coagulate {edwards97}

Low-level langmuir coagulation calculations

Description

The Edwards (1997) model is a Langmuir-based semiempirical model designed to predict OC removal during alum coagulation. The model is on a non-linear function derived from physical relationships, primarily the process of Langmuir sorptive removal (Tipping 1981, Jekyl 1986).

Usage

coagulate(data, coefs)

coagulate_base(DOC, dose, pH, UV254, K1, K2, x1, x2, x3, b, root = -1)

Arguments

data

A data frame containing columns DOC, dose, pH, and UV254.

coefs

The output of edwards_coefs() or a similar named vector containing elements K1, K2, x1, x2, x3, b and root.

DOC

The initial DOC concentration (mg/L).

dose

The coagulant metal concentration (Al3+ or Fe3+) in mmol/L.

pH

The pH of coagulation.

UV254

The absorbance of UV254 (1/cm). With DOC, used to calculate SUVA.

K1, K2

Empirical fitting coefficients relating to SUVA.

x1, x2, x3

Empirical fitting coefficients relating to pH.

b

The Langmuir term.

root

The solution to the equation presented in Edwards (1997) is a quadratic with two roots. root can be 1 or -1 to account for these roots, however we see no evidence that anything except -1 here results in realistic predictions.

Value

A vector of predicted organic carbon concentrations (in mg/L) following coagulation.

References

Edwards, M. 1997. Predicting DOC removal during enhanced coagulation. Journal - American Water Works Association, 89: 78–89. https://doi.org/10.1002/j.1551-8833.1997.tb08229.x

Jekel, M.R. 1986. Interactions of humic acids and aluminum salts in the flocculation process. Water Research, 20: 1535-1542. https://doi.org/10.1016/0043-1354(86)90118-1

Tipping, E. 1981. The adsorption of aquatic humic substances by iron oxides. Geochimica et Cosmochimica Acta, 45: 191-199. https://doi.org/10.1016/0016-7037(81)90162-9

Examples

alum_jar_tests <- edwards_data("Al")
alum_jar_tests$DOC_final_model <- coagulate(alum_jar_tests, edwards_coefs("Al"))
plot(DOC_final_model ~ DOC_final, data = alum_jar_tests)