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Physical-chemical and phytotoxic evaluation of treated/reclaimed wastewater intended for agricultural irrigation

Abstract:

The most widespread application of reuse of treated / reclaimed domestic wastewater is agricultural irrigation. The common regulations on quality of reclaimed water for reuse contemplated physicochemical and biological parameters to minimize health risks, but rarely taken into account phytotoxic parameters that may be limiting for agricultural applications. The physicochemical and phytotoxic parameters change to advance the degree of purification / regeneration of wastewater, so it is of interest to know what stage of the installation provides adequate water for irrigation. This paper presents a correlation study of phytotoxicity with physicochemical parameters in water samples taken at the end of each of the stages of conventional treatment of domestic sewage, including biological reactor activated sludge treatment and tertiary sand filtration, chlorination, filtration cartridge and desalination by electrodialysis reversal. In each sample was measured. Chemical oxygen demand, pH, conductivity, organic carbon, total phosphorus, soluble proteins and ions of Na, K, Ca, Mg, B, F and Cl criteria phytotoxicity were evaluated by Lactuca sativa biomarker.Results showed significant reductions in physicochemical parameters of electrodialysis process, while the effects of phytotoxicity showed reductions in the processes before the final stage of electrodialysis.We conclude that the physico-chemical, together with the biomarker parameters are aspects of practical interest that relates the type of treatment with physical-chemical quality and phytotoxicity of treated / reclaimed water obtained and their suitability for agricultural irrigation applications.