Avaliação da remoção de matéria orgânica em reservatório profundo de estabilização.

Abstract

Wastewater reservoirs were initially conceived in Israel in the early 70's for seasonal storage of wastewater during the winter for agricultural irrigation during the dry season. Today, in Israel, there are around 130 WR with storage capacities from 50,000 to 11 million m3 and depths between 6 and 14 m. Spain and India are exemple of countries where this technology is also in use This work describes the performance of a W R ( ESR-1 ) fed with an anaerobic pond effluent ( A1 2 ) , in relation to the organic matter removal. The pilot scale reservoir was located in the EXTRABES site ( city of Campina Grande - Paraiba - Brazil, 7° 13' 11" S, 35° 52' 31" W, 550 m a.s.l.). Two experiments comprising cycles of filling - resting - emptying were carried out in ESR-1. During the first experiment ( April to September, 1994 ) the reservoir was filled in 34 days while in the second ( September to December 1994 ) in 18 days. Grab samples were taken weekly at 8 a.m and 3 p.m. throughout the water column. During filling and emptying phases, samples were taken only after the water level had risen or fallen by 1 metre, respectively. Samples collected at 8 a.m, were analysed for BOD, COD, pH, suspended solids, temperature, dissolved oxygen and alkalinity. Samples collected at 3 p.m. were analysed only for temperature, pH and dissolved oxygen. Samples of raw sewage and anaerobic pond effluent ( A i 2 ) were taken weekly at 8 a.m.. Results in both experiments were similar to those observed in W R in Israel and others countries.BOD removals of 81 and 78 % were observed in ESR-1 respectively in experiment I and experiment II. The higher filling time in the first experiment did not cause a higher BOD removal.