A. Muela et al., DISCHARGE OF DISINFECTED WASTE-WATER IN RECIPIENT AQUATIC SYSTEMS - FATE OF ALLOCHTHONOUS BACTERIAL AND AUTOCHTHONOUS PROTOZOA POPULATIONS, Journal of applied microbiology, 85(2), 1998, pp. 263-270
The discharge of disinfected effluents affects the bacterivorous abili
ty of protozoa and the effect depends on the disinfectant applied. Chl
orine provokes a decrease in the number of protozoa and a delay in the
bacterivorous ability. The discharge of ozonated and peracetic acid-t
reated wastewater provokes only an initial slight decrease in bacteriv
orous ability. No correlation was found between toxicity values detect
ed using the Microtox(TM) assay and the effect of disinfected effluent
s on freshwater protozoa populations. After the disinfection processes
, recipient systems (fresh and marine water) have different effects on
the survival of Escherichia coli populations discharged to them. The
effect of the freshwater recipient system is less negative than the ef
fect provoked by seawater, and the differences detected depend on the
disinfection treatment applied. The wastewater bacterial population as
a whole is able to grow after discharge of disinfected wastewater to
receiving waters. However, in the absence of predation or competition,
the recipient systems exert selection, with rod-shaped bacteria predo
minating.