# Methane from SWDS New Norwegian calculating model Per Svardal.

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Methane from SWDS New Norwegian calculating model Per Svardal

2Metan fra avfallsdeponi 2004 revision of model from 1999 Many reasons. For reasons and results see www.sft.no/publikasjoner/luft/2079/2079.pdf www.sft.no/publikasjoner/luft/2079/2079.pdf Two of the reasons were: -Complicated model, difficult, poor view of calculations (black box). -Faulty mathematics.

3Metan fra avfallsdeponi Basic mathematics, first order reaction Rate of reaction equation, reactant transforming to methane: dDDOC =DDOC * k * e^-kt *dt Integrated equation for mass calculations, year t: DDOCdiss = DDOC * (e^-k(t-1) – e^-kt) (DDOC = dissimilable organic carbon)

4Metan fra avfallsdeponi Important theory First order reaction -Amount of product formed (DDOCdiss) always proportional to the amount of reactant (DDOC) -When we know the full amount of DDOC it is of no concern to the calculations when the DDOC came into the SWDS: Every year can be regarded as the first year. -First order reaction equation the same as the compound interest equation, with negative interest rate.

5Metan fra avfallsdeponi Yearly steps in new calculating model 1.Calculate reactant deposited (DDOCd) 2.Add this to the reactant left as not dis- similated from last year (DDOCd+DDOCly) 3.Calculate DDOCdiss from 2. 4.Calculate the amount of methane formed from DDOCdiss. 5.Calculate DDOC not dissimilated for next years calculations (new DDOCly).

6Metan fra avfallsdeponi The motor of the new model Two main equations: DDOCdiss = (DDOCd+DDOCly) * (1-e^-k) DDOCly = (DDOCd+DDOCly) * e^-k -(The presented workbook model is a little more complicated because it also handles the option of reaction start in the year of deposition)

7Metan fra avfallsdeponi The workbook Sheet 3 -Parameters Sheet 4 -Material input and final result Sheets 5-7 -Calculations for the different materials Sheet 8 -The accumulation of plastics

8Metan fra avfallsdeponi M D

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