Rev. Bras. Ciênc. Solo.2005;29(6):987-94.
Nitrogen dynamics in sewage sludge stored under distinct conditions
01/Dec/2005
DOI: 10.1590/S0100-06832005000600016
This study aimed to evaluate total N, N-NH4+ and N-NO3– concentrations and pH in columns of alkalinized anaerobic sewage sludge and in percolated liquid, in simulation of real storage conditions. The experiment was conducted in Curitiba – Paraná state, in Cfb climate and rainfall of 197 mm during the incubation period (48 days). The tested factors were: 3 sludge types (covered alkalinized sludge – LCC; uncovered alkalinized sludge – LCD; and uncovered raw sludge – LBD), 4 incubation periods (0; 15; 27; and 48 days) and 5 column sampling depths (0-5; 5-20; 20-50; 50-80; and composite sample 0-80 cm), with 4 replications. The percolated liquid was evaluated on day 1, 5, 9, 13, 27, 36, and 48. Alkalization (CaO) used was equivalent to 50 % sludge dry matter. The cover (sealing with plastic blanket and asbestos cover in LCC) had the purpose to contain gas volatilization, especially ammonia (NH3). The conditions of the environment caused by sludge alkalization significantly reduced the intensity of N mineralization and nitrification. The raw and alkalinized stored sludges presented considerable N-NH4+ and N-org losses. The effect of dilution, NH3 volatilization and organic mineral leaching as result of the alkalization reduced N-total concentration to 50 %. The alkalization process increased N losses through NH3 gas volatilization and N-NH4+ leaching, while the cover reduced N losses in the NH3 form.
24