Initial Sulfate Concentration Research Articles

Nutrient (sulphate) removal from wastewater in inverse fluidized bed biofilm reactor

Sulphate is one of the inorganic nutrient pollutants present in wastewater which needs to be treated due to present day global stringent emission norms. Among the several available biological means to treat industrial wastewaters, the use of inverse fluidized bed biofilm reactors (IFBBRs) has gained much attention in recent years over other fluidized bed reactors. In this work, the feasibility of removal of sulphate from synthetic wastewater having initial concentrations of 13.096, 32.74, and 65.48 mg/l was studied using mixed bacterial culture. Spherical polypropylene balls were taken as biomass support particles having density of 920 kg/m3 and diameter of 5.63 mm. Three different bed-volume to reactor-volume (Vb/Vr) ratios i.e., 0.304, 0.380, & 0.445 and three different superficial air velocities i.e., 0.0065, 0.0085, & 0.0106 m/s were considered for experimental runs. The reactor inoculum was prepared from the sludge collected from local steel industry’s wastewater treatment plant. The effects of different input parameters such as Vb/Vr ratio, superficial air velocities, and initial concentration of sulphate in synthetic wastewater on the output sulphate concentration were studied. Temperature of 30–32 °C and pH of 8.3–8.8 were maintained throughout the degradation studies. The reactor was operated in semi-batch recirculation mode with superficial water velocity of 0.0021 m/s. Sulphate concentration was measured by turbidity method using UV spectrophotometer at 420 nm which is as per APHA standards. The maximum removal efficiency of sulphate was found to be 72–75% which was achieved at a Vb/Vr ratio of 0.380 and the superficial gas velocity of 0.0085 m/s observed at a time of 40 h. Higher sulphate reduction was not achieved due to presence of more inorganic salts in the synthetic wastewater. At higher initial sulphate concentration, reactor operational difficulties were observed.

Mechanism and kinetics study of sulfuric acid leaching of titanium from titanium-bearing electric furnace slag

Titanium(Ti)-bearing electric furnace slag (TEFS) was leached with sulfuric acid in this study. The influence of temperature, acid/solid ratio, particle size, and initial sulfuric acid concentration on the Ti extraction was evaluated. The leaching kinetics indicate that diffusion across the product layer and the interface transfer both affected the decomposition of the TEFS, and the apparent activation energy was24.01kJ/mol. Reaction temperature was the most important factor that influenced the extraction of Ti, followed by the acid/solid ratio, sulfuric acid concentration, and particle size. The Ti leaching rate reached up to 89.46 % under the conditions of an average particle size of 31.5μm, acid/solid ratio of 2.0:1, initial acid concentration of 88.0wt%, reaction temperature of 513.15K, and water leaching temperature of 333.15K for 120min. Fe was almost completely dissolved in the acid, whereas MgO (22.73wt%) and Al2O3 (44.57wt%) in spinel were retained in the leach residue, and SiO2 (45.94wt%) and CaO (34.96wt%) occurred in the form of diopside in the leach residue. During the leaching process, substantial TiOSO4 and CaSO4·2H2O were produced and coated the TEFS particles, which hindered the leaching of Ti.

Growth, biochemical composition and photosynthetic performance of Scenedesmus acuminatus under different initial sulfur supplies

The effects of sulfur availability on growth, biochemical composition and photosynthetic capacity of the freshwater green microalga Scenedesmus acuminatus were investigated. Modified BG-11 media with Na2SO4 concentrations of 0.076 mM (0.25S), 0.153 mM (0.5S), 0.306 mM (control group), 0.459 mM (1.5S) and 0.612 mM (2.0S) were used to culture S. acuminatus. Sulfur repletion promoted the growth and reproduction of this species, while low sulfur supply markedly decreased the reproduction, nitrogen uptake, soluble protein and chlorophyll content, and photosynthetic activity. Elemental analysis showed that nitrogen, sulfur and carbon content per cell was significantly higher in the sulfur-limitation groups than in the control group on day 18. The metabolic response to sulfur limitation was divided into two stages: first, carbon equivalents were diverted from soluble protein to carbohydrates; then, carbohydrates were converted into neutral lipids. The total lipid content in the 0.25S and 0.5S groups reached 55.2% dry weight (DW) and 52.5% DW, respectively; neutral lipids accounted for 92.1% and 90.3% of the total lipids. Low-sulfur (0.5S) and sulfur-replete conditions both enhanced the lipid productivity. The initial sulfur level caused significant changes in the fatty acid composition of S. acuminatus. The sulfur-limited groups accumulated C16:0 and C18:1, while the sulfur-replete groups were mainly enriched in C16:0. Levels of free leucine, isoleucine, valine, lysine, glycine, alanine, aspartic acid and proline were closely related to the initial sulfur concentration. Changes in free phenylalanine, tryptophan, threonine and serine were due more to the duration of culturing. The results of this study will be useful as a reference for regulation of the initial sulfur supply to enhance lipid productivity of S. acuminatus for use in applications such as biodiesel production.

