Long-term experiences of 3.5 mgd Roga-spiral RO installation

The 800,000 GPD Reverse Osmosis Plant was put on stream in late 1971 at the Kashima Steel Works of Sumitomo Metal Industries Ltd., Japan and it has been expanded up to the capacity of 3.5 MGD, the world's largest RO Plant now under commercial operation.

Development of the most appropriate pretreatment process and application of specially determined indexes to evaluate the pretreated RO feed water-quality have greatly contributed to maintain the membrane performance at satisfactory level and to prolong or lengthen the membrane life-time. During these four and half years since its installation, operation results show the plant availability of 98%, the module replacement of 5–6% per year and the flux decline slope of -0.02 with better salt rejection than the guaranteed level.

Kurita Water Industries Ltd. has installed many RO plants since 1971, aggregating to approx. 12 MGD in total capacity. Informations are also reported herein regarding other two bigger installations, 1.4 MGD and 2.5 MGD in capacity respectively.