Sulfide In Wastewater Research Articles

Electrochemical sulfate production from sulfide-containing wastewaters and integration with electrochemical nitrogen recovery

Electrochemical methods can help manage sulfide in wastewater, which poses environmental and health concerns due to its toxicity, malodor, and corrosiveness. In addition, sulfur could be recovered as fertilizer and commodity chemicals from sulfide-containing wastewaters. Wastewater characteristics vary widely among wastewaters; however, it remains unclear how these characteristics affect electrochemical sulfate production. In this study, we evaluated how four characteristics of influent wastewaters (electrolyte pH, composition, sulfide concentration, and buffer strength) affect sulfide removal (sulfide removal rate, sulfide removal efficiency) and sulfate production metrics (sulfate production rate, sulfate production selectivity). We identified that electrolyte pH (3 × difference, i.e., 25.1 to 84.9 μM h−1 in average removal rate within the studied pH range) and sulfide concentration (16 × difference, i.e., 82.1 to 1347.2 μM h−1 in average removal rate) were the most influential factors for electrochemical sulfide removal. Sulfate production was most sensitive to buffer strength (6 × difference, i.e., 4.4 to 27.4 μM h−1 in average production rate) and insensitive to electrolyte composition. Together, these results provide recommendations for the design of wastewater treatment trains and the feasibility of applying electrochemical methods to varying sulfide-containing wastewaters. In addition, we investigated a simultaneous multi-nutrient (sulfur and nitrogen) process that leverages electrochemical stripping to further enhance the versatility and compatibility of electrochemical nutrient recovery.

A promising photo-thermal catalytic approach for hydrogen generation from sulphide bearing wastewater

Platinum (Pt) nanoparticles decorated titanium dioxide (Pt/TiO2) is considered a multifaceted catalyst owing to its wide applicability from photo to thermo-catalysis, as compared to other engineered materials i.e., noble metals supported metal oxide. In this context, the present article provides an in-depth discussion for application of Pt2.5/TiO2 for photocatalytic hydrogen (H2) production under stimulated laboratory (indoor) and natural sunlight (outdoor) condition. It demonstrated the promising method for utilising the light and heat of full solar energy spectrum in tandem with photocatalyst (photo-thermocatalysis) to create hydrogen from waste water. However, its underlying mechanism remains elusive and contentious. The discussion is covered in more details to address the effects of various factors on its performance, including physicochemical characteristics of as-synthesized photocatalyst (e.g., optical absorptivity, morphology, and surface functionalities), water splitting evaluation parameters (e.g., catalyst dose, concentration of sacrificial donors, effect of various sacrificial donors, and illumination sources), and underlying mechanisms. The as-synthesized Pt2.5/TiO2 photocatalyst have shown promising hydrogen production rate of 9 mmol h−1 and exhibited unprecedented stability of 24h using Na2S/Na2SO3 as sacrificial agent. This study will aid in the search for stable photocatalysts to recover hydrogen from sulphide wastewater.

Enhancing Ecological Efficiency in Biological Wastewater Treatment: A Case Study on Quality Control Information System

This study aimed to improve the control system of the biological stage of wastewater treatment using the quality control information system to support the concept of environmental efficiency management. In this case, the object of the study was the treatment facilities of Sumy city (Ukraine). For automatic control of wastewater quality, pH, oxidation reduction potential (ORP), electrical conductivity, and temperature indicators were taken, as well as hydrobiological analysis of activated sludge and mathematical modelling. The pH of wastewater at the input system has systematically unacceptable values (above 8.5 were recorded). Unacceptable concentrations of sulphur-containing toxicants arrive at the entrance of treatment facilities (0.22–1.3 mg/L). The response of activated sludge biocenosis to increasing concentrations of hydrogen sulphide in wastewater was analysed. Furthermore, a mathematical model of monoculture population growth, with two factors that affect population growth (nutrient concentration and monoculture production concentration), was implemented for the initial assessment of possible negative effects on wastewater treatment. The differential equation of the population dynamics of the i-th species of microorganisms in activated sludge was described. The applied system of automated monitoring of wastewater parameters with expert assessment of activated sludge and a unified mathematical model of approaches allows for a complex system of decision-making support to be realised. However, this requires the construction of mathematical models that would take into account the cause–effect relations that operate under conditions of incomplete technological information and the potential presence of emergencies due to natural disasters and military activities.

