Redução de amônia em lagoas de estabiliza em escala real

Abstract

Waste stabilization ponds are a type of sewage treatment system with great acceptability in Brazil, due to the ease and low cost of operation and maintenance. In this type of treatment, there is significant removal of organic matter and nutrients, such as ammoniacal nitrogen, through biological processes involving algae and bacteria. The present study focused on a series of primary facultative ponds located in Rio Grande do Norte, in order to estimate the removal of organic matter and ammonia. The Biochemical Oxygen Demand (BOD) and Chemical Ox-ygen Demand (COD) were used to characterize the organic matter of these ponds. The removal coefficients (k) were calculated on the basis of first order kinetics for the complete mixing regime and piston flow regime. The mean values of k for complete mixing regime were 0.089 d-1; 0.259 d-1; 0.078 d-1; 0.076 d-1; 0.201 d-1 for ammonia, BOD, filtered BOD, COD, filtered COD, respectively. For the piston flow regime, the values of k were 0.053 d-1; 0.095 d-1; 0.048 d-1; 0.047 d-1; 0.083 d-1 for the same parameters mentioned above, in the same order. It was concluded, by correlation analysis, that some coefficients were positively correlated. It was also determined the superficial rates of surface application and removal, which were self-correlated, and it was verified that the higher the loading of organic matter or ammonia in the facultative pond, the greater the respective removal rate.