TREATMENT OF DAIRY EFFLUENTS WITH CHITOSA N

The efficiency of chitosan to reduce organic loads of effluents contai ning various proportions of milk was investigated in laboratory scale. Best results were obtained from substrates at a pH of 6.5. About 16 g chitosan dissolved in 1 % acetic acid were required per kg organic ma tter to obtain the optimum of precipitation. Higher concentration of m ilk demanded a higher proportion of chitosan. In all levels of dilutio n a residual amount of only 4 % of the original quantity of milk fat w as left. The residues of protein to be found after treatment with chit osan were proportional to the concentration of milk in the original su bstrate. About 43 % of the original quantity of protein and 70 to 80 % of lactose, as expected, could not be precipitated. About 50 % of the original amount of organic matter could be removed from mixtures of m ilk and water by the treatment with chitosan. No remarkable influence of various degrees of deacetylation, reaching from 77 % to 94 %, and o f ageing, from 1 to 8 weeks, of the solutions of chitosan were observe d. In two samples, Chemical Oxygen Demand was reduced by treatment wit h chitosan to approximately 40 % of the original level.