Preparation and Dosing Method of Polyaluminum Chloride for Sewage Plant

    Polyaluminum chloride (PAC) is a new type of water purification material and inorganic polymer coagulant, referred to as polyaluminum. It is a water-soluble inorganic polymer between AlCI3 and Al(OH)3. It has a high degree of electrical neutralization and bridging effect on colloids and particles in water, and can strongly remove trace poisons and heavy metal ions with stable performance. Due to the bridging effect of hydroxide ions and polymerization of multivalent anions, the polyaluminum chloride produced is a kind of inorganic polymer water treatment agent with large molecular weight and high electric charge.

    In the selection of coagulants should be adapted to local conditions, in general, you can choose polyaluminum chloride, low temperature can be used with the selection of iron salt coagulant, in the supply and quality assurance conditions, should be as far as possible to choose polyaluminum chloride (polyaluminum chloride corrosive, acidic after adding water, it is recommended to wear gloves, masks when using).

    I. Preparation and addition of polyaluminum chloride

    1、Preparation

    Small water plants in cities and towns usually use the dissolution tank and solution tank for preparation, the dissolution ratio is roughly 3%-10%, large water plants usually use automatic dosing device.

    2、Dosing

    According to the different dosing points and decide, generally divided into gravity dosing and pressure dosing two kinds.

   Gravity dosing: is relying on gravity to add the coagulant to the original water dosing method.

   When the dosing point is selected in the pump suction pipe or suction pipe flare, known as the pump before the dosing. Pump before gravity addition is the use of high-speed rotation of the pump impeller so that the coagulant quickly dispersed into the raw water. This method is safe and reliable, saving coagulant, generally applicable to the water pump from the water plant closer. However, this method of adding the pump impeller has a certain corrosive effect, especially when using iron salt as a coagulant.

  Pressure dosing: the use of water jets in the water pump outlet pipe with pressure dosing.

   Water jet efficiency is low, easy to wear and tear, but the equipment is simple, easy to use, the solution pool height is not too big a limitation. Currently used pressure dosing devices are mostly metering pump pressurized dosing, such dosing is easy to use, the solution pool height is not too large a limitation, dosing can be controlled.