Comportamento de coliformes fecais ao longo de uma série de lagoas de estabilização profundas tratando esgotos doméstico.

Abstract

The objective of this work was to study the distribution of fecal coliforms along the water column of a series of deep stabilization ponds, treating raw sewage from the sewage system of the city of Campina Grande - Pb. (a) anaerobic lagoon (A7), followed by optional Q1 (one) and three (03) maturation ponds (M7, M8 and M9). The investigated reactors presented organic surface loads between 52 and 475 kgDBO5 / ha.day, and depth of 2.20 m, with the exception of the last reactor (Mg), which was 2.25 m deep. The experimental system was located in the Experimental Station of Biological Treatment of Sanitary Sewers (EXTRABES), in the city of Campina Grande (35 ° 52'31M0) (7 ° 13'11 "S), Paraíba, Brazil. in the period from 03/22/87 to 05/11/87, continuing studies on the characterization of the liquid column in deep lagoons, started in 1985. Weekly experiments were carried out with a duration of 24 hours, and collections were performed every 04 hours The parameters analyzed in samples collected along the liquid column were fecal coliforms, pH, temperature, dissolved oxygen, chlorophyll a and identification and algal genera. During the experiments, the fecal coliform densities along the liquid column were observed during The variation of chlorophyll a in this study was significant, mainly in M9, M7 and M8. Variations of pH and dissolved oxygen were observed throughout the deep which was attributed to algae activities. Finally, it was observed that these parameters influenced the number of fecal coliforms in each reactor. The genera of flagellated algae Euglena, Pyrobotrys and Chlamydomonas were present in the five reactors of the series, whereas other genera, appeared sporadically in the lagoons. With the exception of the Anaerobic lagoon A7, the minimum concentrations of fecal coliforms, compared to the maximum, at 5 cm depth, were always related to the higher values ​​of pH and dissolved oxygen, and to the lower values ​​of chlorophyll a. On the other hand, in the deeper layers (195 cm) there was no clear relation between the minimum fecal coliform and the physical-chemical and algological parameters.