water and water treatment in deatil.pptx

water and water treatment

1. Lecture: 01 Water and Water Treatment Dharmsinh Desai University, Nadiad Gujarat - India Prepared by Dr. Yash Jaiswal

2. Importance of Water Fresh water is probably the most important resource in the world since it is required for: Sustenance of human life: Physiological processes, Sanitation. Agricultural activities: Metabolic processes for food production, Evaporative cooling of earth. Industrial needs: Heat transfer processes, Chemical reactions, Nuclear fusion power.

3. Water availability per person is dependent on population of the country and for India, per capita water availability in the country is reducing due to increase in population. The average annual per capita water availability in the years 2001 and 2011 was assessed as 1816 cubic meters and 1545 cubic meters respectively which may further reduce to 1486 cubic meters and 1367 cubic meters in the years 2021 and 2031 respectively. As per Ministry of Housing and Urban Affairs, 135 litre per capita per day ( lpcd ) has been suggested as the benchmark for urban water supply. For rural areas, a minimum service delivery of 55 lpcd has been fixed under Jal Jeevan Mission, which may be enhanced to higher level by states.

4. As mentioned in the report of National Commission for Integrated Water Resources Development (NCIWRD), the percentage of water used for irrigation out of the total water use for the year 1997-98 was 83.30%. Further, as per NCIWRD report, the percentage of water used for irrigation out of the total water use for the year 2025 under high demand scenario was estimated as 72.48%.

5. The country has a diverse landscape and a climate varying from the areas with highest rainfall such as Mawsynram near Cherrapunji (Meghalaya) to the driest parts of western Rajasthan with negligible rain. From a hot and humid southern peninsula to the snowbound Himalayan Mountains. Broadly, the climate of India is of the tropical monsoon type. It has four seasons: winter (January–February), a hot summer (March–May), rainy southwest monsoon (June–September), and post-monsoon (October–December). Sources of Water Distribution of Area According to Annual Rainfall

6. Industrial use of Water

7. Water shortage problems Parts of India are arid or have saline water seepage so that serious fresh water shortage exist. In other areas, the water problem is now becoming serious as the industrial concentration in a given area increases. Factors responsible for water shortage: Failure to provide equalization of surface water run-off. Overconcentration of population and industries. Withdrawal of water from underground aquifers in excess of natural recharging rate. Water wastage since it is relatively cheap. Failure to use salt water in place of fresh water because it requires expensive corrosion-resistant materials. Poor selection of plant sites and lack of industrial coordination. Inadequate design of water-consuming processes and equipment from a water conservation standpoint.

8. Steps to reduce industrial water intake: Reuse water wherever conditions permit. Use cooling water in series operations, adiabatically cool and reuse. Treat waste condensate for reuse. Recondition waste and wash water for reuse. Reduce pressure on lines, watch for leaks, meter and control all streams. Keep heat transfer equipment clean. Insulate hot and cold water lines to avoid mutual heat exchange. Substitute air for water where possible. Note: Even if all of the above measures for water conservation were adopted, it is still anticipated that there will be a general fresh water shortage within the next few centuries. This is because of the population growth and the accompanying increase in industrial and agricultural activities.

9. Methods for Treating Fresh Water: Water treating or conditioning for general use in a community is usually a municipal function serving both residential and industrial needs. The impurities which must be removed from water will vary according to geographical location.

10. Treatment /Conditioning Methods: To remove or reduce a portion or all of the above impurities, several basic processes are available to municipalities or industrial plants. The choice depends on the nature of the raw water and the desired end usage of the conditioned water. Lime-soda process. Filtration – Usually done on sand filters. Decolourization and deodorization – Activated carbon adsorption. Chlorination. Ion exchange (a). Zeolite softening for cation removal (b). Synthetic resins –Used for cation and /or anion exchange. Boiler water feed conditioning (a). Addition of sodium hexametaphosphate (NaPO3)6 to form soluble complexes of Ca, Mg, Fe and Al. (b). Deaeration by means of spraying as hot water or addition of scavenger such as sodium sulfite .

11. Municipal water treatment process: Raw materials:

12. Flow sheet:

13. Major Engineering Problems: