The federal research project, PAkmem, deals with the recycling of industrial wastewater. The aim of the project is to develop and pilot an innovative integrative process for produced water treatment in the oil and gas industry utilizing flotation and ceramic micro-nano-membrane filtrations (MF-NF membranes) as well as the wastewater treatment of the ceramic industry with ceramic NF-membranes and electrodialysis (ED). The process utilized should remove fine particles, organic matter and divalent ions in order to make the water dischargeable or reusable (direct disposal or reuse as process water in the ceramic industry and the enhanced oil recovery reinjection in the oil and gas industry in which the water is conditioned in order to increase the oil production yield). Three pilot plants were designed and built according to strict safety standards and were operated on industrial manufacturing sites in Germany in 2019. Two innovative optical fine particle measuring techniques (inline and online) have been specially adapted for the project and integrated into the pilot plants. The results show promising technical potential for the use of ceramic membranes in the above-mentioned applications.