Lime Soda Research Articles

Removal of heavy metals from effluent streams — Why select a biological process?

The paper addresses the use of biosorptive, bioaccumulative and other separative technologies for the removal/recovery of metals from liquid effluents. The reasons for selecting more conventional chemical treatments are reviewed whilst the advantages of a biosorptive process compared with a bioaccumulative one are described. Comparative costs for biosorptive processes with ion exchange and chemical precipitation using either lime or caustic soda are predicted. It is proposed that these costs, although indicative, are sufficiently accurate to justify further evaluation of bioprocesses. More definitive costs will be achieved by the use of multidisciplinary groups, and will ensure the true potential for metal biosorption/bioaccumulation is achieved.

The treatment of heavy metal effluents by crossflow microfiltration

The application of crossflow microfiltration for the treatment of industrial wastewaters containing toxic heavy metals is described and the performance quantified and compared with technologies which are traditionally used for the treatment of such wastewaters. Case histories of the treatment of wastewaters generated from the metal plating industry and a battery recycling plant are given together with the operational performance of the full scale crossflow microfiltration plants which were subsequently installed. Metals of particular interest are cadmium, mercury and chromium where removals down to the ppb range are currently being requested. Heavy metal bearing effluents have traditionally been treated by the adjustment of the pH with lime or caustic soda to precipitate hydrated metal oxides. Sometimes a sulphide compound or other materials are added which cause the production of heavy metal compounds with lower solubility products. Removal of the heavy metal precipitate is then usually accomplished by settlement, occasionally followed by sand filtration [1]. With the advent of more stringent environmental legislation regarding the quality of the final disposal stream, the use of crossflow microfiltration is becoming an attractive to the more conventional methods of treatment. The performance of settling tanks, settling tanks in conjuction with sand filters and a crossflow microfiltration system was assessed by pilot trials on a mixed planting effluent. The tests were carried out by Cory Environmental at their West Thurrock treatment plant in London. This plant is a toxic waste plant which receives and treats industrial wastewaters from UK industries. Tests were also carried out at a lead-acid battery breaking, lead recovery and refining plant, the waste water from this plant required treatment before disposal into the River Thames. The crossflow microfiltration system is based upon the concept of using a dynamic membrane to form the filtration medium. This membrane is laid down on the internal wall of a woven fabric cloth and may be formed by either the solids naturally present in the feed suspension or by the deposition of materials such as diatomaceous earth, metal hydroxides or kaolin. In this application the heavy metal precipitate provides a suitable membrane without the introduction of filter aids.

Recovery of vanadium from hot metal

Selective oxidation of Si and V in Swedish pig iron have been studied in a laboratory scale to find a way to increase the V concentration in a separate top slag. Injection of O 2, O 2 + lime based top slag, O 2 + lime injection and soda ash injection with and without O 2 were investigated. Good selectivity was found by oxidation with O 2 in the presence of lime based slags at high temperature (1400°C). Complete selectivity could although only be found by oxidation by soda ash without O 2. The selective behavior is explained in terms of preferable formation of the much less stable V 2O 5 compared to V 2O 3 under basic conditions and an assumed decreased oxygen activity in the system for Si oxidation under basic conditions.

Removing soluble organic contaminants by lime‐softening

Lime–soda softening effectively removed several humic substances from solution, including a fulvic acid isolated from a local groundwater supply. Removal increased with increased pH, increased amounts of precipitate, and decreased concentrations of TOC and was enhanced significantly by the presence of magnesium or phosphate, especially when a small amount of precipitate was formed. Lime–soda softening achieved at least partial removal of several soluble organic chemicals, although some were not removed to any significant extent. Soluble calcium caused the precipitation of several organic substances in the absence of carbonate ion, indicating that precipitation is a potential removal mechanism. Experimental evidence for other removal mechanisms is discussed.

Conventional Lime Soda Ash Softening vs Split Treatment at the Owosso, Mich., Water‐Treatment Plant

In its 1970 expansion, Owosso adopted conventional lime–soda‐ash softening followed by recarbonation. The result: maintenance problems arose with sludge deposits in the recarbonation basin and the filter‐influent piping with substantial loss in filter efficiency index. In 1973 operation was changed from conventional to split treatment. Results were phenomenal.

Kinetics of Calcium Carbonate Precipitation in Lime–Soda Ash Softening

Water softening through the precipitation of insoluble carbonates is practiced commonfy enough today via the lime–soda ash process. The actual kinetics involved in removing the hard‐ness‐causing cations are, nevertheless, not well understood. This article reports the results of a research effort seeking insight into the kinetics of calcium ion removal when such removal is accomplished through the precipitation of calcium carbonate.

Heuristic Analysis of Lime—Soda Softening Processes

Here is a textbook type approach to water‐softening calculations that should produce a better understanding of what transpires during the treatment process. Although actual operating conditions usually will require dosage modifications through empiricism, the technique is valuable because it readily provides first order approximations.