Effect of Sulfide on the Processes of Transformation of Nitrogen Compounds and the Microbial Community Composition in the Anammox Bioreactor

Anammox is one of the most important processes in the global nitrogen cycle and the basis for an efficient technology of nitrogen removal from wastewater. The effect of the presence of sulfide in wastewater on the transformation of nitrogen compounds by the anammox community has been insufficiently studied. The present work dealt with the effect of sulfide on nitrogen removal efficiency and the dynamics of nitrogen species in a laboratory sequencing batch bioreactor modeling the functioning of the anammox community carrying out ammonium oxidation via nitritation and anammox and nitrite oxidation. The 16S rRNA gene profiling of the community of the anammox-activated sludge attached to the stationary carrier revealed members of the key physiological groups: ammonium oxidizers of the genus Nitrosomonas, nitrite oxidizers of the genus Nitrosospira, and anammox bacteria of the genera Candidatus Brocadia and Ca. Jettenia, as well as members of other bacterial genera. Nitrate removal was not sensitive to sulfide at concentrations up to 50 mg S/L and decreased by 17% at 100 mg/L. The threshold of sulfide sensitivity for group I nitrifiers was ~50 mg/L, while anammox bacteria were resistant to sulfide concentrations of up to 100 mg S/L in the incoming water. Group II nitrifiers were probably the most sulfide-sensitive components of the community. A drastic increase in the abundance of members of the family Hydrogenophilaceae at elevated sulfide concentrations, together with the precipitation of elemental sulfur, may indicate sulfide oxidation either by molecular oxygen or via nitrate reduction; this finding requires further investigation. This is the first report on the different effects of sulfide on the growth rate of members of the nitrifying genus Nitrosomonas, increasing/decreasing or not affecting it for different phylotypes at elevated sulfide concentrations.

Temperature and pH on microbial desulfurization of sulfide wastewater: From removal performance to gene regulation mechanism

Sulfides are widely present in industrial wastewater cause environmental problems like malodorous, corrosive, and toxic. Microbial desulfurization technology has the advantages of ambient conditions, low energy consumption, and enables the recovery of sulfur (S0). These advantages make it the technology of choice for treating middle and low loads of sulfide wastewater. Temperature and pH are two important factors that affect the product selectivity of microbial desulfurization, but the mechanism of these two factors regulating the genes and metabolic pathways of functional microorganisms remains unclear. In this study, a sequencing batch reactor (SBR) treated sulfide-containing wastewater, achieving complete degradation of 400 mg/L influent sulfide at 30 °C and pH 7.5 and showed the best S0 formation efficiency (91.1 ± 2.1 %). The Halothiobacillus genus dominated the microbial community, with the highest abundance (73.0 %) at 30 °C and pH 7.5. Metagenomic analysis showed that at 30 °C and pH 7.5 compared with 20 °C or pH 6.5, the abundance of sulfide oxidation genes (sqr, fccAB) were significantly increased (49.9 % and 43.0 %, 1303.3 % and 139.4 %). Under unfavorable temperature and pH, fccAB gene abundance decreased significantly (92.9 %, 58.2 %), sqr decreased less (33.3 %, 30.1 %), and sox increased significantly (241.0 %, 122.1 %). The dominate sulfide oxidation pathway from flavocytochrome c (FCC) shifted to the sulfide: quinone oxidoreductase (SQR) and sulfur oxidizing system (SOX) pathways. This work highlights the ability of modulating temperature and pH to optimize the biological treatment of sulfide-containing wastewater processes and obtaining more S0, and elucidates their effects on metabolic pathways associated with sulfide oxidation.

Sulfur-Induced Low Crystallization of Ultrathin Pd Nanosheet Arrays for Sulfur Ion Degradation-Assisted Energy-Efficient H2 Production.

