Galvanic Wastewater Research Articles

Modified Ordered Mesoporous Carbons for Cr(VI) Removal from Wastewater.

The pristine CMK-3 carbon was ozonized and then chemically modified by the Zr and Fe compounds. The synthesized carbonaceous materials were characterized with physicochemical methods. The obtained carbons had a high specific surface area (ca. 800 m2 g-1) and an acidic surface. The Cr(VI) adsorption properties of the oxidized and Zr/Fe-modified carbon were studied. The highest static adsorption capacity towards Cr(VI) ions was evaluated for Zr/Fe-modified carbon (50.1 mg g-1) at pHeq = 5.8 after 240 min. The Elovich and Freundlich theoretical models were well fitted to the Cr(VI) adsorption kinetic and isotherm data on the Zr/Fe-modified CMK-3-type carbon. The leading Cr(VI) adsorption mechanism acting on the Zr/Fe-modified carbon was probably based on the redox reactions between Cr(VI) and the carbonaceous surface. Electrostatic attraction and surface complexation processes could also occur during Cr(VI) adsorption in the studied system. The effect of the competitive anions on the concentration level, such as in the galvanic wastewater for Cr(VI) adsorption onto chemically modified carbon, was negligible. The HCl and HNO3 media were insufficient for the Zr/Fe-modified carbon regeneration after Cr(VI) adsorption. The Zr/Fe-modified carbon was successfully applied for the efficient (>90%) Cr(VI) removal from the model galvanic wastewater.

The Potential of Bentonite as a Low-cost Adsorbent for the Removal of Heavy Metal Ions from Multicomponent Aqueous Systems of the Galvanic Industry

Waste water in the galvanic process contains high concentrations of heavy metals that pose a direct danger to humans and the environment. Conventional methods for their removal are quite expensive and generate a large amount of waste. The development of new and improvement of existing methods for the removal of heavy metals from galvanic wastewater are the subject of many studies. Compared to other purification methods, the adsorption is becoming an increasingly popular method of wastewater purification, especially if the adsorbent is cheap, easily available and does not require any other treatment before use. Therefore, the aim of the work was to investigate the possibility of using natural bentonite for the removal of heavy metal ions from multi-component water systems of the galvanic industry. For this purpose, the physico-chemical characterization of natural bentonite was performed, and then the influence of pH value, time and temperature on the adsorption efficiency was examined. The results of adsorption showed that natural bentonite can be used as an adsorbent for the removal of heavy metal ions from waste galvanic waters, and that at pH 5 it achieves the maximum removal efficiency for Cu(II):Cr(III):Ni(II) ions in the percentage ratio 100 : 99.990 : 99.998. The results showed that the highest removal efficiency for Cu (II) ions was achieved in the first 10 minutes, and 20 minutes for Cr (III) and Ni (II) ions. The maximum efficiency of Cu (II) removal was achieved at all temperatures, while for Cr (III) 99.99% and Ni (II) 100% maximum efficiency was achieved at 35°C, which indicates that the adsorption process is endothermic. The experimental results of the adsorption of Cu (II) metal ions are in good agreement with the Langmuir and Freundlich theoretical models, while for Cr (III) and Ni (II) ions they are in better agreement with the Langmuir adsorption model.

Evaluation of the mobility of heavy metals in the sediments originating from the post-galvanic wastewater treatment processes.

The article presents the assessment of heavy metals mobility in sediments from the process of galvanic wastewater treatment (pH 2.5, Co 1.5mg/L, Cr6+ < 0.02mg/L, Cr(total) 62mg/L, Cu 110mg/L, Ni 129mg/L and Pb 59mg/L) based on the use of hydroxides (Ca(OH)2, NaOH) as well as inorganic and organic sulphur compounds (Na2S, sodium dimethyldithiocarbamate (DMDTC), sodium trithiocarbonate (Na2CS3), trimercapto-s-triazine trisodium salt, TMT). The leachability was assessed after 1, 7, 14 and 21days of sediment contact with the leaching agent (deionized water). FeCl3 was used as a coagulant. The efficiency of metal removal changed within a range of 99.67-99.94% (for NaOH), 98.80-99.75% (for TMT), 99.67-99.92% (for DMDTC), 99.67-99.91 (for Na2CS3). The heavy metal content in the obtained precipitates changed within the following ranges: 0.1-0.2g/kg (Co), 9.8-14.7g/kg (Cr), 23.6-39.8g/kg (Cu) 30.5-43.2g/kg (Ni), 24.3-33.1g/kg (Pb) and 12.2-18.7g/kg (Cd). The leachability tests revealed the release of 34-37% of Cd, 6.4-7.5% of Ni and 0.06-0.07% of Cu after using an excess of Na2CS3 as the precipitant. The use of NaOH resulted in the release of 0.42-0.46% of Cr from the sediment, and the use of TMT 0.03-0.34% of Ni. The best immobilization of heavy metals was observed in the case of the precipitate resulting from the use of DMDTC as a precipitating agent. The findings may be useful for predicting the mobility of heavy metals in the sludge and assessing the risk involved so as to support their removal and management.

