chemdose_ph function

Calculate new pH and ion balance after chemical addition

chemdose_ph calculates the new pH, alkalinity, and ion balance of a water based on different chemical additions.

chemdose_ph(
  water,
  hcl = 0,
  h2so4 = 0,
  h3po4 = 0,
  co2 = 0,
  naoh = 0,
  caoh2 = 0,
  mgoh2 = 0,
  na2co3 = 0,
  nahco3 = 0,
  caco3 = 0,
  cacl2 = 0,
  cl2 = 0,
  naocl = 0,
  nh4oh = 0,
  nh42so4 = 0,
  alum = 0,
  ferricchloride = 0,
  ferricsulfate = 0,
  ach = 0,
  softening_correction = FALSE
)

Arguments

• water: Source water object of class "water" created by define_water
• hcl: Amount of hydrochloric acid added in mg/L: HCl -> H + Cl
• h2so4: Amount of sulfuric acid added in mg/L: H2SO4 -> 2H + SO4
• h3po4: Amount of phosphoric acid added in mg/L: H3PO4 -> 3H + PO4
• co2: Amount of carbon dioxide added in mg/L: CO2 (gas) + H2O -> H2CO3*
• naoh: Amount of caustic added in mg/L: NaOH -> Na + OH
• caoh2: Amount of lime added in mg/L: Ca(OH)2 -> Ca + 2OH
• mgoh2: Amount of magneisum hydroxide added in mg/L: Mg(OH)2 -> Mg + 2OH
• na2co3: Amount of soda ash added in mg/L: Na2CO3 -> 2Na + CO3
• nahco3: Amount of sodium bicarbonate added in mg/L: NaHCO3 -> Na + H + CO3
• caco3: Amount of calcium carbonate added (or removed) in mg/L: CaCO3 -> Ca + CO3
• cacl2: Amount of calcium chloride added in mg/L: CaCl2 -> Ca2+ + 2Cl-
• cl2: Amount of chlorine gas added in mg/L as Cl2: Cl2(g) + H2O -> HOCl + H + Cl
• naocl: Amount of sodium hypochlorite added in mg/L as Cl2: NaOCl -> Na + OCl
• nh4oh: Amount of ammonium hydroxide added in mg/L as N: NH4OH -> NH4 + OH
• nh42so4: Amount of ammonium sulfate added in mg/L as N: (NH4)2SO4 -> 2NH4 + SO4
• alum: Amount of hydrated aluminum sulfate added in mg/L: Al2(SO4)3*14H2O + 6HCO3 -> 2Al(OH)3(am) +3SO4 + 14H2O + 6CO2
• ferricchloride: Amount of ferric Chloride added in mg/L: FeCl3 + 3HCO3 -> Fe(OH)3(am) + 3Cl + 3CO2
• ferricsulfate: Amount of ferric sulfate added in mg/L: Fe2(SO4)3*8.8H2O + 6HCO3 -> 2Fe(OH)3(am) + 3SO4 + 8.8H2O + 6CO2
• ach: Amount of aluminum chlorohydrate added in mg/L: Al2(OH)5Cl*2H2O + HCO3 -> 2Al(OH)3(am) + Cl + 2H2O + CO2
• softening_correction: Set to TRUE to correct post-softening pH (caco3 must be < 0). Default is FALSE. Based on WTP model equation 5-62

Returns

A water class object with updated pH, alkalinity, and ions post-chemical addition.

Details

The function takes an object of class "water" created by define_water and user-specified chemical additions and returns a new object of class "water" with updated water quality. Units of all chemical additions are in mg/L as chemical (not as product).

chemdose_ph works by evaluating all the user-specified chemical additions and solving for what the new pH must be using uniroot to satisfy the principle of electroneutrality in pure water while correcting for the existing alkalinity of the water that the chemical is added to. Multiple chemicals can be added simultaneously or each addition can be modeled independently through sequential doses.

Examples

water <- define_water(ph = 7, temp = 25, alk = 10)
# Dose 1 mg/L of hydrochloric acid
dosed_water <- chemdose_ph(water, hcl = 1)
dosed_water@ph

# Dose 1 mg/L of hydrochloric acid and 5 mg/L of alum simultaneously
dosed_water <- chemdose_ph(water, hcl = 1, alum = 5)
dosed_water@ph

# Dose 1 mg/L of hydrochloric acid and 5 mg/L of alum sequentially
dosed_water1 <- chemdose_ph(water, hcl = 1)
dosed_water1@ph
dosed_water2 <- chemdose_ph(dosed_water1, alum = 5)
dosed_water2@ph

# Softening:
water2 <- define_water(ph = 7, temp = 25, alk = 100, tot_hard = 350)
dosed_water1 <- chemdose_ph(water2, caco3 = -100)
dosed_water1@ph
dosed_water2 <- chemdose_ph(water2, caco3 = -100, softening_correction = TRUE)
dosed_water2@ph

See Also

define_water, convert_units