Development and optimization of a novel industrial process solution for stripping of carbon dioxide and ammonia from bio-process wastewater

Abstract

The production of biologic products by fermentation has grown significantly within the last decade and continues to grow further. Large volumes of wastewater are produced by anaerobic digesters, which contain dissolved CO2 and NH3 in addition to other compounds, making it difficult to treat in an economic way. In this work, we have developed a novel process solution of an NH3 recovery process that first strips off CO2 from the wastewater, then produces a concentrated NH3 solution. This solution not only avoids both precipitation of solids and the use of caustic, but also allows for adjustments of the composition of the concentrated NH3 solution, thus enabling its re-utilization in different applications. Based on this development, pilot plant tests were conducted with the aim of proving process feasibility. Then, a rigorous process optimization was carried out, where the optimal set of process parameters were determined. The results suggest that the optimal operation not only depends on the operating conditions, but also on the process configuration depending on the input and storage conditions; four different configurations were developed, which enable the selection of an optimal design that minimizes both the operating costs via external heat demand, and capital costs via process complexity.