EVALUATION OF DIFFERENT COAGULANTS FOR PHOSPHORUS REMOVAL IN DAIRY INDUSTRY EFFLUENT

Abstract

Effluent treatment processes may be currently performed by physic-chemical or biological processes which may be aerobic as well as anaerobic. Both processes generally aim to remove organic loading. The study aimed to evaluate the application of coagulants for effluent treatment in a dairy industry by using two different coagulants which are ferric chloride and aluminum sulfate - both were dosed at the beginning of the treatment, i.e., in the flotator. Along with phosphorus analysis, pH, conductivity, and total nitrogen were also carried out. Both treatments were robust and efficient regarding the removal of phosphorus, reaching removal percentages of 97.7% of phosphorus when ferric chloride was used and 98.9% when aluminum sulfate was used. Regarding other parameters studied, the total amount of nitrogen was below 20 mg L-1, pH average was 5.56 while conductivity rates increased 30% due to the greater quantity of ions after the treatment. Results are in agreement with the Resolution of CONSEMA no. 128/2006 regarding to liquid effluents for emissions that discharge effluents in superficial waters in Rio Grande do Sul State.