Ferrous Sulfate Dosage Research Articles

Advanced exhaust-gas scrubbing for simultaneous de-SOx/NOx using a wet oxidative process with integrated washwater treatment

Wet Oxidative Scrubbing (WOS) is gaining increasing attention due to its capacity to simultaneously remove SO2, NOx and other pollutants from exhaust gases. In this sense, WOS can be used for the process intensification of Exhaust Gas Cleaning Systems (EGCS) thanks to its high efficiency, compactness and reduced use of chemicals. However, as a wet process, the application of WOS also requires an adequate washwater cleaning treatment. In this work, we investigate the performances of a WOS process based on the use of sodium chlorite (NaClO2) for the simultaneous removal of SO2 and NOx from a simulated exhaust gas, together with an analysis of the main anionic pollutants in the scrubber effluents (NO3−, ClO2−, ClO2(aq) and Cl2(aq)), which must be removed before discharge. A washwater treatment process for residual chlorite and active chlorine contaminants is investigated using ferrous sulfate and caustic soda in a reduction, precipitation, coagulation and flocculation process (R-PCF). The experiments reveal that the R-PCF is a valid option for the treatment of the massive residual concentration of chlorite: a stoichiometric dosage of ferrous sulfate allows reducing the concentration of chlorine species below 1 mg/L even starting from solutions containing a few grams per liter of chlorine species, with overall removal efficiencies above 99.9% at pH around 7. The R-PCF process is completed in a few minutes and the residual solid contains mostly Fe(OH)3(s), which can find application in other water treatments. The longstanding experience in the design and operation of R-PCF equipment makes this process a valuable off-the-shelf technique for washwater cleaning with a simple implementation in the WOS processes.

Recycling of detoxification wastewater from Semen Armeniacae Amarum

Detoxification of Semen Armeniacae Amarum requires large amounts of water, and the detoxifying wastewater contains highly toxic hydrocyanic acid. This paper aims to explore the recovery of water after the removal of cyanide from it by chemical precipitation. The results show that when the dosage of ferrous sulfate is 1.76 times of the theoretical value, the cyanide removal in water can be reduced to about 2.70×105mol/L, the hydrocyanic acid in Semen Armeniacae Amarum can be entirely removed when the treated water is recycled.

Effect of ferrous sulfate dosage and soil particle size on leachability and species distribution of chromium in hexavalent chromium‐contaminated soil stabilized by ferrous sulfate

Ferrous sulfate (FeSO4) is widely used to effectively stabilize hexavalent chromium (Cr(VI))‐contaminated soil. The leaching behavior, Cr(VI) content, and chromium speciation distribution in the stabilized soil are the most important indexes for determining the effectiveness of reduction treatment. Numerous factors, such as reductant dosage and soil particle size, affect the stabilization process; these factors are relatively important. This study investigated the influence of FeSO4 dosage and soil particle size on leachability and speciation distribution of chromium in contaminated soil. Results showed that the increase in FeSO4 significantly reduced the leachability and Cr(VI) content in the soil given the increased reducible species that stem from an acid soluble fraction of chromium. The small particle size of the soil that contains a large surface area facilitated the reaction between Cr(VI) and FeSO4, thereby resulting in low leachability and high reducible species of Cr(VI) in the stabilized soil. The leached Cr(VI) concentration was exponentially correlated to Cr(VI) content in the stabilized soil, and the leachability of Cr from the stabilized soil was linearly correlated to the exchangeable phase of Cr. In addition, the leached Cr(VI) concentration from the stabilized soil conform to the US Environmental Protection Agency and China regulatory limits; meanwhile, considerable Cr(VI) remained in a few stabilized soil and exceeded the environmental quality standards for soil in China. These results illustrated the importance of a comprehensive assessment of Cr(VI)‐contaminated soil, which is treated by reductants for enabling flexible future land use. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 500–507, 2019

Comprehensive assessment of system performance in a full-scale wastewater treatment plant with an anaerobic/anoxic/aerobic membrane bioreactor combined with the ozonation process.

