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Phosphorus Removal Equations

Environmental Engineering · FE Reference Handbook section

Environmental Engineering
0 formulas
10 exam-style examples
~45 min
All Environmental Engineering lectures

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

This section is conceptual; there are no equations to memorise.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Phosphorus Removal Equations — solve for metal salt dose mass — Phosphorus Removal Equations

phosphorus removal chemical dose calculation using metal to phosphorus ratio Given metal to phosphorus molar ratio (MeP) = 1.6000; phosphorus mass to remove (M_P) = 44.0000 kg/day, determine the metal salt dose mass (M_Me) in kg/day.

Given

  • metaltophosphorusmolarratio(MeP)=1.6000metal to phosphorus molar ratio (MeP) = 1.6000
  • phosphorusmasstoremove(MP)=44.0000kg/dayphosphorus mass to remove (M_P) = 44.0000 kg/day

Find

metal salt dose mass (M_Me), in kg/day

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except M_Me is given, so isolate M_Me symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for M_Me:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  3. Step 3 — List the givens: metal to phosphorus molar ratio (MeP) = 1.6000, phosphorus mass to remove (M_P) = 44.0000 kg/day.

  4. Step 4 — Substitute the given values:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  5. Step 5 — Evaluate:

    MMe=70.4000 kg/dayM_{Me} = 70.4000\ \text{kg/day}
  6. Step 6 — Check: returning M_Me = 70.4000 kg/day to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MMe=70.4000 kg/dayM_{Me} = 70.4000\ \text{kg/day}

Why the other options are there

  • 140.8 — kept a factor of two that cancels in the correct rearrangement.
  • 35.2000 — dropped that same factor in the other direction.
  • 77.4400 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 2
Phosphorus Removal Equations — solve for phosphorus mass to remove — Phosphorus Removal Equations (2)

phosphorus removal equations for alum dosing at a treatment plant Given metal to phosphorus molar ratio (MeP) = 1.7000; metal salt dose mass (M_Me) = 971.0 kg/day, determine the phosphorus mass to remove (M_P) in kg/day.

Given

  • metaltophosphorusmolarratio(MeP)=1.7000metal to phosphorus molar ratio (MeP) = 1.7000
  • metalsaltdosemass(MMe)=971.0kg/daymetal salt dose mass (M_Me) = 971.0 kg/day

Find

phosphorus mass to remove (M_P), in kg/day

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except M_P is given, so isolate M_P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for M_P:

    MP=MMeMe/PM_{P} = \dfrac{M_{Me}}{Me/P}
  3. Step 3 — List the givens: metal to phosphorus molar ratio (MeP) = 1.7000, metal salt dose mass (M_Me) = 971.0 kg/day.

  4. Step 4 — Substitute the given values:

    MP=971.0Me/PM_{P} = \dfrac{971.0}{Me/P}
  5. Step 5 — Evaluate:

    MP=571.2 kg/dayM_{P} = 571.2\ \text{kg/day}
  6. Step 6 — Check: returning M_P = 571.2 kg/day to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MP=571.2 kg/dayM_{P} = 571.2\ \text{kg/day}

Why the other options are there

  • 1,142 — kept a factor of two that cancels in the correct rearrangement.
  • 285.6 — dropped that same factor in the other direction.
  • 628.3 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 3
Phosphorus Removal Equations — solve for metal to phosphorus molar ratio — Phosphorus Removal Equations (3)

phosphorus removal via chemical precipitation dose determination Given phosphorus mass to remove (M_P) = 155.0 kg/day; metal salt dose mass (M_Me) = 605.0 kg/day, determine the metal to phosphorus molar ratio (MeP).

Given

  • phosphorusmasstoremove(MP)=155.0kg/dayphosphorus mass to remove (M_P) = 155.0 kg/day
  • metalsaltdosemass(MMe)=605.0kg/daymetal salt dose mass (M_Me) = 605.0 kg/day

Find

metal to phosphorus molar ratio (MeP)

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except MeP is given, so isolate MeP symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for MeP:

    MeP=MMeMPMeP = \dfrac{M_{Me}}{M_P}
  3. Step 3 — List the givens: phosphorus mass to remove (M_P) = 155.0 kg/day, metal salt dose mass (M_Me) = 605.0 kg/day.

