Iron Behavior in the Ozonation and Filtration of Groundwater

In Finnish groundwater, the main substances that require treatment are iron and manganese. In addition to this, groundwaters are soft and acidic. Iron removal is usually relatively effective by oxidizing dissolved iron into an insoluble form, either by aeration or chemical oxidization and removing the formed precipitate by sand filtration. Sometimes, if the untreated water contains high amounts of organic matter, problems may arise for iron removal. In Finland, it is quite common that groundwater contains high levels of both iron and natural organic matter, mainly as humic substances. The groundwater of the Kukkala intake plant in Liminka has been found to be problematic, due to its high level of natural organic matter. This research studied the removal of iron from this water by means of oxidation with ozone and filtration. While the oxidation of iron by ozone was rapid, the precipitate particles formed were small, and thus could not be removed by sand and anthracite filtration, and the iron residue in the treated water was more than 2 mgL^?1. And while the filtration was able to remove iron well without the feed of ozone, the iron residue in the treated water was only 0.30 mgL^?1. In this case, iron was led to the filter in a bivalent dissolved form. So, the result of iron removal was the best when the sand/anthracite filter functioned largely as an adsorption filter.     

Pilot Testing Of Trace Metals Removal With Ozone At Snowbird Ski Resort

A pilot study at the Snowbird Ski Resort in Utah evaluated feasibility of ozonation replacing chlorine and sulfur dioxide for oxidation of iron and manganese in groundwater. Ozonation also was tested for the removal of lead and cadmium, occurring at concentrations exceeding drinking water Maximum Contaminant Levels. An ozone dose of 2 mg/L, contacted with the water for 1 minute prior to filtration, was selected as optimum for iron and manganese removal from 0.4 mg/L and 40 μg/L, respectively, to below detection limits. Lead, copper, and arsenic also were removed to below detection limits. The removal of cadmium and zinc improved when ozone was contacted for 10 minutes. With metals removal through ozonation and filtration, taste and odor enhancement also were reported.     

The Oxidation of Manganese and Disinfection By Ozonation in Water Purification Processing

The surface water of a river has been used as the raw water by the Waterworks Bureau of Osaka City. At present, the manganese contained in the raw water is oxidized by breakpoint chlorination and all oxides are removed by coagulation, sedimentation followed by rapid sand filtration, with chlorine being used as the final disinfectant.

Prechlorination was not conducted in the ongoing pilotplant experiment of an advanced water purification process with ozone and granular activated carbon. It is necessary, therefore, to oxidize manganese by the oxidative effect of ozone instead of prechlorination.

It is important for the treatment of manganese to adjust the ozone dosage because manganese is oxidized up to the soluble septavalent state by the surplus ozone. Since ozone does not continue to exist for very long in water, though its disinfecting power is high, final disinfection by chlorine is required.     

Oxidation Of Iron And Manganese By Ozone

The oxidation of iron and manganese by ozone was studied in the laboratory. Model waters both with and without organic matter were used. Results showed iron to be very rapidly oxidized to an insoluble form in the absence of organic matter. However, in the presence of organic matter the iron was protected from oxidation by ozone and precipitation. The degree to which this occurred depended on the nature of the organic matter and the chemical environment at the time of mixing the iron stock and the dissolved organic matter.

Experiments with manganese allowed the determination of second order rate constants for the reaction of ozone with manganese at various pH values. The oxidation of manganese in the presence of organic matter occurred in competition with oxidation of the organic matter. As a result, high ozone doses were required to achieve the same degree of removal of manganese. An increase in bicarbonate alkalinity from 50 mg/L to 200 mg/L did not result in an acceleration of the manganese oxidation in the absence of organic matter. However, in the presence of organic matter, higher levels of bicarbonate created conditions that resulted in more complete oxidation of the manganese following total consumption of the dosed ozone.     

