NEFFLUENT = total annual amount of nitrogen in the wastewater effluent, kg N/yr
P = human population
Protein = annual per capita protein consumption, kg/person/yr
FNPR = fraction of nitrogen in protein, default = 0.16, kg N/kg protein
FNON-CON = factor for non-consumed protein added to the wastewater
FIND-COM = factor for industrial and commercial co-discharged protein into the sewer system
NSLUDGE = nitrogen removed with sludge (default = zero), kg N/yr