Open access


This paper deals with optimisation and acceleration of the clarification process. It was established that both these objectives are closely inter-related and can be accomplished by the formation of aggregates with a high agitation intensity until the flocculation optimum is reached. This is a new method of formation of aggregates which is called the Inline High Density Suspension (IHDS) formation process. Further, under the IHDS process the aggregates are formed with a single root-mean-square velocity gradient G >> 50 s-1. It was also established that the process of formation of aggregates (expressed by residual e of the observed determinant) passes through a minimum. This minimum is considered to be the flocculation optimum. Furthermore, the agitation intensity (G) was found to be the inherent means influencing compactness and thereby density of the aggregates formed. This proves the vital role of agitation intensity on the morphological and physical properties of aggregates formed. The resultant aggregates formed by the IHDS process are very compact, dense and homogeneous in their size, shape, volume and inner structure. Last but not least, the IHDS process applied to the HR-CSAV type sludge blanket clarifier facilitated its high attainable upflow velocity above of 25 m h-1.

CAMP T.R., 1946: Sedimentation and the design of settling tank. Trans. Soc. Civ. Engrs., 895-901.

CAMP T.R., 1953: Flocculation and flocculation basins. Proc. Am. Soc. Civ. Engrs. 79, 283.

CAMP T.R., 1968: Floc volume concentration. JAWWA 60, 656-673.

CAMP T.R. and STEIN P.C., 1943: Velocity gradients and internal work in fluid motion. J. Boston Soc. Civ. Engrs., 4, 219-237.

DUCOSTE J.J. and CLARK M.M., 1998: The influence of tank size and impeller geometry on turbulent flocculation: I. Experimental. Environ. Eng. Sci., 15, 3, 215-224.

FAIR G.M. and GEYER J.C., 1958: Elements of water supply and wastewater disposal. Willey, New York.

HAM R.K. and CHRISTMAN R.F., 1969: Agglomerate size changes in coagulation. J. San. Engng. Div. SA, 3, 95, 481-502.

HAN M.Y. and LAWLER D.F., 1991: Interaction of two settling spheres: settling rates and collision efficiencies. J. Hydraul. Eng. ASCE, 117, 1269-1289.

HAN M.Y. and LAWLER D.F., 1992: The (Relative) Insignificance of G in flocculation. JAWWA, 84, 79-91.

HARRIS H.S., KAUFMANN W.J. and KRONE R.B., 1966: Orthokinetic flocculation in water purification. Proc. ASCE, J. San. Engng. Div., SA6, 92, 95-111.

HEREIT F., MUTL S. and VAGNER V., 1977: Evalustion of waterworks operation. (In Czech.) Vodní hospodarstvi, 4, rada B.

HUDSON H.R. Jr., 1965: Physical aspects of flocculation. JAWWA, 57, 7, 885-892.

HUDSON H.R. Jr., 1973: Evaluation of plant operating and jar test data. AWWA, 65, 5, 368.

IVES K.J., 1978: The scientific basis of flocculation (Sijthof & Nordhoff Int. Publishers, Alphen aan der Rijn, Netherlands.

LAWLER D.F., 2000: Theory of particle processes: Changes in size distribution in flocculation, sedimentation and filtration. Proc. Workshop on Particle Counting and Characterization in Drinking Water Treatment, November, Johannesburg, South Africa.

MUTL S., POLASEK P., 2002: Particle Sizes and Particle Size-Fraction Distribution in Water Treatment. Conf. IWA, Poster Paper, April 2002, Melbourne, Australia.

PARKER D.S., KAUFMAN W.J. and JENKINS D., 1972: Floc breakup in turbulent flocculation processes. Proc. ASCE J. San. Engng. Div. SA, 1, 98, 79-99.

POLASEK P., 1970 & 1972a: Float-Filter, method and apparatus for two-stage treatment of liquids; Water clarification. SA Patents.

POLASEK P., 1980: HR Clarifier performance results. Proc. Int. Conf. SAFIL, Johannesburg.

POLASEK, P., 2005: High Rate Clarification Technology. PPA Johannesburg, Research Report, HRCT 01/72.

POLASEK P., 2007: Differentiation between different kinds of mixing in water purification - back to basics. J. Water SA, 33, 2, 249-251.

POLASEK, P., 2009: Optimised conditions for application of organic flocculant aids in water purification. J. DWES, paper No. 2009-6 Drink. Water Eng. Sci. Discuss., 2, 205-229, doi: 10.5194/dwesd-2-205-2009.

POLASEK P. and MUTL S., 1995: Guidelines to coagulation and flocculation for surface water - Volume II: Evaluation of treatment process efficiency of different waterworks - Case Studies. PPA, Johannesburg.

POLASEK P. and MUTL S., 2005a: Acceleration of gravity separation process. J. Filtration 5, 1, 33-39.

POLASEK P. and MUTL S., 2005b: High Rate Clarification technology. Proc. IWA Spec. Conf.: Particle Separation 2005, Seoul, South Korea.

POLASEK P. and VAN DUUREN F.A., 1979: Orthokinetic flocculation. Proc. Summer School, University of Pretoria, South Africa.

POLASEK P. and VAN DUUREN F.A., 1981: The performance results from the operation of High Rate Clarifiers at Bethlehem Municipal Waterworks. Proc. Water Industry, 81, Int. Conf. Brighton, UK.

RITCHIE A.R., 1965: Certain aspects of flocculation as applied to sewage purification. PhD Thesis, London, Univ. of London 1955 - cited from Tesarik I. (1968): Discussion to Ives K.: Theory of operation of sludge blanket clarifiers. Proc. Instn. Civ. Engrs, 39, 569.

SCHUTTE F., 2006: Handbook for the operation of Water Treatment Works. Publ. TT 265/06, WRC Pretoria, RSA.

SMOLUCHOVSKI M., 1917: Versuch einer matematischen Theorie der Koagulationskinetik kolloider Lösungen. Z. Physik. Chem. 92, 129.

SOUCEK J. and SINDELAR J., 1967: The use of a dimensionless criterion in the characterization of flocculation. VUV Praha, Prace a Studie, sesit 112.

SPICER P.T. and PRATSINIS S.E., 1996: Shear induced flocculation: The evaluation of floc structure and the shape of the size distribution at the steady size. Wat. Res., 30, 1049-1056.

SWIFT D.L. and FRIEDLANDER S.K., 1965: The coagulation of hydrosols by Brownian motion and laminar shear flow. J. Colloid Sci., 20, 1070.

TAMBO N. and WATANABE Y., 1979: Physical aspects of flocculation process. I. Fundamental treatise. Wat. Res., 13, 429-439.

THOMAS D.N., JUDD S.J. and FAWCETT N., 1999: Flocculation modelling: A review. Wat. Res. Vol. 33, No. 7, pp. 1579-1592.

VAN DUUREN F.A., 1997: Water Purification Works Design. Publ. TT 92/97, WRC Pretoria, RSA.

WALKER J.D., 1968: High energy flocculation and air-and-water backwashing. JAWWA, 60, 321.

Journal of Hydrology and Hydromechanics

The Journal of Institute of Hydrology SAS Bratislava and Institute of Hydrodynamics CAS Prague

Journal Information

IMPACT FACTOR 2017: 1.714
5-year IMPACT FACTOR: 1.639

CiteScore 2017: 1.91

SCImago Journal Rank (SJR) 2017: 0.599
Source Normalized Impact per Paper (SNIP) 2017: 1.084


All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 98 98 8
PDF Downloads 37 37 3