The utilization of thermodynamically favorable sulfur oxidation reaction (SOR) as an alternative to sluggish oxygen evolution reaction is a promising technology for low-energy H2 production while degrading the sulfur source from wastewater. Herein, amorphous/crystalline S-doped Pd nanosheet arrays on nickel foam (a/c S-Pd NSA/NF) is prepared by S-doping crystalline Pd NSA/NF. Owing to the ultrathin amorphous nanosheet structure and the incorporation of S atoms, the a/c S-Pd NSA/NF provides a large number of active sitesand the optimized electronic structure, while exhibiting outstanding electrocatalytic activity in hydrogen evolution reaction (HER) and SOR. Therefore, the coupling system consisting of SOR-assisted HER can reach a current density of 100mA cm-2 at 0.642V lower than conventional electrolytic water by 1.257V, greatly reducing energy consumption. In addition, a/c S-Pd NSA/NF can generate H2 over a long period of time while degrading S2- in water to the value-added sulfur powder, thus further reducing the cost of H2 production. This work proposes an attractive strategy for the construction of an advanced electrocatalyst for H2 production and utilization of toxic sulfide wastewater by combining S-doping induced partial amorphization and ultrathin metal nanosheet arrays.

Anaerobic–anoxic–oxic biological treatment of high-strength, highly recalcitrant polyphenylene sulfide wastewater

This paper outlines an integrated anaerobic–anoxic–oxic (A2O) treatment scheme for high-strength, highly recalcitrant wastewater from the production of polyphenylene sulfide (PPS) resins and their composite chemicals. An integrated anaerobic granular sludge blanket (GSB) and anoxic–oxic (AO) reactor indicated that the A2O removed chemical oxygen demand (COD) of up to 7,043 mg/L with no adverse impact from high total dissolved solids (25,000 mg/L) on the GSB COD removal and effluent suspended solids. At a Total Kjeldahl Nitrogen (TKN) nitrification load of 0.11 g TKN/L.d and 400 mg NH3/L, almost 99 % of the NH3 was degraded with effluent NH3 < 5 mg/L, meeting the limit of 35 mg/L. High S2- levels of up to 1470 mg/L can be transformed through aerobic microbial degradation to meet a limit of 1.0 mg/L. With proper microbial acclimation and process designs, the integrated A2O scheme offers a resilient and robust treatment for high-strength recalcitrant PPS wastewater.

Temperature and Ph on Microbial Desulfurization of Sulfide Wastewater: From Removal Performance to Gene Regulation Mechanism

Temperature and Ph on Microbial Desulfurization of Sulfide Wastewater: From Removal Performance to Gene Regulation Mechanism

Oxidation of sulfide with the CuO catalyst assisted oxygen microbubbles in alkaline wastewater: Efficiency, sulfur conversion, and mechanisms

Alkaline sulfide wastewater is toxic, corrosive, and malodorous, detoxification of which usually be realized by oxidizing S2− to corresponding sulfate salts. Due to complex reaction pathway and sluggish reaction kinetics, complete oxidation of S2− to SO42− usually can only be realized under extreme reaction condition. In this study, MgO-supported CuO catalyst assisted oxygen microbubble oxidation of S2− in NaOH solution has been investigated. It was concluded that the oxidation efficiency of S2− reached 99.98% at 90 °C and ambient pressure in 180 min, with 98.70% being converted to SO42−. This coupled process exhibits the same oxidation effect as the wet catalytic oxidation method operating under high temperature and high pressure. Mechanism study suggested that SO3− and SO4− were primary reactive oxygen species responsible for S2− deep oxidation. Furthermore, the microbubbles could inhibit the S poisoning of the CuO catalyst to ensure the continuation of the catalytic reaction. The generation of reactive oxygen species under mild conditions was achieved under physicochemical action in this process. The proposed novel oxidation method featuring CuO catalyst assisted microbubble oxidation therefore can be considered an attractive alternative approach for alkaline sulfide wastewater treatment.

