Environmental & Water Calculators
Activated Sludge
SVI = SV · 1000 / MLSS
Sludge volume index, settling volume, and biomass parameters for activated-sludge treatment.
Calculate →Atmospheric Dispersion Model
C = (Q / (π·σy·σz·u)) · … (Gaussian plume)
Ground-level concentration from a point source via Gaussian plume model and stack height.
Calculate →Biochemical Oxygen Demand
BOD_t = BOD_u · (1 − e^(−k·t))
BOD exertion over time from ultimate BOD and deoxygenation rate constant.
Calculate →Cyclone
d_p* = √(9μW / (2π·N·v·(ρp − ρ)))
Cyclone cut diameter, pressure drop, radial velocity, and separation efficiency.
Design →Electrostatic Precipitator Design
η = 1 − exp(−w · A / Q) (Deutsch)
Particle collection efficiency from drift velocity, collection area, and gas flow rate.
Design →Flocculation
G = √(P / (μ · V))
Velocity gradient and power dissipated for water-treatment flocculation tanks.
Design →Ideal Reactor
θ = V / Q · C(t) (CMR / batch)
Residence time and concentration response for completely mixed reactors (pulse and step).
Calculate →Microorganism Disinfection
CT = C · t
Concentration-time product for water disinfection regulatory compliance.
Calculate →Microorganism Kinetics
μ = μmax · S / (Ks + S) (Monod)
Monod specific growth rate from substrate concentration and saturation constant.
Calculate →Mixing Design
P = K · μ · n² · D³ · Re_mix
Power, Reynolds number, and headloss for static, propeller, and pneumatic mixers.
Design →Permeameter
K = (Q · L) / (A · h)
Soil hydraulic conductivity from constant-head permeameter test.
Calculate →Rainwater Collection Design
V = A · P · runoff_coeff
Rainwater harvest volume from roof area, rainfall depth, and surface runoff coefficient.
Design →Reverse Osmosis Membrane Design
π = i · C · R · T (van't Hoff)
Osmotic pressure and salt rejection for reverse-osmosis membrane sizing.
Design →Solid Waste
DW = WW · (1 − MC) · landfill volume
Solid-waste dry weight, moisture content, and landfill storage volume.
Calculate →Swimming Pool Water Maintenance
Turnover = V / Q · water balance
Pool turnover time, filtration flow rate, and water balance equations.
Calculate →Threshold Odor Number
TON = (V_sample + V_dilution) / V_sample
Drinking-water threshold odor number from dilution ratios at first detectable odor.
Calculate →Trommel Screen
n_c = (1 / 2π) · √(g / r)
Trommel screen critical speed and drum radius for waste classification.
Design →Ultrafiltration Membrane Design
J = ΔP / (μ · (R_m + R_g))
Membrane water flux and resistance for ultrafiltration design.
Design →Unconfined Aquifer Well Design
Q = π · K · (h₁² − h₂²) / ln(r₁/r₂)
Steady-state flow rate for a fully penetrating well in an unconfined aquifer.
Design →Venturi Scrubber
ΔP ∝ v_gas² · L/G (Calvert)
Pressure drop for a venturi scrubber from gas velocity and liquid-to-gas ratio.
Design →Wastewater Screening Design
hL = K · v² / 2g
Headloss across bar racks and fine screens for wastewater treatment plant design.
Design →Environmental science calculators: water hardness, dissolved oxygen, BOD (biochemical oxygen demand), dilution math, runoff, and groundwater flow.
When to use these calculators
Used in environmental science coursework, water-treatment plant operations, and field investigations. Each calculator handles the standard form of the equation with conversion between common units.
Frequently Asked Questions
- How does the calculator show its work?
- Each calculator displays the substituted arithmetic step-by-step below the solution, so the user can verify the math by hand if needed. The 'Copy result' button captures the full formula → substitution → answer block.
- Are the formulas cross-verified?
- Every calculator's math has been cross-verified against textbook references and round-trip consistency tests (solve A from B, then solve B from A — the result must match the input). Spot-checks against Wolfram Alpha confirm the precision.
- How do I switch between solving for different variables?
- Most calculators in this category support multiple solve-for modes. Pick the unknown variable from the pill-toggle (or equation-card group) above the input fields, then enter the known values. The calculator auto-computes as you type.