Treatment of Effluents by the Reverse Osmosis Process

1,179,423. Treatment of an aqueous coating medium by reverse osmosis. PRESSED STEEL FISHER Ltd. 6 March, 1968 [22 March, 1967], No. 13431/67. Addition to 1,071,458. Heading B1X. Effluent from a plant for the electrodeposition of a coating by an electrophoretic process, which plant includes a coating tank containing aqueous coating medium (which medium may be pigmented) and a rinsing station remote from the coating tank and in which process a coated article after leaving the coating tank is subjected to a water rinse at the rinsing station, is treated by a process which is characterized in that rinse water effluent is returned to the coating tank and the contents of the coating tank (i.e. aqueous coating medium and returned rinse water effluent) are passed under pressure through a reverse osmosis unit, that part of the effluent from the reverse osmosis unit which has a high concentration of coating medium being returned to the coating tank and that part of the effluent from the reverse osmosis unit which is substantially water or which has a low concentration of coating medium being discharged to waste or led away for other uses or recirculated through the rinsing station and coating tank. The process may be carried out either continuously or intermittently and whilst the coating tank is either idle or in use. Two illustrated embodiments of the process are disclosed in the Specification with reference to the painting of vehicle bodies; the reverse osmosis unit may be a unit disclosed in Specification 1,071,458.