Population Equivalent (Organic Load)
The population equivalent of a discharge, figured three ways.
Example
You enter
- Discharge flow (MGD) 0.5
- BOD concentration (mg/L) 600
- Suspended solids (mg/L, 0 to skip) 400
You get
- Pe BOD 14718
- Pe flow 5000
- Pe governing 14718
Checked against published worked examples from: Population equivalent (organic load), standard sanitary engineering.
Details, formula, and sources
ScopeFrom BOD (0.17 lb/capita/day), flow (100 gpd/capita), and suspended solids (0.20 lb/capita/day) -- with the GOVERNING value being the largest, not BOD alone. A 0.5 MGD cannery at 600 mg/L BOD is worth ~14,700 residents in oxygen demand though its gallons look like 5,000; billing on flow alone under-charges it.
Formula or tablebod_load = MGD x BOD x 8.34; PE_bod = bod_load / 0.17; PE_flow = gpd / 100; PE_ss = ss_load / 0.20; PE = max(PE_bod, PE_flow, PE_ss).
Source and editionPopulation equivalent (organic load), standard sanitary engineering, by name.
Free accessThe per-capita loading bases and the population-equivalent relation are public sanitary-engineering conventions; the pretreatment ordinance and the authority govern.
What governsEstimate. AHJ and licensed professional govern.
API field namesflow_mgd, bod_mg_l, ss_mg_l, pe_bod, pe_flow, pe_governing
- Per-capita bases 0.17 lb BOD, 100 gpd, 0.20 lb SS per person per day (editable conventions)sanitary engineering
- Governing max the largest of PE_bod, PE_flow, and PE_ss governs, not BOD alonesanitary engineering