Waste waters with chloride

Molecular chlorine, CI2, is an ideal chemical for delignification as it is cost-efficient and has reasonable selectivity, well capable of removing 75-90% of the residual lignin in a single stage. However its undesirable effects - waste water with chlorides that is corrosive, and a tiny by-product of chlorinated organic compounds -means that molecular chlorine has been abandoned entirely in some countries and where it is still used this is often in conjunction with chlorine dioxide (D) whose environmental footprint is some 2.6 times smaller. Today, more than 75% of pulps are bleached without any molecular chlorine. These are described as elemental chlorine-free (ECF). Only c. 6% of bleached pulps are total chlorine-free (TCF),... 

To check the efficiency of the direct extraction of PNAs from waste-water with methylene chloride, a water sample was spiked with 14C BaA and 14C BaP extracted with methylene chloride and both the radioactivity and UV absorption measured on successive extracts. Figure 6, a plot of the UV absorbance and 14C radioactivity vs. number of extractions, illustrates very clearly that 98% of the PNAs are recovered by three extractions. 

Noridur 9.4460 cf GX2CrNiMoCuN25-6-3-3, 1.4517 For chemical waste waters with extremely low pH values and high chloride concentrations also for low concentra tions of abrasive solids... 

This carbon dioxide-free solution is usually treated in an external, weU-agitated liming tank called a "prelimer." Then the ammonium chloride reacts with milk of lime and the resultant ammonia gas is vented back to the distiller. Hot calcium chloride solution, containing residual ammonia in the form of ammonium hydroxide, flows back to a lower section of the distiller. Low pressure steam sweeps practically all of the ammonia out of the limed solution. The final solution, known as "distiller waste," contains calcium chloride, unreacted sodium chloride, and excess lime. It is diluted by the condensed steam and the water in which the lime was conveyed to the reaction. Distiller waste also contains inert soHds brought in with the lime. In some plants, calcium chloride [10045-52-4], CaCl, is recovered from part of this solution. Close control of the distillation process is requited in order to thoroughly strip carbon dioxide, avoid waste of lime, and achieve nearly complete ammonia recovery. The hot (56°C) mixture of wet ammonia and carbon dioxide leaving the top of the distiller is cooled to remove water vapor before being sent back to the ammonia absorber. 

Water waste water Extraction of sample with methylene chloride and olean-up on Florisil oolumn GC/ECD 0.49 [jg/L ( endo-sulfan) 6.1 pg/L ( "endosulfan) 2.7 pg/l (endosulfan sulfate) No data EPA 19860 (Method 8080)... 

The rate of biological oxidation may vary considerably under different test conditions. Gotaas [205] reported that waste waters containing less than 10 000 mg/1 chloride diluted with fresh water had a rate of biological oxidation... 

Water/waste water Extract with methylene chloride exchange to hexane Florisil cleanup, if required GC/ECD 0.03 pg/L 99 EPA 1982... 

Waste water Extract continuously with methylene chloride under alkaline and then acidic conditions Isotope dilution, capillary column GC/MS 10 pg/L No data EPA 1990c... 

Water, waste water Extract with methylene chloride at pH >11 and again at pH <2 dry concentrate GC/MS 2.5 pg/L 4-146 APHA 1992... 

Waste water Add stable isotopically labeled analogs of the compounds to 1 L of waste-water sample extract sample at pH 12-13, then at pH <2, with methylene chloride using continuous extraction techniques dry extract over sodium sulfate concentrate add internal standard inject GC/MS 10 pg/L NR EPA 1990b (Method 1625)... 

Waste water Extraction with methylene chloride clean-up by column chromatography i f requi red GC/FPD... 

Waste water Extraction with methylene chloride solvent removal optional clean-up using GPC and/or SPE columns Capillary GC/FPD confimation using second GC column... 

Waste water Addition of isotopically-labeled standard, extraction with methylene chloride at pH 12-13, then at pH <2, removal of water, volume reduction, addition of internal standard. GC/IDMS (EPA Method 1625) 50 g/L 106 (25% RSD) at 100 g/L EPA 1984a ... 

In full-scale applications very fast corrosion (formation of holes over the course of weeks, especially at improper welds) has been observed in off-gas piping, even when made from stainless steel. The problem is most evident when aerosols, for example containing chloride, escape from the reactor into the pipes where they form a very corrosive wet film. But corrosion may also occur in stainless steel pilot or full-scale reactors, especially when treating waste waters. Such reactors are best made of stainless steel because of the possibility to operate them at elevated pressures, e. g. 200-600 kPa, which can readily be achieved with commercially available ozone generators (Masschelein, 1994). 

Although flotation was developed as a separation process for mineral processing and applies lo the sulfides of copper, lead, zinc, iron-molybdenum, cobalt, nickel, and arsenic and to nonsullides, such as phosphates, sodium chloride, potassium chloride, iron oxides, limestone, feldspar, fluorite, chromite, tungstates, silica, coal, and rhodochrosilc, flotation also applies to nonmineral separations. Flotation is used in the water disposal field, particularly in connection with petroleum waste water cleanup. 

Hg CV-AAS Organic Hg is oxidized to inorganic Hg by KMn04, K2S2Og, and heating. The Hg is chemically reduced to the elemental state with stannous chloride or sodium tetrahydroborate the vapor generated is transferred to the absorption cell and measured at 253.7 nm Applicable to 0.1-10 pg L 1 in surface, ground, and waste waters 51,109... 

Wear nitrile rubber gloves, laboratory coat, and eye protection. Selenium powder may be mixed with sand and treated as normal refuse, as may the disulfide. Soluble selenites and selenates can be dissolved in water and run to waste, diluting with at least 50 times its volume of running water. Soda ash should be applied liberally to spills of selenium dioxide, selenic and selenous acids, and selenyl and selenium chlorides, which may then be mopped up cautiously with plenty of water wash down the drain, diluting greatly with at least 50 times its volume of water.16... 

The work of Mosko [116] is important in that he is one of the few workers who have given serious consideration to the determination of nitrite in water. His paper is concerned with the determination of chloride, sulphate, nitrate, nitrite, orthophosphate, fluoride and bromide in industrial effluents, waste water and cooling water. Two types of analytical columns were evaluated (standard anion and fast run series). Chromatographic conditions, sample pretreatment and the results of interference, sensitivity, linearity, precision, comparative and recovery studies are described. The standard column provided separation capabilities which permitted the determination of all seven anions. The fast run column could not be used for samples containing nitrite or bromide owing to resolution problems. 

Tanaka and Ishizuki [8] have investigated the possibility of determining orthophosphate in waste waters by ion exclusion chromatography on a cation exchange resin in the H+ form by elution with acetone water. They discuss optimal conditions for the separation of phosphate from chloride, sulphate, carbonate, etc. which are always present in waste water and sewage samples. 

Alberti and Jonke [60] describe a gas chromatographic method for the determination of vinyl chloride in surface waters using a flame ionisation detector and a Poropak Q or Chromosorb 101 column. The detection limit is 0.3mg L 1 and samples of waste waters from vinyl chloride or PVC factories can be injected direct into the gas chromatograph, while water samples with lower concentrations require preliminary enrichment for which a gradient-tube method is described. 

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