(US5790934-A)      A reactor for photocatalysed conversion of contaminants in a fluid stream comprises a light source, a photocatalyst and fins supporting the catalyst; the fins are parallel to the direction of flow, and orthogonal to the light source, so that the photocatalyst is illuminated by light that is capable of activating the catalyst. In a variant, the reactor consists of one or more cylinders for fluid flow, with pleats in cylinder walls running parallel to the longitudinal axis of the cylinder; the catalyst is deposited on the inner surface of the cylinder, and a light source is placed within the cylinder to illuminate the catalyst.    USE -   A stream of water or air is treated to remove contaminants, e.g. organic or halogenated organic compounds, nitrogen oxides, hydrogen cyanide or microorganisms.    ADVANTAGE -   There is low pressure drop, good contact with catalyst and effective use of light, with simple maintenance and low manufacturing cost.    (EP949970-A2)      A reactor for photocatalysed conversion of contaminants in a fluid stream comprises a light source, a photocatalyst and fins supporting the catalyst; the fins are parallel to the direction of flow, and orthogonal to the light source, so that the photocatalyst is illuminated by light that is capable of activating the catalyst. In a variant, the reactor consists of one or more cylinders for fluid flow, with pleats in cylinder walls running parallel to the longitudinal axis of the cylinder; the catalyst is deposited on the inner surface of the cylinder, and a light source is placed within the cylinder to illuminate the catalyst.    USE -   A stream of water or air is treated to remove contaminants, e.g. organic or halogenated organic compounds, nitrogen oxides, hydrogen cyanide or microorganisms.    ADVANTAGE -   There is low pressure drop, good contact with catalyst and effective use of light, with simple maintenance and low manufacturing cost.    (US6063343-A)      A reactor for photocatalysed conversion of contaminants in a fluid stream comprises a light source, a photocatalyst and fins supporting the catalyst; the fins are parallel to the direction of flow, and orthogonal to the light source, so that the photocatalyst is illuminated by light that is capable of activating the catalyst. In a variant, the reactor consists of one or more cylinders for fluid flow, with pleats in cylinder walls running parallel to the longitudinal axis of the cylinder; the catalyst is deposited on the inner surface of the cylinder, and a light source is placed within the cylinder to illuminate the catalyst.    USE -   A stream of water or air is treated to remove contaminants, e.g. organic or halogenated organic compounds, nitrogen oxides, hydrogen cyanide or microorganisms.    ADVANTAGE -   There is low pressure drop, good contact with catalyst and effective use of light, with simple maintenance and low manufacturing cost.    (JP2001502220-W)      A reactor for photocatalysed conversion of contaminants in a fluid stream comprises a light source, a photocatalyst and fins supporting the catalyst; the fins are parallel to the direction of flow, and orthogonal to the light source, so that the photocatalyst is illuminated by light that is capable of activating the catalyst. In a variant, the reactor consists of one or more cylinders for fluid flow, with pleats in cylinder walls running parallel to the longitudinal axis of the cylinder; the catalyst is deposited on the inner surface of the cylinder, and a light source is placed within the cylinder to illuminate the catalyst.    USE -   A stream of water or air is treated to remove contaminants, e.g. organic or halogenated organic compounds, nitrogen oxides, hydrogen cyanide or microorganisms.    ADVANTAGE -   There is low pressure drop, good contact with catalyst and effective use of light, with simple maintenance and low manufacturing cost.