Effects of Some Metals and Chelating Agents on Patulin Degradation by Ozone

The efficiency of ozone treatment for degradation of the mycotoxin patulin in the presence of various metal ions was evaluated in model systems. An initial patulin concentration of 250 μg/L was ozonated and residual ozone concentration was about 0.17±0.01 mg/L at the end of the experiment. Patulin showed a weak resistance to ozone, because up to 98% of this toxin was oxidized in only one minute. Degradation rates in the presence of calcium, aluminum, copper and zinc were almost the same in the absence of these metals. However, degradation of patulin was reduced from 98 to 37% when the concentration of manganese increased from 0 to 3 mg/L. Patulin was almost completely degraded in the absence of iron, while the degradation was only 8.5% in the presence of 0.5 mg/L of iron. These results have revealed that manganese and iron significantly reduce the detoxification of patulin by ozone. Agents such as ethylenediaminetetraacetic acid and sodium polyphosphate effectively chelated iron and increased the degradation rate of patulin. None of the tested agents were able to chelate manganese and to enhance patulin degradation by ozone.     

Ozone decomposition and benzene oxidation catalysts based on iron and manganese oxides as industrial wastes from water decontamination by ozone treatment

Effective ozone decomposition catalysts were created on the basis of iron oxides as side products from natural water treated with ozone at water treatment plants. Iron oxide catalysts doped with manganese oxide are by 40% more active in benzene oxidation. These iron-manganese catalysts can be recommended for industrial manufacture by the designed technologies and application in ozone decomposition and benzene oxidation processes.     

A Review of Ozone Systems Costs for Municipal Applications. Report by the Municipal Committee – IOA Pan American Group

Ozone has proven effective in improving water treatment plant performance, increasing customer satisfaction, and meeting increasingly stringent regulatory requirements. The benefits include disinfection; reducing chlorine disinfection by-products; micro-coagulation; enhanced filter performance; biological filtration; oxidation of iron, manganese, sulfide, taste- and odor-causing compounds, pharmaceuticals and personal care products (PPCPs), and endocrine disrupting compounds (EDCs). Despite the effectiveness of ozone in water treatment, a perception remains that ozone may be too expensive for consideration at many water treatment facilities. This paper presents an evaluation by the Municipal Committee of the International Ozone Association (IOA-MC) that aims to provide a realistic assessment of the current capital and operating costs of ozone in the North American water treatment practice. A general strategy is proposed for developing preliminary estimates of ozone capital and operating costs that could be used by engineers and/or owners for planning purposes. The information presented may benefit utilities, managers, and engineers engaged in the evaluation of treatment options.     

Control of Iron and Manganese Ozone Removal by Differential Turbidity Measurements

A new method for continuous monitoring of ozone concentration and the effective removal of iron and manganese was tested. The offered alternative to the ORP system was comprised of two self-cleaning turbidimeters. The turbidimeters were installed at the same locations as the ORP sensors and initial calibration test was performed with different ozone dosage. The conducted long term monitoring study showed stable performance of the differential turbidity system. The system confirmed the continuous and desired result of increased turbidity immediately after oxidation of the unwanted iron and manganese species. Therefore, the method can be expanded to other similar applications involving ozone.     

Iron and Manganese Removal with Ozonation in the Presence of Humic Substances

The conditions for the removal of iron and manganese contained in slightly mineralized water, rich in humic substances, were determined in a case where an intermediate oxidation was provided in a conventional potabilization line comprising a coagulationflocculation stage with iron salts.

The experiments were conducted both on a synthetic water, with or without addition of humic substances, and on raw water from the Moulin-Papon dam. While iron was easily removed by simply increasing the pH measurement from 8.2 to 8.5 without intermediate oxidation, ozonation applied to water with a pH of nearly 8.4 did not enable the manganese to be removed with a low ozone dose (about 1 mg/L) unless a significant amount of bicarbonates (120 to 130 mg/L as CaCO₃) were injected prior to the ozonation-filtration stage.

As it removes the manganese from the water, intermediate ozonation also removes the abatement of organics on the filters, and lowers the THM buildup potential.     

Effects of Ozonation on AOC Content of Humic Finnish Groundwater

The effects of ozonation on assimilable organic carbon (AOC) content of humic groundwater were investigated in batch experiments on three different groundwaters used as drinking water in Finland. All water samples had quite high concentrations of iron (range 2–10 mg/L) and manganese (range 0.1–0.2 mg/L) and therefore combined ozonation and filtration is a possible water purification method. The ozone dosage used varied from 0 to 16.6 mgO₃/L (ΔO₃/TOC?=?0–1.6). The ozone treatment increased the AOC concentration in the groundwater samples to different degrees. For example, an ozone dose of 3.9 mg/L increased the AOC concentration in different water as follows: from 49 μg/L to 55/L, from 7 μg/L to 119 μg/L and from 23 μg/L to 226 μg/L.     

