Assessment of Phosphate Laundries Wastewater Phytotoxicity and Biotreatment Assays

Abstract

The phytotoxicity potential of phosphate laundries wastewater (PLW) is assessed. Likewise, the assays of biotreatment of the PLW by microbial detoxification are investigated. Chemical characterization results show that PLW are alkaline, saline, highly turbid, and rich in suspended matter and total solids. PLW samples are loaded with potentially toxic metals, presented in decreasing order as follows: calcium (1230 mg L−1), potassium (1032 mg L−1), iron (275.45 mg L−1), lead (1.64 mg L−1), zinc (1.12 mg L−1), copper (1.04 mg L−1), and cadmium (1.03 mg L−1). Besides, PLW exhibits high phytotoxicity values for Raphanus sativus, Medicago sativa, and Sorghum bicolor seeds germination. The microbiological enumeration reveals considerable autochthonous microflora. Biotreatment includes five selected native strains (Se, S16, S19, S20, and S29) used as a tool of PLW detoxification. The strains tested manifest a bioprocessing performance according to the following decreasing order: S29 > S16 > S20 > S19 > Se. The biotreated phosphate laundries wastewater (BTPLW) achieves a noticeable reduction of toxicity. Indeed, analysis of the correlation matrix between the potentially toxic metal content and the germination index (GI) values shows significant correlations (p ≤ 0.01).

Isolation, Characterization and Identification of a New Lysinibacillus fusiformis Strain ZC from Metlaoui Phosphate Laundries Wastewater: Bio-Treatment Assays

“…It was noticed that the COD, BOD 5 and TSS were all exceeding the previously reported ranges for industrial wastewaters [6]. Similar results were reported by many researchers [4,6]. The TSS/DBO 5 ratio explains that the material in suspension unsettles the oxygenation and bacterial activity.…”

“…The reported DBO 5 /DCO provides important indications on the origin of the pollution of the employed waters and the proper treatment to be accomplished [31]. It was noticed that the COD, BOD 5 and TSS were all exceeding the previously reported ranges for industrial wastewaters [6]. Similar results were reported by many researchers [4,6].…”

“…In addition, the Metlaoui phosphate laundries release a fine fraction (<70 µm) in effluents directly into the hydrographic network. Such effluents were rich in organic matter, which promotes an additional capacity to trap toxic elements [4,6]. It has been reported that these effluents contain high concentrations of sulfates, fluorine and various metals [36].…”

“…It has been reported that these effluents contain high concentrations of sulfates, fluorine and various metals [36]. In addition, many negative effects of mud on the structure and permeability of soils bordering laundries were reported [6]. On the other hand, it was reported that the MPLW effluents of the laundries of Metlaoui, Gafsa, contain various metal contaminants, such as cadmium, chromium, copper, nickel and strontium [5].…”

“…The accumulation of toxic metal ions in the soils receiving phosphate industries effluents as well as their phytotoxicity were equally demonstrated [4,5]. In fact, exposure to many elements present in the MPLW effluents was associated with several health repercussions, such as affecting the human respiratory system and causing dental fluorosis due to fluoride, while mining activities might lead to cancer [4,6].…”