A built-in zero valent iron anaerobic reactor to enhance treatment of azo dye wastewater

Abstract

Waste scrap iron was packed into an upflow anaerobic sludge blanket (UASB) reactor to form a zero valent iron (ZVI) - UASB reactor system for treatment of azo dye wastewater. The ZVI acted as a reductant to decrease ORP in the reactor by more than 40 mv and functioned as an acid buffer to increase the pH in the reactor from 5.44 to 6.29, both of which improved the performance of the anaerobic reactor. As a result, the removal of color and COD in this reactor was 91.7% and 53%, respectively, which was significantly higher than that of a reference UASB reactor without ZVI. The UV-visible spectrum demonstrated that absorption bands of the azo dye from the ZVI-UASB reactor were substantially reduced. The ZVI promoted methanogenesis, which was confirmed by an increase in CH(4) content in the biogas from 47.9% to 64.8%. The ZVI bed was protected well from rusting, which allowed it to function stably. The effluent could be further purified only by pH adjustment because the Fe(2+) released from ZVI served as a flocculent.

Biodegradation of Rubine GFL by Galactomyces geotrichum MTCC 1360 and subsequent toxicological analysis by using cytotoxicity, genotoxicity and oxidative stress studies

“…The use of bioremediation for treatment of dye-containing textile effluent is cost-effective, environmentally friendly and is a better alternative than physicochemical and abiotic methods (Joe et al, 2008). Such bioremediation includes the use of fungal, yeast and bacterial cultures for the removal of dyes from textile effluent (Cervantes et al, 2010;Parshetti et al, 2010;Waghmode et al, 2011a;Jadhav et al, 2011;Yu et al, 2011;Zhang et al, 2011).…”

Groundwater Water Remediation by Static Diffusion Using Nano‐Zero Valent Metals (Fe0, Cu0, Al0), n‐FeHn+, n‐Fe(OH)x, n‐FeOOH, n‐Fe‐[OxHy](n+/−)

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Groundwater water remediation by static diffusion usinG nano-zero valent metals (fe 0 , cu 0 , al 0 ), n-feH n+ , n-fe(oH) x , n-feooH, n-fe-[o x H y ] (n+/−) 1

introduction

Zero valent metals (ZVM) and ZVM combinations, including magnetic ZVM [1-4] and reduced ZVM [5][6][7], are highly efficient water treatment agents [8][9][10][11][12]. The principal ZVM used in pilot and commercial water treatment are Fe 0 and Fe 0 + Cu 0 [13][14][15][16][17]. The principal ZVM used in pilot and commercial water treatment are Fe 0 and Fe 0 + Cu 0 [13][14][15][16][17].

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Simulated Dairy Wastewater Treatment in a Pilot Plant Scale Magneto-Active Hybrid Anaerobic Biofilm Reactor (Ma-Habr)

“…Depending on the applied OLR, the efficiencies of phosphorus and COD removal were respectively higher by 16.4 -68.1% and 1.0 -3.1% in the reactor filled with steel elements as compared to performance rates achieved in a conventional UASB system. Zhang et al . (2011) reported a 53% increase in the COD removal in an UASB reactor filled with iron elements as compared to the efficiency noted in a digester without such elements.…”

“…Corrosion of metal elements stimulates the biochemical degradation of organic compounds by modification of the anaerobic environment inside the reactor through a reduction in the oxidationreduction potential (ORP) and an increase in the buffer capacity (Zhang et al, 2011;Wu et al, 2015). It also enhances abiotic processes of contaminant removal, because the formed colloids (i.e., Fe(OH) 2 and Fe(OH) 3 ) help to eliminate organic suspended solids in flocculation, adsorption and precipitation reactions (Jeon et al, 2003;Noubacept, 2008).…”