Influence of aerosol type and NH3-concentration on sulfate production in droplets near cloud base

An adiabatic parcel model which describes cloud microphysics and liquid phase chemical reactions was used to investigate the influence of aerosol chemical composition and NH₃-concentration on S(IV)-oxidation in single droplets near cloud base. Sulfate is produced by the reactions of S(IV) with H₂O₂, O₃ and O₂. The latter reaction is catalyzed by iron and manganese. The amount of sulfate produced by the reactions of S(IV) with ozone and with oxygen catalyzed by iron and manganese increases with rising NH₃-concentration. It also depends on the concentrations of the catalytic active metals iron and manganese in the droplets which are affected by the aerosol type. Most of the sulfate is produced in small, activated cloud droplets with dry volume equivalent radii between 0.04 and 1 μm.     

Study Of The Ozone - Manganese Reaction And The Interactions Of Disulfonate Indigo Carmin/Oxidized Manganese Forms As A Function Of pH

Ozone used in preoxidation for water treatment processes allows the removal of inorganic compounds such as iron and manganese. The reactivity of ozone and manganese has been studied in a wide pH range. However, some difficulties appeared in the determination of the different species because of secondary reactions, the main difficulty being the interaction between indigo (used to determine ozone concentration) and manganese dioxide formed during ozonation.     

地下水固锰除铁工程设计

地下水固锰除铁工艺中在跌水曝气后过氧化问题一直是该工艺的关键内容,将跌水曝气池、滤池、反冲洗水池合建形成一体化固锰除铁单元,可以根据水量控制曝气强度,防止过曝气,稳定过滤水头,而且可以节约占地,减少滤池面积,并方便运行管理。     

钛白废酸-软锰矿-硫铁矿制备高纯硫酸锰

研究以硫铁矿为还原剂,在钛白废酸中湿法还原软锰矿制备硫酸锰的工艺过程。探讨反应温度、反应时间、酸矿比和矿浆浓度等因素对硫酸锰浸出率的影响。实验结果表明：在反应温度为95 ℃、反应时间为2.5 h、硫铁矿与软锰矿（以锰计）的质量比为0.95～1.0、硫酸与软锰矿（以锰计）的质量比为1.30、矿浆质量分数为28%～30%的条件下,硫酸锰的浸出率达到95%以上。通过加入碳酸钙中和浸出溶液使其pH为5～6,以除去溶液中的铁、钛、铝等杂质;加入自制硫化锰以除去溶液中的重金属离子;加入二氟化锰以除去溶液中的钙镁离子等。所得溶液经陈化、过滤、浓缩和结晶后得高纯一水硫酸锰,产品纯度为99%以上。     

Ozonation kinetics of iron and manganese in aqueous solution

Ozonation kinetics of iron and manganese in aqueous solution is experimentally investigated. The effects of pH, initial ion concentration and the ozone dosage on the kinetic rate parameters are examined. It has been found that ozonation of those ions in general follows zero order kinetics.     

Long Contact Time Ozanation For Swimming Pool Water Treatment

The elimination of contaminants in pool water through the “ozone – activated carbon process” is done stepwise. Sieving, flocculation and filtration steps are followed by ozonation. According to the German standards for the Treatment of Swimming Pool Water, the toxic ozone has to be removed from the water by filtration through an activated carbon layer before the water is brought back into the swimming pool. The treatment step is followed by chlorination for disinfection. In the ozone process described and in most of its modifications the time available for the reaction of the ozone is very short, usually 1.5 up to 3 min. First results with ozonation of model compounds, such as urea, creatinine, amino acids, etc., have shown–that the reaction rates are rather slow. Consequently, a longer reaction time leads to an improved decontamination of the swimming pool water. The efficiency of the ozonation process with longer reaction times followed by slower filtration has been proven in a research project, e.g. by experiments with the so–called “Ozone Combi Block^R – Process”. The potassium permanganate consumption and the combined chlorine as well as the formation potential of haloforms can be reduced effectively by elongated contact timeof ozone.     

