Water purification method by adding flocking agent and removing ammonia, comprises reducing pH, contacting air and heating before ammonia desorption and absorption steps

摘要

The pH of the liquid being purified is reduced to less than 6, then the liquid is contacted with air to remove carbon dioxide and then the liquid is heated before the ammonia desorption and absorption steps. A method for purifying liquid comprises increasing liquid pH to a value greater than 7 and adding flocking agents, removing ammonia with air in a desorption step, absorbing ammonia in an acidic solution in an absorption step and recirculating the air. The pH of the liquid is reduced to less than 6 before the pH is increased, the acidic liquid is contacted with air so that carbon dioxide is removed and a substantially carbon dioxide-free liquid is obtained and the temperature of the liquid is increased to 40-100[deg]C before the desorption and absorption steps.