Highly-efficient photocatalytic activity of TiO2-AC nanocomposites for hydrogen production from sulphide wastewater

Photocatalytic water splitting is one of the prospective green energy technologies, particularly, for hydrogen production from wastewater under natural sunlight irradiation. Herein, we report experimental data on the synthesis and characteristics of the biomass activated carbon (b-AC)-anchored anatase titanium oxide (a-TiO2) nanocomposites, which were ultrasonically prepared by using the sol-gel-grown a-TiO2 spherical nanoparticles and the KOH-activated citron-derived b-AC nanoflakes. The a-TiO2/b-AC nanocomposites displayed an aggregated morphology with the interconnected spherical nanoparticles, and they showed a high surface area (495 m2/g). When using a-TiO2/b-AC as a photocatalyst for hydrogen production from sulphide wastewater (0.15 M) under solar irradiation (740 W/m2), the superb hydrogen production efficiency was achieved up to 400 mL/h. The results suggest the a-TiO2/b-AC nanocomposites to hold an ample potential for photocatalytic hydrogen production from the wastewater.

The recovery of sulfur as ZnS particles from sulfide-contained wastewater using fluidized bed homogeneous crystallization technology

Sulfide wastewater that is anthropogenically generated from industrial activities is highly corrosive, hazardous, and harms the natural ecosystem. This study uses a novel fluidized-bed homogeneous crystallization (FBHC) method to remove sulfide ions from an aqueous solution. Zinc is used as a precipitant to crystallize ZnS homogeneously in the FBHC reactor to reduce the sludge, which is commonly produced in a conventional chemical precipitation process. The optimal pH value, [Zn2+]0/[S2-]0 M ratio, sulfide cross-sectional surface loading (L, kg-S/m2.hr), and hydraulic retention time (HRT) for the system are established, to optimize the sulfur removal efficiency. The maximum crystallization ratio and the total removal efficiency for sulfur are 97.7% and 98.8%, respectively, at pH = 5.4, a [Zn2+]0/[S2-]0 M ratio of 1, a cross-sectional surface loading of 2.2 kg-S/m2.hr, and an HRT number of 6 with an initial sulfur concentration of 320 mg/L. The solid products are collected and identified as zinc sulfide (wurtzite) using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS).

Synthesis and characterization of β-MnO2 nanoparticles for hydrogen production

The nanoparticles were hydrothermally synthesized using β-MnO2 nanoparticles were primed using a chemical reduction method. β-MnO2 nanoparticles were validated to occur in the type of nanocrystals with a high specific surface area of 109 m2 /g. While β-MnO2 nanoparticles were used as a photocatalyst for wastewater treatment, they demonstrated vastly more efficient hydrogen production action. The greater hydrogen production evaluate (750 mol-1 /h) was attained by separating the artificial sulphide effluent (0.2 M) using β-MnO2 NPs in a photocatalytic reaction. The findings demonstrate the β-MnO2 NPs' efficient power abilities, notably for photocatalytic hydrogen detachment from sulphide wastewater. From this investigation, we evidenced a recyclable tactic for impactful sewage treatment through the use of photocatalytic water splitting employing βMnO2 NPs.

Effect of Oxidizers on Sulphide Removal from Hair Dissolving Liming Wastewater in Tannery

Liming and unhairing is the conventional operation in the tannery where raw animal skins are treated with sodium sulphide and calcium hydroxide to remove keratin proteins e.g., hair and wool epidermis and to dissolve nonstructural proteins. The hair dissolving liming process discharges wastewater containing soluble sulphide. In acidification, the sulphide in wastewater generates toxic hydrogen sulphide, which has a negative impact on the environment. In this present study, the efficiency of hydrogen peroxide (H2O2) and sodium chlorite (NaClO2) oxidizers are compared to remove sulphide from the hair dissolving liming wastewater. The soluble sulphide in the raw liming wastewater was 3666 mg/L. At optimized dose and pH for H2O2 and NaClO2 soluble sulphide in the solution were 109.2 and 54.6 mg/L, respectively. The sulphide removal efficiency for H2O2and NaClO2 were 97.0% and 98.5%, respectively at an optimum pH (pH 7). Before and after treatment the physicochemical parameters of the liming wastewater were analysed by observing different water quality parameters viz: pH, TDS, EC and salinity. At optimized condition TDS and salinity removal efficiency was 47.2%, 52.3% and 8.1%, 11.2% for H2O2 and NaClO2, respectively. This simple and easy method would be effective for treating hair dissolving liming wastewater in reducing soluble sulphide discharge from the tanneries. Journal of Engineering Science 12(3), 2021, 67-72