The system performance, economic cost and environmental impact of a full-scale anaerobic/anoxic/aerobic/membrane bioreactor (3AMBR) combined with the ozonation process were evaluated. The 3AMBR/ozonation process removed biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids, NH4-N and total phosphorus efficiently, with removal percentages above 94%, while the total nitrogen removal percentage was only 70%. The multiple linear regression analysis showed that hydraulic retention time (HRT) had a significant effect on nitrogen removal. A low HRT benefited nitrogen removal. Ferrous sulfate dosage close to the optimal value and a high mixed liquid suspended solid could enhance the phosphorus removal. The electricity cost accounted for 88% of the total economic costs. Greenhouse gas (GHG) emissions from the BOD oxidation and endogenous decay accounted for more than 50% of total emissions. The second largest GHG emission source was electricity consumption, accounting for 41%. The key to reduce the eutrophication was to enhance nitrogen removal. The composite cost of the 3AMBR/ozonation process was 251 CNY/t CODeq removed, among which economic cost accounted for 82.5%, while environmental impact cost accounted for a small proportion.

Treatment of compost leachate by ferro-sonication process: Effect of some operational variables

Aim: Application of composting process for the management of organic solid waste led to the production of leachate, which causes many problems to environment. This study was aimed at investigation of ferro-sonication (FS) process in composting leachate degradation. Materials and Methods: Leachate samples were collected in composting factory located in Isfahan. In each run, 400 ml of leachate was sonicationed through an ultrasonic homogenizer in a cylindrical glass reactor. Ferrous sulfate was added to the reactor as accelerator agent. The effect of various parameters including pH, ferrous sulfate doses, sonication times, and ultrasonic intensity was studied in the removal of chemical oxygen demand (COD) and biological oxygen demand (BOD) from composting leachate. Results: The results showed that the COD and BOD removal rate was increased by increasing ferrous sulfate dosages, sonication time, and ultrasonic intensity. In addition, lower pH was favored for leachate degradation. In general, the optimum conditions for pH, ferrous sulfate dosage, irradiation time, and ultrasonic intensity were 3, 8 mmol, 180 min, and 150 W, respectively. Approximately 46% of COD and 33% of BOD were removed in optimum condition. Conclusion: These results revealed that FS can be effective in degradation of compost leachate and can be presented as a good choice for pretreatment of leachate.

Using Fenton Oxidation Method to Advanced Treatment of Landfill Leachate

Hydrogen peroxide and ferrous sulfate were used to advanced treatment of landfill leachate effluent from biochemical tanks. Some influences on removing COD and chroma including the pH value of solution, the dosage of ferrous sulfate, the dosage of hydrogen peroxide and reaction time were investigated. The test results showed that for removal of COD and chroma the optimal pH was 3.0, the best ferrous sulfate and hydrogen peroxide dosage was 1500mg/L, 20mL/L respectively, and the optimal reaction time was 60min. Under optimal conditions, COD and chroma removal rate could reach 79.7% and 95.2% respectively.

Experimental Research on the Treatment of Printing and Dyeing Wastewater Using Ultrasound Combined with Fenton Reagent

Experimental research on the treatment of printing and dyeing wastewater has been carried out. The method of ultrasonic combined Fenton has been used.Separately by using ultrasonic and Fenton oxidation method to treat printing and dyeing wastewater, the hydrogen peroxide dosage, FeSO4•7H2O dosage, shaking time, pH value, ultrasonic time, ultrasonic power and other factors are investigated.The COD and chromaticity removal effect of printing and dyeing wastewater are calculated. The experimental results show that the above factors have a certain impact on the treatment effect. Based on these results, the orthogonal test method is used in this experiment, the optimal conditions of ultrasound combined with Fenton reagent for dealing printing and dyeing wastewater has been determined.The orthogonal experimental results show that the optimal reaction conditions of orthogonal test are below:pH value is 3, the best time for the experiment is 1.5h, hydrogen peroxide dosage is 5mL, seven water ferrous sulfate dosage is 0.7grams, ultrasonic power is 142.5W. Experiments are conducted in accordance with the best reaction conditions. On the optimal process conditions, the removal rate of COD reaches 94.6% and the chroma removal rate reaches 87.5%. The effect of using ultrasonic combined with Fenton reagent to treat printing and dyeing wastewater is better than the use of single method.

