JPS59177189A - Desalination of sea water by reverse osmosis method - Google Patents

Abstract

PURPOSE:To perform the desalination of sea water without the need to make the capacity of a tank for supplying water to a reverse osmosis device larger and without using a pump for backwashing water, by using desalinated liquid waste of sea water discharged from the reverse osmosis device as backwashing water in a sand filter for the pretreatment of sea water. CONSTITUTION:Sea water is supplied 2 to a plurality of sand filters 3 by a sea water intake pump 1. The sea water from which suspended matter has been removed by the sand filters 3 is introduced under a highly pressurized condition through a conduit 6 having a check filter 4 and a high pressure pump 5 into a plurality of reverse osmosis modules 8 of a reverse osmosis device 7. Then, said sea water is desalinated by the device 7, and the formed sea water is withdrawn through a conduit 9. On the other hand, highly pressurized salty conc. liquid waste is introduced through a conduit 10 for backwashing water to the outlet parts of the sand filters 3 and used as backwashing water therefor.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a seawater desalination method using reverse osmosis, and more particularly to a method for backwashing a sand filter for seawater pretreatment.

Conventionally, in seawater desalination equipment using the reverse osmosis method, the high-pressure concentrated salt wastewater discharged from the reverse osmosis equipment was disposed of as is or after pressure energy recovery, into the sea from which the water was taken. By the way, in the seawater desalination method using the reverse osmosis method, in order to prevent the seawater from clogging the reverse osmosis device, a sand filter is provided for pre-treatment of the seawater to remove suspended solids from the seawater. Water supplied to the reverse osmosis equipment was used to water the sand in the filter.

Therefore, it was necessary to make the reverse osmosis supply water tank larger to accommodate the backwash water, and a backwash water pump was also required to send the backwash water to the sand filter. In addition, the capacity of backwash water is quite large, so a backwash water storage tank is required in addition to the above supply water tank, and the capacity of the backwash pump needs to be increased, which requires a corresponding increase in the power supply capacity. There was resentment that the burden on the staff was increasing.

This invention was made in view of the above-mentioned actual situation, and an object thereof is to provide a seawater desalination method using reverse osmosis that can solve all of the above-mentioned problems.

In the seawater desalination method according to the present invention, in a seawater desalination device consisting of a sand filter for seawater pretreatment and a reverse osmosis device, the salt-rich wastewater discharged from the reverse osmosis device is used as backwash water for the sand filter. It is characterized by (,z).

Hereinafter, specific song numbers for embodiments of the present invention will be explained.

In the seawater desalination apparatus 1 shown in the drawings, seawater ζ4 is supplied to a plurality of sand filters (3) via conduits (2) by a water intake pump (1). The seawater, free of suspended solids in the sand filter (3), passes through a conduit (6) with a check fin (4) and a high-pressure pump (5) to multiple reverse osmosis units (7). It is led under high pressure to the osmosis module (8). The seawater is desalinated in a reverse osmosis device (7) and the produced fresh water is removed via a conduit (9). On the other hand, the high-pressure salt-rich waste liquid is led to the outlet portions of the plurality of sand filters (3) through the backwash water conduit (10) and is used as the backwash water.

As described above, according to the present invention, the Hl/liquid discharged from the reverse osmosis device is used as backwash water for the sand filter. , the reverse osmosis supply water tank needs to have a large capacity, and a backwash water storage tank and backwash water pump are also required.
A <, therefore, the load on the generator can also be significantly reduced.

[Brief explanation of drawings]

The drawing is a schematic diagram of a seawater desalination apparatus showing an embodiment of the present invention. (3)...Sand filter, (7)...Reverse osmosis device, (8
)...Reverse osmosis module, (101...-Backwash water conduit. Patent applicant: Hitachi Zosen Corporation Agent)
Einosuke Kishimoto

Claims (1)

[Claims] In a seawater desalination system consisting of a sand filtration device for seawater pretreatment and a reverse osmosis device, the salt-rich wastewater discharged from the reverse osmosis device is used as backwash water for the sand filtration device. Seawater desalination method using osmosis method.