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SEA WATER TREATMENT

Water treatment and demineralization systems for drinking water production

DESIGNATION

The proposed systems are designed for drinking water production by cleaning fresh water from open sources, as well as by treatment (demineralization) of sea water. Each system will be developed according to local conditions and requirements of a particular customer.
Systems have a capacity 1 – 100 m3 per hour which could be increased using the modular assembly.

Composition

The whole process of water purification can be split into two technological stages:
Stage 1: water treatment, regardless of its salinity. As a result of this stage - fresh water becomes drinkable and sea water gets ready for Stage 2.
Stage 2: sea water demineralization by the reverse osmosis method.

FRESH WATER TREATMENT AND SEA WATER PRELIMINARY TREATMENT EQUIPMENT

Equipment for sea water preliminary treatment is used prior to the reverse osmosis unit.

Source water, after preliminary removal of large suspended particles in the coarse filters (mesh- or disk-type), is pumped into the inlet tank. Then water is treated with sodium hypochlorite and delivered to the filter of mechanical treatment. After that water is filtered in the ultrafiltration membranes. Then, by dosing of sodium bisulphate, water is dechlorinated. As a result of this treatment, sea water meets the requirements for source water for reverse osmosis units, and fresh water can be used for drinking purposes.

SEA WATER TREATMENT (DEMINERALIZATION) EQUIPMENT

Demineralization equipment is intended for sea water treatment and drinking water production after stage 1 of preliminary water treatment.

Requirements for source water quality:
1. free chlorine - less than 0,1 mg/l;
2. suspended particles - less than 0.1 mg/l;
3. turbidity - less than 0.1 NTU;
4. oxidability – less than 5 mg2/l;
5. total iron - less than 0,3 mg/l;
6. colloidal silicon - less than 5 mg/l;
7. colloidal index (SDI) - less than 5;
8. boron content less than 3 mg/l;
9. oil products content none;
10. microbiological impurities - none.

Water is demineralized at special membranes of the high-pressure reverse osmosis unit, wherein the total salt content is considerably reduced down to 500 mg/l. To prevent salt deposit on the membrane surfaces, antiscalant is dosed before the reverse osmosis unit. If necessary alkaline or acid is dosed to correct pH. The plant operates in the automatic mode. When the membranes get dirty the plant is periodically (once in 2-3 months) chemically cleaned. The system can be equipped with a correction (conditioning) unit of salt content in the drinking water.

Technical characteristics of the preliminary water treatment system

Value

Water treatment system capacity, by filtrate1-100 m³/h at water temperature of 25°
Operating modecontinuous with a lower output - 80% of the rated output, during routine maintenance
Duration of the routine maintenanceno more than 6 hours
Power consumption of the water treatment systemabout 2-4 kWh per 1 m³ of water
Source water feeding to the water treatment systemup to 120% of the plant rated output
Water (concentrate) drain from the water treatment systemno more than 20% of the clean water produced

Technical characteristics of the water demineralization equipment

Value

Water treatment capacity, byfiltrate1-100 m³/h at feeding water temperature not to exceed 35-45
Operating mode continuous with a lower output - 60% of the rated output, during routine maintenance
Duration of the routine maintenanceno more than 6 hours
Power consumption of the water treatment systemabout 5-10 kWh per 1 m³ of water
Foul membranes – interval for chemical cleaningonce in 2-3 months

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