solvect_chlorine: Determine disinfection credit from chlorine.

In tidywater: Water Quality Models for Drinking Water Treatment Processes

Determine disinfection credit from chlorine.

Description

This function takes a water defined by define_water and other disinfection parameters and outputs a data frame of the required CT (ct_required), actual CT (ct_actual), and giardia log removal (glog_removal). For a single water, use solvect_chlorine; to apply the model to a dataframe, use solvect_chlorine_once. For most arguments, the ⁠_chain⁠ and ⁠_once⁠ helpers "use_col" default looks for a column of the same name in the dataframe. The argument can be specified directly in the function instead or an unquoted column name can be provided.

Usage

solvect_chlorine(water, time, residual, baffle, free_cl_slot = "residual_only")

solvect_chlorine_once(
  df,
  input_water = "defined_water",
  time = "use_col",
  residual = "use_col",
  baffle = "use_col",
  free_cl_slot = "residual_only",
  water_prefix = TRUE
)

Arguments

water	Source water object of class "water" created by define_water. Water must include ph and temp
time	Retention time of disinfection segment in minutes.
residual	Minimum chlorine residual in disinfection segment in mg/L as Cl2.
baffle	Baffle factor - unitless value between 0 and 1.
free_cl_slot	Defaults to "residual_only", which uses the residual argument. If "slot_only", the model will use the free_chlorine slot in the input water. "sum_with_residual", will use the sum of the residual argument and the free_chlorine slot.
df	a data frame containing a water class column, which has already been computed using define_water_chain
input_water	name of the column of Water class data to be used as the input for this function. Default is "defined_water".
water_prefix	name of the input water used for the calculation will be appended to the start of output columns. Default is TRUE.

Details

CT actual is a function of time, chlorine residual, and baffle factor, whereas CT required is a function of pH, temperature, chlorine residual, and the standard 0.5 log removal of giardia requirement. CT required is an empirical regression equation developed by Smith et al. (1995) to provide conservative estimates for CT tables in USEPA Disinfection Profiling Guidance. Log removal is a rearrangement of the CT equations.

For large datasets, using fn_once or fn_chain may take many minutes to run. These types of functions use the furrr package for the option to use parallel processing and speed things up. To initialize parallel processing, use plan(multisession) or plan(multicore) (depending on your operating system) prior to your piped code with the fn_once or fn_chain functions. Note, parallel processing is best used when your code block takes more than a minute to run, shorter run times will not benefit from parallel processing.

Value

solvect_chlorine returns a data frame containing required CT (mg/Lmin), actual CT (mg/Lmin), and giardia log removal.

solvect_chlorine_once returns a data frame containing the original data frame and columns for required CT, actual CT, and giardia log removal.

Source

Smith et al. (1995)

USEPA (2020)

See references list at: https://github.com/BrownandCaldwell-Public/tidywater/wiki/References

Examples

example_ct <- define_water(ph = 7.5, temp = 25) %>%
  solvect_chlorine(time = 30, residual = 1, baffle = 0.7)
library(dplyr)
ct_calc <- water_df %>%
  define_water_chain() %>%
  solvect_chlorine_once(residual = 2, time = 10, baffle = .5)

chlor_resid <- water_df %>%
  mutate(br = 50) %>%
  define_water_chain() %>%
  mutate(
    residual = seq(1, 12, 1),
    time = seq(2, 24, 2),
    baffle = 0.7
  ) %>%
  solvect_chlorine_once()

tidywater documentation built on Aug. 8, 2025, 7:15 p.m.