The Hampering Effect of Precipitated Carbon on Hot Metal Desulfurization with Magnesium

Carbon may precipitate during the hot metal desulfurization (HMD) process as a result of carbon oversaturation because of temperature decrease. The precipitated carbon flakes form a layer between hot metal and slag. It is postulated that this carbon layer hampers desulfurization with magnesium by preventing MgS particles from reaching the slag phase. At Tata Steel in IJmuiden, the Netherlands, carbon in hot metal is measured in 657 heats after reagent injection. With this data, it can be determined whether the hampering effect of precipitated carbon on MgS flotation has a significant effect on the performance of the industrial HMD process. Plant data show a correlation between the precipitated carbon and the specific magnesium consumption for hot metal with a low initial sulfur concentration (below 225 ppm). This correlation cannot be found for hot metal with a higher initial sulfur concentration (above 275 ppm). Furthermore, a sulfur mass balance is made over the converter process, that shows no effect of carbon precipitation during HMD on resulfurization in the converter. The limited experimental accuracy of the plant data prevents a quantitative description of the hampering effect. The measurements do suggest that the effect is small.

Investigation of the parameters affecting the treatment of mining waters by electrocoagulation

Recently electrochemical methods have been studied as an alternative to conventional methods to treat industrial and municipal waters. One such water, the mining water, has been mainly treated previously by electrocoagulation (EC) to remove metals. Few studies have been performed on the removal of sulfate, nitrate and cyanide from mining waters. In this paper, results from 39 lab-scale experiments on the elimination of sulfate by electrocoagulation with iron electrodes are presented. Significance of parameters affecting the removal of sulfate by EC was studied using response surface methodology (RSM). Also, results from kinetic studies and comparison of synthetic and real mining waters are reported. According to kinetics studies, it was suggested that both physical and chemical mechanisms are involved in sulfate removal. At the same test conditions, sulfate removal from both synthetic and real mining waters followed the same pattern. The study concludes that the most significant parameters in sulfate removal are initial sulfate concentration and applied current when initial pH was insignificant in batch operation. From a technology development perspective, this study enhances knowledge about the significance of process parameters and their interactions as well as allows further scale-up of the process

Extractive desulfurization of fuels using trialkylamine-based protic ionic liquids

Despite the extraction desulfurization of fuel oils using ionic liquids (ILs) as promising alternatives to traditional extractants has attracted worldwide attention, the drawbacks of ILs, such as poor extraction efficiency, high cost and complex preparation, have limited their further application in industrial scale. In this study, a series of trialkylamine-based protic ionic liquids (PILs) were synthesized and characterized, and their extraction desulfurization for thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT) in model oil was carried out. Effects of PIL species, extraction time, temperature, PIL dosage, and initial sulfuric concentration on desulfurization efficiency were investigated. Experimental results showed that the PILs exhibited higher extraction ability for TH, BT, and DBT as compared to the reported ILs. Under optimal conditions, the removal efficiency of TH, BT, and DBT using tris(3,6-dioxaheptyl) ammonium salicylate ([TDA][SA]) as extractant was 72.68%, 76.31%, and 83.94%, respectively. Finally, the suggested PIL can be easily regenerated and reused via a back extraction process. After 5 extraction cycles, the removal efficiency has no noticeable decrease. With advantages such as higher desulfurization efficiencies, cheap and easily obtained raw materials and simple synthetic process, this study will provide new green solvents for extraction desulfurization process of fuels.