Temperature and Ph on Microbial Desulfurization of Sulfide Wastewater: From Removal Performance to Gene Regulation Mechanism

Temperature and Ph on Microbial Desulfurization of Sulfide Wastewater: From Removal Performance to Gene Regulation Mechanism

Smartphone-based digital colorimetric measurement of dimethyl sulfide in wastewater

A simple and low-cost method for the measurement of dimethyl sulfide (DMS) in wastewater was developed using digital imaging colorimetry based on a smartphone. This method involved the generation of a pink color through the complexation reaction of DMS with sodium nitroprusside and subsequent acidification. A smartphone camera recorded the developed color through a digital image of the colored reaction mixture and color values in the red (R), green (G) and (B) blue color space were obtained through digital image analysis. The G value was found to provide a basis for the sensitive measurement of DMS. Light box parameters (position and distance of the light source relative to the camera) and reaction parameters (NaOH concentration, reaction time and HCl concentration) were optimized. This method exhibited linearity in the working range of 500–6000 μg kg−1 with a Pearson coefficient of 0.996. The sensitivity, which was based on the slope of the calibration line, was calculated to be −0.017 (μg kg−1)−1, and the limit of detection was 222 μgkg−1. Good precision (0.8 to 1.3% relative standard deviation) was obtained. The G value exhibited good correlation (Pearson correlation coefficient = 0.997) with the absorbance obtained from a spectrophotometer. Measurement of the DMS of a wastewater sample yielded a result which was in agreement (98 % recovery) with the results of a reference GC-FPD analysis, validating its capability for an accurate measurement.

Model-Driven Strategies for Sulfide Control in a Regional Wastewater System Receiving Tannery Effluents in Portugal

Ageing infrastructure are a concern for many wastewater utilities. This is accentuated with the presence of hydrogen sulfide within the sewer headspace, known to induce concrete corrosion, toxicity and odours. Some industrial effluents contain significant sulfide concentrations, however most field studies in the literature refer to domestic networks, or lab/pilot scale sulfide abatement strategies for varied effluents. Hence, the objectives of this work are: (1) To obtain data regarding the evolution of sulfides in a full-scale industrial sewer system in Portugal, receiving wastewater from a number of tanneries; (2) model their fate within the system and (3) experimentally evaluate sulfide precipitation with iron salts. Field work evidenced heavily sulfide loaded effluents, exceeding by far literature values for sewer systems. Modelling was carried out based on the AeroSept+ model, specifically calibrated to this type of effluent. Results showed the model was capable of reproducing the overall levels of sulfide in wastewater and H2S in the sewer headspace, while allowing insights into industrial discharges, originating a set of proposed interventions for sulfide abatement. This may be carried out by iron salts addition, in a ratio of 2.75:1, at existing monitoring stations. This approach was fundamental for an affordable performance assessment, under considerable uncertainty.

Excellent photocatalytic performances of Co3O4–AC nanocomposites for H2 production via wastewater splitting

Natural sunlight-driven photocatalytic hydrogen production from wastewater is one of the most desirable techniques that can realize future green energy technology. Herein, we report the synthesis and the characterization of the biomass activated carbon (AC)-decorated cobalt oxide (Co3O4) nanocomposites for solar-stimulated photocatalytic hydrogen production from sulphide wastewater. The Co3O4-AC nanocomposites were ultrasonically synthesized by using hydrothermally-grown spinel Co3O4 nanoflakes and biomass-derived AC nanoflakes. Co3O4-AC showed a nanobundle-like aggregated morphology, and exhibited a large specific surface area (~133 m2/g). Through utilizing Co3O4-AC as a photocatalyst for photocatalytic splitting of sulphide wastewater (0.2 M) under solar irradiance with 730 W/m2, an enhanced H2 production efficiency (~70 mL/h) was achieved owing to the synergic effects from 2-dimentionally configured Co3O4 and AC microstructures; i.e., large surface area of Co3O4 and high electrical conductivity of AC. These findings suggest the nanocomposites of Co3O4-AC to hold great promise for the green approach of photocatalytic wastewater splitting.

