Wastewater as a Resource: Utilization and recovery of wastewater ingredients

Wastewater and process wastewater – valuable resources

The technological challenges in connection with water are manifold. Innovative approaches and methods are needed to use existing resources more effectively and to exploit new strategies, such as semi-centralized and adaptable infrastructure systems for collecting and distributing water or – just as important – finding possibilities for reusing water. It is obvious that e.g. rainwater should be treated to open up a new resource. Wastewater can be purified with modern, cost-effective filter technologies and in adapted biological processes. Ideally, the substances recovered from wastewater during the purification process can be recycled almost completely for energy and solids.

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Material or energy use of organic load

If wastewater or process water contain high concentrations of a single compound, it may also be worthwhile to separate the substance for further material use. In a project with dairy wastewater containing high amounts of lactose, the objective was to develop an environmentally sound process for the manufacturing of lactic acid from acid whey, in order to combine waste treatment with the production of valuable materials.

Recycling of nutrients

Besides organic solids, wastewater also contains large amounts of nutrients such as nitrogen, phosphorus, magnesium or potassium. Great efforts and in some cases huge amounts of energy are being put into eliminating nutrients from wastewater by means of nitrification, denitrification and/or biological phosphorus elimination, to prevent them from entering and eutrophying surface waters.

We are working on concepts and processes to recycle inorganic nutrients as fertilizers.

Removal and recovery of metals – biosorption and bioprecipitation

Metals from process wastewater can be bound to microbial surfaces by means of biosorption. In bioprecipitation dissolved metals (CuSO4, NiSO4, ZnSO4) are precipitated in the aqueous phase by microbial processes, for example with anaerobic microorganisms as catalysts and transferred to particulate components that are difficult to dissolve (CuS, NiS, ZnS). For effective process control we use immobilized or suspended biomass. In this way, heavy metals can be concentrated from solutions with metal ion concentrations in the mg/L range and precipitated as solids with metal concentrations in the g/kg range.