Energy from wastewater

The Swedish dairy company Norrmejerier, based in Umeå, Sweden, had to handle large quantities of whey, which is a by-product of their production process, on a daily basis. Around 90% of the milk used in cheese production ends up as the high-energy by-product whey.

EnviroChemie developed and installed a sustainable, efficient and cost-saving Biomar® anaerobic wastewater plant for the treatment of wastewater and whey.

• Objective

  Objective

  The objective was to develop an alternative to the high costs of disposing of the whey, which previously could only be reduced by marketing it as a whey-based drink and as a feedstuff for livestock feed. But the volumes involved were so huge that these marketing channels alone were not enough.

  The Norrmejerier dairies commissioned EnviroChemie to develop a concept for a biological wastewater treatment plant with energy recovery. The aim was to install an efficient, resource-saving plant solution that simultaneously reduced the dairy company’s operating costs.

• Solution

  Solution

  After separating the valuable proteins from the whey, the remaining organic load in the whey permeate is converted together with other production wastewater into energy-rich biogas using Biomar® anaerobic wastewater treatment. Some of the thermal energy stored in the wastewater is recovered using heat exchangers and heat pumps.

  Every day, up to 300 m³ of whey and whey permeate with a COD load of up to 25 tonnes of COD a day is produced at the dairy, which is then transferred to the anaerobic wastewater treatment system. Biogas generation takes place in two biogas reactors with a total volume of 5,000 m³. Up to 10,000 m³ of biogas with a methane content of 65 to 70% is produced every day. The energy from the biogas that is produced is then used to generate steam.

  In a second expansion stage, plant capacity was adapted and an additional treatment stage was installed, which removes more than 90% of the phosphates from the wastewater.
• Benefits

  Benefits

  The smart process technology combination of biological wastewater treatment, biogas/energy recovery and whey permeate disposal provides a clear commercial benefit to the Norrmejerier dairies, as well as significantly improved energy efficiency.

  In 2009 more than 2,000,000 m³ of biogas were generated, saving over 1,200,000 l of heating oil. Moreover, thanks to the high biogas yield, the investment costs of this EU-supported project were amortised sooner than expected.