In the sewage treatment, the Mogden formula is a pricing strategy used to estimate the difficulty in treating industrial wastewater. It is named after Mogden Sewage Treatment Works.[1]

The Mogden formula calculates cost as a combination (empirical coefficients) of volume, strength in terms of normal treatment oxidation demand and the suspended solids proportion.[1] Applicable to the whole works, it also approximates the cost for tested industrial waste water that may, if treatable, be lawfully sent to a regular sewage works.[1][2][3][4]

The Mogden formula is:

C = R + [(V + Bv) or M] + B(Ot/Os) + S(St/Ss)

where:

C = charge per volume of effluent (£/m3)
R = reception and conveyance charge [£/m3]
V = primary treatment (volumetric) charge [£/m3]
Bv = additional volume charge for biological treatment [£/m3]
M = treatment and disposal charge where effluent goes to sea outfall [£/m3]
B = biological oxidation of settled sewage charge [£/m3]
Ot = chemical oxygen demand (COD) of effluent after one hour of quiescent settlements at pH 7 [mg/litre]
Os = chemical oxygen demand (COD) of effluent after one hour of quiescent settlement [mg/litre]
S = treatment and disposal of primary sewage sludge charge [£/m3 or £/kg]
St = total suspended solids of effluent at pH 7 [mg/litre]
Ss = total suspended solids of effluent [mg/litre]

Thus the less biologically friendly the effluent (see wastewater quality indicators including pH), and more solid-laden, the higher the charge should be for treating the lawful effluent.[5]

References

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  1. ^ a b c Mogden, Hidden London, retrieved 12 November 2013.
  2. ^ Effluent + Water Treatment Journal 16 (1976) 409.
  3. ^ John S. Hills, Cutting Water and Effluent Costs, Rugby: Institution of Chemical Engineers, 1995, ISBN 9780852953617, p. 52.
  4. ^ Stephen Merrett, The Price of Water: Studies in Water Resource Economics and Management, London: IWA, 2005, ISBN 9781843390817, p. 139.
  5. ^ "Mogden formula" (PDF).