Recovery of precious metals from processed wastewater: conventional techniques nexus advanced and pragmatic alternatives

Abstract

The loss of highly sought-after metals such as gold, silver, and platinum during extraction processes not only constitutes a significant waste of valuable resources but also contributes to alarming environmental pollution. The ever-growing adverse impacts of these highly valued metals significantly increase the contamination of water bodies on discharge, while reducing the reusability potential of their corresponding processed wastewater. It is, therefore, of great interest to identify pragmatic solutions for the recovery of precious materials from processed water. In this review, pollution from targeted precious metals such as gold, silver, platinum, palladium, iridium, ruthenium, and rhodium was reviewed and analyzed. Also, the hazardous effects are elicited, and detection techniques are enumerated. An insightful approach to more recent treatment techniques was also discussed. The study reveals nano- and bio-sorption techniques as adoptable pragmatic alternatives, among other techniques, especially for industrial applications with merits of cost, time, waste management, and eco-friendliness. The results indicate that gold (46.2%), palladium (23.1%), platinum (19.2%), and silver (11.5%) are of utmost interest when considering recent recovery techniques. High yield and cost analysis reduction are reasons for the observed preference of this recovery process when considering groups of precious metals. The challenges and prospects of nanomaterials are highlighted.

Valuable elements in sludge from eight municipal wastewater treatment plants in relation to their recovery potential

“…The spectrometer was optimized to provide minimal values of the ratios CeO + /Ce + and Ba 2+ /Ba + and optimal intensity of the analytes. The concentrations of the elements were determined using the isotopes as follows: 7 Li, 11 B, 24,25,26 Mg, 27 Al, 31 P, 39 K, 42,44 Ca, 46−49 Ti, 51 V, 52 Cr, 54,57 Fe, 55 Mn, 59 Co, 60,62 Ni, 63,65 Cu, 64,66 Zn, 69 Ga, 75 As, 86,88 Sr, 96, 98 Mo, 105, 108 Pd, 107,109 Ag, 112,114,116 Cd, 121,123 Sb, 197 Au, 200,202 Hg and 206,207,208 Pb. Due to the presence of spectral polyatomic interferences on the isotopes of As and Pd, their concentrations were determined in DRC mode [36,37].…”

“…The circular economy concept gives new perspectives for sludge utilization as a source of critical elements and appears alternative to sludge utilization in agriculture [25][26][27]. The ever growing development of electrical, IT and telecommunication industry, the search for energy storing facilities has raised significantly the demand of metals such as nickel, lithium, copper, cobalt, manganese [28].…”

“…Also, palladium (Pd), platinum (Pt) and rhodium (Rh) are better to be recovered after incineration of sludge as they are more concentrated and no longer bound to the organic matter [27]. The advancements in recent recovery techniques from sewage sludge, reported by Adeeyo et al suggest that due to increased yield and cost reduction, gold, palladium, platinum, and silver are of the highest interest for recovery from sludge [26].…”

Sustainable Recovery of Platinum Group Metals from Spent Automotive Three-Way Catalysts through a Biogenic Thiosulfate-Copper-Ammonia System

“…The recovery of precious metals like Pd, Pt, and Rh from the liquid phase after a leaching process is indeed a complex process that often involves adjusting the pH and introducing a suitable precipitating agent to cause the precious metals to form insoluble compounds, which can then be separated from the liquid phase [74,75]. Additionally, as the conditions change, such as controlled cooling or evaporation of the leachate solution, precious metal compounds may precipitate out of the solution in the form of solid crystals [76]. These crystals can be further processed to obtain the pure metal forms.…”

Adsorption Behavior and Mechanism of Palladium on Diethylaminoethyl-Modified Polyglycidyl Methacrylate Macroporous Spheres

“…Several separation technologies, such as precipitation, adsorption, electrowinning, supercritical fluid, and biomediated approaches, are available for the recovery of precious metals from aqueous solutions . Among these techniques, adsorption is emerging as the most preferred technique due to its high efficiency, eco-friendliness, and applicability to solutions with low concentrations of noble metals. Adsorption has been demonstrated to be a selective means of recovering valuable metals , or removing harmful metals from different media or wastewaters. , …”