ISHS Acta Horticulturae 573: International Symposium on Techniques to Control Salination for Horticultural Productivity
INDICATOR MICROORGANISMS IN RECLAIMED WATER USED FOR IRRIGATION |
| Authors: | J.J. Posnett, R.E. Longdin, M. Costa, L.P.C. Dionísio |
| Keywords: | Reclaimed waters, sewage treatment, indicators, faecal pollution, coliphages |
| Abstract:
A survey on the microbiological quality of water from a waste stabilisation pond, of about 30ha in size was conducted. This pond corresponds to secondary treatment of a domestic wastewater plant, and produced about 3 x 106 m 3 of reclaimed water per year which is used for irrigation purposes. Faecal indicators are enumerated in order to obtain information about their evolution along the sampling period, as well as the factors that influence the variations observed. Classical indicators of faecal pollution, such as total coliforms (TC), faecal coliforms (FC) and faecal streptococci (FS) were enumerated by the membrane filtration technique. Other indicators such as somatic coliphages were used and quantified by direct counting using a double agar layer. Physico-chemical parameters (temperature, pH and salinity) were also determined. Studies of microbial inactivation rates were evaluated using the T90 parameter. The relationships between the studied microorganisms, the physic-chemical parameters and their survival rates were established. It was found that the total coliforms ranged between 7x104 to 3.65 x107. As expected faecal coliforms were less abundant ranging from 4 x101 to 5.57 x105. Faecal streptococci ranged from 1 x102 to 2.19 x106(UFC/100 ml). Coliphages went up to 1.5 x104 (PFU/100ml). | |
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