Category
Environmental Engineering
Environmental engineering formulas and calculators for water treatment, air quality, and pollution control used to protect ecosystems and public health. Includes contaminant transport, filtration, and emissions equations.
29Formulas
2Subcategories
Updated Oct 2026
Water Treatment
Wastewater Treatment Plant Peak Flow Factor
Peak Flow = Average Flow * Peaking Factor
Air Quality
Simplified Ecological Footprint
Footprint (gha) = Consumption / Yield Factor
Water Treatment
Biodegradation Half-Life
t1/2 = ln(2) / k
Water Treatment
Water Footprint of a Product
Water Footprint = Σ(Water used at each production stage)
Air Quality
Carbon Sequestration by Trees (Simplified)
CO2 Sequestered = Tree Biomass Growth * Carbon Fraction * 3.67
Water Treatment
Composting Carbon-to-Nitrogen (C:N) Ratio
C:N Ratio = Total Carbon (kg) / Total Nitrogen (kg)
Water Treatment
Recycling Rate
Recycling Rate (%) = (Mass Recycled / Total Waste Generated) * 100
Water Treatment
Municipal Solid Waste Generation per Capita
Waste per Capita = Total Waste Generated / Population
Air Quality
Landfill Gas Generation Estimate (Simplified)
LFG Rate ≈ L0 * k * W * e^(-k*t)
Air Quality
Carbon Footprint from Fuel Combustion
CO2 Emissions = Fuel Used (L or kg) * Emission Factor
Air Quality
Carbon Footprint from Electricity Use
CO2 Emissions = Electricity Used (kWh) * Emission Factor
Air Quality
Particulate Matter Mass Concentration
C = m / V
Air Quality
Combined Sound Level from Multiple Sources
L_total = 10*log10(Σ 10^(Li/10))
Air Quality
Noise Level Attenuation with Distance
L2 = L1 - 20*log10(d2/d1)
Air Quality
Air Changes per Hour (Ventilation Rate)
ACH = (Airflow Rate (m3/hr)) / Room Volume (m3)
Air Quality
Stack Emission Rate
E = C * Q
Air Quality
Air Quality Index (AQI) Linear Interpolation
AQI = ((AQI_hi - AQI_lo)/(C_hi - C_lo)) * (C - C_lo) + AQI_lo
Water Treatment
Water Quality Index (Simplified)
WQI = Σ(Wi * Qi) / ΣWi
Water Treatment
Daily Per Capita Water Demand
Per Capita Demand = Total Daily Water Supplied / Population Served
Water Treatment
Sludge Volume Index
SVI = (Settled Sludge Volume (mL/L) * 1000) / MLSS (mg/L)
Water Treatment
Total Dissolved Solids from Electrical Conductivity
TDS (mg/L) = EC (µS/cm) * Conversion Factor
Water Treatment
Rapid Sand Filtration Rate
Filtration Rate = Flow Rate / Filter Surface Area
Water Treatment
Coagulant Dosage Scale-Up (Jar Test to Full Scale)
Full-Scale Dose (kg/day) = Jar Test Dose (mg/L) * Plant Flow (m3/day) / 1000
Water Treatment
Water Hardness (as CaCO3)
Hardness (mg/L as CaCO3) = [Ca2+](mg/L)*2.5 + [Mg2+](mg/L)*4.1
Water Treatment
Chlorine Dosage for Water Disinfection
Dose (kg/day) = Flow (m3/day) * Concentration (mg/L) / 1000
Air Quality
Gaussian Plume Concentration
C(x,y,0) = Q/(πuσ_yσ_z) · exp(−y²/2σ_y²)
Air Quality
Mass Balance (General)
Accumulation = In − Out + Generation − Consumption
Water Treatment
Pollutant Removal Efficiency
E = (C_in − C_out) / C_in × 100%
Water Treatment
Hydraulic Retention Time
HRT = V / Q