Biological Desulfurization Research Articles

Ionic Liquids as Green and Efficient Desulfurization Media Aiming at Clean Fuel.

With increasingly stringent emission limits on sulfur and sulfur-containing substances, the reduction and removal of sulfur compounds from fuels has become an urgent task. Emissions of sulfur-containing compounds pose a significant threat to the environment and human health. Ionic liquids (ILs) have attracted much attention in recent years as green solvents and functional materials, and their unique properties make them useful alternatives to conventional desulfurization organic solvents. This paper reviews the advantages and disadvantages of traditional desulfurization technologies such as hydrodesulfurization, oxidative desulfurization, biological desulfurization, adsorptive desulfurization, extractive desulfurization, etc. It focuses on the synthesis of ionic liquids and their applications in oxidative desulfurization, extractive desulfurization, extractive oxidative desulfurization, and catalytic oxidative desulfurization, and it analyzes the problems of ionic liquids that need to be solved urgently in desulfurization, looking forward to the development of sulfuric compounds as a kind of new and emerging green solvent in the field of desulfurization.

Investigating the biodesulfurization potential of isolated microbial consortia: Impact of sulfide loading, pH and oxidation-reduction potential on sulfur recovery

Acid rain is regarded as one of the major concerns due to the release of sulfur-containing wastewaters from petrochemical and other allied industries. Biological desulfurization, an ecofriendly process offers no secondary pollution and allows for the recovery of elemental sulfur as a valuable product in a useable form as fertilizer and can be used as raw material in various industries. Therefore, this work explores the bio desulfurization potential of mixed microbial consortia that was isolated from various sources for the removal of sulfur containing compounds from synthetic wastewater at varying influent sulfide loading rate. Further, this study focused on optimizing the critical process parameters such as influent sulfide loading rate, ORP and pH to achieve maximum sulfur recovery. The experiments were performed at varying sulfide loading of 3000, 4000, 5000 and 6000 mg/L using the isolated mixed consortia at an ORP of −300 ± 20 mV and −360 ± 20 mV for an incubation period of 70 h. Results revealed that the isolated microbial consortia belong to the genera 73% Pseudomonas, 24% Alishewanella and 3% Zobellella. The maximum sulfide conversion efficiency to sulfite 309 mg/L, elemental sulfur 1152 mg/L and sulfate 1813 mg/L was exhibited by microbial consortia at an initial sulfide load of 6000 mg/L and ORP of −360 ± 20 mV.

Influence of oxidation–reduction potential and pH on polysulfide concentrations and chain lengths in the biological desulfurization process under haloalkaline conditions

Biological desulfurization under haloalkaline conditions has been applied worldwide to remove hydrogen sulfide (H2S) from sour gas steams. The process relies on sulfide-oxidizing bacteria (SOB) to oxidize H2S to elemental sulfur (S8), which can then be recovered and reused. Recently, a dual-reactor biological desulfurization system was implemented where an anaerobic (sulfidic) bioreactor was incorporated as an addition to a micro-oxic bioreactor, allowing for higher S8 selectivity by limiting by-product formation. The highly sulfidic bioreactor environment enabled the SOB to remove (poly)sulfides (Sx2−) in the absence of oxygen, with Sx2− speculated as a main substrate in the removal pathway, thus making it vital to understand its role in the process. The SOB are influenced by the oxidation–reduction potential (ORP) set-point of the micro-oxic bioreactor as it is used to control the product of oxidation (S8 vs. SO42−), while the uptake of Sx2− by SOB has been qualitatively linked to pH. Therefore, to quantify these effects, this work determined the concentration and speciation of Sx2− in the biological desulfurization process under various pH values and ORP set-points. The total Sx2− concentrations in the sulfidic zone increased at elevated pH (8.9) compared to low pH (< 8.0), with on average 3.3 ± 1.0 mM-S more Sx2−. Chain lengths varied, with S72− only doubling in concentration while S52− increased 9 fold, which is in contrast with observations from abiotic systems. Changes to the ORP set-point of the micro-oxic reactor did not produce substantial changes in Sx2− concentration in the sulfidic zone. This illustrates that the reduction degree of the SOB in the micro-oxic bioreactor does not enhance their ability to interact with Sx2− in the sulfidic bioreactor. This increased understanding of how both pH and ORP affect changes in Sx2− concentration and chain length can lead to improved efficiency and design of the dual-reactor biological desulfurization process.

