Energy from wastewater
The Norrmejerier dairies generate energy, conserve resources and reduce operating costs using a Biomar® anaerobic wastewater treatment system.
What we did
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
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
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
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.
