Eficiência de remoção de nitrato e amônia de efluente secundário com microalga Chlorella vulgaris imobilizada em esferas de alginato de cálcio

Abstract

The treatment of sewage in Brazil has, in most cases, four stages: preliminary, primary, secondary and tertiary. It is known that domestic sewage without adequate treatment in water can cause eutrophication, with nitrogen being one of the responsible for this process. This work uses the microalgae Chlorella vulgaris to remove nitrogen in the form of nitrate and ammonia from secondary domestic sewage. In this sense, the pre-sent work aims to evaluate the efficiency of the removal of nitrate and ammonia from domestic sewage collected from the Sanitation Company of Paraná, located in Ponta Grossa, using C. vulgaris immobilized in calcium alginate spheres. The methodology used was the encapsulation technique, in which a biopolymer is mixed with the micro-organism and dripped over a solution of calcium chloride. The immobilization technique is used to facilitate the recovery of cells and generate protection against environmental stress in the culture medium. Spheres with C. vulgaris are kept in Erlenmeyer flasks, under artificial lighting and temperature control, in order to increase the efficiency of nutrient removal. The microalgae C. vulgaris was able to remove 85.19% of ammonia and 30.95% of nitrate from the effluent in question. There was an increase in pH from 7.05 to 9.25 due to the photosynthetic activity of the microalgae. With the results of the work, it is possible to reduce the nitrogen load in the effluent treatment process using microorganisms. Thus, future studies of the application of the generated biomass can be carried out, contributing to the treatment of effluents and increasing the income with the generated products.