Removal nitrates

Water Treatment. The two primary appHcations in water treatment are softening and deionization. Other important but less frequendy used appHcations include dealkalization, softening of produced water, desilicizing, and nitrate removal. 

R. Grinstead K.C. Jonos, Nitrate Removal from Waste Water by Ion Exchange , Rpt 17010 FSJ, US Environmental Protection Agency (1971) 11) D.H. Rosenblatt, G-E. 

Reaction of ammonium hexanitrocerate and cyclopentadienylsodium under inert conditions gives tris(cyclopentadienyl)cerium and sodium nitrate, removed by filtration before evaporation of solvent [1]. When the filtration step was omitted, and the evaporated solid mixture was heated to 75°C, a violent explosion occurred. This may have involved complexes of the type Ce(N03)Cp2.NaN03[2], but a direct redox reaction between the reactive CeCp3and the oxidant is also possible. 

NitRem [Nitrate Removal] A process for removing nitrate from water supplies by elec-trodyalysis through a selective membrane. Developed in the 1980s by OTTO Oeko-Tech Company, Germany. 

C. Unpublished results of nitrate removal rates for biofilms under sewer conditions have shown values around 0.05 gN03-N m-2 h-1 for normal wastewater from households and from 0.10-0.18 for wastewater with readily biodegradable substrate. 

Prediction of Nitrate Removal under Anoxic Conditions... 

Prediction of the nitrate removal rate under anoxic conditions in a sewer can be done by a simple empirical approach. The following equation including transformations in the water phase and the biofilm of a sewer pipe may be applied under substrate nonlimited conditions ... 

Vw,max = nitrate removal rate at 20°C in the water phase under substrate nonlimited conditions (gN03-N m-3 h-1)... 

Based on Equation (5.15), the nitrate removal in a sewer pipe can be calculated ... 

Nitrate Removal for Small Public Water Systems 600375030 Nitrogen in the Subsurface Environment... 

Baker CJ, Maltby E. 1995. Nitrate removal by river marginal wetlands factors affecting the provision of a suitable denitrification environment. In Hughes JMR, Heath-waite AL, eds. Hydrology and Hydrochemistry of British Wetlands. Chichester Wiley, 291-313. 

Desilva, F.J. Nitrate removal by ion exchange. Water Qual. Prod. 2003, 8 (4), 9-30. 

Practical considerations and implementation. Most investigations involve the use of distilled/deionised water with KNO3 as the nitrate ion source thereby avoiding any potential impact of water hardness and dissolved salts on the catalytic removal of nitrates. It has been pointed out that in the presence of anions such as S04 and bicarbonates, which may be present in tap-water at concentrations of above 90 ppm, reduced nitrate reduction rates are to be expected as a result of competitive anion adsorption. Pintar and co-workers have indicated that nitrate removal rates are reduced when using drinking water as opposed to distilled water. Chloride ion is known to reduce the rate of nitrate removal while the choice of cation as counter ion influences the rate in the order, < Na < Ca < Mg + <... 

The basic material used by this technology, vegetable oil, is inexpensive (D14820J, p. 2). Column data suggest that 1 ounce of oil would remove 10 parts per million (ppm) nitrate from approximately 195 gal of oxygenated water. Based on this efficiency of nitrate removal, a dollar s worth of oil (about 0.4 gal) should remove 10 ppm nitrate from about 10,600 gal of water. Theoretically, under anaerobic conditions, 1 ounce of oil should remove 10 ppm nitrate from about 650 gal of water (D179424, p. 82). 

Bench- and pilot-scale tests were used to prepare cost estimates for Krudico, Inc., ion exchange system treatment of groundwater contaminated with nitrate and perchlorate at the DOE s Lawrence Livermore National Laboratory. Data were provided for three options nitrate removal only, perchlorate removal only, and removal of both nitrate and perchlorate. Estimates were... 

Researchers concluded that ion exchange removal of nitrate was cost prohibitive at the Livermore site because of the high cost of waste disposal. The perchlorate-only alternative with nitrate removal using another technology was the most cost-effective solution. Perchlorate disposal costs under this option were 350/year, and minimal maintenance of the treatment unit would be required (D20493D, p. 12). The cost estimates are summarized in Table 1. 

Based on the result of bench- and pilot-scale testing, cost estimates were determined for Krudico, Inc., ion exchange system treatment of groundwater contaminated with nitrate and perchlorate at the U.S. Department of Energy s (DOE s) Lawrence Livermore National Laboratory. Costs were estimated to cover three options nitrate removal only, perchlorate removal only, and removal of both nitrate and perchlorate. The proposed treatment system would treat approximately 1,839,600 gal of contaminated groundwater at a treatment rate of 3.5 gallons per minute (gpm). Nitrate removal was estimated to cost 0.15/gal, perchlorate removal was estimated at 0.02/gal, and a combined removal system was estimated to cost 0.16/gal (D20493D, p. 12). 

Phenyl isothiocyanate may be prepared in quantity (Expt 6.98, Method 2) by allowing aniline to react with carbon disulphide to form phenyldithiocarbamic acid (cf. 1), which is isolated as the ammonium salt. Treatment of the latter with lead nitrate removes the elements of hydrogen sulphide to produce phenyl isothiocyanate. As indicated in the preparation of p-bromophenyl isothiocyanate which is given as a further example, a slightly modified procedure which requires the use of rectified spirit as a reaction solvent is necessary in order to obtain good yields of isothiocyanates from substituted anilines. 

Fig. 10.2. Cu(II) coverage (T) of Gly-Gly-His modified gold electrodes on mixed SAMs of MPA and MP, determined by integration of CV peaks. Mixed SAMs comprising MPA and MP were prepared by immersing the gold-coated substrates in solutions of mixtures of MPA and MP of a given fraction. In all cases, Cu(II) was accumulated at the Gly-Gly-His modified electrode at open circuit for 10 min in a 0.05 M ammonia acetate buffer solution (pH 7.0) containing 0.1 iM copper nitrate, removed, rinsed and then placed in a copper-free ammonium acetate buffer solution. Scan rate 100 mV s-1. Reproduced with permission of The Royal Society of Chemistry from Ref. [6], Copyright, Royal Society of Chemistry (2003).

Nitrate removal from drinking water NaCl removal from amino acid solutions... 

In the case of clarified feeds and low current densities, membrane lifetime can be as long as seven or 10 years for brackish water desalination or drinking water nitrate removal, respectively. However, if the feed solution is fouling or scaling or the ED separation plant has not been well designed or is not properly conducted, membrane lifetime is no longer than a year. 

Ludtke, K., Peinemann, K.-V., Kasche, V., and Behling, R.-D. (1998). Nitrate Removal of Drinking Water by Means of Catalytically Active Membranes. Journal of Membrane Science, 151,3-11. 

A. Elmidaoui, F. Elhanouni, M. Taky, L. Chay, M.A.M. Sahli, L. Echihabi, M. Hafsi, Optimization of nitrate removal operation from ground water by electrodialysis, Sep. Purif. Technol. 29 (2002) 235-244. 

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