Rehabilitation of a complex industrial wastewater containing heavy metals and organic solvents using low cost permeable bio-barriers – From lab-scale to pilot-scale

Abstract

This work addresses the treatment of a complex industrial effluent containing high concentrations of metals and spiked with two organic solvents (diethylketone -DEK, and methyl ethyl ketone -MEK) using an eco-friendly approach. The treatment system herein proposed consists of a bio-barrier that combines the adsorption capacity of sepiolite with the properties of a Streptococcus equisimilis biofilm with proven ability in the degradation and bioremoval of a wide range of pollutants.Results from the open-systems experiments conducted with raw sepiolite exposed to a binary mixture of DEK and MEK revealed the preference of the sorbent towards DEK. The results from the biodegradation experiments also revealed the preference of S. equisimilis to degrade/bioremove DEK over MEK independently of their initial concentration (100 mg/L to 3200 mg/L). Bioremoval percentages higher than 95% were reached for all the concentrations of DEK tested. The lab-scale experiments conducted in open-system with sepiolite and sepiolite covered with biofilm, and the pilot-scale experiment conducted in closed-loop, revealed similar performances on the rehabilitation of an industrial effluent containing heavy metals and additionally spiked with DEK and MEK. Regarding the selectivity towards the different pollutants, Cu was preferentially removed over Cr and Ni, and DEK over MEK. The presence of the biofilm allowed an improvement on the removal of heavy metals, particularly Cr, besides preventing the leaching of Al, Fe, and Mg from the sepiolite structure, an extremely important advantage in comparison to the system without biofilm. EDS analyses performed in sepiolite samples revealed the presence of several metals (Cr, Cu and Ni), proving thus the occurrence of sorption processes by sepiolite and by sepiolite covered by biofilm. The breakthrough data obtained in the open-systems were properly described by the Dose Response and the Yoon and Nelson mathematical models. More research work needs to be performed with complex industrial effluents aiming the optimization of the treatment systems to be applied in real context scenarios.

Cleaner Approach for Atrazine Removal Using Recycling Biowaste/Waste in Permeable Barriers

“…Raw sepiolite (Figure 3A) exhibits a micro-fibrous texture, with inter-fibers/bundles spaces. Its textural properties were reported in previous works by this research group: surface area (S BET ) of 181.35 m 2 /g, pore volume of 0.30 cm 3 /g and average pore size of 65.8 Å [28]. Figure 3C shows a radial view of a ray of Pinus pinaster bark constituted of small pits.…”

“…In this model, α is the parameter that is associated with the shape of the breakthrough curve. When α ≤ 1, the model displays a parabola-like curve, and for α > 1 the curve assumes a sigmoidal shape [28].…”

Microbe–Mineral Interaction-Induced Microorganism-Augmented Permeable Reactive Barriers for Remediation of Contaminated Soil and Groundwater: A Review

“…12 Furthermore, sepiolite or sepiolite-immobilized S. equisimilis was used to construct two types of Bio-PRB columns for the remediation of Cr(VI)-contaminated groundwater in a chromium plating factory (Figure 1). 34 Compared to that of sepiolite PRBs (11.7 mg g −1 ), the adsorption ability (26 mg g −1 ) of Cr(VI) in sepiolite-immobilized S. equisimilis Bio-PRBs increased by 122%, and the removal rate (0.03 day −1 ) of sepiolite-immobilized S. equisimilis Bio-PRBs increased by 233% compared to that of sepiolite PRBs (0.009 day −1 ). Cr(VI) was removed through surface complexes [H 2 O and hydroxyl radicals (-OH)] on the surface of sepiolite, and the Cr 6+ ions that were produced were transformed by ion exchange with Mg 2+ ions in the lattice of sepiolite (Figure 1).…”

“…Moreover, the immobilization carriers peanut shell biochar, 21 clay composite adsorbent, 23 high-density luffa sponge, 31 ZVI, 32 activated carbon, 12 herbal fruit residue biochar and spruce biochar, 33 sepiolite, 34 rice straw biochar, 35 and shell 36 can immobilize microorganisms to significantly improve the performance of Bio-PRBs. Various types of Bio-PRBs have been successfully developed for the remediation of groundwater and soil contaminated with atenolol, giferozil, and ciprofloxacin, 23 1,1,1-trichloroethane (1,1,1-TCA), 31 1,4-dioxane, 32 tetracycline (TC), 37 Cr(VI), 12 TCE, 33 Cu(II) and Ni(II), 34 nitrobenzene (NB), 35 2,4,6-trichlorophenol (2,4,6-TCP), 21 and V(V) 36 (Table 1). Furthermore, abiotic reactive materials, including zeolite, 38 clay minerals, 39 bimetal, 40 CaO 2 , 35 MgO 2 , 41 etc., have been shown to promote the removal of NB, 35 cesium-137 ( 137 Cs), 39 phosphorus, 40 and naphthalene and toluene 41 in Bio-PRBs.…”

A comprehensive review on comparison among effluent treatment methods and modern methods of treatment of industrial wastewater effluent from different sources

“…Various products can be recovered from wastewater apart from nutrient, energy and reusable water. There are wide range of recovery strategies available that sustain that includes chemical production, raw commodity chemicals, energy recovery, fertilizers, animal feeds and consumer products (Silva B et al 2021 ). Techniques like partition-based biological process, acid-bioleaching, thermo- and meso-anaerobic digestion, bio-precipitation using bioelectrical system, trans-esterification (separation) are in practice for the effective recovery of valuable products such as biochar, single-cell protein-based foods, bioplastic, struvite (MAP—Magnesium, Ammonia, Phosphate compound), biogas, metals, radionuclides, etc.…”