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Comparison of model approaches for predicting coliform removal in waste stabilization ponds
Author(s) -
Buchauer Konrad
Publication year - 2007
Publication title -
water and environment journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 37
eISSN - 1747-6593
pISSN - 1747-6585
DOI - 10.1111/j.1747-6593.2006.00055.x
Subject(s) - continuous stirred tank reactor , effluent , environmental science , fecal coliform , environmental engineering , continuous flow , flow (mathematics) , stabilization pond , hydraulic retention time , plug flow , volumetric flow rate , mathematics , chemistry , engineering , ecology , water quality , biochemical engineering , biology , physics , geometry , quantum mechanics , thermodynamics
This paper compares the two most frequently used approaches for the prediction of faecal coliforms in the effluent (FC e ) of waste stabilization ponds (WSPs): the continuous stirred reactor (CSTR) model and the dispersed flow (DF) model. On the basis of theoretical and practical analysis, it is concluded that, under most conditions usually found in practice, the DF model can be expected to predict unrealistically low FC e . This trend is more pronounced the more the flow conditions in the pond(s) approach plug flow, and the higher the average retention time per pond. Model differences in FC e prediction typically deviate from one another by up to 1–2 log units. This can lead to the design of substantially different pond sizes, with footprint differences between the two models of 30–50% not being exceptional. Consequently, on the basis of usually applied model parameters, for the time being it appears safer to use the CSTR model for FC e prediction in WSP systems.