  4. Step 4 — Substitute the given values:

    MeP=605.0MPMeP = \dfrac{605.0}{M_P}
  5. Step 5 — Evaluate:

    MeP=3.9032MeP = 3.9032
  6. Step 6 — Check: returning MeP = 3.9032 to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MeP=3.9032MeP = 3.9032

Why the other options are there

  • 7.8065 — kept a factor of two that cancels in the correct rearrangement.
  • 1.9516 — dropped that same factor in the other direction.
  • 4.2935 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 4
Phosphorus Removal Equations — solve for metal salt dose mass (case 2) — Phosphorus Removal Equations (4)

phosphorus removal chemical dose calculation using metal to phosphorus ratio Given metal to phosphorus molar ratio (MeP) = 1.5500; phosphorus mass to remove (M_P) = 100.0 kg/day, determine the metal salt dose mass (M_Me) in kg/day.

Given

  • metaltophosphorusmolarratio(MeP)=1.5500metal to phosphorus molar ratio (MeP) = 1.5500
  • phosphorusmasstoremove(MP)=100.0kg/dayphosphorus mass to remove (M_P) = 100.0 kg/day

Find

metal salt dose mass (M_Me), in kg/day

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except M_Me is given, so isolate M_Me symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for M_Me:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  3. Step 3 — List the givens: metal to phosphorus molar ratio (MeP) = 1.5500, phosphorus mass to remove (M_P) = 100.0 kg/day.

  4. Step 4 — Substitute the given values:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  5. Step 5 — Evaluate:

    MMe=155.0 kg/dayM_{Me} = 155.0\ \text{kg/day}
  6. Step 6 — Check: returning M_Me = 155.0 kg/day to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MMe=155.0 kg/dayM_{Me} = 155.0\ \text{kg/day}

Why the other options are there

  • 310.0 — kept a factor of two that cancels in the correct rearrangement.
  • 77.5000 — dropped that same factor in the other direction.
  • 170.5 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 5
Phosphorus Removal Equations — solve for phosphorus mass to remove (case 2) — Phosphorus Removal Equations (5)

phosphorus removal equations for alum dosing at a treatment plant Given metal to phosphorus molar ratio (MeP) = 2.7000; metal salt dose mass (M_Me) = 448.0 kg/day, determine the phosphorus mass to remove (M_P) in kg/day.

Given

  • metaltophosphorusmolarratio(MeP)=2.7000metal to phosphorus molar ratio (MeP) = 2.7000
  • metalsaltdosemass(MMe)=448.0kg/daymetal salt dose mass (M_Me) = 448.0 kg/day

Find

phosphorus mass to remove (M_P), in kg/day

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except M_P is given, so isolate M_P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for M_P:

    MP=MMeMe/PM_{P} = \dfrac{M_{Me}}{Me/P}
  3. Step 3 — List the givens: metal to phosphorus molar ratio (MeP) = 2.7000, metal salt dose mass (M_Me) = 448.0 kg/day.

  4. Step 4 — Substitute the given values:

    MP=448.0Me/PM_{P} = \dfrac{448.0}{Me/P}
  5. Step 5 — Evaluate:

    MP=165.9 kg/dayM_{P} = 165.9\ \text{kg/day}
  6. Step 6 — Check: returning M_P = 165.9 kg/day to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MP=165.9 kg/dayM_{P} = 165.9\ \text{kg/day}

Why the other options are there

  • 331.9 — kept a factor of two that cancels in the correct rearrangement.
  • 82.9630 — dropped that same factor in the other direction.
  • 182.5 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 6
Phosphorus Removal Equations — solve for metal to phosphorus molar ratio (case 2) — Phosphorus Removal Equations (6)

phosphorus removal via chemical precipitation dose determination Given phosphorus mass to remove (M_P) = 355.0 kg/day; metal salt dose mass (M_Me) = 608.0 kg/day, determine the metal to phosphorus molar ratio (MeP).

