (Fig. 13).

This paper was presented at the WEF Residuals & Biosolids and Innovations in Treatment Technology Joint Conference, May 6-9, 2025.

SpeakerCaliskaner, Onder

Presentation time

13:45:00

14:00:00

Session time

13:30:00

15:00:00

SessionDifferent Approaches to Diverting COD Upstream of Nutrient Removal Facilities

Session numberITT Session 18

Session locationBaltimore Convention Center, Baltimore, Maryland, USA

TopicBiogas Production, Intensification, Primary Treatment, Process Intensification, Secondary Treatment, Solids Retention Time, wastewater

Author(s)

Caliskaner, Onder, Dursun, Derya, Wu, Yuanbin, Martinez, Everardo, Tchobanoglous, George, Davis, Brian

Author(s)O. Caliskaner1, D. Dursun1, Y. Wu1, E. Martinez1, G. Tchobanoglous2, B. Davis3

Author affiliation(s)Caliskaner Water Technologies, Inc.1, University of California at Davis2, Linda County Water District, 3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2025

DOI10.2175/193864718825159789

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count17

Description: Performance Evaluation of Parallel Operation of Conventional Primary Treatment...

Performance Evaluation of Parallel Operation of Conventional Primary Treatment versus Primary Filtration and Biofiltration Systems

Abstract

In this project, the performance of two advanced primary treatment (APT) technologies, a pile cloth disk primary filter (CDPF) and a compressible media filter (CMF), were compared to conventional primary treatment. Conventional primary treatment (i.e., primary clarifier) typically removes 55 to 60% of total suspended solids (TSS) and 30 to 40% of biochemical oxygen demand (BOD) from raw wastewater (Metcalf and Eddy, 2014). Primary filtration (PF) and biofiltration are emerging APT technologies that can remove high solids and organics load from raw wastewater after screening. PF typically achieves removal efficiencies of 75 to 85% for total suspended solids and 50 to 65% for biochemical oxygen demand (Caliskaner et al., 2018). Biofiltration also offers the potential for removing soluble organic fractions due to biological activity, which occurs because of increased depth of the filter medium and longer contact times. Additionally, the impact of APT on downstream operations such as secondary treatment and anaerobic digestion was evaluated.

SpeakerCaliskaner, Onder

Presentation time

16:00:00

16:30:00

Session time

15:30:00

16:30:00

SessionCellulose Recovery From Wastewater

Session number7F

TopicBiosolids and Residuals, Energy Production, Conservation, and Management, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

O. CaliskanerG. TchobanoglousL.N. ImaniJ. LundB. DavisJ. Rios FariasT. Reid

Author(s)O. Caliskaner1; G. Tchobanoglous2; L.N. Imani1; J. Lund1; B. Davis3; J. Rios Farias3; T. Reid4;

Author affiliation(s)Kennedy/Jenks Consultants1; University of California at Davis, CA2; Linda County Water District3; Aqua-Aerobics Systems, Inc. 4; WesTech Engineering, Inc. 5

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157434

Volume / Issue

Content sourceWEFTEC

Word count16

Description: Taking Intensification One Step Further: Can We integrate Advanced Secondary...

Taking Intensification One Step Further: Can We integrate Advanced Secondary Treatment Processes after Advanced Primary Treatment ?

Abstract

Introduction:
The main purpose of this study is to reduce the energy demand of water resource recovery facilities (WRRFs) through intensification of both primary and secondary treatment processes. Three Advanced Secondary Treatment (AST) Technologies (Aerobic Granular Sludge (AGS), Membrane Aerated Bioreactor (MABR) and MicroVi ) were integrated after an Advanced Primary Treatment (APT). A full scale Cloth Disk Primary Filter was used for APT technology. The performance of three advanced secondary treatment technologies were also evaluated with primary clarifier effluent (conventional primary treatment) to be able to understand the impact of advanced primary treatment on advanced secondary treatment process. The project is funded by the California Energy Commission (CEC) Project EPC-20-044.

The specific objectives of this project are to:
- Establish the design criteria, ability to meet effluent objectives, and determine supplemental carbon addition requirements when treating advanced primary treatment (APT) effluent.
- Quantify the differences in design capacity, energy and supplemental carbon demand when the process is treating primary clarifier effluent.