Performance of Electrocoagulation Process Using Iron and Aluminum Electrodes with and without Perforations

Electrocoagulation process is widely used for the removal of pollutants from the industrial wastewater. In the present study, an attempt was made to investigate the performance of electrocoagulation process using alu-minum and iron electrodes to treat the metal ions present in the synthetic galvanic wastewater. The electrodes used are with and without perforations and it was observed that the efficiency of electrodes with perforation (80 %) was higher than without perforations (50 %). The removal efficiency of heavy metal ions increased with retention time and direct current. The optimized values of residence time, voltage, pH, current, electrode spacing were 160 min, 6 V, 5, 0.2 A, and 3 cm, respectively. The maximum removal percentage of nickel and copper ions using perforated iron electrodes was 90.7 % and 86.0 %, respectively, and for chromium using a combination of perforated iron and aluminum electrodes it was 93.1 %. The removal of metal ions followed pseudo second order kinetic model with current dependent parameters.

Circular Economy Approach in Treatment of Galvanic Wastewater Employing Membrane Processes

According to the idea of sustainable development, humanity should make every effort to care for the natural environment along with economic development. Decreasing water resources in the world makes it necessary to take action to reduce the consumption of this resource. This article presents the results of research conducted to improve the use of recyclable materials in line with the circular economy model. The research focused on the development of a technological solution for the recovery of raw materials from galvanic wastewater. The concept of a galvanic wastewater treatment system presented in the article includes wastewater pre-treatment in the ultrafiltration (UF) process and water recovery in the reverse osmosis (RO) process. In addition, the purpose of the work was to manage post-filtration waste (RO retentate) containing high concentrations of zinc in the process of galvanizing metal details. The obtained results indicate that it is possible to reduce the amount of sewage from the galvanizing industry by reusing the recovered water as technical water in the process line. The carried-out model tests of galvanizing confirmed the possibility of using RO retentate for the production of metal parts. The achieved results are a proposal to solve the problem of reducing the impact of galvanic wastewater on the environment and to improve the profitability of existing galvanizing technologies by reducing the consumption of water and raw materials.

Removal of Zinc from Concentrated Galvanic Wastewater by Sodium Trithiocarbonate: Process Optimization and Toxicity Assessment

In the present research, the removal of zinc from concentrated galvanic wastewater (pH 3.1, conductivity 20.31 mS/cm, salinity, 10.16 g/L, Chemical Oxygen Demand (COD) 2900 mg O2/L, Total Organic Carbon (TOC) 985 mg/L, zinc (Zn) 1534 mg/L and ethylenediaminetetraacetic acid (EDTA) 70 mg/L) by combination of lime (Ca(OH)2) and sodium trithiocarbonate (Na2CS3) as precipitation agents is studied. Central Composite Design (CCD) and response surface methodology (RSM) were applied for modelling and optimizing the designed wastewater treatment process. Analysis of Variance (ANOVA) and the experimental verification of the model confirmed the consistency of the experimental and estimated data calculated from the model (R2 = 0.9173, R2adj. = 0.8622). The use of Ca(OH)2 and Na2CS3 in the optimal condition calculated from the model (pH = 10.75 ± 0.10, V Na2CS3 dose 0.043 mL/L and time = 5 min) resulted in a decrease in the concentration of Zn in treated wastewater by 99.99%. Other physicochemical parameters of wastewater also improved. Simultaneously, the application of Ca(OH)2 and Na2CS3 reduced the inhibition of activated sludge dehydrogenase from total inhibition (for raw wastewater) to -70% (for treated wastewater). Under the same conditions the phytotoxicity tests revealed that the seed germination index for the raw and treated wastewater increased from 10% to 50% and from 90% to 100% for white mustard (Sinapis alba) and garden cress (Lepidium sativum L.), respectively. The parameters of root and shoot growth showed a statistically significant improvement. Treated wastewater (1:10) showed a stimulating effect (shoot growth) compared to the control sample (GI = -116.7 and -57.9 for S. alba and L. sativum L., respectively). Thus, the use of Na2CS3 is a viable option for the treatment of concentrated galvanic wastewater containing zinc.

