In general, a promising strategy to circumvent the mentioned issues is the immobilization of the photocatalyst. By this, heterogeneous mixtures that have to be pumped or suspended are avoided and no further downstream processing regarding particle separation is required. However, the accessible catalyst surface is reduced. Consequently, maximizing the accessible as well as irradiated catalyst surface becomes a major optimization objective. In comparison to a reactor for suspensions, the reactor design has to be completely revised. The use of static mixers which contain or are manufactured out of a material that contains the photocatalyst represents an attractive option. In combination with additive manufacturing technologies, also complex static mixer geometries can be realized.