What problems should be paid attention to in the selection and use of coagulant

     Among inorganic coagulants, the floc density formed by iron salt is higher, and the dosage of flocculant is less. Especially for the regulation of activated sludge, its coagulation effect is equivalent to that of polymer coagulant, but it is corrosive and difficult to store and transport. When the dosage of ferric salt coagulant is large, lime should be used as coagulant aid to adjust pH value. The floc formed by aluminum salt coagulant has low density and high dosage, but it has weak corrosiveness and is convenient for storage and transportation.

     The inorganic coagulant is cheap and easy to obtain, but the amount of slag is large, which is greatly affected by pH value. After treated by inorganic coagulant, the amount of sludge increased, the proportion of inorganic components in sludge increased, and the combustion value of sludge decreased.

     The main characteristics of polymer coagulants are that the consumption of chemicals is much lower than that of inorganic coagulants, safe treatment, easy operation, weak acidity or weak alkalinity in water, small corrosivity and little increase in filter cake quantity; when the filter cake is used as fuel, it has high calorific value and less ash after incineration. However, before using polymer coagulant, it is necessary to do coagulation test on various sludge. It should also be noted that although the coagulation and precipitation properties of suspended particles can be improved sometimes, the dehydration performance may not be improved.

The following points should be paid attention to when using coagulant.

(1) It is necessary to pay attention to the dosing sequence when the coagulants are used together. For example, when ferric chloride and lime are used, iron salt should be added first and then lime should be added. At this time, the filtering speed is fast and the reagent is saved. When polymer coagulant is combined with coagulant aid, coagulant aid should be added first.

(2) Different types of coagulant are needed for different mechanical dewatering methods. Generally, the effect of vacuum filtration and pressure filtration dehydration using inorganic coagulant or polymer coagulant is similar, centrifugal dewatering requires the use of polymer coagulant.

(3) Pump circulation mixing or stirring will affect the coagulation effect, and increase the filtration specific impedance, so it is difficult to dehydrate.

      Doyen specializes in providing belt press equipment for the Southeast Asian market. Welcome to visit our workshop, according to the actual situation of your company, develop a more scientific dehydration program.Welcome to joyce@doyenchina.com or visit https://www.doyenchina.com.