Risk Management During Effluent Application for Irrigation

Reuse of treated wastewater is a favourable direction for solving water shortage problems and meeting environmental quality criteria. Domestic wastewater in isolated communities in arid regions can be treated efficiently in a stabilization pond system. The effluent quality can be further improved when stored in a series of stabilization reservoirs. However the salinity of the wastes in the ponds will increase due to evaporation. There is a series of parameters that characterize the effluent quality for agricultural reuse. The conventional biological parameters include faecal coliforms as a microbial indicator. The use of faecal coliforms does not reflect the viral pollution of the effluent due to the poor correlation with virus occurrence. Therefore, phages are proposed as enteric virus pollution indicators. Phages exhibit similar behaviour and survival in an aquatic environment, and their quantitative assessment is easy and a reliable enteric virus measure. Field results from the treatment plant of the City of Arad (Israel) reveal the possibility of characterizing the effluent quality in stabilization ponds and additional reservoir systems. The field data also allows the type of reactor of which the system consists to be defined, and the kinetic expressions for further forecasting of the treatment system behaviour and removal rate of the pathogens.