Method of reducing waste sludge using acid treatment and method of carbonating carbon dioxide with high purity using paper mill waste sludge

The present invention provides a method of carbonating carbon dioxide with high purity using a paper mill waste sludge by preparing a paper mill waste sludge which is a waste product discharged during the production of papermaking， adding acid to the paper mill waste sludge and reacting the acid therewith to produce a mixed solution and stirring， separating a supernatant of the mixed solution into an eluate， adding a basic substance to the eluate and adjusting pH to precipitate some of the ions in the eluate， and then adding a reaction initiator to the eluate in which some ions are precipitated and removed， and injecting carbon dioxide for a carbonation reaction.