STUDY CONCERNING PERFORMANCES OF TWO TYPES OF PREHYDROLYZED POLYMER IN COMPARISON WITH ALUMINUM SULPHATE AS A COAGULANT FOR WASTE WATER

Abstract

The main environmental problems of pulp and paper production are water consumption, pollutant fillings of effluents (biogenic and refractory organic compounds, suspended solids, colloids, toxic inorganic compounds). This industry is obliged to minimize its impacts on the aquatic environment and at the same time, due to huge water consumption, must adopt strategies for sustainable use of water resources, in the context of ensuring European requirements for integrated pollution prevention and control and implementation of the Framework Directive of water.

The original experimental research refers to the improvement of the efficiency of conventional physicochemical treatment of residual effluents from the pulp and paper industry by using new prehydrolysed coagulation-flocculating agents. This stage is preliminary to the advanced effluent treatment stage, for its recirculation in the technological process.

Correlating these structures with the efficiencies obtained in coagulation, it is noted that the low coagulant doses of PAC-1 and PAC-2 compared to SA, are due to the existence of more active polymeric species of Al₁₃⁷⁺ or Al₃₀¹⁸⁺, with higher load and molecular weight than in the case of aluminium monomeric species formed in the use of aluminium sulphate.

There are high efficiencies for removing turbidity between 98-99% as well as organic loading of about 70% for the three coagulants studied (SA, PAC-1, PAC-2), but for the same efficiencies the doses of SA were double or even triple those required for PAC-1 and PAC-2.