Certification Corner

Lime soda softening, soft water, benefits of lime soda, magnesium hardness, and noncarbonate hardness of water are some of the topics of questions in this month's “Certification Corner.”

DIATOMITE FILTRATION SYSTEM OF LOMPOC, CALIF.

Lompoc, Calif., pioneered the use of diatomaceous earth filtration for a large lime soda softening plant. After 5 years of operation, the installation's performance profile is now well outlined and shows that performance exceeds prior expectations.

Lime and Caustic Soda Softening at Fremont, Ohio

This article describes how Fremont, Ohio, treated its sludge accumulation problem by using caustic soda. Following laboratory jar tests, which indicated no adverse effects on the quality of the water treated, Fremont tried several plant‐scale tests of sufficient duration that equilibrium was reached and the results identified. The trials were continued long enough to get identifiable sludge; this was tested for particle size on wet screens and for settling rate. It appeared that, while caustic soda sludge did not settle as fast as lime sludge in the treatment tanks, as long as this property did not interfere with treatment capacity, it could be turned to good use in preventing the building of sludge banks in the receiving stream.

Effects of Synthetic Detergents on Lime–Soda Ash Treatment

This article discusses a study to evaluate the effects of a standard alkyl benzene sulfonate (ABS) solution, condensed phosphates, orthophosphate, and a commercial syndet on the softening of lake water by lime treatment alone and by lime‐soda ash treatment, and investigates the removal of phosphates and ABS by lime and soda ash. Water samples were analyzed before and after treatment and the concentration of alkalinity, hardness, ABS, hydrogen ions, orthophosphate, and total phosphate was recorded. The analytic procedures used in these studies were in accordance with Standard Methods.

Significance of Radioactivity in Water Supply and Treatment

This article begins by providing a brief overview of the biologic effects of radioactivity. Variables that affect the extent of health effects of radiation include: quantity of material absorbed; distribution of radioactive material in the body; the half‐life of the material; and, the rate at which the material is excreted from the body. Various forms of potential sources of radioactive contamination of water supplies are discussed, along with methods for removal of radioactive materials from the water supply that include: natural processes of riverbed sedimentation, ion exchange capabilities of silts, the biologic processes of both plants and animals including some forms of algae, the natural filtration of water percolating down through the earth to an aquifer, and the ion exhange properties of minerals and clays; conventional treatment plant processes of coagulation and sedimentation, filtration, lime soda ash softening, and ion exchange; and, beds of steel, clay pellets, activated carbon, and cation‐anion‐exchange resins in series. Distillation units are also mentioned as capable of removing nonvolatile materials, but are expensive and limited in capacity.

CHEMICAL COMPOSITION OF ARGILLITES OF THE COBALT SERIES (PRECAMBRIAN) AND THE PROBLEM OF SODA-RICH SEDIMENTS

Two new chemical analyses show that the varved argillites of the Precambrian Cobalt series of Ontario, Canada, contain more Na 2 O than K 2 O and have a Na 2 O/K 2 O ratio higher than most pelitic rocks but similar to that found in many graywackes. Published chemical data substantiate these observations. The Cobalt materials are also low in CaO but otherwise have a composition compatible with their presumed glacial origin. Albitization of the detrital plagioclase feldspar seems to best account for the low lime and high soda content of these rocks. X-ray data confirm the presence of albite. Spectrographic analyses of the argillites are also given.

Experiments with a differential Pirani gauge leak detector

Abstract : A differential leak detector was developed in which 2 matched Pirani gages having their filaments connected in adjacent arms of a balanced Wheatstone bridge were connected to the same point in a vacuum system. A lime soda trap was placed between the vacuum system and 1 gage to absorb the COsub2 which was used to probe the leak. The COsub2 could make its way only into the untrapped gage to cause a differential change in the indication of the 2 gages. With the detector located on the backing side of a diffusion pump where the average pressure was 15 micro Hg, the noise level of pressure fluctuations registered by the galvanometer in the detector control circuit was 7 times less than that registered by a single Pirani gage. The minimum air pressure change detected by the differential arrangement was 10 to the -5th power mm Hg. With the optimum leak-hunting conditions employed, this value corresponded to a leak on the high- vacuum side of about 10 to the -3rd power lusec (1 lusec = the leak causing a pressure rise of 1 micro Hg/sec in an isolated volume of 1 liter).