Mechanistic Evidence for Hg Removal from Wastewater by Biologically Produced Sulfur.

A significant quantity of biologically produced sulfur (BPS) is generated as a by-product of chemical and biological desulfurization processes applied to landfill gas treatment. The beneficial upcycling of BPS has seen limited use in the environmental context. The effectiveness and underlying mechanism of BPS as an adsorbent for removing Hg2+ from both solution and wastewater were elucidated based on experiments encompassing surface characterization, adsorption isotherms, kinetics, and thermodynamics. The BPS exhibited remarkable efficacy in removing Hg2+ from solution, with the Langmuir model accurately describing the adsorption process and showing a maximum adsorption capacity of 244 mg g-1. Surface analysis through X-ray photoelectron spectroscopy and scanning electron microscopy revealed that Hg2+ complexed with sulfide on BPS surfaces, forming stable HgS. The adsorbed Hg was strongly retained in BPS, with less than 0.2% of the adsorbed Hg desorbed by strong acids. Adsorption kinetics followed the double-exponential first-order model, showing an initial rapid adsorption phase wherein 75% of the initial Hg2+ was removed within 5 min, followed by a slower adsorption rate. The thermodynamic parameters suggested that adsorption of Hg2+ by BPS was a spontaneous and endothermic process. Additionally, BPS effectively removed Hg2+ from wastewater, showing preference for Hg over other co-existing metals. These findings underscore the potential of BPS as an effective adsorbent for Hg2+ removal from wastewater.

Biological desulfurization of biogas by a controlled aeration system

The excessive demand of modern society for resources implies the need for development, propagation and use of energy sources more interesting from the environmental and economic point of view. Biogas is a potential alternative, originating from anaerobic degradation composed essentially of methane (CH4), carbon dioxide (CO2) and traces of other gases such as hydrogen sulfide (H2S) and moisture. To enable its use, a purification process is necessary, especially with regard to H2S, since it has characteristics that cause corrosion of equipment and toxicity to human health. This study aims to implement a biological desulfurization system for biogas generated from the anaerobic digestion of the effluent treatment system in an egg processing company. Both the monitoring of the biogas composition and the control of air injection into the system were performed automatically from a device from the manufacturer Awite, which proved to be interesting for full-scale applications. The system showed removal efficiency of up to 71.63% (June 17th) in the concentration of H2S at the exit of the biodigester when the extreme values obtained were used, and removal of 61.23% when the selected period was considered. Still, the temperature behavior was shown to influence the variable [H2S] in a directly proportional way. However, it was noticeable the restriction of the efficiency of the technique especially due to the low content of solids in the effluent and a need for adaptation in the engineering of the reactor.

A comparison between Claus and THIOPAQ sulfur recovery techniques in natural gas plants

A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data.

Comparison of the capacity of biological desulfurization of Thiobacillus ferrooxidans from different sulfur-containing substrates with or without additional ferrous iron

Comparison of the capacity of biological desulfurization of Thiobacillus ferrooxidans from different sulfur-containing substrates with or without additional ferrous iron

From Genes to Bioleaching: Unraveling Sulfur Metabolism in Acidithiobacillus Genus.