Sulphate induced changes of rheological properties of cemented paste backfill

The rheological properties of cemented paste backfill (CPB) are important properties, which determine its flow ability or ease of transport in pipelines to fill underground voids. However, no research has been conducted to understand the effects of the sulphate content in CPB on its rheological properties, even though sulphate ions are usually found in CPB mixtures. Evaluating and understanding the effect of sulphate on the rheological properties of fresh CPB are important in carrying out backfilling with cemented paste. Therefore, the objective of this paper is to experimentally study the effects of the initial sulphate content on the rheological properties of CPB. Samples made with two different types of tailings (silica tailings and polymetallic tailings) with an initial sulphate content of 0, 5000, 15,000 and 25,000 ppm are prepared and cured at room temperature (20 °C). Their yield stress and apparent viscosity at different curing times of 0, 0.15, 1, 2, and 4 h are determined and then analyzed. Additional tests or measurements are carried out to further investigate the experimental results, which include monitoring through electrical conductivity (EC), measuring the pH and zeta potential as well as conducing thermal and XRD analyses. The results show that the initial sulphate concentration can significantly affect the rheological properties of CPB. The initial sulphate concentration can cause different microstructural or chemical changes in fresh CPB, such as inhibition of the cement hydration process or affecting the repulsive forces between particles. These changes significantly affect the yield stress and apparent viscosity of CPB. More specifically, the yield stress shows a trend of decline as the initial sulphate concentration is increased, while the apparent viscosity shows the opposite trend. The findings of this research demonstrate the significance of sulphate and its effects on the rheological behaviors or properties of CPB and can significantly contribute to the optimization of the transport of CPB through pipelines.

Reductive dechlorination of trichloroethene under different sulfate-reducing and electron donor conditions

The effect of sulfate presence on reductive dechlorination of chlorinated ethenes has been a matter of conflict among the limited reports found in literature. This paper aims to clarify the misconceptions regarding the performance of trichloroethene biotransformation under sulfate reducing conditions by evaluating the effect of different sulfate concentrations on reductive dechlorination and to assess the influence of electron donor dose on dechlorination rate. To this end, batch experiments containing different sulfate and butyrate concentrations were conducted using trichloroethene-dechlorinating and sulfate-reducing parent cultures. Results demonstrated that if sufficient time and electron donor is provided, complete dechlorination can be achieved, even at up to 400 mg/L initial sulfate concentration. However, the rate of dichloroethene and vinyl chloride degradation is reduced as sulfide concentration increases. Moreover, the excess electron donor dose induced a slightly slower dechlorination rate. The findings of this paper present an explanatory framework for the dechlorination of TCE under sulfate reducing conditions and can contribute to the state-of-art bioremediation of contaminated sites.

Reductive leaching of indium-bearing zinc ferrite in sulfuric acid using sulfur dioxide as a reductant

Indium extraction from synthetic indium-bearing zinc ferrite (IBZF) was investigated using sulfur dioxide as a reductant in sulfuric acid medium, and the recovery of indium and the full use of sulfur dioxide were achieved. The leaching kinetics of indium from synthetic IBZF were studied, and the influence of leaching temperature, particle size, initial sulfuric acid concentration and sulfur dioxide partial pressure were investigated. The results showed that the leaching efficiencies increased as the leaching temperature increased from 65 to 85 °C, the initial sulfuric acid concentration increased from 5 to 65 g/L, the sulfur dioxide partial pressure increased from 0.10 to 0.30 MPa, and the particle size decreased from 150–270 μm to 48–58 μm. The unreacted shrinking core model was applied well to the kinetics of indium leaching, which showed that the rate was controlled by a chemical reaction with a calculated activation energy of 57.22 kJ/mol. The order of indium leaching with respect to particle size, initial sulfuric acid concentration and sulfur dioxide partial pressure was −0.2343, 0.02625 and 0.35618, respectively. Meanwhile, sulfur dioxide could reduce the dependency of IBZF dissolution on the initial sulfuric acid concentration.

Two-stage leaching of zinc and copper from arsenic-rich copper smelting hazardous dusts after alkali leaching of arsenic

In order to efficiently recover zinc and copper from arsenic-rich copper smelting hazardous dusts after alkali leaching of arsenic, an optimum two-stage leaching process by using sulfuric acid media was developed in this study. The leaching behaviors of zinc, copper, arsenic and iron under different experimental conditions (such as: leaching time, temperature, sulfuric acid concentration and oxidant addition), were studied systematically. The results indicated that 98.4% zinc and 96.01% copper were leached using the first-stage of neutral leaching under conditions including final pH 5.0 ± 0.1, time 1 h, temperature 90 °C and the second-stage of sulfuric acid leaching under conditions including initial sulfuric acid concentration 190 g/L, leaching time 2 h, temperature 90 °C and 1.4 times oxidant addition. Meanwhile, 99.58% lead and 98.93% bismuth were remained in the sulfuric acid leaching residues which can be recovered by pyrometallurgical processes. The leaching behavior relationships among copper, zinc, arsenic and iron were also modeled. Results indicated that the ferric ion improved copper and zinc leaching. SEM study demonstrated that the leached surface was corroded, and EDS and XRD results indicated that zinc and copper oxides were disappeared during leaching while lead oxide was transformed into anglesite, and tin oxide was remained in the residues.

