SOME ENVIRONMENTAL-PROBLEMS ASSOCIATED WITH THE USE OF TREATED WASTE-WATER FOR IRRIGATION IN JORDAN

Treated effluent was used for eggplant (aubergine) irrigation through a trickle system at As-Samra experimental site. The soil characteristi cs were determined prior to irrigation. Physical, chemical and biologi cal characteristics of the effluent were determined during the growing season. Suitability of the effluent for irrigation was studied. The c rop and soil were tested for pathogenic pollution. The accumulation of salts and heavy metals in the soil as well as concentration of the nu trients and heavy metal accumulation in the plant tissues were determi ned. Clogging of the irrigation system was evaluated and treated. Yiel d was determined. Results of the study showed that the effluent has a low heavy metal content. It showed moderate restriction for surface tr ickle irrigation. Regarding the microbiological quality of the treated wastewater, it was found that the faecal coliform ranged from 2.1 X 1 0(3) to 1.8 X 10 Most Probable Number (MPN) per 100 ml at the irrigate d site, while it is free from nematode eggs. The soil surface under th e effluent irrigation water was found to contain faecal coliform, but the count drastically decreased with depth. Except for a very low coli form count on fruit skins, no coliform count was found on the crop lea ves, whether they were Free or in contact with the soil. The effluent showed a rather high concentration of chlorophyll a due to the presenc e of algae. Results of soil analysis after eggplant harvest showed a s light increase in heavy metals and salt accumulation at the periphery of the wet zone. Nutrients and heavy metal concentration in eggplant t issue under treated effluent irrigation was within the normal range in agricultural crops. Although filtration of the effluent was not pract ised, there was minimum clogging of the irrigation system. This cloggi ng was successfully controlled with acid and chlorine. Eggplant yield under treated effluent was twice the average eggplant production under fresh water irrigation using conventional fertiliser application in J ordan. (C) 1997 Elsevier Science B.V.