Acid Mine Drainage Treatment and Metal Removal Based on a Biological Sulfate-Reducing Process

Abstract

The key purpose of this research was to explore the capacity of an anaerobic stirred batch reactor (ASBR) to deal with acid mine drainage (AMD) based on the activity of sulfate reducing bacteria (SRB). The tests showed that SRB produced hydrogen sulfide that precipitated the metals Fe 2+ , Zn 2+ , and Cu 2+ . Ethanol was used as both the only source of carbon and electron donor. Throughout the experiment, the ratio of chemical oxygen demand (COD) to sulfate was constant at 1.0. The reactor was operated for 218 days using synthetic AMD at pH 4.0 containing 1000 and 1500 mg·L -1 of sulfate,100 mg·L -1 of Fe 2+ , 20 mg·L -1 Zn 2+ , and 5 mg·L -1 Cu 2+ . The metal removal rates were greater than 99 %with effluent pH of 6.5 to 7.4. The sulfide concentration reached 56.6 mg·L -1 and sulfate removal was 43 to 65 %.

Achieving Long-Term Stability of Partial Nitrification and Autotrophic Denitrification in an MABR via Sulfide Dosing

“…The combined strategy in Stage 3.5 yielded average NAR of 45% and effluent nitrite concentration at 16 mg N/L. When the pH < 7.0, sulfide mainly existed as H 2 S, which escaped from the liquid, resulting in the insufficient sulfide concentration. In addition, continuous dosing of sulfide at a lower concentration can be rapidly oxidized directly by O 2 or by sulfur oxidizing bacteria (SOB).…”

“…Different from the in situ batch tests, we chose inoculum sludge with the same nitrifiers as the biofilm for ex situ batch tests because the NOB in the biofilm had been inhibited by sulfide. Eight ex situ batch tests (A1-A4, B1–B4, as shown in Figure S1) were implemented to explore sulfide inhibition on NOB with different pH conditions since sulfide speciation is affected by pH . Hydrogen sulfide and bisulfide were the dominant forms at pH values below 6 and above 8, respectively.…”

“…Eight ex situ batch tests (A1-A4, B1−B4, as shown in Figure S1) were implemented to explore sulfide inhibition on NOB with different pH conditions since sulfide speciation is affected by pH. 26 Hydrogen sulfide and bisulfide were the dominant forms at pH values below 6 and above 8, respectively. At pH 7, hydrogen sulfide and bisulfide were 50% each.…”

Global research progress on mining wastewater treatment: a bibliometric analysis

“…However, the most prevalent method for treating AMD contamination is the addition of alkaline reagents such as lime, limestone, sodium carbonate, or sodium hydroxide. 75 This treatment aims at neutralizing acidic water and the precipitation of heavy metals. This includes all necessary pretreatment, ultra-filtration, reverse osmosis, evaporators, and crystallizers.…”

Investigating bisulfide sorption onto bentonite through laboratory batch experiments

“…The initial pH values of the samples were found in the range of 8-10. As HSis the dominant sulfide species at pH > 9 (Lewis, 2010;Ahlatci et al, 2016;Neto et al, 2018), the pH values of the samples were adjusted at ≈9.5 (by adding 0.1 M NaOH and/or 0.1 M HCl) to avoid loss of HSdue to H2S gas formation.…”