Given

  • phosphorusmasstoremove(MP)=355.0kg/dayphosphorus mass to remove (M_P) = 355.0 kg/day
  • metalsaltdosemass(MMe)=608.0kg/daymetal salt dose mass (M_Me) = 608.0 kg/day

Find

metal to phosphorus molar ratio (MeP)

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except MeP is given, so isolate MeP symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for MeP:

    MeP=MMeMPMeP = \dfrac{M_{Me}}{M_P}
  3. Step 3 — List the givens: phosphorus mass to remove (M_P) = 355.0 kg/day, metal salt dose mass (M_Me) = 608.0 kg/day.

  4. Step 4 — Substitute the given values:

    MeP=608.0MPMeP = \dfrac{608.0}{M_P}
  5. Step 5 — Evaluate:

    MeP=1.7127MeP = 1.7127
  6. Step 6 — Check: returning MeP = 1.7127 to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MeP=1.7127MeP = 1.7127

Why the other options are there

  • 3.4254 — kept a factor of two that cancels in the correct rearrangement.
  • 0.8563 — dropped that same factor in the other direction.
  • 1.8839 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 7
Phosphorus Removal Equations — solve for metal salt dose mass (case 3) — Phosphorus Removal Equations (7)

phosphorus removal chemical dose calculation using metal to phosphorus ratio Given metal to phosphorus molar ratio (MeP) = 1.9500; phosphorus mass to remove (M_P) = 121.0 kg/day, determine the metal salt dose mass (M_Me) in kg/day.

Given

  • metaltophosphorusmolarratio(MeP)=1.9500metal to phosphorus molar ratio (MeP) = 1.9500
  • phosphorusmasstoremove(MP)=121.0kg/dayphosphorus mass to remove (M_P) = 121.0 kg/day

Find

metal salt dose mass (M_Me), in kg/day

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except M_Me is given, so isolate M_Me symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for M_Me:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  3. Step 3 — List the givens: metal to phosphorus molar ratio (MeP) = 1.9500, phosphorus mass to remove (M_P) = 121.0 kg/day.

  4. Step 4 — Substitute the given values:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  5. Step 5 — Evaluate:

    MMe=236.0 kg/dayM_{Me} = 236.0\ \text{kg/day}
  6. Step 6 — Check: returning M_Me = 236.0 kg/day to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MMe=236.0 kg/dayM_{Me} = 236.0\ \text{kg/day}

Why the other options are there

  • 471.9 — kept a factor of two that cancels in the correct rearrangement.
  • 118.0 — dropped that same factor in the other direction.
  • 259.5 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 8
Phosphorus Removal Equations — solve for phosphorus mass to remove (case 3) — Phosphorus Removal Equations (8)

phosphorus removal equations for alum dosing at a treatment plant Given metal to phosphorus molar ratio (MeP) = 1.9000; metal salt dose mass (M_Me) = 218.0 kg/day, determine the phosphorus mass to remove (M_P) in kg/day.

Given

  • metaltophosphorusmolarratio(MeP)=1.9000metal to phosphorus molar ratio (MeP) = 1.9000
  • metalsaltdosemass(MMe)=218.0kg/daymetal salt dose mass (M_Me) = 218.0 kg/day

Find

phosphorus mass to remove (M_P), in kg/day

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except M_P is given, so isolate M_P symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for M_P:

    MP=MMeMe/PM_{P} = \dfrac{M_{Me}}{Me/P}
  3. Step 3 — List the givens: metal to phosphorus molar ratio (MeP) = 1.9000, metal salt dose mass (M_Me) = 218.0 kg/day.