Modeling and optimization of the coagulation of highly concentrated coking wastewater by ferrous sulfate using a response surface methodology

The coagulation process by ferrous sulfate was used to pretreat coking wastewater prior to a subsequent biological treatment. The central composite Box–Behnken experimental design and response surface method were applied to evaluate and optimize the interactive effects of three operating variables, namely the initial pH, dosage of ferrous sulfate, and interaction time, on the physical and chemical performances of coagulation. Four dependent parameters, namely COD removal, cyanide removal, sulfide removal, and total oil removal, were either directly measured or calculated as responses. According to analysis of variances results, the four models proposed in this work can be used to navigate the design space, with the high regression coefficient R2 varying from 0.9158 to 0.9877. The initial pH, ferrous sulfate dosage, and interaction time had significant effects on the COD removal, cyanide removal, sulfide removal, and total oil removal due to their respective effects on chemical precipitation and coagulation removal. The synergies effect of chemical precipitation and coagulation during ferrous sulfate coagulation process controlled the treatment. A visual search of the overlaying critical response contours plot was carried out, and the results indicated the optimum conditions to an initial pH 11, ferrous sulfate dosage of 1.5 g/L, and reaction time of 120 min. The experimental date and models’ predictions agreed well. COD removal, cyanide removal, sulfide removal, and total oil removal of 15.25, 93.82, 73.36, and 4.73%, respectively, were demonstrated. The results of a B/C analysis and cost evaluation show that FeSO4 coagulation is an appropriate technology for coking wastewater pretreatment.

Treatment of Phenol WasteWater with Modified Coal Fly Ash-Fenton Reagent

Autonomous coal fly ash modified by vitriol (H2SO4) was used to treat Phenol Waste Water. The treatment influences were determined by single-factor experiment and the prioritizing importance and optimizing combination of the influences were studied using orthogonal experiment. We found that the prioritizing importance of the influencing factors was as follow: dosage of ferrous sulfate (FeSO4) > dosage of hydrogen peroxide (H2O2) > initial concentration of phenol > PH > the dosage of modified coal fly ash. The optimizing combination of the influences was 5 wt.% FeSO4, 1 mL ; 3 wt.%H2O2, 7 mL; PH=5; initial concentration of phenol , 300 mg/L and the dosage of modified coal fly ash, 200 mg/L. Under the condition above, phenol removal rate was 99.46%.

Optimization of COD, apparent color, and turbidity reductions of landfill leachate by Fenton reagent

ABSTRACTThe efficiency of Fenton reagent (Fe2+ + H2O2 + H+) for the leachate generated from Pulau Burung sanitary landfill site, located in Malaysia, was evaluated with the objectives of chemical oxygen demand (COD), apparent color, and turbidity reductions. Response surface methodology was used to study the effect of hydrogen peroxide (as oxidant) and ferrous sulfate (as catalyst) on COD, apparent colour, and turbidity reductions of sanitary landfill leachate. A central composite design in two factors [hydrogen peroxide dosage (mg/L) and ferrous sulfate dosage (g/L)] was employed to build a model as well as to perform optimization of the Fenton process. The optimum results for COD, apparent color, and turbidity reductions were 68, 81, and 86%, respectively, setting [H2O2] at 747.8 mg/L and [FeSO4] at 12.8 g/L.

Investigation on pretreatment of centrifugal mother liquid produced in the production of polyvinyl chloride by air-Fenton technique

Centrifugal mother liquid (CML) is one of the main sources of wastewater produced during the production of polyvinyl chloride in chlor-alkali industry. CML is a typical poorly biodegradable organic wastewater, containing many kinds of refractory pollutants. Specifically, it contains dissolved refractory polymers, especially polyvinyl alcohol (PVA), which can pass though the biotreatment processes and clog the membranes used for further treatment. In this study, to ensure the CML applicable to biotreatment and membrane treatment, a novel efficient and mild technique, air-Fenton treatment, was employed as a pretreatment technique to improve biodegradability of the CML and to break down the polymers in the CML. Firstly, the technique was optimized for the CML treatment by optimizing the main parameters, including the dosage of ferrous sulfate, initial pH of the wastewater, [H2O2]/[Fe(2+)], aeration rate, reaction time, and temperature, based on removal efficiency of COD and PVA from the CML. Then, the optimized technique was tested and evaluated. The results indicated that under the optimized conditions, the air-Fenton treatment could remove 66, 98, and 55 % of the COD, PVA, and TOC, respectively, from the CML. After the treatment, biodegradability of the wastewater increased significantly (BOD/COD increased from 0.31 to 0.68), and almost all of the PVA polymers were removed or broken down. Meanwhile, concentration of the remaining iron ions, which were added during the treatment, was also quite low (only 2.9 mg/L). Furthermore, most of the suspended materials and ammonia nitrogen, and some of the phosphorus in the wastewater were removed simultaneously.

