En-RecoTreat – Innovative membrane distillation for the recovery of valuable substances and energy recovery in municipal wastewater treatment

The conventional municipal biological-aerobic waste-water treatment is an energy intensive process. The energy-supplier carbon respective the energy bonded in carbon as well as the nutrients (nitrogen) is destroyed with a high electrical energy consumption (aerobic aeration). In Austria, 546.000MWh of electrical energy per year must be spent for municipal waste-water-treatment.

The overall objective is the reduction of the high energy-consumption of the municipal waste-water treatment. By separation and recovery of ammonia from the municipal waste-water by using energy efficient membrane distillation processes, the oxygen demand and thus the energy demand for biological oxidation of ammonia can be massively reduced. By taking the commodity “ammonia water” on the one hand revenues and on the other hand cost savings are generated.

The second direction of impact of the project is the concentration of municipal waste-water by separating clean water or ammonia water by energy efficient membrane distillation to enable the efficient operation of a high performance anaerobic reactor by increasing the carbon concentration. The use of anaerobic treatment-technologies enables an energy-recovery from waste-water content in the form of biogas.

Membrane distillation is an energy efficient, low temperature technology with low thermal and electrical energy consumption and enables the integration of waste heat and solar thermal energy as a heat source.

To be able to analyse the membrane distillation under realistic operating conditions, the technical scale facility is installed and tested directly in a waste-water treatment plant. Furthermore, the long-term behaviour of membrane distillation for ammonia separation and concentration of waste-water can be analysed extensively. In the scope of this project a concept for the integration of the membrane distillation facility for ammonia separation, recovery from sludge water and the waste-water concentration for the use of an anaerobic high-efficiency reactor is developed and the potential for the integration of waste heat or solar thermal energy is pointed out.

The result of this project will form the basis for the subsequent optimisation of a membrane-distillation pilot scale facility and characteristic membrane-modules for the separation of ammonia, ammonia-water and clean water with detailed knowledge about the operation parameters such as flow rates, temperatures, energy consumption etc.