solvedose_ph: Calculate a desired chemical dose for a target pH

In tidywater: Water Quality Models for Drinking Water Treatment Processes

Calculate a desired chemical dose for a target pH

Description

Calculates the required amount of a chemical to dose based on a target pH and existing water quality. The function takes an object of class "water", and user-specified chemical and target pH and returns a numeric value for the required dose in mg/L. For a single water, use solvedose_ph; to apply the model to a dataframe, use solvedose_ph_once. For most arguments, the ⁠_once⁠ helper "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

solvedose_ph(water, target_ph, chemical)

solvedose_ph_once(
  df,
  input_water = "defined_water",
  output_column = "dose_required",
  target_ph = "use_col",
  chemical = "use_col"
)

Arguments

water	Source water of class "water" created by define_water
target_ph	The final pH to be achieved after the specified chemical is added.
chemical	The chemical to be added. Current supported chemicals include: acids: "hcl", "h2so4", "h3po4", "co2"; bases: "naoh", "na2co3", "nahco3", "caoh2", "mgoh2"
df	a data frame containing a water class column, which has already been computed using define_water_chain. The df may include a column with names for each of the chemicals being dosed.
input_water	name of the column of water class data to be used as the input. Default is "defined_water".
output_column	name of the output column storing doses in mg/L. Default is "dose_required".

Details

solvedose_ph uses stats::uniroot() on chemdose_ph to match the required dose for the requested pH target.

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

A numeric value for the required chemical dose.

solvedose_ph_once returns a data frame containing the original data frame and columns for target pH, chemical dosed, and required chemical dose.

See Also

chemdose_ph, solvedose_alk

Examples

water <- define_water(ph = 7, temp = 25, alk = 10)

# Calculate required dose of lime to reach pH 8
solvedose_ph(water, target_ph = 8, chemical = "caoh2")


example_df <- water_df %>%
  define_water_chain() %>%
  solvedose_ph_once(input_water = "defined_water", target_ph = 8.8, chemical = "naoh")


# Initialize parallel processing
library(dplyr)
library(furrr)
#  plan(multisession, workers = 2) # Remove the workers argument to use all available compute
example_df <- water_df %>%
  define_water_chain() %>%
  mutate(finpH = seq(9, 10.1, .1)) %>%
  solvedose_ph_once(chemical = "naoh", target_ph = finpH)

# Optional: explicitly close multisession processing
#  plan(sequential)

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