WATER TREATMENT and Demineralization Systems for Drinking Water Production
Water Treatment and Demineralization Systems for Drinking Water Production 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. Below is the general layout of a sea water treatment plant for producing drinking water with a capacity of 1-100 m3 per hour. 2
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Fig. 1. Sea water treatment general layout
The water treatment system – list of basic equipment: 1. Source water pumps 2. Source water chlorination 3. Inlet tank 4. Coarse filter 5. Ultrafiltration feeding pump 6. Ultrafiltration unit 7. Backwashing pump 8. Clarified water tank 9. Clarified water dechlorination
10. Reverse osmosis feeding pump 11. Microfiltering unit 12. Reverse osmosis unit with high pressure pump and energy recuperator 13. Drinking water tank 14. Water distribution pumps with an ultraviolet lamp – optional
The whole process can be split into two technological stages: Stage 1 (steps 1-9): 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 (steps 10-13): sea water demineralization by the reverse osmosis method. Fresh water treatment and sea water preliminary treatment 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 bisulphite, 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. Technical characteristics of the preliminary treatment system: •W ater treatment system capacity, by filtrate – 1-100 m3/h at water temperature of 25°С. •O perating mode – continuous with a lower capacity of 80% during routine maintenance. •D uration of the routine maintenance – no more than 6 hours. •P ower consumption of the water treatment system – about 2-4 kWh per 1 m3 of water. •S ource water feeding to the water treatment system – up to 120 % of the plant capacity. •W ater (concentrate) drain from the water treatment system: no more than 20% of the clean water produced.
Fig. 2. Water treatment station
Fig. 3. Mobile water treatment plant
Sea water demineralization Demineralization equipment is intended for sea water treatment and drinking water production with a capacity of 1-100 m3/h. The source water should meet the following quality requirements: • free chlorine – less than 0,1 mg/l; • suspended particles – less than 0.1 mg/l; • turbidity – less than 0.1 NTU; • oxidability – less than 5 mgО2/l; • total iron – less than 0,3 mg/l; • colloidal silicon – less than 5 mg/l; • colloidal index (SDI) – less than 5; • boron content – less than 3 mg/l; • oil product content – 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 unit of salt composition in the drinking water. Power consumption of a sea water demineralization equipment is about 5-10 kWh per 1 m3 of water. Other conditions Protection index – IP 65. The temperature of water supplied has not to exceed 35-45°C. Therefore in countries with hot climate it is necessary to provide air conditioning of rooms with water-desalinating (reverse osmosis) units. The sea water treatment plant enables execution of the routine maintenance at a lower capacity of down to 60% of the normal one. The control system provides the correct and safe start-up and shutdown of the installation, activation of the automatic mode and keeping the operation parameters (flow rate of concentrate and filtrate) unattended. In case of an emergency or dangerous situation, the system will be switched off by the control unit. The plant has two operating modes: an automatic (standard) mode and a manual mode. The plant is operated by specially trained personnel. Additional options At the customer’s request the water treatment equipment could be supplied with: • Drinking water distribution pumps with a UV lamp • Automatic quality control unit for drinking water (to test electrical conductivity, pH etc., according to the customer’s requirements).
Tetraedr UE 20A, Platonova str., Minsk, 220005, Republic of Belarus Tel./fax: (+375 17) 2966206, 2966207 email: info@tetraedr.com http://www.tetraedr.com