The Effect of Ozonation on the Size Fractions of Manganese

Manganese is a commonly found substance in groundwater in Finland. As a powerful oxidant, ozone can be used for the oxidizing of manganese even without raising the pH. The SFS (Finnish Standards Association) standard has set the accepted limit for soluble manganese to 0.45 μm. However, some research papers have used the limit of 30 kD (kilodalton) for soluble manganese. This research concentrates on the size fractions of manganese in four samples of untreated groundwater and in four samples of ozonized groundwater when treated with 0.45 μm, 0.20 μm, 100 kD, 30 kD, and 10 kD filters. In all tests, nearly all manganese contained in raw water penetrated all filters. There were slight variations in the flocculation of manganese in ozonized groundwater; nevertheless, hardly any reduction in manganese levels took place beyond 100 kD. After ozonation, there were two water samples which surpassed the manganese limit of 50 μgl^?1 set for domestic water when the filtration was 0.20 μm and another two samples when the filtration was 100 kD.     

Treatment of iron and manganese in simulated groundwater via ozone technology

This paper deals with experimental investigations related to removal of iron and manganese from simulated contaminated groundwater via ozone technology. Ozone as a powerful oxidizing agent, which was used in this study to oxidize iron and manganese converting ferrous ions (Fe²⁺) iron to ferric state (Fe³⁺) and (Mn²⁺) to (Mn⁴⁺) state, the oxidized salts will precipitate as ferric hydroxide and manganese oxide, that to reach the concentrations of these pollutants under their limit values in drinking water. The initial concentrations of (Fe²⁺) and (Mn²⁺) in synthetic water sample under study were 2.6 mg/l and 1 mg/l respectively. The effects of ozone dose concentration, operating temperature, and pH on the percentage removal of (Fe²⁺) and (Mn²⁺) have been discussed. For optimum removal of iron and manganese species the ozone dose has been noted as 3 mg/l at optimum temperature of 20 °C which improved removal of (Fe²⁺) and (Mn²⁺) to more than 96% and 83% respectively. The removal percentage of both metals was also affected by changing pH with the range of 5-12; where the maximum removal of iron and manganese was observed in pH (9-10). Experiments also studied the effects of coagulant type and bicarbonate concentration in raw water, as a result it was found that the optimum concentrations of coagulant was a mixture of 30 mg/l of aluminum sulfate with 10 mg/l of lime.     

锰砂生物过滤在钢铁废水回用中的工艺参数研究

试验研究了锰砂生物过滤工艺在钢铁废水回用处理中的工艺参数。试验采用粒径为0.6～1.2 mm的巩义锰砂,锰砂滤层厚度100 cm。生物膜培养成熟后,滤柱出水总铁和锰的质量浓度分别达到0.3和0.1 mg/L以下。通过不同滤速下处理效果的对比,建议滤速为5 m/h以下,工作周期为4 d,反冲洗强度为27 L/(s.m2),冲洗历时5 min。溶解氧的质量浓度维持在4～5 mg/L可满足生物氧化需氧要求。     

温度对生物净化滤柱中氨氮、铁、锰去除效果的影响

温度是生物净化滤柱运行的一个重要参数,采用生物净化滤柱处理模拟含氨氮、铁、锰地下水,考察水温从约25℃降到约6℃过程中氨氮、铁、锰的去除效果。结果表明,出水氨氮、总铁、锰的浓度分别低于0.15mg/L、0.1mg/L、0.05mg/L,均低于国家标准。出水总铁、锰均未受到水温下降的影响,但是出水氨氮浓度逐渐从约0.02mg/L升高到约0.12mg/L。进一步分析发现,铁主要在滤层的0~0.4m段去除,去除效果没有受到水温变化的影响。氨氮、锰主要在滤层的0~0.8m段去除,其沿程浓度均随水温降低而明显升高。氨氮、锰的生物去除符合一级动力学反应,水温为24.6℃、15.3℃、6.7℃时,两者的动力学常数k分别为0.154min^-1、0.186min^-1,0.143min^-1、0.175min^-1,0.103min^-1、0.163min^-1;半反应时间t_1/2分别为4.51min、3.72min,4.83min、3.96min,6.72min、4.24min。随着试验水温的降低,氨氮、锰的去除效果明显受到影响。