Separation of chosen heavy metals from multi-component mixtures and galvanic wastewater in adsorption on unmodified and modified magnetite

Separation of chosen heavy metals from multi-component mixtures and galvanic wastewater in adsorption on unmodified and modified magnetite

Mathematical Modeling and Software for Calculating Regimes of Galvanic Wastewater Purification from Heavy and Nonferrous Metals in Devices with Flow-Through Three-Dimensional Electrodes

The paper briefly discusses progressive technologies of wastewater treatment from ions of heavy and nonferrous metals of industrial and small enterprises of urban agglomerations. An analysis of the efficiency of three-dimensional flow-through electrodes for wastewater treatment of harmful reagents is given. The mathematical models of electrochemical processes in three-dimensional flow-through electrodes as applied to extract metals from the solutions of galvanochemical industries are presented. The description of the set of programs developed in the programming language Object Pascal for computational experiments according to the obtained mathematical models is given. Numerical solution of scientific problem of practical importance has been obtained by using the program complex. A good correspondence between the results of calculations and experiments is shown.

Copper(II) ions removal from model galvanic wastewater by green one-pot synthesised amino-hypophosphite polyampholyte

The amino-hypophosphite polyampholyte (AHP) obtained from cheap and safe building blocks lacks a typical ion-scavenger matrix derived from crude-oil intermediates like poly(divinylbenzene), which is an advantage to commercial solutions. AHP is characterised by sorption capacity comparable to some ion scavengers available on the market, as it was found that its maximum capacity in the temperature range from 298 K to 328 K varies between 114 and 146 mg Cu(II) g−1 of dry AHP. The possible application of the AHP in the Cu(II) removal process from galvanic effluent was investigated. The results show that it is possible to achieve a good removal rate for model wastewater. The inlet Cu2+ concentrations of model wastewater were 6.4 mg Cu(II) dm-3 and 36,2 mg Cu(II) dm-3, acidic and basic galvanic wastewater respectively. After the removal process concentrations were lowered to 1.3 mg Cu(II) dm-3 and 5.1 mg Cu(II) dm-3, for acidic and basic galvanic wastewater respectively. It was found that the presence of Ca(II) and Na(I) did not significantly influence the Cu(II) removal process. The obtained results indicate that the prepared more environmentally safe ion scavenger can be applicable in a wide range of metal ion removal processes.

Sunlight assisted photocatalytic degradation using the RSM-CCD optimized sustainable photocatalyst synthesized from galvanic wastewater

In this study, a sustainable and highly efficient photocatalyst for the degradation of azo dyes using sunlight was engineered. For the first time, photocatalyst was prepared using galvanic wastewater (GWW) along with graphitic-carbon nitride (g-C3N4) by the sol-gel method. The ratio of GWW (1–5 mL) to g-C3N4 (0.1–0.5 g) was optimized to obtain the best photodegradation efficiency using Response Surface Methodology-Central Composite Design (RSM-CCD) model. A mixture of azo dyes (Tartrazine, Congo Red, Orange G, and Bismarck Brown R: 25 ppm each) was utilized to study the photodegradation under sunlight for 2 h. The optimum ratio of the photocatalyst was found to be 0.5 g g-C3N4 and 5 mL GWW which was used to photodegrade a mixture of azo dyes with an efficiency of 98.3% under sunlight. Characterization of the photocatalyst was performed using ICP-OES, UV-DRS, PL, GC-MS, TGA, XRD, XPS, FESEM, and FTIR to validate the optical performance and the anchoring of GWW on g-C3N4.

Copper Deionization of Industrial Wastewater by Ash of Consumption Residual

The possible use of organic consumption residual as a secondary energy resource by a process recovery boiler and further application of generated ash for heavy-metal deionization of wastewater at industrial enterprises was demonstrated. Elemental constituents and technological characteristics of organic biomass, boiler parameters and generated ash toxicity were determined. The adsorption isotherm of copper cations under static conditions and F absorption diagram under dynamic conditions of standardized test solutions by organic waste of consumption residual were simulated. The treatment flowchart of galvanic wastewater was presented. The post-treatment adsorber for heavy-metal deionization of wastewater was proposed.

