592 Fermentation and Biochemical Engineering Handbook Regardless of the source, the first step in knowing or designing a system is to obtain a complete analysis of the supply wate Table 2 is an example water analysis. Please note that a water analysis on a sample obtained at the city treatment plant may be significantly different from one obtained at the site Table 2. Typical Water Supply Analysis It Plant Feed Color Alkalinity 10 mg/L 3.2 mg Potassium 3. 1 mg/L 0.04 27 mg/L Nitrogen(nitrate) 0.002mg/L SDI(fouling index) Usually, immediately upon entering the plant, supply water is split into potable water and process water. This is done by using an air break or back flow preventers. This is a precaution against process contaminants backing up into potable or city water and vice versa. Often a break tank is used as the air break since it also provides storage capacity for demand surges592 Fermentation and Biochemical Engineering Handbook Regardless of the source, the first step in knowing the water supply or designing a system is to obtain a complete analysis of the supply water. Table 2 is an example water analysis. Please note that a water analysis on a sample obtained at the city treatment plant may be significantly different from one obtained at the site. Table 2. Typical Water Supply Analysis Item Plant Feed Turbidity Color Alkalinity Hardness (as CaCO,) Calcium Magnesium Sodium Potassium Iron Manganese Sulfate Chloride Nitrogen (ammonia) Nitrogen (nitrite) Nitrogen (nitrate) Copper SDI (fouling index) PH 0 0 8.8 16 mgk 38 mgk 10 mgk 3.2 mg/L 23 mg/L 3.1 mg/L 0.04 mg/L 0.03 mg/L 27 mgk 49 mg/L 0.05 mg/L 0.30 mg/L 0.002 mg/L 0.002 mg/L 25 Usually, immediately upon entering the plant, supply water is split into potable water and process water. This is done by using an air break or back flow preventers. This is a precaution against process contaminants backing up into potable or city water and vice versa. Often a break tank is used as the air break since it also provides storage capacity for demand surges at the use points