ENV-48

Hardness as CaCO3

Equivalent CaCO3 hardness.

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GoverningHardness as CaCO3

Governing equation

H=2.5\\,[Ca]+4.1\\,[Mg]

where

Ca: Ca (mg/L)
Mg: Mg (mg/L)
H: Hardness as CaCO3 (mg/L)

Lecture brief

Historical brief

Streeter–Phelps (1925) oxygen sag, settling theory and Guldberg–Waage kinetics made water and air quality a rate problem. The lab computes sag, overflow and a snapshot of reactor mass balance. This sheet (ENV-48 — Hardness as CaCO3) is the form associated with Hardness as CaCO3. Working symbols: $Ca$ , $Mg$ $\rightarrow$ $H$ . Equivalent CaCO3 hardness. Pedagogical SI sheet with a live model and a swept parameter.

Purpose

Purpose: compute

H

from

Ca

Mg

in Environmental via

H=2.5\\,[Ca]+4.1\\,[Mg]

Equivalent CaCO3 hardness. Use it when a real environmental question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

Ca = 40.000\,\mathrm{mg/L}

Mg = 12.000\,\mathrm{mg/L}

, the governing relation

H=2.5\\,[Ca]+4.1\\,[Mg]

yields

H = 149.200\,\mathrm{mg/L}

. One governing identity, SI units, a single sweep on the sheet. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Ca Ca40 mg/LMg Mg12 mg/L

Outputs

Hardness as CaCO3 H149.200 mg/L

Reading speed

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Narration of this film

One governing identity, SI units, a single sweep on the sheet.

Equivalent CaCO3 hardness. Pedagogical SI sheet with a live model and a swept parameter.

Reading speed

Watch on YouTube