Effects of Treated and Untreated Wastewater from Municipal Solid Waste (MSW) Leachates on the Nutritional State of Viola spp.: Sodium, Potassium, Calcium, and Magnesium

Abstract

The scarcity of water for different uses has created a need for using nonconventional water resources, such as wastewater and saline water. Their use could contribute to reduced water resource consumption in arid areas and biosphere contamination. Wastewaters are normally unbalanced solutions rich in sodium (Na⁺), calcium (Ca²⁺), magnesium (Mg²⁺), sulfate (SO₄ ²⁻), and chloride (Cl⁻), which can cause damages to crops, but if they are treated, their quality can increase. The aim of this trial was to study the effects of pure, diluted, sand-filter depurated, and phytodepurated wastewater from municipal solid waste (MSW) leachates, compared with groundwater on the nutritional state of the ornamental plant Viola spp. The experimental design was unifactorial (type of irrigation water). Five treatments were tested: R9.0 [wastewater, electrical conductivity (EC) 9.0 dS m⁻¹], R4.5 (wastewater, EC 4.5 dS m⁻¹), D4.5 (depurated water, EC 4.5 dS m⁻¹), FD4.5 (phytodepurated water, EC 4.5 dS m⁻¹), and P (groundwater, EC 1.5 dS m⁻¹). Nutrient (Na⁺, K⁺, Ca²⁺, and Mg²⁺) concentrations and partitioning per fraction (flowers, aerial vegetative fraction, including stems and leaves [called AVF], and roots) were studied. Similar total Na⁺ extractions were found in the 4.5 dS m⁻¹ treatments, being greater than in the 9.0 dS m⁻¹ treatment, all of the surpassing the control. Nevertheless, there were Na⁺ partitioning per fraction differences depending on Na⁺ concentration. Total K⁺ extraction was the greatest in FD4.5, related with its greater root concentration. Potassium was mainly located in AVF, followed by flowers. Calcium and Mg²⁺ extractions showed a similar behavior. The greatest Ca²⁺ extraction was noticed in control plants, which is related with Ca²⁺ accumulation in roots.

Keywords:

• Nutrient concentration
• nutrient partitioning
• phytodepuration
• phytopurification
• sulfate

Acknowledgments

The first author is supported by a Formación de Protesorado Universitario (FPU) grant through the MICINN (AP2007-02786) at the University of Almería. The authors thank Eva Borghesi, Cecilia Diara, Rita Maggini, and Giorgio Incrocci for their assistance with the laboratory work.