Assessment of Municipal Treated Wastewater Quality for Irrigation in Orathanadu Block of Tamil Nadu, India

Aim: The current study focuses on the threats to the environment and human health that relate to using treated wastewater produced from the municipal sewage treatment plant of Orathanadu for irrigation purposes.

Study Design: For this purpose, samples were taken monthly from the outflow wastewater and grouped into seasons.

Place and Duration of study: Municipal sewage treatment plant located at Orathanadu, Tamil Nadu, during 2019.

Methodology: The treated wastewater quality parameters such as pH, EC, total dissolved solids, total suspended solids, five days biological oxygen demand, chemical oxygen demand, and sodium adsorption ratio were measured monthly and grouped season-wise.

Results: In treated wastewater, the minimal mean electrical conductivity values, total dissolved solids, five days biochemical oxygen demand, chemical oxygen demand, and sodium adsorption ratio were 0.81 dS m-1, 515.20 mg L-1, 25.50 mg L-1, 14.85 mg L-1, and 1.59, respectively. The suitability for irrigation based on the Sodium Adsorption Ratio (SAR) was calculated with standard equations and found experimentally as 1.59, 1.62, 1.59 and 1.56 during winter, summer, monsoon and post-monsoon seasons, respectively. To assess water suitability for irrigation, irrigation water classes are utilized for salinity hazard (EC) and sodium hazard (SAR), and samples were C3-S1 class in all four seasons. Furthermore, the data indicated a slight to moderate restriction on using this treated wastewater in irrigation due to chloride hazards.

Conclusion: The results showed that treated wastewater meets national and international irrigation criteria and that treated wastewater can be used without restriction in light and medium-textured soils and in clay soils with leaching and drainage.