Phosphorus biostimulation and phytoremediation in wastewater treatment used for alfalfa plant irrigation

ABSTRACT This study addresses the potential of combining phosphorus biostimulation and phytoremediation as a sustainable strategy for wastewater treatment. Various physico-chemical analyses and microbiological parameters were assessed in different treatments: biostimulation, phytoremediation, and a combined method. These assessments were conducted for both treated (STWW) and untreated wastewater (SWW) categories. The alfalfa plots were then irrigated with the treated wastewater (TWW), followed by enzymatic activity analyses, microbiology, physico-chemical properties, and plant growth. The results show that the selected strain, identified as Aspergillus flavus OQ269829, increased the assimilable phosphorus content of the SWW, raising it to about 3.25 mg/L in the irrigated soil. The TWW presents a neutral pH of less than 8 and a chemical oxygen demand value below 120 mg O2.L−1, together with an increased phosphorus transformation. Dehydrogenase activity in soil irrigated with STWW supplemented with fungi and phosphorus rose from 4.5 to 10.5-μg TPF g−1·h−1 by the end of the incubation period. The plant exhibited significant growth and earlier flowering. Concurrent with this, there was an increase in plant nutrient content when irrigated with a combined application of K+ and Na+, ranging from 104.36 to 189.59 mg·g−1 dry weight for K+ and 15.3–29.9 mg.g−1 dry weight for Na+.