Sulfur oxidation stands as a pivotal process within the Earth's sulfur cycle, in which Acidithiobacillus species emerge as skillful sulfur-oxidizing bacteria. They are able to efficiently oxidize several reduced inorganic sulfur compounds (RISCs) under extreme conditions for their autotrophic growth. This unique characteristic has made these bacteria a useful tool in bioleaching and biological desulfurization applications. Extensive research has unraveled diverse sulfur metabolism pathways and their corresponding regulatory systems. The metabolic arsenal of the Acidithiobacillus genus includes oxidative enzymes such as: (i) elemental sulfur oxidation enzymes, like sulfur dioxygenase (SDO), sulfur oxygenase reductase (SOR), and heterodisulfide reductase (HDR-like system); (ii) enzymes involved in thiosulfate oxidation pathways, including the sulfur oxidation (Sox) system, tetrathionate hydrolase (TetH), and thiosulfate quinone oxidoreductase (TQO); (iii) sulfide oxidation enzymes, like sulfide:quinone oxidoreductase (SQR); and (iv) sulfite oxidation pathways, such as sulfite oxidase (SOX). This review summarizes the current state of the art of sulfur metabolic processes in Acidithiobacillus species, which are key players of industrial biomining processes. Furthermore, this manuscript highlights the existing challenges and barriers to further exploring the sulfur metabolism of this peculiar extremophilic genus.

Polysulfide Concentration and Chain Length in the Biological Desulfurization Process: Effect of Biomass Concentration and the Sulfide Loading Rate.

Removal of hydrogen sulfide (H2S) can be achieved using the sustainable biological desulfurization process, where H2S is converted to elemental sulfur using sulfide-oxidizing bacteria (SOB). A dual-bioreactor process was recently developed where an anaerobic (sulfidic) bioreactor was used between the absorber column and micro-oxic bioreactor. In the absorber column and sulfidic bioreactor, polysulfides (Sx2-) are formed due to the chemical equilibrium between H2S and sulfur (S8). Sx2- is thought to be the intermediate for SOB to produce sulfur via H2S oxidation. In this study, we quantify Sx2-, determine their chain-length distribution under high H2S loading rates, and elucidate the relationship between biomass and the observed biological removal of sulfides under anaerobic conditions. A linear relationship was observed between Sx2- concentration and H2S loading rates at a constant biomass concentration. Increasing biomass concentrations resulted in a lower measured Sx2- concentration at similar H2S loading rates in the sulfidic bioreactor. Sx2- of chain length 6 (S62-) showed a substantial decrease at higher biomass concentrations. Identifying Sx2- concentrations and their chain lengths as a function of biomass concentration and the sulfide loading rate is key in understanding and controlling sulfide uptake by the SOB. This knowledge will contribute to a better understanding of how to reach and maintain a high selectivity for S8 formation in the dual-reactor biological desulfurization process.

Isolation and Characterization of A Novel Iron–Sulfur Oxidizing Bacterium Acidithiobacillus Ferrooxidans YQ-N3 and its Applicability in Coal Biodesulfurization

Acidithiobacillus ferrooxidans is a chemotrophic, aerobic, acidophilic, and Gram-negative bacterium that plays a key role in iron and sulfur cycling and has a wide range of applications in the industrial field. A novel A. ferrooxidans strain, hereinafter referred to as strain “YQ-N3”, was isolated from sediments of a river polluted by acid mine drainage (AMD) of an abandoned mine in Shanxi, China. The whole genome sequencing results revealed that A. ferrooxidans YQ-N3 has a 3,217,720 bp genome, which is comprised of one circular chromosome and five circular plasmids (Plasmid A, Plasmid B, Plasmid C, Plasmid D, Plasmid E). Plasmid E, a new plasmid, had not been annotated in the reference database. A. ferrooxidans YQ-N3 had a close evolutionary relationship with A. ferrooxidans ATCC23270 and A. ferridurans JCM18981 and exhibited higher similarity in its genomic structure with A. ferrooxidans ATCC23270. Multiple genes related to environmental resistance and iron and sulfur metabolism were predicted from its genome. A. ferrooxidans YQ-N3 can remarkably increase the oxidation rate of Fe2+ and S0 and enhance the hydrophilicity of S0, which was supported by functional gene analysis and laboratory experiments. The biological desulfurization experiment demonstrated that A. ferrooxidans YQ-N3 can reduce the sulfur content in coal by removing pyrite sulfur and organic sulfur.

Research on Desulfurization Technology of Low Sulfur Marine Fuel Oil

With the implementation of the International Maritime Organization (IMO) marine fuel oil sulfur restriction policy in 2020, the desulfurization technology of marine residual fuel oil has received more attention from the industry. Heavy feedstock is the main component of marine residual fuel oil, and this paper introduces some of the heavy feedstock desulfurization technologies, mainly hydrodesulfurization, oxidation desulfurization, reactive metal desulfurization, adsorption desulfurization, biological desulfurization and extraction desulfurization. The respective advantages, disadvantages and applicability of these heavy feedstock desulfurization technologies are summarized.