Leaching Chalcopyrite Concentrate with Oxygen and Sulfuric Acid Using a Low-Pressure Reactor

This article presents a copper leaching process from chalcopyrite concentrates using a low-pressure reactor. The experiments were carried out in a 30 L batch reactor at an oxygen pressure of 1 kg/cm2 and solid concentration of 100 g/L. The temperature, particle size and initial acid concentration were varied based on a Taguchi L9 experimental design. The initial and final samples of the study were characterized by chemical analysis, X-ray diffraction and particle size distribution. The mass balance showed that 98% of copper was extracted from the chalcopyrite concentrate in 3 h under the following experimental conditions: 130 g/L of initial sulfuric acid concentration, temperature of 100 °C, oxygen pressure of 1 kg/cm2, solid concentration of 100 g/L and particle size of −105 + 75 μm. The ANOVA demonstrated that temperature had the greatest influence on copper extraction. The activation energy was 61.93 kJ/mol. The best fit to a linear correlation was the chemical reaction equation that controls the kinetics for the leaching copper from chalcopyrite. The images obtained by SEM showed evidence of shrinking in the core model with the formation of a porous elemental sulfur product layer.

Deep oxidative desulfurization of model fuels catalysed by immobilized ionic liquid on MIL-100(Fe).

Deep desulfurization of fossil fuels has become urgently required because of the serious pollution by the large-scale use of fossil fuels. In this study, [PrSO3HMIm]HSO4@MIL-100(Fe) was synthesized by wet-impregnation of the ionic liquid (IL) of [PrSO3HMIm]HSO4 on MIL-100(Fe). The construction of [PrSO3HMIm]HSO4@MIL-100(Fe) was then confirmed by X-ray powder diffraction, N2 adsorption–desorption experiments, infrared spectroscopy and elemental analysis, and then applied in the oxidative desulfurization of model fuels. In comparison with the corresponding IL, [PrSO3HMIm]HSO4@MIL-100(Fe) showed an enhanced performance in the desulfurization rate of model fuels due to the increase of the mass transfer rate. Under the optimized conditions (oxidant to sulphur ratio = 25, oil to acetonitrile ratio = 1, and temperature = 60 °C), a sulphur removal rate of 99.3% was observed (initial sulphur concentration = 50 ppm). The sulphur removal of three sulphur compounds by catalytic oxidation and extraction followed the order of dibenzothiophene (DBT) > thiophene (T) > benzothiophene (BT).

Experimental research on the pressure oxygen leaching rhenium of waste platinum-rhenium catalyst with low acid

Experimental material was the waste platinum-rhenium catalyst; X diffraction was used to characterize the material, and the results showed that the main phase of the waste platinum-rhenium catalyst was Al2O3. The process of rhenium pressure oxygen leaching in platinum-rhenium catalyst with low acid was put forward. The effects of leaching pressure, leaching temperature, leaching time, initial acidity of sulfuric acid and liquid-solid ratio on the leaching rate of rhenium during leaching were investigated in this paper. The results showed that the initial acidity of sulfuric acid had a significant effect on the leaching rate of platinum and rhenium. As the acidity increased, the leaching rate of platinum and rhenium also increased, and the leaching rate of carrier Al2O3 also increased. The experimental results show that the leaching of the optimal process conditions were as follows: leaching pressure 5 MPa, leaching time 3h, leaching temperature 140 °C, the initial sulfuric acid concentration 10%, liquid-solid ratio 4:1, mixing speed 350 rpm. Under these conditions, the leaching rate of rhenium and platinum was 98.11% and 83.59% respectively, and the slag rate was 75.56%. In order to prevent platinum from dispersing, ferrous sulphate was added at the end of the leaching process to reduce the platinum into the leaching residue. This process has the advantages of simple operation, high rhenium leaching rate, less impurity elements in the leaching liquid and low acidity, etc., which can provide reference for rhenium extraction from the waste platinum-rhenium catalyst.

