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Bioremediation Calculator

Calculate nutrient dosing for enhanced bioremediation using the C:N:P ratio of 100:10:1.

About this calculator

This calculator sizes nitrogen and phosphorus fertilizer dosing for enhanced bioremediation, a common in-situ or ex-situ treatment technique that adds nutrients to stimulate the native soil microbes that break down petroleum and other organic contaminants. It starts from the treatment zone's physical dimensions (length, width, depth) and soil bulk density to get total soil mass, then applies contaminant concentration and the estimated carbon fraction of the contaminant to determine total carbon mass available for microbial metabolism -- diesel is roughly 87% carbon by mass, benzene about 92%, and PAHs about 90%, so this fraction varies meaningfully by contaminant type. Nutrient requirements follow the standard C:N:P ratio of 100:10:1 used broadly in bioremediation practice, meaning microbes need roughly one part nitrogen and one-tenth part phosphorus for every ten parts carbon they metabolize.

Because soil volume feeds directly into soil mass, contaminant mass, and every downstream nutrient calculation, the physical treatment-zone dimensions (length, width, depth) and bulk density are the only inputs that move soil volume and soil mass at all -- contaminant concentration, carbon fraction, and fertilizer grades have zero effect on those two outputs, since they only enter the calculation after soil mass is already established. The fertilizer product mass outputs convert elemental nutrient requirements into purchasable product quantities using your entered fertilizer grade -- a higher-grade nitrogen fertilizer like urea (46% N) requires proportionally less product mass to deliver the same elemental nitrogen than a lower-grade product like ammonium nitrate (34% N).

Inputs

ft
ft
ft
%
%

Results

Contaminant mass (kg)

900

Nitrogen required (kg N)

72

N fertilizer product (kg)

156.52

Soil volume (m³)1,200
Soil mass (tonnes)1,800
Phosphorus required (kg P)7.2
P fertilizer product (kg)36
N fertilizer rate (kg/m²)0.26
P fertilizer rate (kg/m²)0.06
How to Use This Calculator
  1. Enter the treatment area dimensions (length, width, depth in meters) to define the contaminated zone.
  2. Set the soil bulk density (default 1.5 t/m³) and contaminant concentration in mg/kg.
  3. Enter the carbon fraction of your contaminant (diesel ~0.87, PAHs ~0.9) to size nutrient demand.
  4. Input your fertilizer grades (%N and %P) to convert nutrient needs into product quantities.
  5. Review soil volume, contaminant mass, and fertilizer application rates (kg/m²) to plan amendments.

How the result changes with Treatment area length (m)

Treatment area length (m)Contaminant mass (kg)Nitrogen required (kg N)N fertilizer product (kg)
154503678.26
2369055.2120
451,350108234.78
752,250180391.3

What each input means

Treatment area length (m)
Length of the contaminated zone in meters.
Treatment area width (m)
Width of the contaminated zone in meters.
Treatment depth (m)
Depth of contaminated soil to be treated.
Soil bulk density (t/m³)
Dry bulk density of soil. Sand ~1.6, clay ~1.3, loam ~1.4 t/m³.
Contaminant concentration (mg/kg)
Average contaminant concentration in soil (ppm).
Carbon fraction of contaminant
Fraction of the contaminant mass that is carbon. Diesel ~0.87, benzene ~0.92, PAHs ~0.9.
N fertilizer grade (%N)
Nitrogen content of fertilizer product. Urea = 46%, ammonium nitrate = 34%.
P fertilizer grade (%P)
Elemental phosphorus (P) content, not P2O5. Triple superphosphate is ~20% elemental P even though bags are typically labeled 0-46-0 (46% P2O5) -- don't enter 46 here.

What each result means

Soil volume (m³)
Total volume of soil in the treatment zone.
Soil mass (tonnes)
Total mass of soil to be treated.
Contaminant mass (kg)
Total mass of contaminant in the treatment zone.
Nitrogen required (kg N)
Elemental nitrogen needed based on C:N = 10:1 ratio.
Phosphorus required (kg P)
Elemental phosphorus needed based on C:P = 100:1 ratio.
N fertilizer product (kg)
Mass of nitrogen fertilizer product to purchase.
P fertilizer product (kg)
Mass of phosphorus fertilizer product to purchase.
N fertilizer rate (kg/m²)
Nitrogen fertilizer application rate per square meter of treatment area.
P fertilizer rate (kg/m²)
Phosphorus fertilizer application rate per square meter.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    8 parameters
    Treatment area length (m) = 30, Treatment area width (m) = 20, Treatment depth (m) = 2, Soil bulk density (t/m³) = 1.5, Contaminant concentration (mg/kg) = 500, Carbon fraction of contaminant = 0.8, N fertilizer grade (%N) = 46, P fertilizer grade (%P) = 20 = 8 input(s) provided
  2. Calculate Contaminant mass
    Contaminant mass = soilMass * contaminantConc * 1e-3
    900 = 900
  3. Calculate Nitrogen required
    Nitrogen required = carbonMass * 0.1
    72 = 72
  4. Calculate N fertilizer product
    N fertilizer product = nitrogenRequired / (nFertilizerPct / 100)
    156.52 = 156.52
  5. Calculate Soil volume
    Soil volume = length * width * depth
    1200 = 1200
  6. Calculate Soil mass
    Soil mass = soilVolume * bulkDensity
    1800 = 1800

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Why doesn't contaminant concentration affect soil volume or soil mass?

Soil volume is calculated purely from treatment area length, width, and depth, and soil mass simply multiplies that volume by bulk density -- neither calculation involves contaminant concentration at all. Contaminant concentration only enters the calculation afterward, when soil mass is multiplied by the concentration to determine contaminant mass, which is the starting point for the nutrient dosing calculations further downstream.

Why does a higher-grade nitrogen fertilizer require less product mass for the same treatment?

The calculator converts elemental nitrogen requirement into fertilizer product mass by dividing by the fertilizer's nitrogen percentage, so a higher-grade product like urea (46% N) delivers the required elemental nitrogen with proportionally less total product mass than a lower-grade product like ammonium nitrate (34% N). This is a straightforward concentration effect: a 46%-N product is roughly 35% more nitrogen-dense than a 34%-N product, so you need correspondingly less of it by weight.

What is the C:N:P ratio of 100:10:1 and where does it come from?

The 100:10:1 ratio is a commonly cited rule of thumb in bioremediation practice describing the approximate proportions of carbon, nitrogen, and phosphorus that soil microbes need to efficiently metabolize organic contaminants -- roughly ten parts carbon for every one part nitrogen, and about ten parts nitrogen for every one part phosphorus. It's a starting point for nutrient amendment planning rather than a universal constant; site-specific factors like existing soil nutrient levels and the specific microbial community present can shift the optimal ratio somewhat.

Why does carbon fraction matter so much for sizing nitrogen dosing?

Carbon fraction determines how much of the total contaminant mass actually counts as the carbon substrate microbes will metabolize, and nitrogen requirement is calculated directly from that carbon mass using the C:N ratio. A contaminant with a higher carbon fraction (like benzene at roughly 92%) requires proportionally more nitrogen dosing per unit of contaminant mass than one with a lower carbon fraction, so using an accurate carbon fraction for your specific contaminant matters for getting the nutrient dose right.

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