Influence of aeration rate and method of process activation on the degree of purification of zinc-containing waste water by ferritization

The aeration rate for the degree of purification of highly concentrated galvanic wastewater from zinc and ferrum ions was investigated using various activation methods. It is shown that the intensity of aeration has a significant effect on the quality of wastewater treatment and the characteristics of water treatment sludge. The efficiency of the use of an energy-saving method for activating the ferritization process with the use of electromagnetic pulses for the extraction of zinc ions from wastewater has been confirmed. It was determined that with an increase in the aeration rate to 3.5 dm3/min per 1 dm3 of the reaction mixture and the use of thermal activation of the process, the residual concentration of zinc ions remains within the range of 0.12÷0.2 mg/dm3. In this case, the concentration of ferrum ions decreases to values of 0.08÷0.14 mg/dm3. It was found that at an aeration rate of 2.5 dm3/min and the use of pulsed electromagnetic (EMP) activation, the residual concentrations of heavy metal ions decrease to values of 0.08÷0.16 mg/dm3. Comparison of the results indicates the advisability of using low rates of aeration of the reaction mixture. This, together with the use of resource-saving EMR process activation, allows to achieve a significant reduction in energy costs. The quantitative phase composition of ferritization precipitates was determined, in which the crystalline phases of zinc ferrite Zn2Fe2O4 and magnetite Fe3O4, as well as ferrum oxyhydroxide FeO (OH) and sodium sulfate Na2SO4, prevail. It is found that with an increase in the volumetric aeration rate, the proportion of the ferrite phase increases. At an aeration rate of 2.0 dm3/min, more than 85 % of the zinc ferrite phase was found in the sediments. Taking into account the qualitative and quantitative composition of precipitates, it is recommended to use them in the production of building materials. The experimental results obtained make it possible to provide a comprehensive processing of liquid galvanic waste.

New technology of increasing the operation of local sewage treatment facilities, providing electric activation treatment of alkaline process solutions

The results of laboratory testing of the process of intensification of unconventional cleaning of electroplating drains of an instrument-making enterprise, which provides for electroactivation treatment of technological solutions of sodium hydroxide in a membrane electrolyzer with steel anodes, are presented. It was found that the electroactivation treatment of a 40 % aqueous sodium hydroxide solution in a membrane electrolyzer for T = 1.5 h at an anodic current density i = 400 А/м2 makes it possible to achieve the concentration of sodium ferrate in the activated alkaline solution Сf = 12 g / L, while the value of the current efficiency of sodium ferrate is Кv = 0.47. The use of an alkaline solution that has undergone electro-activation treatment in the technological process of neutralization treatment at local treatment facilities of an instrument-making enterprise equipped with filtration additional treatment units will significantly increase the barrier function, improve the quality of treated galvanic wastewater and bring the concentration of metal ions contained in them to a level, mg / l: iron 0.03; copper 0.01 mg / l; chromium 0.02; zinc 0.01; nickel 0.02.

Concentrating hexavalent chromium electroplating wastewater for recovery and reuse by forward osmosis using underground brine as draw solution

The purpose of this work was to investigate forward osmosis (FO) for the concentration of hexavalent chromium (Cr (VI)) in electroplating wastewater from processing Acrylonitrile Butadiene Styrene/Polycarbonate plastics to enable the reuse of recovered Cr(VI) in the plating baths. The feed solution (FS) was chromium galvanic wastewater, while the draw solution (DS) was underground brine with osmotic pressures of 28 and 226.8 bar, respectively. Baseline and FO filtrations were performed using commercially available Aquaporin Inside membrane hollow fibre FO (AIM™ HFFO) modules. Each filtration procedure consisted of a sequence of performed baselines, filtrations and cleanings. During the first filtration (F1), the water flux decreased on average from an initial value of 28.7 LMH at 46.7 % water recovery to 18.5 LMH and from 20.1 LMH at 28.4 % water recovery to 16.8 LMH for the second filtration (F2). The corresponding FS volume reduction factors were 1.9 and 1.4 with a concomitant FS concentration factor of Cr (VI) of 1.6 and 1.3 for F1 and F2, respectively. After 1.5 h of filtration, the Cr (VI) rejection by the membrane was 99.74 % and 95.83 % for FO1 and FO2, respectively. As the AIM™ HFFO membrane is negatively charged electrostatic repulsion between the membrane surface and the negative ions (HCrO4− and Cr2O72) will contribute to the rejection of Cr (VI). A loss of integrity of the AIM™ HFFO was observed after the cleaning step which was ascribed to chemical degradation of the membrane due to the oxidizing character of Cr (VI) in the draw solution. Thus, the results show that FO can be used in this type of application, but the membrane material must be adapted to withstand harsh environments.

