Various chemicals are used in the operation of SWRO desalination plants. The use of
chemicals has significant environmental and economic influences, such as increased amounts of
waste and plant operational costs. Therefore, a process in which the chemical consumption is
reduced or no chemicals are used is highly desired. Mitsubishi Heavy Industries, Ltd. (MHI) has
been working on the development of chemical-free pretreatment technology that is both
environmentally-friendly and economically efficient. MHI conducted a demonstration experiment
in Japan and Qatar, adopting the chemical-free sand filtration technology utilized in the Japanese
salt manufacturing industry. As a result, the experiment verified that the operation of RO
membranes is possible with stable desalination performance and SWRO differential pressure,
proving the applicability of chemical-free sand filtration to SWRO desalination using RO
membranes.
