Reuse of Treated Wastewater for Crop Irrigation: Water Suitability, Fertilization Potential, and Impact on Selected Soil Physicochemical Properties

Abstract

This study evaluates the suitability of treated wastewater (TWW: secondary effluent and membrane effluent) for crop irrigation and the resultant impact on crop growth and soil physicochemical characteristics. Carrot seeds (Daucus carota subsp. sativus) were grown on loam soil and irrigated with tap water (Tap), secondary effluent (SE), and membrane effluent (ME) until maturity. Bacteriological analyses showed four log counts of E. coli and thermotolerant coliforms for secondary effluent, making it unsafe for the irrigation of carrots. Tap water and membrane effluent fulfilled the microbial limit for water reuse and were suitable for irrigation. The sodium absorption ratio, Kelly index, and magnesium hazard assessments indicated that all three irrigation water streams were suitable for irrigation. The average mass of carrot fruits for Tap, SE, and ME was 2.14 g, 3.96 g, and 3.03 g, respectively. A similar trend was observed for the dry matter composition: Tap had 15.9%, SE had 18.3%, and ME had 16.6%. The soil pH increased from 7.08 to 7.26, 7.39, and 7.33 for tap water-, secondary effluent-, and membrane effluent-irrigated soils, respectively. Nitrate-nitrogen and potassium levels increased in the TWW-irrigated soil, while that of the tap water-irrigated soil decreased. Sodium levels in the TWW-irrigated soil increased significantly but did not induce soil sodicity. The application of the TWW enhanced the growth of the carrot plants and increased the soil nutrient levels. Hence, using TWW in agricultural irrigation could promote food production and also limit the overdependency on freshwater resources. However, TWW should be disinfected by using UV disinfection and ozonation to reduce the risk of microbial contamination. Such disinfection methods may not lead to the formation of toxic byproducts, and therefore secondary pollution to crops is not anticipated.

A Data-Driven Method for Water Quality Analysis and Prediction for Localized Irrigation

“…The main physicochemical and bacteriological parameters that provide initial insights into water characteristics, including temperature (T), pH (hydrogen potential), conductivity (EC), suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), chloride, carbonate and bicarbonate, sulfate, nitrogen compounds, total aerobic mesophilic flora (TAMF), thermotolerant coliforms (TtC), total coliforms (TC), and fecal streptococci (FS) [3]. Ofori et al [21] stated that E. coli and thermotolerant coliforms in water make it unsafe to irrigate vegetables and fruits. Storlie (1995) [22] compiled the main causes of emitter clogging and the degree of restriction to water use in irrigation (Table 1).…”

Integrated environmental management and GPS-X modelling for current and future sustainable wastewater treatment: A case study from the Middle East

“…The treated wastewater (TWW) can be used in various sectors, including agriculture, landscape irrigation, artificial recharge, and industries [ 19 , 20 ]. For instance, the use of TWW is one of the most effective ways to address water shortages and nutrient requirements in agricultural systems [ 14 ].…”