Iron health

Iron health

New method to study oxidative damage and antioxidants in the human small bowel: effects of iron application

Iron may induce oxidative damage to the intestinal mucosa by its catalyzing role in the formation of highly reactive hydroxyl radicals. This study aimed to determine iron-induced oxidative damage provoked by a single clinical dosage of ferrous sulfate and to elucidate the antioxidant defense mechanisms in the human small intestine in vivo. A double-lumen perfusion tube was positioned orogastrically into a 40-cm segment of the proximal small intestine in six healthy volunteers (25 +/- 5 yr). The segment was perfused with saline and subsequently with saline containing 80 mg iron as ferrous sulfate at a rate of 10 ml/min. Intestinal fluid samples were collected at 15-min intervals. Thiobarbituric acid reactive substances concentrations as an indicator of lipid peroxidation increased significantly from 0.07 microM (range, 0-0.33 microM) during saline perfusion to 3.35 microM (range, 1.19-7.27 microM) during iron perfusion (P < 0.05). Nonprotein antioxidant capacity increased significantly from 474 microM (range, 162-748 microM) to 1,314 microM (range, 674-1,542 microM) (P < 0.05). These data show that a single dosage of ferrous sulfate induces oxidative damage and the subsequent release of an antioxidant in the small intestine in vivo in healthy volunteers.

Decolorization of textile wastewater by ozonation and Fenton's process

The aim of this study is to investigate the effect of some operational parameters on the efficiency of ozonation and Fenton's process for decolorization and COD removal. Acid Red 337 and Reactive Orange 16 dye solutions and the effluents of acid and reactive dye-bath effluents were used in the experiments. The influence of ozone dose and pH for color and COD removal from the wastewater were studied. Increasing the ozone dose increased the rate constants, and color and COD removal efficiencies. Ozone consumption ratio per unit color and COD removal at any time was found to be almost the same while the applied ozone dose was different. pH did not significantly affect color and COD removal from the wastewater by ozonation. In spite of having high color removal efficiencies (60-91%), limited COD removal efficiencies between 9-17% at 30 minutes ozonation time were obtained. In the Fenton oxidation experiments, the effects of pH, temperature, dosage of ferrous sulfate and hydrogen peroxide, and the proper ratio of Fe(II)/H2O2 were studied. The result indicates that up to 99% color removal and 82% COD removal can be obtained by Fenton's oxidation. While Fenton's oxidation was greatly affected by the pH value, temperature of wastewater did not significantly affect the Fenton process for color removal. Increasing the dose of both hydrogen peroxide and ferrous sulfate enhanced the removal efficiencies of color and COD. Suitable ratios of Fe(II)/H2O2 were found to be between 0.5 and 0.83.

Effects of reaction conditions on the oxidation efficiency in the Fenton process

The purpose of this study is to efficiently operate Fenton’s oxidation process with quantitative analysis of the amount of the organic substances removed by oxidation and coagulation in treatment of the non-biodegradable landfill leachate by Fenton’s reagents. The sample used was the biologically treated leachate in the Kimpo metropolitan landfill site in Korea and its COD, BOD 5, NH 3–N and Cl − concentrations were about 1500, 30, 1300 and 4500 mg/l, respectively. The COD removal by oxidation of the organic substances with hydrogen peroxide was most efficient in the pH range of 2.5–4. However, it drastically decreased according to the pH value above 5. The COD removal efficiency by coagulation increased with the increase of the ferrous sulfate dosage, but the overall efficiency over a minimum dosage of 500 mg/l was scarcely changed. The efficiency of hydrogen peroxide actually used in the oxidation of the organic substances was only about 45%. The optimum range of the coagulation pH to maximize the COD removal efficiency by coagulation was 3–6, but that was slightly lower than the pH range of 6–9 generally known in the literature.

The chemistry of reduced sulfur species and their removal from groundwater supplies

The removal of hydrogen sulfide from groundwater supplies was investigated by using various catalysts and oxidants in bench‐scale jar tests that simulated assumed actual conditions in a water treatment plant. Variations in aeration rate, chemical dosage, recycled solids, pH, and detention time were also examined. A ferrous sulfate dosage of 9 mg/L reduced sulfide concentrations to 0.05 mg/L, largely owing to the catalytic effect of Fe(II). Peroxide, permanganate, and ferrate also lowered the sulfide concentrations, with more rapid kinetics than Fe(II). An economic analysis showed that Fe(II) is a cost‐effective alternative for sulfide removal. The other oxidants may also prove economical under certain conditions.

Certification Corner

This month's “Certification Corner” covers ferrous sulfate dosage equivalents, available chlorine equivalents, gauge pressure, calculation of total dynamic head and water horsepower, pipe carrying capacity, carbon dioxide removal, free available chlorine residual, and filter media growth.