Mathematical Modelling of Processes in Apparatus with Flowing Three-Dimensional Electrodes for Calculation of Galvanic Waste Water Purification Modes

The ecology of the urban environment significantly depends on the intensity and toxicity of industrial and other wastewater discharges, both within the city limits and in the areas adjacent to the city. This paper discusses advanced technologies for wastewater treatment from heavy and non-ferrous metal ions in industrial and small enterprises of urban agglomerations. An analysis of the efficiency of using flow-through three-dimensional electrodes for wastewater treatment from harmful reagents is presented. The use of mathematical modeling allows calculating and predicting the results of the technological process, as well as optimizing the process by calculating the effective values of the control parameters, in particular, calculating the modes of treatment of galvanic wastewater from heavy and non-ferrous metals in devices with three-dimensional flow electrodes. The given mathematical models of electrochemical processes in three-dimensional flow electrodes in relation to the extraction of metals from solutions of galvanochemical production allow us to conduct computational experiments. For this purpose, a set of programs has been developed that allows calculating the parameters of the electrochemical process of metal deposition from electrolyte solutions on three-dimensional flow electrodes. The input data for the calculation are the parameters of the deposited component (ion valence, diffusion coefficient), the ion concentration of the deposited component in the solution, the flow rate of the solution, the mass transfer coefficient, the electrical conductivity of the solid and liquid phases of the electrode – solution system, the overall current density, the electrode parameters (porosity, fiber radius, electrode thickness), the electrolysis time. The results of the calculation are: the concentration of metal ions (calculation can be carried out for one or two metal ions contained in the solution), the distribution through the thickness (volume) of the electrode, its conductivity, the mass of metals, the speed of flow of the electrolyte, the coefficients of mass transfer of metal ions, the mass transfer coefficient for oxygen, the potential profiles of the current metals, profile of the current oxygen profile of the current hydrogen, given the profile of the current metals. The solution of a scientific problem of practical importance for improving the ecological state of the urban environment is presented.

Studying the extraction of heavy-metal ions from galvanic wastewater by reagent method

This paper presents the study of the possibility to increase the extraction degree of heavy metal ions (HMIs) from two types of galvanic wastewater (GWW 1 and GWW 2) by the reagent method. It is established that, as a result of interaction between GWW 1 components and Na2S pentahydrate, the largest amounts of the resultant precipitate were registered in alkaline medium, which is 13.4 and 91.5% greater than in neutral and acidic media, respectively. A greater precipitate weight increase was observed when using 0.7% of Na2S pentahydrate in alkaline medium than when using 0.14% of that solution. The following efficient conditions are determined for removing HMIs from GWW 1 by the reagent method: Na2S pentahydrate solution concentration of 0.7%; volumetric reagent/GWW ratio: 1:42; alkaline medium; and retention time of 20 minutes. Implementing the method proposed allows achieving the extraction degree of 99.97% for Cu2+ ions and 99.93% for Ni2+ ions. A greater efficiency of extracting HMIs from GWW 2 was identified with adding Na2CO3, as compared to Ca(OH)2 when depositing for 25 minutes. Implementing the technique proposed for cleaning of GWW 1, GWW 2 from HMIs leads to achieving the standards of threshold limit values for fishery water bodies.