The kinetics of vanadium extraction from spent hydroprocessing catalyst by leaching with sulfuric acid at atmospheric pressure

The dissolution kinetics of vanadium from spent hydroprocessing catalyst was investigated by leaching with sulfuric acid at atmospheric pressure. The effects of stirring speed (400–800 rpm), initial sulfuric acid concentration (0.60–1.20 mol/l) and reaction temperature (373–423 K) on the vanadium dissolution were studied. The results showed that the vanadium dissolution ratio was practically independent of stirring speed at the investigated range, while increasing with the increases of sulfuric acid concentration and reaction temperature. The experimental data agreed quite well with the shrinking core model, with solid membrane diffusion as the rate controlling step. The apparent activation energy was calculated as 11.44 kJ/mol, and the reaction order with respect to sulfuric acid concentrations was determined to be 1.51. The kinetics equation of the leaching process was established as: 1 − 2x/3 − (1 − x)2/3 = 0.067[H2SO4]1.51exp[ − 11563/RT ]t.

Synthesis of porous carbon via a waste tire leavening strategy for adsorptive desulfurization.

Adsorptive desulfurization is an effective technology for removing harmful sulfur under mild conditions. Carbon materials have many advantages and are often used in adsorption desulfurization research, but until now have been synthesized using complicated methods and have shown limited adsorption capacity. Using an NaHCO3-assisted leavening method, waste tires were in the current work used as raw materials to produce hierarchically porous carbon that exhibits a high specific surface area and abundant oxygen-containing functional groups. In contrast to the sulfur removal by the carbon material prepared using a commonly used method, the as-prepared carbon material shows excellent adsorption performance, and was able to achieve an ultra-deep desulfurization of pentanethiol, specifically removing up to 99.7% of the sulfur from a model fuel with an initial sulfur concentration of 28 ppm. Therefore, we have provided a simple method for synthesizing adsorbents with high adsorption performance, and we expect these adsorbents to be used for industrial adsorptive desulfurization.

Deep Desulfurization of Fuels Using Imidazole Anion-Based Ionic Liquids

An extractive desulfurization method was developed with 1,8-diazabicyclo[5.4.0]undec-7-ene Im ([DBU][Im]) and 1,1,3,3-tetramethylguanidine Im ([TMG][Im]) as extractants. Effects of extraction time, ionic liquid (IL):model fuel mass ratio, ILs species, initial concentration of sulfur, and temperature on removal efficiency of sulfur compound were investigated. The removal efficiencies of dibenzothiophene, 4,6-dimethyldibenzothiophene, and benzothiophene with [DBU][Im]/[TMG][Im] as extractants were 79.2%/69.4%, 68.4%/57.7%, and 61.2%/54.4%, respectively. The interaction between [DBU][Im] and sulfur compounds could be enhanced by extra heterocyclic aromatic ring in DBU cation and imidazolium ring in Im anion. Both extraction processes with these two ILs as extractants were fast (extraction equilibrium was reached within 10 min). The reusability of prepared ILs was studied, and the multistage cross-current extraction experiments were performed. Moreover, the characterization methods of nuclear magnetic resonan...

Precipitation of a layered double hydroxide comprising Mg2+ and Al3+ to remove sulphate ions from aqueous solutions

This work presents an alternative route to remove sulphate ions from aqueous solutions, which is simple and fast, and its efficiency of sulphate removal is slightly influenced by temperature (26 °C–70 °C) and pH (4–12). The lowest residual sulphate concentration was about 60 mg L−1, which was observed in continuous experiments using wastewater (26 °C, pH 6 and initial sulphate concentration of 630 mg L−1). All these outcomes together have not been observed in the current most used processes of sulphate precipitation, i.e. gypsum and ettringite precipitation. Sulphate removal experiments were carried out in the batch and continuous systems using synthetic solutions. In these conditions, about 75% of sulphate ions were removed for an initial ion concentration of 1800 mg L−1. A continuous test was also performed using a wastewater sample in addition to a synthetic solution. The system reached steady-state conditions after four residence times (40 min) in the experiment with synthetic solutions, whereas three residence times (30 min) were necessary for the tests with the wastewater (initial sulphate concentration of 630 mg L−1). In the latter case, the sulphate removal efficiency was approximately 90%. The characterisation of the experimentally precipitated solids was carried out by DRX, FTIR, SEM-EDS, elemental analysis and thermal analysis. These techniques showed that, except in pH 4, the sulphate removal process occurred due to the precipitation of a layered double hydroxide, comprising Mg2+ and Al3+ as its metallic ions and nitrate (due to the salts used for precipitation) and sulphate anions occupying its interlayer space.

