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

...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.