Integrated sulfide alkali wastewater treatment using spent galvanic solutions

We identified the efficiency of spent Ni2+-containing galvanic solutions for removing sulfide ions from sulfide alkali wastewater. It was found that the removal of sulfide ions led to achieving 89.7 % of purification degree by the chemical oxygen demand value. We also studied how various concentrations of nickel (II) and copper (II) ions affect the oxidation intensity of pollutants in mixed wastewater with ambient oxygen and with ozone-air mixture. Optimal conditions were identified for cleaning sulfide alkali wastewater from hydrocarbons: Oxidation of organic components by ozone-air mixture for 30 minutes, containing 300 mg/dm3 of nickel (II) ions; implementing such conditions resulted in the greatest reduction of the chemical oxygen demand value (down to 798 mg of O/dm3. A comprehensive method for the purification of sulfur-alkaline wastewater is proposed, which includes the stages of removing readily volatile hydrocarbons by simple distillation, sulfide ions by reagent deposition using spent Ni2+-containing galvanic solutions, and soluble hydrocarbons by oxidation of ozone-air mixture with adding 300 mg/dm3 of nickel (II) ions contained in galvanic wastewater. Implementation of this technique led to achieving 96% of the wastewater purification degree by the chemical oxygen demand value, which allows discharging wastewater into biological treatment.

The Use of Hydrogen Peroxide and Hydrazine Sulfate for Removal of Chromium from Electroplating Effluents

The use of hydrogen peroxide and hydrazine sulfate for the treatment of chrome-containing rinsing waters of galvanic production of machine-building enterprises is proposed. The process of reducing chromium (6+) to (3+) from rinsing waters with a concentration of 8.55 mg/dm3 was studied. These reagents allow reducing more than 99% of chromium (6+) to chromium (3+) and maintaining a low salt content of treated wastewater. The consumption of hydrogen peroxide is 1.5 mg/dm3, and the consumption of hydrazine sulfate is 10 mg/dm3. The current situation in the treatment of galvanic wastewater leads to pollution of the environment with dangerous substances (CN-, Cr6+, F-, Cd2+), irrational use of raw materials and significant economic losses. The possibility of extracting valuable components from wastewater, in order to recycle them and return the treated water to production, is considered. Hydrogen peroxide is effective for treating acidic wastewater, and hydrazine sulfate can be used for both acidic and alkaline wastewater. Removal of excess hydrogen peroxide from the solution after reduction of chromium (6+) before precipitation of chromium (3+) hydroxide is required. The toxicity of hydrazine compounds must be taken into account.

Optimisation of environmental protection measures in the electrodeposition industry

At present, the quality of wastewater treatment at machine-building enterprises and disposal of generated sludge does not meet modern technical, economic and ecological requirements. In the course of research into galvanic wastewater, the problem of its neutralization at galvanic production was analyzed. The quality of industrial waste water and the structural composition of pollutant compounds molecules containing heavy metal ions were studied. Physical and chemical characteristics of real and model solutions were studied when different system parameters were changed: pH, temperature, oxidant impact (6% solution H2O2), reagent concentration). The negative impact of complex formation processes on the depth of electroplating methods was also studied and experimentally confirmed, which technical essence is due to the structure, size, charge size of pollutant particles (electrochemical, membrane, coagulation). The data obtained formed the basis of the methodology for determining the effectiveness of the treatment of these effluents using known methods.

Removal of Heavy Metal Ions from Wastewaters: An Application of Sodium Trithiocarbonate and Wastewater Toxicity Assessment.

The synthesis and application of sodium trithiocarbonate (Na2CS3) for the treatment of real galvanic wastewater in order to remove heavy metals (Cu, Cd and Zn) was investigated. A Central Composite Design/Response Surface Methodology (CCD/RSM) was employed to optimize the removal of heavy metals from industrial wastewater. Adequacy of approximated data was verified using Analysis of Variance (ANOVA). The calculated coefficients of determination (R2 and R2adj) were 0.9119 and 0.8532, respectively. Application of Na2CS3 conjugated with CCD/RSM allowed Cu, Cd and Zn levels to be decreased and, as a consequence, ∑Cu,Cd,Zn decreased by 99.80%, 97.78%, 99.78%, and 99.69%, respectively, by using Na2CS3 at 533 mg/L and pH 9.7, within 23 min. Implementation of conventional metal precipitation reagents (NaOH, Ca(OH)2 and CaO) at pH 11 within 23 min only decreased ∑Cu,Cd,Zn by 90.84%, 93.97% and 93.71%, respectively. Rotifer Brachionus plicatilis was used to conduct the assessment of wastewater toxicity. Following the application of Na2CS3, after 60 min the mortality of B. plicatilis was reduced from 90% to 25%. Engagement of Na2CS3 under optimal conditions caused the precipitation of heavy metals from the polluted wastewater and significantly decreased wastewater toxicity. In summary, Na2CS3 can be used as an effective heavy metal precipitating agent, especially for Cu, Cd and Zn.