Turbulence and Flocculation

Stirred Tanks

“…Very few studies that combine theory and experiment on disruption of aggregates in turbulent flows have appeared, e.g. Argaman and Kaufman (1968), Patterson and Kamal (1974), Pandya and Spielman (1982), Lu and The observation that mean aggregate &izes decrease at shear rates is often interpreted in terms of deriving an inverse power relationship between the mean diameter of the aggregates and the average shear rate (Glasgow and Luecke (1980), Tambo and Watanabe (1979) and Francois and van Haute (1985)).…”

Further investigation of the irreversible floc breakup in flocculation kinetics modelling

“…First, the K B value is directly proportional to the value of Ф, suggesting that excessive dosages may increase the occurrence of the rupture process. Second, K B is also directly proportional to the value of K P squared, indicating that K B is more influenced by the mixing aspects of the system than K A (Argaman & Kaufman 1970;Haarhoff & Joubert 1997;Crittenden et al 2012;Bratby 2016;Di Bernardo et al 2017;Ferreira Filho 2017).…”

“…However, due to its complexity, flocculation still requires a universal model (Thomas et al 1999;Watanabe 2017). Argaman and Kaufman's original model, although knowingly limited for design purposes, can be useful for the evaluation of existing units and routine process control since it requires only results from jar test assays (Argaman & Kaufman 1970;Bratby 2016). This is particularly interesting for DWTPs in developing countries, as they usually are not equipped with sophisticated laboratories (Di Bernardo et al 2017;Ferreira Filho 2017).…”

“…Providing data for these coefficients is critical, especially when correlated with raw water composition and coagulant/particle ratio, as it can be useful for future studies and predictive model applications. Moreover, previous methods for determining K A and K B values were mostly manual computations (Argaman & Kaufman 1970;Bratby 1981;Haarhoff & Joubert 1997). Today, the increase of technology has brought new computational methods that can be used to calculate these coefficients.…”

“…All K A and K B values, minimum N t /N 0 , and CoD results are presented in the Supplementary Material for all assays.With an alum dosage of 20 mg•L À1 , equilibrium was achieved with G values of 20 and 30 s À1 , as depicted in Figure2. Increasing coagulant dosage usually increases K A value(Argaman & Kaufman 1970;Bratby 2016) and since K B values remained considerably low, equilibrium was achieved in a low N t /N 0 level (0.10 and 0.20) with approximately 30 to 35 minutes. Higher G values led to equilibrium faster, however at a higher N t /N 0 values (worsen clarified water quality).…”