  4. Step 4 — Substitute the given values:

    MP=218.0Me/PM_{P} = \dfrac{218.0}{Me/P}
  5. Step 5 — Evaluate:

    MP=114.7 kg/dayM_{P} = 114.7\ \text{kg/day}
  6. Step 6 — Check: returning M_P = 114.7 kg/day to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MP=114.7 kg/dayM_{P} = 114.7\ \text{kg/day}

Why the other options are there

  • 229.5 — kept a factor of two that cancels in the correct rearrangement.
  • 57.3684 — dropped that same factor in the other direction.
  • 126.2 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 9
Phosphorus Removal Equations — solve for metal to phosphorus molar ratio (case 3) — Phosphorus Removal Equations (9)

phosphorus removal via chemical precipitation dose determination Given phosphorus mass to remove (M_P) = 353.0 kg/day; metal salt dose mass (M_Me) = 120.0 kg/day, determine the metal to phosphorus molar ratio (MeP).

Given

  • phosphorusmasstoremove(MP)=353.0kg/dayphosphorus mass to remove (M_P) = 353.0 kg/day
  • metalsaltdosemass(MMe)=120.0kg/daymetal salt dose mass (M_Me) = 120.0 kg/day

Find

metal to phosphorus molar ratio (MeP)

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except MeP is given, so isolate MeP symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for MeP:

    MeP=MMeMPMeP = \dfrac{M_{Me}}{M_P}
  3. Step 3 — List the givens: phosphorus mass to remove (M_P) = 353.0 kg/day, metal salt dose mass (M_Me) = 120.0 kg/day.

  4. Step 4 — Substitute the given values:

    MeP=120.0MPMeP = \dfrac{120.0}{M_P}
  5. Step 5 — Evaluate:

    MeP=0.3399MeP = 0.3399
  6. Step 6 — Check: returning MeP = 0.3399 to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MeP=0.3399MeP = 0.3399

Why the other options are there

  • 0.6799 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1700 — dropped that same factor in the other direction.
  • 0.3739 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

Example 10
Phosphorus Removal Equations — solve for metal salt dose mass (case 4) — Phosphorus Removal Equations (10)

phosphorus removal chemical dose calculation using metal to phosphorus ratio Given metal to phosphorus molar ratio (MeP) = 1.4500; phosphorus mass to remove (M_P) = 285.0 kg/day, determine the metal salt dose mass (M_Me) in kg/day.

Given

  • metaltophosphorusmolarratio(MeP)=1.4500metal to phosphorus molar ratio (MeP) = 1.4500
  • phosphorusmasstoremove(MP)=285.0kg/dayphosphorus mass to remove (M_P) = 285.0 kg/day

Find

metal salt dose mass (M_Me), in kg/day

Start with the thinking

  • The governing relation printed in this handbook section is Phosphorus Removal Equations.
  • Everything except M_Me is given, so isolate M_Me symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Phosphorus removal equations determine the metal salt dose needed for chemical precipitation of phosphorus.

Step-by-step solution

  1. Step 1 — State the governing relation:

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P
  2. Step 2 — Rearrange symbolically for M_Me:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  3. Step 3 — List the givens: metal to phosphorus molar ratio (MeP) = 1.4500, phosphorus mass to remove (M_P) = 285.0 kg/day.

  4. Step 4 — Substitute the given values:

    MMe=(MeP)MPM_{Me} = \left(\dfrac{Me}{P}\right)M_P
  5. Step 5 — Evaluate:

    MMe=413.3 kg/dayM_{Me} = 413.3\ \text{kg/day}
  6. Step 6 — Check: returning M_Me = 413.3 kg/day to

    MMe=MeP×MPM_{Me} = \dfrac{Me}{P} \times M_P

    reproduces the given quantities, and both sides carry the same units.

Answer:
MMe=413.3 kg/dayM_{Me} = 413.3\ \text{kg/day}

Why the other options are there

  • 826.5 — kept a factor of two that cancels in the correct rearrangement.
  • 206.6 — dropped that same factor in the other direction.
  • 454.6 — rounded an intermediate value before the final step.

Reference: FE Handbook — Phosphorus Removal Equations

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