ARRUDA, C. B. A.; ARRUDA, Carolina Baracuhy Amorim.
Résumé:
This work evaluated the operational performance of a deep anaerobic pond (8 m), situated
in the Sewage Treatment Plant of Paraiba River Basin in Joao Pessoa city (7° 10" South;
34° 49" West), Paraiba state, northeast Brazil, built upon a limestone exploitation
degraded area. Monitoring of both influent raw sewage and the pond effluent was carried
out from February to October 2003 with the analysis of the following variables: pH, BOD5,
COD, Temperature, Suspended solids, Electrical conductivity and Total alkalinity as well
as the fecal indicator - Thermotolerant coliform. A study of the inflow variability and two
24 hour-profiles have also been done. Results concerning the flow-rates monitoring have
enabled the estimating of the pond actual hydraulic retention time around 4.5 days for a
daily average flow of approximately 216 1/s. The volumetric organic loading of 86,45 g
BODs/m ,d has been determined. The study carried out in this system showed that the deep
anaerobic pond performance was typically the same of those of conventional anaerobic
ponds treating domestic wastewater, because the treatment process based on the anaerobic
digestion does not seem to be affected by the depth of the reactor. The experience of
adaptating a deactivated quarry as anaerobic pond has been proved as satisfactory,
although its effluent does not yet comply with the requirements for discharge into
receiving water bodies. Thus, since the area which the pond Is located In, has other quarries
that are being deactivated, it is possible to plan the adaptation of other treatment units,
subsequently to the anaerobic pond studied herein.
