Optimized centre-feed clarifier design for the Tai Po Sewage Treatment Works, Hong Kong

• Published in: Water and environment journal : WEJ Vol. 24; no. 2; pp. 140 - 146
• Main Authors: Zhou, Siping, Mak, Bevis W.L, Leong, Echo, Hon-Shing, Kan, Shu-kuen, Ip, Tze-Kwan, Liu
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-06-2010; Blackwell Publishing Ltd; Blackwell
• Subjects: Applied sciences; CFD modelling; clarifier; computational fluid dynamics; Exact sciences and technology; General purification processes; inlet; optimization; Pollution; Wastewaters; Water treatment and pollution; ISEW, China, People's Rep., Hong Kong; China, People's Rep., Hong Kong, New Terr., Sha Lo Tung, Tai Po; Activated sludge; Turbulence; Stability; Computational fluid dynamics; Modeling; clarifier; inlet; Optimization; Biological purification; Design; Storage; Loading; Flocculation; Physicochemical purification; Waste water purification; CFD modelling
• ISSN: 1747-6585; 1747-6593
• DOI: 10.1111/j.1747-6593.2009.00167.x

Stability of sludge blanket is a critical factor controlling the performance of clarifiers. A three-dimensional computational fluid dynamics (CFD) model was applied to optimize the clarifier design at the Tai Po Sewage Treatment Works, Hong Kong. Validated by field data, the CFD model evaluated the key clarifier design elements including side-water depth, centre-feed inlet, flocculation well and returned activated sludge (RAS) flow. Based on field observations and modelling results, the new design aims at eliminating the strong turbulence typical of centre-feed inlets in the clarifier, thus creating a better flocculation environment, and reducing disturbance to the sludge blanket. The modelling results also demonstrated a marked improvement in clarifier performance after the increase in clarifier depth and hence sludge storage capacity. The increased storage capacity reduces the risk of high sludge blanket levels upsetting the clarified effluent quality under high flow or solids loading conditions.