Photocatalytic oxidative desulfurization of liquid petroleum fuels using magnetic CuO–Fe3O4 nanocomposites

In the present study, dual-functional CuO–Fe3O4 magnetic nanocomposites (MNCs) have been prepared through a simple impregnation method and used as catalyst for photocatalytic oxidative desulfurization of model-fuel (dibenzothiophene, DBT in n-hexane) and real naphtha at moderate conditions. The CuO–Fe3O4 MNCs were characterized by X-ray diffraction, BET surface area and pore volume using nitrogen adsorption–desorption and VSM methods The effects of different reaction parameters such as initial DBT concentration in model-fuel, CuO–Fe3O4 MNCs dose, reaction time, H2O2/DBT molar ratio and CuO:Fe3O4 weight ratio of the MNCs were studied in detail. Results for model-fuel treatment showed that the prepared nanocomposite can eliminate 95.2% of DBT after 120 min under the following conditions: CuO:Fe3O4 weight ratio of 1:1, catalyst dose of 10 g/l, H2O2/DBT mole ratio of 7.5:1 and initial DBT concentration of 250 mg/l. Furthermore, 93% of sulfur conversion was obtained for naphtha fuel (initial sulfur concentration of 533 mg/l) after 240 min reaction time. The synthesized CuO–Fe3O4 magnetic nanocomposites combines the photocatalytic activity of CuO and the adsorption capacity of both Fe3O4 and CuO species, which make it have important applications in the deep desulfurization of liquid fuels.

Optimization of kinetics and operating parameters for the bioleaching of heavy metals from sewage sludge, using co-inoculation of two Acidithiobacillus species.

This study explores the potential for synchronous extraction of Cu, Cr, Ni and Zn during sewage sludge bioleaching processes, using three types of bacterial cultures: a pure culture of Acidithiobacillus ferrooxidans (A. ferrooxidans); a pure culture of Acidithiobacillus thiooxidans (A. thiooxidans); and a mixed culture of A. ferrooxidans and A. thiooxidans. Variable operating parameters included initial pH, solids concentration, sulfur concentration and ferrous iron concentration, with optimization via Box-Behnken design of response surface methodology. Results indicate that the mixed culture of A. ferrooxidans and A. thiooxidans, was the most effective at bioleaching heavy metals from sewage sludge. The optimal operating conditions were as follows: an initial pH of 2.0, with concentrations of 3% solids, 6.14 g L-1 sulfur and 4.55 g L-1 ferrous iron. Maximum extraction efficiencies obtained after 14 days of bioleaching under optimal conditions, were 98.54% Cu, 57.99% Cr, 60.06% Ni and 95.60% Zn. Bioleaching kinetics were effectively simulated using a shrinking core model to explain the leaching reaction, with modelling results suggesting that the rate was determined by the diffusion step.

Effects of elevated sulfate concentration on the mobility of arsenic in the sediment–water interface

The adsorption/desorption of arsenic (As) at the sediment–water interface in lakes is the key to understanding whether As can enter the ecosystem and participate in material circulation. In this study, the concentrations of As(III), total arsenic [As(T)], sulfide, iron (Fe), and dissolved organic carbon (DOC) in overlying water were observed after the initial sulfate (SO42−) concentrations were increased by four gradients in the presence and absence of microbial systems. The results indicate that increased SO42− concentrations in overlying water triggered As desorption from sediments. Approximately 10% of the desorbed As was desorbed directly as arsenite or arsenate by competitive adsorption sites on the iron salt surface; 21% was due to the reduction of iron (hydr)oxides; and 69% was due to microbial activity, as compared with a system with no microbial activity. The intensity of microbial activity was controlled by the SO42− and DOC concentrations in the overlying water. In anaerobic systems, which had SO42− and DOC concentrations higher than 47 and 7 mg/L, respectively, microbial activity was promoted by SO42− and DOC; As(III) was desorbed under these indoor simulation conditions. When either the SO42− or DOC concentration was lower than its respective threshold of 47 or 7 mg/L, or when either of these indices was below its concentration limit, it was difficult for microorganisms to use SO42− and DOC to enhance their own activities. Therefore, conditions were insufficient for As desorption. The migration of As in lake sediments was dominated by microbial activity, which was co-limited by SO42− and DOC. The concentrations of SO42− and DOC in the overlying water are thus important for the prevention and control of As pollution in lakes. We recommend controlling SO42− and DOC concentrations as a method for controlling As inner-source pollution in lake water.