Organic layer characteristics and microbial utilization of the biosulfur globules produced by haloalkaliphilic Thioalkalivibrio versutus D301 during biological desulfurization.

The haloalkaliphilic genus Thioalkalivibrio, widely used in bio-desulfurization, can oxidize H2S to So, which is excreted outside cells in the form of biosulfur globules. As by-product of bio-desulfurization, information on biosulfur globules is still very scant, which limits its high-value utilization. In this paper, the characteristics of biosulfur globules produced by Thioalkalivibrio versutus D301 and the possibility of cultivating sulfur-oxidizing bacteria as a high biological-activity sulfur source were studied. The sulfur element in the biosulfur globules existed in the form α-S8, which was similar to chemical sulfur. The biosulfur globule was wrapped with an organic layer composed of polysaccharides and proteins. The composition of this organic layer could change. In the formation stage of biosulfur globules, the organic layer was dominated by polysaccharides, and in later stage, proteins became the main component. We speculated that the organic layer was mainly formed by the passive adsorption of organic matter secreted by cells. The existence of organic layer endowed biosulfur with better bioavailability. Compared with those found using chemical sulfur, the growth rates of Acidithiobacillus thiooxidans ATCC 19377T, Thiomicrospira microaerophila BDL05 and Thioalkalibacter halophilus BDH06 using biosulfur increased several folds to an order of magnitude, indicating that biosulfur was a good sulfur source for cultivating sulfur-oxidizing bacteria.

Enhanced Biodesulfurization with a Microbubble Strategy in an Airlift Bioreactor with Haloalkaliphilic Bacterium Thioalkalivibrio versutus D306.

Biodesulfurization under haloalkaline conditions requires limiting oxygen and additional energy in the system to deliver high mixing quality control. This study considers biodesulfurization in an airlift bioreactor with uniform microbubbles generated by a fluidic oscillation aeration system to enhance the biological desulfurization process and its hydrodynamics. Fluidic oscillation aeration in an airlift bioreactor requires minimal energy input for microbubble generation. This aeration system produced 81.87% smaller average microbubble size than the direct aeration system in a bubble column bioreactor. The biodesulfurization phase achieved a yield of 94.94% biological sulfur, 84.91% biological sulfur selectivity, and 5.06% sulfur oxidation performance in the airlift bioreactor with the microbubble strategy. The biodesulfurization conditions of thiosulfate via Thioalkalivibrio versutus D306 are revealed in this study. The biodesulfurization conditions in the airlift bioreactor with the fluidic oscillation aeration system resulted in the complete conversion of thiosulfate with 27.64% less sulfate production and 10.34% more biological sulfur production than in the bubble column bioreactor. Therefore, pleasant hydrodynamics via an airlift bioreactor mechanism with microbubbles is favored for biodesulfurization under haloalkaline conditions.

Synergism of hydrolytic acidification and sulfate reducing bacteria for acid production and desulfurization in the anaerobic baffled reactor: High sulfate sewage wastewater treatment

High sulfate concentrations in sewage wastewater restricts the application of treatment technologies. In this present study, acid production-sulfate reduction reaction system effectively improved the high concentration sulfate removal from the sewage wastewater. Acid-generating phase in the two-phase anaerobic process was used. After 33 days of low-load start-up, COD removal efficiency in the acid-producing phase reached > 40%. Effluent VFA stable around 1400 mg/L and pH 4.0 ∼ 4.3. Effluent alkalinity was continuously reduced until zero, acidogenic phase started successfully. In acid production-sulfate reduction reactor, when COD/SO42− 3, the hydrolytic acidification bacteria maintained stable hydrolysis acidification ability. Sulfate-reducing bacteria increased the degree of acidification by 10%∼15%. The metabolic rate of acid bacteria reflected the good synergistic effect. When hydraulic retention time was controlled at 8.5 h and influent COD 3000 mg/L, with the decrease of COD/SO42− ratio, effluent sulfate removal efficiency gradually decreased. For COD/SO42− 6, ABR reactor had obvious phase separation characteristics of acid production-sulfate reduction and methanogenic phase. With the decrease of COD/SO42−, SO42− removal affected each compartment (methanogenesis weakened). For COD/SO42− 3, the effluent sulfate removal efficiency decreased with the decrease in HRT. At HRT 8 h, the sulfate removal by ABR reactor mainly occurred in I compartment. As the HRT decreases, the compartment that takes the main sulfate removal gradually moves backwards. When the HRT was 2 h, the sulfate removal occurred mainly in the II and III compartments. This present study can effectively solve the contradictions and drawbacks in the traditional biological desulfurization process and improves the efficiency of biological desulfurization.

