Ferric Precipitation Research Articles

Combined Chemical and Biological Removal of Phosphate in Activated Sludge Plants

Biological phosphate removal has been achieved in nutrient removal plants in Johannesburg by generating the required substrate for the process. Substrate generation has taken place by primary fermentation and subsequent elutriation. This technique, coupled with control of nitrate return to the anaerobic zone, has allowed phosphorus to be removed almost exclusively by biological means in plants designed for nutrient removal. However, operational problems with primary sedimentation tanks being used for fermentation, for which they were not designed, necessitated the occasional use of chemicals in the Northern Works plant. Contrary to current literature, the addition of ferric sulphate to this plant resulted in inhibition of polyphosphate storage; the cornerstone of the biological process. Laboratory batch studies revealed that iron-treated activated sludge showed a lower propensity for ferric phosphate precipitation than an untreated sludge. These laboratory studies were borne out by practical experence on two extended aeration plants, not designed for nutrient removal. The performance of these plants with different chemicals is discussed and possible reasons are advanced for some of the plant observations.

Collaborative Study of Three Screening Methods for Aflatoxin in Corn

Abstract The 3 rapid screening methods studied all involved chromatography of partially purified extracts on minicolumns. In one method acetonitrile-water is used to extract aflatoxin from corn and a lead acetate precipitation removes impurities from the extracts. The second method specifies acetone-water as the extracting solvent and ammonium sulfate as the precipitant. The third method is based on acetone-water as the extracting solvent and ferric gel as the precipitant. The most sensitive method was the ferric gel precipitation, which could detect 5 ppb aflatoxin, but it was very time-consuming. The most satisfactory method (timewise) used the ammonium sulfate and had a sensitivity of 10 ppb. This method also led to the best differentiation between levels of aflatoxin. These 2 methods have been adopted as official first action.

Selective Element Recovery from Oil Field Brines

With the attention now being focused on the two problems of water pollution and usage and natural resource utilization, the recovery of compounds dissolved in subsurface brines takes on greater importance with each passing year. More than 325 billion gallons of oil field brines (∼ 8 × 109 barrels) are brought to the surface yearly in the United States. Most of these brines are wasted and/or are returned to the subsurface without any attempt of stripping the contained salts. The volume of this brine is such as to warrant greater consideration of the economic feasibility of extracting much, if not all, of the dissolved components therein. In many instances the salts dissolved in oil field brines could be extracted profitably, if modern extraction techniques were used or refined. Simple extraction processes for soda ash, sodium carbonate, caustic soda, magnesium and calcium sulfate, trace elements and others are available. For example, sulfur can be recovered by using a barium resin to precipitate the sulfate as BaSO4, which can then be made to yield sulfur by a short four step conversion process. Magnesium can be precipitated in the hydroxide form and selected trace elements can be scavenged and concentrated by ferric iron precipitation.

Effect of iron/phosphorus ratio and acid concentration on the precipitation of ferric inositol hexaphosphate

AbstractThe precipitation of ferric inositol hexaphosphate has been measured under a variety of experimental conditions.The salt can be precipitated in a wide range of concentrations of both hydrochloric and sulphuric acids, but in the presence of excess iron soluble complexes are formed. The ratio of iron to phosphorus which causes maximum precipitation depends upon acid concentration. In presence of excess iron precipitation is minimum in hydrochloric acid at pH I. Precipitation in sulphuric acid is greater than in hydrochloric acid, but can be increased in the latter by the presence of sodium chloride or a small amount of sulphate ion, or by raising the temperature of the system. If ferric ammonium sulphate instead of ferric chloride is used for precipitating inositol hexaphosphate from hydrochloric acid solution, then quantitative precipitation will be obtained with a wider range of ester concentrations.The presence of relatively high amounts of soluble iron in plant material can interfere with phytate extraction by °.5N‐hydrochloric acid. In the estimation of phytate by ferric precipitation other inositol phosphates will be included if present in sufficient concentration.

A STUDY OF PROVENTION FOR CONTACT CORROSION OF LIGHT METALS

When light metals contact with other metals, for instance steel, it eroded especially in the presence of electrolytic solution, such as NaCl.Aluminum alloy (52S) panels are worn with steel bands with or without various coating or insulating pastes, and submerged into a aqueous solution containing 5.85%NaCl, 0.3%H2O2.In untreated (direct contact and bare) panels, aluminum panels generals gas bubbles and considerably eroded, but steel band not so eroded. When insulating cloth tape (cloth painted with paste consists of polybutene, paraffine, boiled oil, gilsonite and zinc chromate etc.) Placed between aluminum alloy and steel, the corrosion rectrogressed. Steel band eroded and aluminum alloy not affected. After the submerge over 1 month, significant lowering in tensile strength of aluminum alloy not founded.When panels are coated with various coatings, (zinc chromate primer, wash-primer, vinyl resin primer) showed good resistance.Between insulating paste, polybutene-boiled oil-zinc chromate type showed best results, and in coatings, vinyl type primer was best and wash primer-zinc chromate primer (synthetic resin vehicle) was the second.It is interesting what then metals are contact directly, erosion occured at aluminum panel and produce white precipitate, aluminum hydroxide, and when metals are insulated by paste, erosion occured at steel and produce reddish ferric precipitate.

