Sludges: Analysis procedure for evaluating the utilisation potential

A study was conducted to develop an analytical procedure that would provide information of the utilization potential of sludge fractions. The possibility to recirculated material within a process was investigated including the cleanliness of the fractions, along with the determination of the share of organic and inorganic material. The reuse of fractions of primary sludge from a chemical pulp mill and flotation froth, along with fine screening rejects from deinking plant were examined and the utilization potential of the fractions were discussed. The primary sludge was taken from a chemical pulp mill waste water treatment plant while flotation froth reject and fine screening reject were taken from a deinked pulp mill. A deinked pulp sample was also taken from the fine-screening accept after pre-flotation to be used as a reference. The first stage of the procedure involved removing any disturbing material from the sludge sample which harmed the following analysis stages.