Assessment of hydraulic flocculation processes using CFD

Abstract

The performance of flocculation tanks either in full‐ or pilot‐scale systems cannot be fully quantified using average velocity gradient values (G values) alone. The computational fluid dynamics (CFD) process was used to investigate the turbulent flow characteristics of a three‐stage hydraulic flocculation facility at the J.D. Kline Water Supply Plant in Halifax, Nova Scotia. Calculations of the local velocity gradient were achieved using predicted energy dissipation rates. CFD analysis showed unbalanced mixing conditions in the hydraulic flocculation tanks resulting from short‐circuiting and from recirculation zones. Inconsistent mixing energy, interrupted with severe spikes in the localized G values at the weir columns, led to little or no mixing energy in most of the regions in the flocculation tanks. Practical outcomes of operating at such varying mixing gradients can be detrimental to the flocculation process and overall organic removal in the treatment plant.

Biomass Evolution in Full‐Scale Anthracite‐Sand Drinking Water Filters Following Conversion to Biofiltration

“…Filter effluent was also used for backwashing; therefore, removal of prechlorination also resulted in the removal of chlorinated (~0.05 mg/L) backwash. The facility source water is Pockwock Lake, which is characterized by low turbidity (~0.4 ntu), low pH (~5.5), low alkalinity (<1 mg/L), and low organic carbon (~2.5 mg DOC/L; ~2.5 mg total organic carbon [TOC]/L) content (Stoddart & Gagnon 2015, Knowles et al 2012, Vadasarukkai et al 2011). Plant siting resulted in a large seasonal temperature fluctuation (~1–23°C) during the analysis; however, raw water pH, turbidity, and TOC and DOC concentrations remained stable seasonally (Stoddart & Gagnon 2015).…”

Role of iron and aluminum coagulant metal residuals and lead release from drinking water pipe materials

“…Kline Water Supply Plant (JDKWSP) in Halifax, Canada. The JDWSP: is a direct filtration that utilizes alum for coagulation, as described by Vadasarukkai et al [27] In this study, fountains were covered the day prior to testing in order to allow water to stagnate for 8 to 16 h before testing. Following the stagnation period, first draw samples of 250 mL were collected, chilled, and delivered to the laboratory for lead analysis.…”

Mean oxidation state of organic carbon: A novel application to evaluate the extent of oxidation of natural organic matter in drinking water biological treatment

“…J. D. Kline Water Supply Plant is a direct filtration water treatment plant with a designed capacity of 227 ML/day (Figure 11.1). The source water comes from Pockwock Lake, which is characterized as low-turbidity (~0.4 NTU), low-alkalinity (<1mg/L), low-pH (~5.5), and low-organic carbon (~2.5 mg DOC/L; ~2.5 mg TOC/L) (Stoddart et al, 2016;Stoddart & Gagnon, 2015;Vadasarukkai et al, 2011). In the J. D. Kline Water Supply Plant, the pre-mix process involves the addition of calcium hydroxide and potassium permanganate for the oxidation of metal, pH adjustment by carbon dioxide, and coagulation with aluminium sulfate.…”