On iron flagellates

The physiology and morphology of iron- and manganese-depositing flagellates are investigated by means of cultural experiments, with special reference to Anthophysa vegetans Stein, Siderodendron manganiferum n.gen., n.sp., Siphomonas Fritschii n.gen., n.sp. and Bikosoeca ( Poteriodendron ) petiolata (Stein) n.comb. Anthophysa multiplies in various liquid media containing small amounts of organic substances, hay decoction being specially favourable. Still better results are achieved with soil-water cultures, which afford the only successful cultures of Siderodendron and Siphomonas , while Bikosoeca also grows well in hay infusions. Addition of Fe" and Mn" is essential. The brown colour of biological iron deposits is shown to be due to admixture of manganese compounds, while mere ferric precipitates are in microscopical amounts almost colourless. Anthophysa and Siderodendron deposit more manganese than iron, so that their stalks appear brown, while those of Siphomonas are generally light brown. The envelopes of Bikosoeca are almost entirely composed of ferric compounds and appear colourless or faintly yellowish. All four organisms exhibit various modifications according to the habitat conditions. The formation of stalks and envelopes respectively depends on the availability of the relevant metals in the form of lower oxides, but the organisms here described can also exist without producing these structures. The oxidation of ferrous and manganese compounds is catalysed by the cells of these flagellates, although the role of this process in the cellular metabolism is not known. Nutrition is holozoic, chiefly by ingestion of bacteria. Like other holozoic flagellates these organisms cannot exist in the presence of an abundant bacterial vegetation owing to the resulting lack of oxygen. They thrive in quiet, well-aerated waters, with a small content of organic substances, above zones in which Fe and Mn compounds are reduced and from which ferrous and manganous compounds diffuse to the overlying oxidation zone, where these flagellates deposit Fe"' and Mn'" in a morphologically defined form. ‘Iron’ flagellates generally live in association and competition with iron bacteria of the Leptothrix group, the removal of which produces much better growth. A description of the relevant flagellates and of their appearance under various conditions, as well as diagnoses of Siderodendron and Siphomonas , are given.

Selenic acid and iron.—Reduction of selenic acid by nascent hydrogen and hydrogen sulphide.—Preparation of ferrous selenate and double selenates of iron group

Exceptional difficulties have been met with in the preparation of the iron (ferrous) group of double selenates of the monoclinic isomorphous series R 2 M ( S Se O 4 ) 2 , 6H 2 O, and some new and unexpected chemical facts have been revealed, which form the subject of this communication. When the author, in pursuing the course of the crystallographic and physical investigation of the double selenates of this grand series on exactly parallel lines to those followed in the completed investigation of the corresponding double sulphates, arrived at the iron group, three difficulties were encountered. The first was that of preparing the simple salt ferrous selenate, common to the group. The second was the rapid decomposition, with brown deposition, of the aqueous solution of any ferrous selenate obtained, also that of the mixed solution obtained by adding to the latter solution a solution of the molecular equivalent of the alkali selenate, with the object of preparing any one of the four salts of the group, K 2 Fe(SeO 4 ) 2 , 6H 2 O, Rb 2 Fe(SeO 4 ) 2 , 6H 2 O, Cs 2 Fe(SeO 4 ) 2 , 6H 2 O, (NH 4 ) 2 Fe(SeO 4 ) 2 , 6H 2 O. The third difficulty was offered by the fact that no crystals of the potassium ferrous salt were ever obtained at all. The author's first efforts to obtain these salts were made eight years ago in the cases of the potassium and rubidium salts. The result was that, under conditions which were obscure, but undoubtedly included a moderately low temperature, it being winter time, one excellent and permanent crop of rubidium ferrous selenate was obtained, the small quantity employed of the ferrous selenate considerable quantity of moderately dilute selenic acid on much iron wire, the action being very slight. All other solutions of the constituents of this salt, and all the solutions of the constituents of potassium ferrous selenate, decomposed with much brown ferric precipitation, and no trace of the potassium salt crystals was ever obtained.