Gram-scale synthesis of ZnS/NiO core-shell hierarchical nanostructures and their enhanced H2 production in crude glycerol and sulphide wastewater

Design and development of the efficient and durable photocatalyst that generates H2 fuel utilizing industrial wastewater under solar light irradiation is a sustainable process. Innumerable photocatalysts have been reported for efficient H2 production, but their large-scale production with the same efficiency of H2 production is a challenging task. In this study, a few gram-scale syntheses of ZnS wrapped with NiO hierarchical core-shell nanostructure via the surfactant-mediated process has been reported. Morphology and crystal structure analysis of ZnS/NiO showed spherical shaped hierarchical core-shell with cubic and face-centered cubic crystal structures. The surface examination confirmed the presence of Zn2+, S2−, Ni2+ and O2− ions in the nanocomposite. The photocurrent and photoluminescence studies of pristine and nanocomposites revealed that core-shell material is non-corrosive with a prolonged life-time of photo-excitons. Parametric studies on photocatalytic H2 generation in lab-scale photoreactor using crude glycerol in water recorded a high rate of H2 generation of 9.3 mmol h−1.g−1 of catalyst under the simulated solar light irradiation. Optimized reaction parameters are extended to a demonstrative photoreactor containing aqueous crude glycerol produced 18.5 mmol h−1 of H2 generation under the natural solar light irradiation. The same nanostructures were further tested with the simulated sulfide wastewater and the optimized catalyst showed H2 production of 350 mL h−1. The experimental results of time-on stream and catalytic stability demonstrated that ZnS/NiO hierarchical core-shell nanostructures can be recyclable and reusable for the continuous photocatalytic H2 generation.

Biomass activated carbon-decorated spherical β-Ni(OH)2 nanoparticles for enhanced hydrogen production from sulphide wastewater

Aiming at demonstrating the highly-efficient wastewater treatment via photocatalytic hydrogen production, the nickel hydroxide-anchored biomass activated carbon (NH-AC) nanocomposites were synthesized through the facile sol-gel method followed by the ultrasonication process. The NH-AC nanocomposites exhibited an aggregated nanostructure with the large surface area of 75.02 m2/g. For the sulphide wastewater treatment, the nanocomposites showed the enhanced hydrogen production rate of 420 mL/h. Such a superb photocatalytic reaction for NH-AC can be ascribed to the synergic effects from both the high porosity of nickel hydroxide and the high electrical conductivity of activated carbon. These results depict that the NH-AC nanocomposites possess a great potential for photocatalytic hydrogen production from the wastewater.

Upcycling of Wastewater via Effective Photocatalytic Hydrogen Production Using MnO2 Nanoparticles-Decorated Activated Carbon Nanoflakes.

In the present work, we demonstrated the upcycling technique of effective wastewater treatment via photocatalytic hydrogen production by using the nanocomposites of manganese oxide-decorated activated carbon (MnO2-AC). The nanocomposites were sonochemically synthesized in pure water by utilizing MnO2 nanoparticles and AC nanoflakes that had been prepared through green routes using the extracts of Brassica oleracea and Azadirachta indica, respectively. MnO2-AC nanocomposites were confirmed to exist in the form of nanopebbles with a high specific surface area of ~109 m2/g. When using the MnO2-AC nanocomposites as a photocatalyst for the wastewater treatment, they exhibited highly efficient hydrogen production activity. Namely, the high hydrogen production rate (395 mL/h) was achieved when splitting the synthetic sulphide effluent (S2− = 0.2 M) via the photocatalytic reaction by using MnO2-AC. The results stand for the excellent energy-conversion capability of the MnO2-AC nanocomposites, particularly, for photocatalytic splitting of hydrogen from sulphide wastewater.