Wastewater treatment reagents used

Chapter 6 of this volume by Niyazi et al. deseribe determination of the sorption properties of polymer eellulose and natural carbonate sorbents for use in wastewater treatment applications. Niyazi et al. thus summarize, the article shows the comparative characteristics of the sorption properties of polymer cellulose and natural carbonate sorbents. The influence of the mass of sorbents on the degree of extraction as well as the pH changing are analyzed. The optimum phase ratio has been determined. Kinetic cmves have been plotted. The work of Niyazi et al. thus advances our understanding and development of wastewater treatment reagents for applications of clarifying wastewater in many and varied areas, both industrial and domestic, in everyday life. 

The examination of the total reagent usage in the two processes (last row in Table 8.3) clearly shows that the new enzymatic route (with recycling of 4) utilizes 7 times less input of chemicals. This includes 12 times less input of solvents as compared to the first-generation route. Moreover, in the optimized process, every chemical reaction is run in water with minimal solvents used for work-up. Some of the process water can be sent directly to the wastewater treatment plant, and the solvent from the hydrolysis/decarboxylation process is recovered. Further improvements from pilot plant and production scale runs have been demonstrated and will be implemented in the future. 

One of the most friendly, attractive and economically justified techniques used in homogeneous systems consists of the photo-Fenton method. The photo-Fenton reagent (Fe3+/Fe27H202) is an efficient and cheap reagent, which in a very simple way produces OH radicals for wastewater treatment, due to the fact that iron is a very abundant and non-toxic element and hydrogen peroxide is easy to handle and environmentally safe. Iron in its ferrous and ferric forms acts as a photocatalyst and requires a working pH <4. At higher pH values, iron precipitates as a hydroxide. The Fenton reaction, which usually operates at or near ambient temperature and pressure ... 

Metal ions are generally recovered or removed from aqueous discharges by selective precipitation of their insoluble compounds. One of the most popular precipitating agents is the OH- ion. The addition of commercial bases to wastewaters so as to precipitate and remove insoluble metal hydroxides is a common practice for water treatment. This is a relatively simple operation, and the reagents used (typically lime and soda ash) are inexpensive, safe, and readily available. The approximate relative cost of the commercial bases Ca(OH)2, Na2CC>3 andNaOH is 1 3 5, respectively. 

TCI. Iswahymu, Phenolic Wastewaters Treatment using Fenton s Reagent and... 

Fenton chemistry refers to an oxidation process that uses H2O2 as oxidant and a transition metal catalyst, generally Fe, to oxidize organic substrates. This process is commonly used for wastewater treatment. Two reaction mechanisms were proposed for the Fenton reagent. One assumes the production of free hydroxyl radicals by the metal-catalyzed decomposition of peroxide [78], whereas the other involves... 

Elemental composition H 3.73%, C 44.44%, N 51.83%. HCN may be analyzed by GC or GC/MS. The aqueous solution may be directly injected onto the GC column and determined by an FID. For GC/MS determination, an alcoholic solution may be injected into the column. The characteristic mass ions are 27 and 26. The cyanide ion in aqueous solution also may be measured by cyanide ion-selective electrode, titrimetry, and by colorimetric methods (APHA, AWWA, WEF. 1999. Standard Methods for the Examination of Water and Wastewater, 20th ed. Washington, DC American Public Health Association). For colorimetric analysis, the aqueous solution may be treated with a dilute caustic soda solution, followed by treatment with chloramine-T, and then with pyridine-barbituric acid reagent. A red-blue color develops, the absorbance of which is measured by spectrophotometer at 578 nm. The concentration of CN is determined from a standard cahbration curve using KCN standards. 

Lime or caustic precipitation is the most commonly used method for treating aqueous wastes with non-complexed metals. Alkaline reagents such as lime, or caustic raises the pH of the wastewater and causes metals to precipitate out of the solution as metal hydroxides. For many metals there is a specific pH at which the metal hydroxide is least soluble, as shown in Figure 1. Because several metals co-exist in a waste in most cases, it is not possible to operate a treatment system at a single pH value that is optimum for all metal removals. As a compromise, a pH between 9.5 and 12.0 is maintained for typical mixed metals removal. A typical precipitation reaction is as follows ... 

Treatment of olive mill wastewater has also been carried out with Fenton reagent [44]. This study also used Fenton treatment in conjunction... 

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