Water info

Daily Water Usage

As explained by The US Geological survey, the average person uses about 80-100 gallons of water per day for indoor home use[1]. Enter the number of people in the box bellow and the total water usage will appear next to it.


Saltyness of Ocean Water

The concentdation of salt in seawater in about 35 parts per throusand, 35 grams per liter or 3.5%[2]. When converted to milligrams per liter the number becomes 35,000 mg per liter. This number is far beyond the safe limit for drinking, agriculture, or livestock. The safe level of salinity for irrigation is 360 mg/L and the safe level for livestock is shown in the cahrt bellow[3].The goal of this electdodialysis solution is to find the parameters that give both eanough water for a population and enough of the salt removed to be used for the three uses mentioned above.

Ocean water breakdown

Safe Levels

Salinity levels for human consumption

Salinity (mg/L) Quality
0-600 Good
600-900 Fair
900-1,200 Poor
>1,200 Unappeptable (unpalatable)

Salinity levels for livestock

Animal recomended salinity for drinking
poultdy 2,000 mg/L
dairy cattle 2,400 mg/L
4,000 mg/L beef cattle, sheep and horses

Info for both tables comes from The EPA page listed bellow [3]

Break down of ocean water

Reference Composition name $$ mmol kg^{-1} $$ $$ mg kg^{-1} $$
$$ Na^{+} $$ Sodium 468.9675 10781.45
$$ Mg^{2+} $$ Magnesium 52.8170 1283.72
$$ Ca^{2+} $$ Calcium 10.2820 412.08
$$ k^{+} $$ Potassium 10.2077 399.10
$$ Sr^{2+} $$ Strontuim 0.0907 7.94
$$ Cl^{-} $$ Chloride 545.8695 19352.71
$$ SO_4^{2-} $$ Sulfate 28.2353 2712.35
$$ HCO_3^{-} $$ Bicarbonate 1.7178 104.81
$$ Br^{-} $$ Bromide 0.8421 67.29
$$ B(OH)_3 $$ Boric acid 0.3143 19.43
$$ CO_3^{2-} $$ Carbonate 0.2389 14.34
$$ B(OH)_4^- $$ Tetrahydroxyborate 0.1008 7.94
$$ F^- $$ Fluoride 0.0683 1.30
$$ CO_2 $$ Carbon dioxide 0.0097 0.43
$$ OH^- $$ Hydroxide 0.0080 0.14

Info for this chart comes from Electrical Properties of Sea Water: Theory and Applications [5]

Calculations

Diagram


Formulas


Comercial cation exchange membranes
Membrane Company Thickness (mm) Area resistance $$ ( \Omega cm^2) $$
CMV Asahi Glass 0.13 - 0.15 2.0 - 3.5
MC-3470 Ionac 0.34 5
CM-1 Tokuyama 0.15 - 0.17 2.2 - 3.0
CMX Tokuyama 0.17 - 0.19 2.5 - 3.5
CMS Tokuyama 0.14 - 0.17 1.5 - 2.5
CMB Tokuyama 0.18 - 0.24 4.0 - 5.0
R1010 PALL 0.04 0.3
R4010 PALL 0.07 0.6
RA4010 PALL 0.64 2.0
CDS Solvay 0.16 1.1 - 1.8
CRA Solvay 0.16 1.3 - 3

Comercial anion exchange membranes
Membrane Company Thickness (mm) Area resistance $$ ( \Omega cm^2) $$
AMV Asahi Glass 0.11 - 0.15 1.5 - 3.0
ASV Asahi Glass 0.11 - 0.15 2.3 - 3.5
AM-1 Tokuyama 0.13 - 0.16 1.3 - 2.0
AMX Tokuyama 0.16 - 0.18 2.5 - 3.5
ACS Tokuyama 0.15 - 2.0 2.0 - 2.5
AFN Tokuyama 0.15 - 0.20 0.4 - 1.5
AHA Tokuyama 0.18 - 0.24 8.0 - 14.0
R1030 PALL 0.04 1.0
R4030 PALL 0.07 1.7
ADP Solvay 0.16 1.8 - 3.5

Select your membrane

Cation exchange membrane

Anion exchange membrane

Calculations

Symbol Name Input unit
$$ C_s^{fd} $$ Input water salinity $$ K_{eq} \over {m^3} $$
$$ F $$ Faraday's constant $$ 9.65 x 10^4 $$ $$ C/mol $$
$$ U $$ Applied voltage $$ V $$
$$ N $$ Number of cell pairs NULL
$$ \Delta $$ Thickness of unit cell m
$$ Q $$ Production rate $$ m^3 \over day $$
$$ dA_{eff} $$ Membrane effecive area $$ m^2 $$
$$ \rho_c $$ cation membrane area resistance Select membrane to get value $$ ( \Omega cm^2) $$
$$ \rho_a $$ anion membrane area resistance Select membrane to get value $$ ( \Omega cm^2) $$
$$ \zeta $$ current utilization NULL

Output

Name Number Unit
Input salinity $$ K_{eq} \over {m^3} $$
Degree of desalination $$ K_{eq} \over {m^3} $$
Output salinity $$ K_{eq} \over {m^3} $$

Sources

  1. USGS: How much water do I use at home each day?
  2. USGS: Why is the Ocean Salty?
  3. EPA : Environmental Info Threats
  4. Designing of an electdodialysis desalination plant
  5. Electdical Properties of Sea Water: Theory and Applications