If process is carried out at room temperature it is called cold lime soda process.

1) Cold process i) Batch process

ii) Cold Continuous process:-

Coagulant is necessary because at room temperature precipitate is finally divided. But do not settle easily & cannot easily filtered.

$NaAlO_{2}+2H_{2}O--\rightarrow NaOH+Al(OH)_{3}$

Mechanical stirrer is …