Methodology:
This demonstration project was conducted at the Linda WWTP located in Olivehurst, CA. AGS and MicroVi units were evaluated at demonstration scale (Figures 1&2), whereas MABR was installed at full scale (Figure 3). The technology demonstration period was at least (8) months for AGS, MABR and around 2 years for MicroVi process. During the demonstration period, the performance of these technologies were monitored with the effluent from an AquaPrime APT and baseline performance following primary clarifier. To monitor the performance of the demonstration units, a comprehensive sampling and analyses plan was prepared. Analyses performed at the laboratory were assessed with process and real time sensor data on a weekly basis.

The basis for evaluations were dictated by the effluent requirements. Hence, COD and cBOD removal, Nutrient removal (Nitrogen and Phosphorus) and TSS removal rates were monitored throughout the project. Samples were taken from influent, effluent of each process.

Results: The results from the AGS system tested downstream of the APT system (Reactor A) were compared with operating AGS with Conventional Primary Treatment (CPT) effluent (Reactor B). The main observation was that the AGS system can create aggregated microbial granules in both Reactor A and B. The faster settling rates of the sludge granules and higher biomass concentrations in reactors were observed. Figure 4 clearly shows the SVI values below 60 mL/g all the times for Reactor A, and most of the times for Reactor B. When both reactors were operated at steady state, SVI's were averaging around 40 mL/g. Improved settling characteristics leads to significant secondary treatment footprint and energy savings. The nutrient removal performance was assessed in detail in both Reactors. The preliminary results clearly showed full nitrification in both reactors. Effluent ammonia numbers consistently stayed below 1 mg/L in both Reactors. (Figure 5). Effluent nitrate numbers were kept below 10 mg/L and nitrite was lower than 1 mg/L. Effluent total nitrogen have been below 15 mg/L without any carbon addition. The study also showed promising results in Phosphorus removal. The full paper will elaborate on the carbon demand for Reactor A and B.

AGS performance was aimed to be improved further with APT effluent consisting of soluble BOD and smaller particulates rather than insoluble BOD associated with larger particulate material of primary clarifier effluent. Colloidal and smaller particulates are readily hydrolysable by the AGS bacteria that are responsible for denitrification of oxidized nitrogen forms. As a result, the larger organic particles that represent less efficient carbon sources for the denitrifying bacteria are sent to the digester (via primary filtration) to produce energy rather than consume energy within the AGS reactor. The reduced quantity of larger organic particulates is anticipated to improve the AGS efficiency and eliminate the additional oxygen demand required to oxidize the solids. Hence, the airflow into the reactors were also compared to determine the energy demand of the reactors.

Similarly, the nutrient removal performance of MicroVi and MABR technologies were evaluated. Combination of Advanced Primary Plus Microvi Biocatalyst provided a very compact Total Nitrogen Removal System with reactor Nitrogen Loading Rates 3 — 4 times higher than conventional Activated Sludge process. However, particulate removal may require additional mechanisms to meet target effluent quality. MABR technology also provided benefits with increase nitrification rate.

The project was initiated in 2021 and will be completed in March 2025. Our full paper will provide detailed performance analyses for AGS, MABR and MicroVi. The final findings and conclusions will be available in the full paper.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionOptimizing the Treatment Train using Advanced Primary Filtration and its impact on Secondary Treatment

Session locationMcCormick Place, Chicago, Illinois, USA

TopicLiquid Stream Treatment Technology - Secondary & Tertiary Treatment

Author(s)

Dursun, Derya, Caliskaner, Onder, Wu, Yuanbin, martinez, Evan, Funtila, Alexy, Okan, Bora, Davis, Brian, Tchobanoglous, George

Author(s)D. Dursun1, O. Caliskaner1, Y. Wu1, E. martinez1, A. Funtila1, B. Okan1, B. Davis2, G. Tchobanoglous

Author affiliation(s)Caliskaner Water Technologies1, Linda County Water District2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825159980

