Simultaneous As(III) and Cd removal from copper smelting wastewater using granular TiO2 columns

Abstract

Fixed-bed columns Adsorbent regenerationOn-line treatment process a b s t r a c t Remediation of metallurgical industry wastewater has presented a great environmental challenge for decades. In this study, a complete remediation technology was proposed for simultaneous As(III) and Cd adsorptive removal, adsorbent regeneration, and recovery of As and Cd. Using three granular TiO 2 columns in series, As(III) and Cd in the raw water at 2590 ± 295 and 12 ± 2 mg/L, respectively, could be reduced to 0.16 ± 0.11 and 0.0133 ± 0.0134 mg/L, well below the wastewater discharge limit. Spent TiO 2 media could be regenerated using H 2 SO 4 and NaOH, and the regenerated adsorbent could be re-used for at least 10 treatment cycles and 770 bed volumes with no decrease in its adsorption capacity.Remediation of 1 L wastewater generated 0.89e1.5 g solid residue which could be used as an intermediate for the As and Cd chemical refinement. The waste solution can be further treated after mixing with raw water to adjust the raw pH from 1.4 to 7. This adsorption, regeneration, and reuse process provides an innovative technology for metallurgical industry wastewater remediation that is promising for practical application.© 2014 Elsevier Ltd. All rights reserved. IntroductionMining and smelting are major industrial processes that are associated with multiple toxic metal contaminants (Bian et al., 2012). In these industrial wastewaters, coexistence of As(III) and Cd is a great public concern because of their carcinogenicity (Barrett, 2012;Lubin et al., 2008). Thus, developing effective and robust wastewater treatment technology for simultaneous As(III) and Cd removal has motivated extensive research (Allende et al., 2012;Deschamps et al., 2005;Dey et al., 2009;Jiang et al., 2014;Johnson and Hallberg, 2005). Many efforts have been made to solve this problem over past decades, with the result that neutralization-precipitation has been adopted as a commonly used method for removal of heavy metals, including As(III) and Cd, from mining and smelting wastewaters (Dong et al., 2011;McDonald et al., 2006;Wang et al., 2003). For example, an approach using iron precipitation and high density sludge (HDS) recycling has become a benchmark procedure in acid mine drainage treatment (Dey et al., 2009). This HDS process requires increasing the pH with hydrated lime and subsequently adding iron salts to form precipitates with As. However, HDS generates large volumes of sludge with low chemical stability (Dey et al., 2009;McDonald et al., 2006), which may release As under the attack of carbon dioxide (Nishimura and Robins, 1998;Pantuzzo and Ciminelli, 2010 Available online at www.sciencedirect.com ScienceDirect journal homepage: ww w.else vier.com/locate /wa tres w a t e r r e s e a r c h 6 8 ( 2 0 1 5 ) 5 7 2 e5 7 9http://dx

Recent progress of arsenic adsorption on TiO 2 in the presence of coexisting ions: A review

“…TiO 2 has been investigated to simultaneously remove high concentrations of As(III) and Cd from metallurgical wastewater (Luo et al, 2010;Yan et al, 2015). A strategy for determining As(III) and Cd treatability was implemented in three successive fixed-bed columns, and the initial concentration averages of 2590 mg/L As(III) and 12 mg/L Cd in the raw water were reduced to below discharge limit in the effluent each time for 10 treatment cycles (Fig.…”

“…Following As adsorption, it is usually regenerated with NaOH (Arumugam et al, 2013;Hu et al, 2015a). For a typical study using granular TiO 2 to remediate wastewater with a high concentration of As(III) and coexisting Cd (Yan et al, 2015), spent TiO 2 media were regenerated using H 2 SO 4 and NaOH. The total desorption ratio was in the ranges of 76%-93% for As(III) and 62%-89% for Cd in 10 treatment cycles, and the regenerated TiO 2 adsorbent was able to be re-used with no decrease in its adsorption capacity, which was 162 ± 20 mg/g for As(III) and 1.00 ± 0.16 mg/g for Cd.…”

“…1). Many efforts have attempted to synthesize effective TiO 2 -based materials including nanocrystalline TiO 2 particles (Dutta et al, 2004;Guo et al, 2013;Jegadeesan et al, 2010;Kocabas-Atakli and Yurum, 2013;Nabi et al, 2009;Pena et al, 2005;Xu and Meng, 2009), hydrous TiO 2 (Pirila et al, 2011;Sun et al, 2013;Xu et al, 2010), titanate nanotubes (Niu et al, 2009;Wu et al, 2013), granular TiO 2 (Bang et al, 2005;Cui et al, 2015a;Hu et al, 2015a;Yan et al, 2015), TiO 2 -impregnated chitosan beads (Miller and Zimmerman, 2010), and TiO 2 -coated sand (Nabi et al, 2009). The performances of those TiO 2 -based materials are summarized in Table 1.…”

“…Granular TiO 2 (0.18-0.83 mm), mesoporous titania beads (0.5 mm) (Dwivedi et al, 2012), and TiO 2 -impregnated chitosan beads (1.0 mm) with a large particle size that can be operated in fixed-bed columns have been developed in recent years for As removal. Due to its high adsorption efficiency, ability to be regenerable and reusable, cost-effectiveness, and feasible operation (Chen and Mao, 2007;Luo et al, 2010;Yan et al, 2015), TiO 2 is becoming a promising material in field filtration of As tainted waters.…”

“…Second, the simulation of As breakthrough curves in TiO 2 filtration columns is far from satisfactory, and the methods of obtaining the parameters from batch adsorptions in the laboratory used to accurately predict the field filtration need more effort to decipher (Cui et al, 2015a;Hu et al, 2015a). Third, the regeneration and reuse of spent TiO 2 media is still a challenge for the practical application of TiO 2 (Arumugam et al, 2013;Bang et al, 2005;Hu et al, 2015a;Yan et al, 2015).…”