Chemical and membrane desalination of natural water with high content of iron-organic compounds

Under the conditions of modernization of Russian thermal power plants (TPP), water treatment plants based on imported membrane technologies are often put into operation without consideration of the quality of the source (natural) water and variable-performance operating modes. At the same time long-running water treatment plants and their capabilities are not considered. In this regard, the cost of additional water is three or more times higher, and the average output is respectively lower than at traditional water treatment plants. Often, one doesn’t take the advantages of reverse osmosis installations based on the rejection of the use of aggressive reagents such as sulfuric acid, etc. The aim of the study is to increase the efficiency of desalinated water production. It is especially important to conduct studies of natural waters with high content of iron-organic compounds characteristic of the regions of the center and north of Russia. The authors have carried out laboratory studies of various, primarily new filter materials, regents, and devices, both at the stages of pre-purification of water i.e., clarification, and at the stages of demineralization of clarified water. Water treatment plants of Ivanovo combined-cycle plant (CCP) and Cherepovets state district power station (GRES) are considered as the subject of the research. It is found out that if one applies ion-exchange and membrane water treatment technologies to treat water with high content of iron-organic compounds, high-quality desalinated water can be obtained. The properties of water are the following: specific electrical conductivity of no more than 0,2 mcm/cm and permanganate oxidizability of no more than 1 MgO/l. Results of studies at the Ivanovo CCP and Cherepovets GRES have shown practicability to coagulate water with aluminum sulfate using an anionactive flocculant, for example, during the flood period. Application of coagulation and ultrafiltration units before reverse osmosis installation ensures removing organic impurities from the water. Based on the obtained research results, recommendations are given for the implementation of the results at Ivanovo water treatment plants.