Volume / Issue

Content sourceWEFTEC

Word count18

Thickening through Suspended Air Application Aims to Reduce Energy Consumption

Abstract

Conventional thickening processes use gravitational forces or mechanical methods such as centrifuges or belt filter presses for solids separation. Although these methods have proven to be efficient, gravity based thickening methods require large footprint and mechanical thickening processes can be energy intensive. Recently, several innovative technologies have been introduced that aim to enhance energy efficiency of thickening process while reducing the footprint. Dissolved Air Flotation (DAF) process has been around for over a century and initially used in the early 1900s, primarily in the pulp and paper industry to remove fibers and other solids from water. Interest in DAF resurged in the 1960s for wastewater treatment applications and since then DAF has been used as one of the main thickening processes. DAF introduces air into the wastewater solids, and creates tiny bubbles. Then these bubbles attach to the sludge particles, causing them to float to the surface, where they form a thickened sludge layer. This layer is then skimmed off, leaving clearer water below. However, DAF has shown to be energy intensive since it requires recirculation pumps, compressors. Lately, a new thickening technology called Suspended Air Flotation (SAF) was introduced into the wastewater industry. SAF operates similar to DAF by using air to float sludge. However, there is a key difference: SAF employs charged particles for bubble flotation. SAF also aims to float the particles but without the use of dissolved air. Therefore, thickening performance is not limited by changing conditions such as gas solubility, pressure, and temperature. The flotation occurs by the application of froth made from an anionic surfactant, water, and air instead of air bubbles for flotation. Similar to DAF, SAF mixes feed sludge with a conditioning polymer before it enters the flotation tank. Froth, composed of charged microbubbles called aphrons, is then introduced downstream of the polymer injection. The micron-sized air bubbles, ranging from 7 to 50 Âµm, in water to attain a volumetric air content of 40 to 50%. These bubbles are coated with a thin layer of soap film derived from an electrically charged anionic or cationic surfactant. The charged bubbles offer a substantial interfacial area for the adsorption of oppositely charged flocculated wastewater solids. In practice, suspensions of charged bubbles are introduced into the flotation tank to interact with wastewater solids. The solids then ascend to the surface and are skimmed off. The clarified effluent is recirculated to the headworks. SAF enhances traditional thickening methods like Dissolved Air Flotation (DAF) by eliminating the need for dissolved air, thus obviating the requirement for pressurization systems, recirculation pumps, compressors, and airlines, leading to considerable energy savings. SAF's capability to manage high solids loads also results in substantial footprint and power savings, high solids recovery (up to 98%), and a high solids loading rate (up to 40 lb/ft2/hr). Moreover, no polymer is needed to thicken sludge to 4% solids. Owing to these benefits, adopting SAF technology can lead to a reduction in greenhouse gas emissions by more than 60-70% and energy savings of up to 90% compared to its conventional counterparts, such as DAF. In a recent project funded by California Energy Commission (CEC), this innovative thickening process was selected to be tested at demonstration scale. The demonstration facility is located at Linda County California, north of Sacramento. The project includes several advanced treatment processes for biosolids. Another innovative technology Supercritical water oxidation (SCWO) is also included after SAF to replace anaerobic digesters. Figure 1 shows the process flow diagram at demonstration facility. SAF process have already shown promising results for their low energy consumption. Recent findings indicated over 90% savings in energy use by switching from DAF to SAF. Table 1 compares SAF process with conventional thickening processes. The cost savings for SAF process was also evaluated with other conventional thickening processes including Rotary Drum Thickener (RDT) and also DAF. Table 2 summarizes the 30 year net present value comparison of SAF process. This presentation will evaluate this novel technology, discuss the critical design criteria for this process and assess its performance focusing on energy savings.

This paper was presented at the WEF Residuals & Biosolids and Innovations in Treatment Technology Joint Conference, May 6-9, 2025.

SpeakerDursun, Derya

Presentation time

09:30:00

09:50:00

Session time

08:30:00

10:00:00

SessionAdvancements in Thickening Technologies: Operational Optimization and Cost Savings

Session number23

Session locationBaltimore Convention Center, Baltimore, Maryland, USA

TopicAsset Management, Efficiency, Solids Thickening