SOUZA FILHO, J. E.; SOUZA FILHO, José Erasmo de.
Resumo:
The paper presents a study on the behavior of
forms of nitrogen and sulfur in a deep reservoir of
stabilization of sewage. They were monitored over time
the sulfate contents, total sulfide, organic nitrogen,
ammonia, nitrate and nitrite in domestic sewage (BOD5 = 200 mg / L)
treated in a deep stabilization tank, in order to
check whether these levels met the required requirements
water intended for unrestricted irrigation. The system
pilot scale, was composed of a
deep reservoir (REI: 1186 m3, 6,5 m deep),
whose effluent was the effluent of an anaerobic lagoon (A12: 45
m3; 6.5 m deep). It was operated by the
Experimental Biological Treatment of Sewage Systems
(EXTRABES) of the Federal University of Paraíba (UFPb), which
is located on the premises of the old
sewage treatment plant in Campina Grande, Paraíba,
northeastern Brazil (latitude 7 ° 13'11 "south and longitude 35 °
52'31 '' west, 550 m above sea level). Were done
two experiments (exp. I and exp. II), involving the phases of
filling, rest and emptying, with 159 and 70 days of
duration (30/3 to 5/9/94 and 26/9 to 5/12/94). No exp. I the times
of the reservoir and anaerobic lagoon were
35 days and 1 day, respectively, while in exp. I have been
used half of those times (18 days and 1/2 day, respectively). During the rest there was no
of the reservoir (operating
"batch"), except precipitation and / or evaporation. O
system was monitored in these periods through the collection of
samples every week and at 8 o'clock in the morning.
different levels along the liquid column. Were
analyzed in the laboratories of EXTRABES, in addition to the
of sulfur and nitrogen, pH, temperature, oxygen
dissolved, DB05, COD, suspended solids, chlorophyll a and fecal coliforms. It was not remarkable the occurrence of odors
unpleasant From the data obtained it was estimated that the
maximum permissible concentrations of sulfide and nitrogen
would be achieved in times less than three and
seven months, respectively, and, after those periods,
water to be used for unrestricted irrigation (without
consideration of the presence of other constituents). Is suggested
additional studies on the removal of
main constituents (organic matter, phosphorus,
faecal organisms, etc.) of domestic wastewater,
as well as alternative operational schemes, with a view to
technically, economically and environmentally sound use of
deep stabilization reservoirs, mainly in
regions such as the Brazilian Northeast.
