ALKALINITY OF WATER Alkalinity of water is a capacity of water to neutralized acid. Alkalinity is important in coagulation process in water treatment. It is caused due to presence of carbonite, bicarbonate and hydroxide of salts. There are three form of alkalinity carbonate alkalinity, Bicarbonate alkalinity and Hydroxide alkalinity. It is also important in determination of component of hardness of water. Hardness Components Carbonate Hardness (CH) and Non Carbonate Hardness (NCH) Total Hardness= Carbonate Hardness (CH) + Non Carbonate Hardness (NCH) Alkalinity is only Carbonate and Bi-carbonate alkalinity If TH > Alkalinity, CH=Alkalinity, NCH=TH-CH If TH ≤ Alkalinity, then CH=TH, NCH=0 PERMISSIBLE LIMITS Highest Desirable Limits (HDL) Maximum Permissible Limit (MPL) 200 mg/L as CaCo 3 600 mg/L as CaCo 3 ALKALINITY AND PH RELATION Forms of alkalinity depend on pH value of water. pH Alkalinity >11.3 OH – only 10.5 – 11.3 (OH – & CO 3 — ) or CO3 — only 8.3 – 10.5 (CO 3 — & HCO 3 – ) or CO 3 — only 4.5 – 8.3 HCO 3 – <4.5 Nil ALKALINITY CALCULATION (THEORETICAL) POST NAVIGATION