Rate-based model for predicting and evaluating H2S absorption in the haloalkaliphilic biological desulfurization process

The highly efficient performance of H2S absorption is the crucial indicator for haloalkaliphilic biological desulfurization (HBDS) because it immediately concerns the H2S removal efficiency and pH change of alkaline solutions. Therefore, we investigated the effect of operating parameters on the H2S absorption's performance under haloalkaline conditions. The gas–liquid ratio and packing height significantly improve H2S removal efficiency, from 80% to 90% and 66% to 99%, respectively. The absorption temperature had a trivial impact on the H2S removal efficiency, and the maximum value appeared at 45 °C. Additionally, all operating parameters caused pH changes that varied in the acceptable range (0.1 to 0.5) during the absorption process. A rate-based model was successfully developed to predict the haloalkaliphilic H2S absorption process accurately. Moreover, this model could be implemented to effectively evaluate the HBDS system's stability and provide reliable theoretical guidance for the industrial HBDS process to ensure good process stability.

Effect of Polyaniline and Graphene Oxide Modified Carbon Felt on Adsorption and Immobilization of Acidithiobacillus ferrooxidans.

Biological desulfurization plays an increasingly important role in desulfurization industry. A strain of Acidithiobacillus ferrooxidans ZJ-2 with high Fe2+ oxidizing efficiency was in this study isolated and screened to remove hydrogen sulfide from biogas. To further improve its oxidation efficiency, A. ferrooxidans ZJ-2 was immobilized using carbon felt (CF), modified with graphene oxide (GO) and polyaniline (PANI), as immobilized carrier. The effects of immobilization on strain's Fe2+ oxidation efficiency and impact of PANI and GO on CF were also investigated. Raman spectra and atomic force microscopy showed that CF was successfully modified using GO and PANI. Cyclic voltammetry and electrochemical impedance spectroscopy measurements revealed that the electrochemical properties of modified CF were improved, presenting the following trend in conductivity: CF< GO-modified CF (GO-CF) < PANI-modified CF (PANI-CF) < PANI/GO-modified CF (PANI/GO-CF). The resistance of modified CF was lower than that of unmodified CF, and exhibited the following trend: CF > GO-CF > PANI-CF > GO/PANI-CF. While PANI-CF inhibited growth of free and immobilized A. ferrooxidans ZJ-2, GO-CF was conducive to microbial growth and increased cell density and oxidation ability of A. ferrooxidans ZJ-2. Thus, the present study developed an immobilized bacterial carrier that had better conductivity and lower resistance and was efficient in immobilizing A. ferrooxidans and could be used for biogas desulfurization in biological and biochemical combined reactors.

Effect of sulfide on morphology and particle size of biologically produced elemental sulfur from industrial desulfurization reactors

We investigated the effect of polysulfide formation on properties of biologically produced elemental sulfur (S8) crystals, which are produced during biological desulfurization (BD) of gas. The recent addition of an anoxic-sulfidic reactor (AnSuR) to the BD process resulted in agglomerated particles with better settleability for S8 separation. In the AnSuR, polysulfides are formed by the reaction of bisulfide (HS-) with S8 and are subsequently oxidized to S8 in a gas-lift reactor. Therefore, sulfur particles from the BD are shaped (i.e. morphology and particle size) both by formation and dissolution. We assessed the reaction of HS- with S8 particles in anoxic, abiotic experiments in a batch reactor using two S8 samples from industrial BD reactors. Under these conditions, the sulfur particle surface became coarser and more porous, and in addition the smallest particles disappeared. Agglomerates initially fell apart but were reformed at a later stage. Moreover, we found different observed polysulfide formation rates for each S8 sample, which was related to the initial morphology and size. Our findings show that particle properties can be controlled abiotically and that settleability of S8 is increased by increasing both the HS--S8 ratio and retention time.

