Precipitation and recovery of metal sulfides from metal containing acidic wastewater in a sulfidogenic down‐flow fluidized bed reactor

Abstract

This study reports the feasibility of recovering metal precipitates from a synthetic acidic wastewater containing ethanol, Fe, Zn, and Cd at an organic loading rate of 2.5 g COD/L-day and a COD to sulfate ratio of 0.8 in a sulfate reducing down-flow fluidized bed reactor. The metals were added at increasing loading rates: Fe from 104 to 320 mg/L-day, Zn from 20 to 220 mg/L-day, and Cd from 5 to 20 mg/L-day. The maximum COD and sulfate removals attained were 54% and 41%, respectively. The biofilm reactor was operated at pH as low as 5.0 with stable performance, and no adverse effect over COD consumption or sulfide production was observed. The metals precipitation efficiencies obtained for Fe, Zn, and Cd exceeded 99.7%, 99.3%, and 99.4%, respectively. The total recovered precipitate was estimated to be 90% of the theoretical mass expected as metal sulfides. The precipitate was mainly recovered from the bottom of the reactor and the equalizer. The analysis of the precipitates showed the presence of pyrite (FeS2), sphalerite (ZnS) and greenockite (CdS); no metal hydroxides or carbonates in crystalline phases were identified. This study is the first in reporting the feasibility to recover metal sulfides separated from the biomass in a sulfate reducing process in one stage.

Biotreatment of acidic zinc- and copper-containing wastewater using ethanol-fed sulfidogenic anaerobic baffled reactor

“…After drawing sludge from Compartment 1 for metal recovery, the compartment can be reseeded from other compartments, without adversely affecting the reactor operation. For other types of reactors, such as fluidizedbed reactor, recovering metal-sulfide precipitate may cause losing high amount of SRB, which may adversely affect the reactor operation [13]. Hence, ABR has a high application potential for the sulfidogenic biotreatment of AMD and metal recovery.…”

“…Hence, there is a great interest to develop a technology for effective biotreatment of AMD and metal recovery in one reactor [13]. For this purpose, sulfidogenic down-flow fluidized-bed reactor was used by Gallegos-Garcia et al [13]. In this study, however, accumulation of acetate led to relatively low sulfate and COD removal efficiencies as well as low alkalinity production.…”

“…Generally, metal-sulfide precipitates and biomass are recovered in separate units, which may increase the process cost. Hence, there is a great interest to develop a technology for effective biotreatment of AMD and metal recovery in one reactor [13]. For this purpose, sulfidogenic down-flow fluidized-bed reactor was used by Gallegos-Garcia et al [13].…”

Removal of Sulphate and Manganese on Synthetic Wastewater in Sulphate Reducing Bioreactor Using Indonesian Natural Zeolite

“…The continuous laboratory scale of down-flow fluidizedbed reactor (DFBR) inoculated with mixed SRB was used in this study [23]. The DFBR was fed with synthetic wastewater that prepared freshly every day.…”

Nâng Cao Khả Năng Tạo Sulfide Của Hỗn Hợp Chủng Vi Khuẩn Khử Sunfate Thu Được Từ Nước Thải Ô Nhiễm Chì

“…Phương pháp này dựa trên khả năng khử ion sulfate (SO 4 2-) đồng thời oxy hóa các hợp chất hữu cơ (lactate, acetate, ethanol, pyruvate...) tạo ion sulfide của vi khuẩn KSF. Sau đó, ion sulfide phản ứng với ion kim loại hòa tan độc hại tạo kết tủa kim loại dưới dạng muối sulfide bền vững [6]. Cơ chế của quá trình này cho thấy hiệu quả loại chì của vi khuẩn KSF phụ thuộc vào hàm lượng sulfide do nhóm vi khuẩn này tạo ra.…”