Research Notes from NERI no. 208: Emission of CH4 and N2O from wastewater Treatment Plants (6B). Thomsen, M. & Lyck, E. 2005. 46 pp.
Summary
There have not previously been any country-specific methodologies developed for estimating CH4 or N2O emissions from wastewater handling in Denmark. The methodology developed for this submission for estimating the emission of methane from wastewater handling is following the IPCC Guidelines (1996) and IPCC Good Practice Guidance (2000). The methodology is based on the calculation of a so-called gross emission of methane, which is the theoretical maximum possible emission. This gross emission is based on the total methane potential of the total amount of degradable organic matter at the wastewater treatment plants (WWTPs). The amounts of methane or methane potential that are recovered by biogas production or combusted are subtracted from the gross emission. The resulting net methane emission is an estimate of the actual amount of emitted methane during wastewater treatment at Danish WWTPs. Key parameters are the fraction of sewage sludge that are treated anaerobically and the total organic degradable waste quantified by the biological oxygen demand (BOD) of the wastewater influent.
A national methodology for calculating the emission of nitrous oxide from wastewater treatment processes (direct N2O emission) and from the effluent wastewater (indirect N2O emission), respectively, has been developed. The IPCC default methodology only includes N2O emissions from human sewage based on annual per capita protein intake. The methodology account for nitrogen intake, i.e. faeces and urine, only and neither the industrial nitrogen input nor non-consumption protein from kitchen, bath and laundry discharges are included. All aspects have been included in the present methodology for estimating the emission of nitrous oxide from waste category 6B.
The data on the inlet and outlet amounts of industrial and municipal wastewater and treatment processes are according to the official registration performed by DEPA. Data are documented in the report series Wastewater from municipal and private wastewater treatment plants (Danish title: Spildevandsslam fra kommunale og private renseanlæg), DEPA 1989, 1999, 2001, 2003 and 2004, and Point sources (Danish title: Punktkilder), DEPA 1994, 1996, 1997, 1998, 1999, 2001, 2002 and 2003. Some of the data can be found in the DEPA database Environment Data and for point sources before 2003 in the Statistics Denmark's database StatBank Denmark. For the check method, data on Population are found in Statbank Denmark. Data on protein consumption are found in the FAOSTAT database.
Until year 2002 the Statistics Denmark registered the load of nitrogen, phosphorus and organic matter in effluent wastewater from different types of point sources. Data on the nitrogen in effluents are extracted from the Statistics Denmark's database and point source data reported within the Danish Monitoring programme by the Danish EPA (report series from the DEPA with English title: Point Sources).
Hele rapporten i pdf format (391 kB).