Novel Agglomeration Strategy for Elemental Sulfur Produced during Biological Gas Desulfurization.

This article presents a novel crystal agglomeration strategy for elemental sulfur (S) produced during biological desulfurization (BD). A key element is the nucleophilic dissolution of S by sulfide (HS–) to polysulfides (Sx2–), which was enhanced by a sulfide-rich, anoxic reactor. This study demonstrates that with enhanced Sx2– formation, crystal agglomerates are formed with a uniform size (14.7 ± 3.1 μm). In contrast, with minimal Sx2– formation, particle size fluctuates markedly (5.6 ± 5.9 μm) due to the presence of agglomerates and single crystals. Microscopic analysis showed that the uniformly sized agglomerates had an irregular structure, whereas the loose particles and agglomerates were more defined and bipyramidal. The irregular agglomerates are explained by dissolution of S by (poly)sulfides, which likely changed the crystal surface structure and disrupted crystal growth. Furthermore, S from Sx2– appeared to form at least 5× faster than from HS– based on the average Sx2– chain length of x ≈ 5, thereby stimulating particle agglomeration. In addition, microscopy suggested that S crystal growth proceeded via amorphous S globules. Our findings imply that the crystallization product is controlled by the balance between dissolution and formation of S. This new insight has a strong potential to prevent poor S settleability in BD.

Biodeodorization of Barrels Containing Natural Gas Odorants by Bacillus cereus

Introduction: All sulfur organic odorants used in the Iranian gas industry enter the country in 200-liter barrels. There are ways to clean up the empty barrels contaminated with these materials. In the Gas Company, the currently used method is chemical oxidation (using sodium hypochlorite and caustic). In this study, the biological desulfurization and degradation method of mercaptan was studied.Materials and Methods: Desulfurizing bacteria in the university microbial collection, together with bacteria isolated from gas odorant barrels, were examined, among which one of the species had the highest and fastest decomposition rate. This bacterium belongs to the Bacillus cereus family. The most important factors affecting biological desulfurization including initial bacterial concentration, the concentration of odorant, and the Oil Fraction Phase (OFP) were optimized.Results: These three factors were studied using an experimental design. Initial bacterial concentrations were evaluated at five levels from 10 to 50 ml with an optimum concentration of 30 ml. The OFP was also evaluated at five levels from 10 to 90%, with 50% being optimized. Concentrations of odorant were also evaluated from 2500 to12500 ppm, with an optimum concentration of 7500 ppm.Conclusions: Operational testing was carried out in one of the barrels in the optimized conditions for 48 h. The results showed 79.8% efficiency in removing odorant.

Biologically produced sulfur as a novel adsorbent to remove Cd2+ from aqueous solutions

Biological desulfurization processes of landfill gas yield an enormous amount of biologically produced S (BPS) as a byproduct. Capability of BPS to remove Cd2+ from aqueous solutions was tested and its removal efficiency was compared to that of granular activated carbon (GAC). Kinetics of Cd2+ removal by BPS was a two-stage process with an initial rapid adsorption showing 45% of initial Cd2+ was removed within 5 min, followed by a slower adsorption. Cadmium adsorption onto the BPS fitted the Langmuir isotherm model and maximum adsorption capacity of the BPS (63.3 mg g−1) was 1.8 times higher than that of GAC (36.1 mg g−1). Thermodynamic parameters showed that Cd2+ adsorption by BPS was favorable and endothermic. Data from XPS proved the main adsorption mechanism to be complexation of Cd2+ with sulfides in the BPS. Results demonstrated that BPS can be recycled as a novel adsorbent for Cd2+ removal from wastewater.