Biogas from mechanical pulping industry : Potential improvement for increased biomass vehicle fuels

• Biogas is a vehicle fuel of the first generation of biofuels with great potential for reducing the climate impact from the transport sector. Today biogas is mainly produced by digestion in Sweden and the total amounts to 1.4 TWhLHV/year (2010) of which about 0.6 TWhLHV is upgraded and used in the transport sector. Using industrial wastewater, e.g. from a pulp and paper mill, as substrate for production of biogas, the amount of renewable fuel to the transport sector could be increased. In the pulping industry, substantial amounts of organic matter are generated; this is commonly treated aerobically to reduce the chemical oxygen demand (COD) in the effluent streams before discharge to a recipient. Treating these effluent streams mainly anaerobically instead could contribute to the transport sector's energy supply. The aim of this study is to investigate the potential for using effluent streams from the Swedish mechanical pulp and paper industry to produce biogas. A typical Swedish mechanical pulp mill is considered for anaerobic treatment of the wastewaters. This type of pulp mill presently uses conventional methods for wastewater treatment to reduce COD, but converting most of this to anaerobic treatment would increase the amount of biogas produced. When considering this conversion in a larger context, supposing that anaerobic treatment would be applied to all Swedish mechanical pulp mills, which stand for about 30% of the total Swedish pulp production, it is shown that the production could amount to as much as 0.5 TWhLHV/year of biogas. This represents about one third of the biogas produced in Sweden today. The main conclusion of this study is that if anaerobic treatment of effluent streams from the pulping industry were introduced, the biogas production in Sweden could be significantly increased, thus moving one step further in reducing the transport sector's climate impact.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Energisystem (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Energy Systems (hsv//eng)

Nyckelord

Anaerobic digestion

Biofuel

Biogas

Mechanical pulping

Vehicle fuel

Wastewater treatment

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