Process for removing CO2 and NH3 from biogas plant waste water

The process of ammonium removal is an environmentally friendly concept that has been implemented successfully for some years now to process waste water that contains ammonium whilst simultaneously gaining recyclable substances such as "strong water" = 25% ammonia water. In future, this tried and tested process will also help solve the problem in terms of separated, fluid fermentation products overloaded with nitrogen.

This process is characterised by the application of 3 steps in which hydrogen carbonate and then ammonium are removed from the waste water one after the other through steam stripping. Without using chemicals, ammonium reduction levels can reach 85-95%. This means that ammonium removal without simultaneous salination of the process water is possible, which is very significant not just economically but ecologically. Correction of the pH value with additional chemicals is not required. In addition, waste water is freed from unpleasant odours.

At the end of this process there is no substance requiring disposal, but rather 25% strong water and therefore a recyclable substance that can also be reintroduced into the industrial economic cycle.

The stripping plant that is used comprises three different process stages:
1. Decarbonisation (removal of CO2 by means of steam)
2. Rectification (NH3 stripping by means of steam)
3. NH3 absorption (with cooling) into strong water

The whole plant is designed in such a way that the lowest possible operating costs are incurred. In particular, volumes of heating steam or heating water for steps 1 and 2 are kept very close to the minimum thermodynamic volume. Through optimum recovery of residual heat from the process flows in heat exchangers, it is possible to reduce energy consumption during decarbonisation. The consideration of all of these process-related characteristics leads to extremely low specific treatment costs for the waste water.

By selling the product of ammonia water, the economic viability of the GMS alpha plant is sustainably increased.