Copper-Deficiency Disease of Apple Trees

THE communication by Mr. J. O. Jones1 dealing with the copper-deficiency disease of pear trees has tempted me to write briefly of my experience of the summer-spraying of apple trees in Northern Ireland with Bordeaux mixture. In the early nineteen-twenties, the 6,000 acres of apple orchards in the north of County Armagh and the south of County Antrim, which are mainly planted with the variety Bramley's Seedling, were in a very poor condition. The position was so serious that unless something could be done to restore the health of the trees, it looked as if the apple crop might become entirely unprofitable. Except for occasional winter-spraying with lime or caustic soda (tar-oil washes had only just been introduced) and the application of lead arsenate in summer to control caterpillar attack, no regular spraying programme was in operation and no suitable spraying machinery was available. Apple scab (Venturia inaequalis Aderh.) had just commenced to attack the variety Bramley's Seedling, and it was obvious that the control of this disease presented a major problem.

Viscosity of Associated Liquids

AN equation representing the temperature variation of the viscosity (I·) of water and lime soda glass has just been published by Douglas1, namely, where A', B' C' and D' are constants, and T the absolute temperature.

Cold Lime–Soda Water Softening EXPERIENCES WITH SPAULDING PRECIPITATORS

Cold Lime–Soda Water Softening EXPERIENCES WITH SPAULDING PRECIPITATORS

Sarasota's Automatic Sea Water Regeneration Zeolite Water Softening Plant

This paper will present the various problems which confronted the City of Sarasota in its endeavor to obtain an adequate and dependable supply of potable soft water for the municipal water works system, as well as the problems which confronted the engineers in designing and constructing the automatic sea-water regeneration zeolite water-softening plant. Sarasota is now installing an automatic, sea-water regeneration zeolite water softening plant. This plant is, to the writer's knowledge, the first municipal plant of its type. The operating costs of this softening plant, per unit of hardness removed, will be only a fraction of the operating costs of any other type of municipal water softening plant. As an illustration, a lime soda water softener, in this location, would have had an operating cost of $193.00 per million gallons for chemicals alone. With sea-water regeneration, Sarasota's municipal zeolite water softening plant will have an operating cost of only $14.00 per million gallons. This includes the costs of pumping, coagulating, filtering and chlorinating the sea-water required and also the costs of pumping the water through the zeolite softeners and maintenance of the zeolite units at their full capacity. Possibly, with some bicarbonate waters, which require only lime for softening, the comparative operating costs would not be quite so marked but, in any event, they would be only a fraction of the operating costs with any other method of water softening.

EFFECT OF TYPICAL SLAGS ON FIRE BRICK WITH A METHOD OF DETERMINATION CORRELATED TO SERVICE1

ABSTRACTIn an investigation of the problem of producing refractories which would give maximum resistance to slags encountered in service, laboratory slag tests were made in a rotary slagging test furnace. A photograph and sketch of the furnace are given and the method of operation is described. A photograph of a typical test is shown and test data are given for typical high iron oxide, high lime, and high soda slags. These data include the numerical rating of ten test bricks in each case. Ten slag tests have been made with 50 different mixes, all in the field of fireclay and diaspore refractories.Bricks of the brands which give best results in the laboratory were tested in service in malleable iron air furnaces, gray iron cupolas, and “bull” ladles where sodium carbonate purifier is used. Operating conditions are given and chemical analyses of slags presented in several instances. Special firing treatment was given a few bricks prior to service tests.Excellent correlation between laboratory and service tests was obtained in cases where high‐temperature abrasion was not severe, demonstrating the reliability of the rotary furnace type of slagging test in predicting service results insofar as slag alone is concerned.Of equal importance with the reliability of the slag test is the need of a reliable high‐temperature abrasion test. The data indicate that in many installations high‐temperature abrasion is the major cause of failures that are charged entirely to slag erosion.

稿稈類ノ解化ニ就テ

An investigation was made on the disintegration-effect of boiling milk of lime or caustic soda solution upon the nutritive value and chemical composition of wheat or barley straw. The results obtained may be summarised as follows:1). The each disintegrated straw was prepared as follows: (a) The wheat lime straw-by boilling wheat straw for three hours in 1% milk of lime. (b) The wheat soda straw-by soaking for four hours in 0.9% solution of sodium hydroxide at ordinally temperature. (c) The barley lime straw No. I-by boiling barley straw for three hours in 1% milk of lime. (d) The barley lime straw No. 2-by boiling for 1.5 hours in the solution above mentioned.2). The ammounts of digestible nutrients, starch value and net energy value in therms per 100 pounds of each fodder, the moisture content of which was eaqually 13.6%, together with the ammount of incrusting substances (lignin+cutin) were shown in the following table.3). Although the decrease in incrusting substances causes a rapid increase in nutritive value, further decrease in the former does no longer accompany any considerable increase in the latter. In fact the nutritive value approaches almost to its maxmum point just about the time when lignin+cutin shows about 10% decrease.4). The time required to boil in the case of lime disintegration may be shortened to 1.5 hours, for both the barley lime straw No. 1 and No. 2 have the same nutritive value.