Phosphorus removal from wastewater by carbonated bauxite residue under aerobic and anoxic conditions

Abstract

This study aimed at evaluating the potential use of carbonated bauxite residue (CBR) as filter substrate to upgrade phosphorus (P) removal in small wastewater treatment plants such as constructed wetlands. Comparative experiments of P removal were performed in two columns continuously fed with synthetic and real wastewater to investigate the behavior of CBR under aerobic (column A) and anoxic biotic conditions (column B). The effect of various parameters, including pH, temperature, addition of organic carbon, and dissolved oxygen concentration, was investigated. Also, a series of chemical extractions was performed to elucidate the main mechanisms of P removal achieved by CBR. Over 140 days of operation, columns A and B showed a total P removal performance of 98.5% and 91.6%, thus reaching a total P removal capacity of 0.63 mg P/g CBR and 0.61 mg P/g CBR, respectively. The results indicate that 2 aeration conditions and microbial activity can significantly affect the performance of CBR filters. Under aerobic conditions, precipitation of CaP complexes appears to be the main mechanism leading to P removal. Under anoxic biotic conditions, microbially driven mobilization of Fe from CBR may provide Fe ions for Fe-P precipitation, but also it may lead to Fe release from the filters. This study provides crucial information to evaluate the potential use of CBR at different steps of the wastewater treatment process. Overall, the results indicate that the use of CBR filters is particularly suitable as a tertiary treatment step to remove P from effluents with low organic load under aerobic conditions.

Effect of different wastewater composition on kinetics, capacities, and mechanisms of phosphorus sorption by carbonated bauxite residue

“…Then, the supernatants from each extraction were filtered (0.45 µm filters) before P, Ca, Al, and Fe analyses. This three-step extraction protocol has also been applied to raw CBR, with the aim of quantifying the P fractions in CBR before its use for wastewater treatment, and to CBR after 140 days of continuous flow P sorption experiments (Column A in Barca et al [25]), with the aim of investigating P removal mechanisms of CBR under continuous flow conditions. All the supplementary batch experiments and chemical extractions were performed in duplicate.…”

Technospheric Mining of Mine Wastes: A Review of Applications and Challenges

“…More than 2.7 billion tonnes of bauxite residue have been stockpiled so far, and every year, 150 million tonnes are being added to this inventory [12,42]. Only 3~5% of bauxite residue, at the moment, is being repurposed for cement and ceramic production [19]. This presents the immense potential for bauxite residue as a valuable source of Sc.…”

“…Bauxite residue from aluminium processing can be used as an additive in cement, concrete, bricks, and geopolymer production [79]. Recent research showed that carbonate bauxite residue can be suitable as a filter to remove phosphorus from wastewater streams [19] and also as a catalyst [81]. Mine wastes have also found applications in geopolymer preparations.…”

Phosphorus adsorption from aqueous solutions using different types of cement: kinetics, isotherms, and mechanisms

“…8 In contrast, industrial wastes and by-products like steel slag, bauxite residue, mine drainage residuals, and red mud demonstrate superior P adsorption capacity owing to the presence of aluminum, iron, and calcium salts. [9][10][11][12][13][14] However, the efficacy and potential impacts on ecological systems of employing these adsorbents for P adsorption depend signicantly on factors such as organic matter, alkalinity, pH, coexisting ions, and raw materials. 15,16 A recent research using mine drainage residuals for internal P control has indicated that only negligible amounts of trace metals are introduced into the water column and sediments.…”