Water treatments denitrification

Kepro [Kemira process] A process for recovering valuable products from municipal sewage sludge. It makes four products crude iron phosphate, a biofuel, water treatment chemicals, and a carbon source for denitrification in the sewage plant. Developed by Kemira Chemicals in the 1990s and first installed in Helsingboig, Sweden... 

Very small quantities of methanol are now consumed in the denitrification of waste water. Methanol is used as a carbon source by bacteria which convert nitrates and nitrites to nitrogen. Methanol is an efficient carbon source and decreases the production of byproducts. The potential requirement for a carbon source for water denitrification is large but the use of methanol is threatened by cheaper feedstocks. One large denitrification plant in the U.S., for example, uses brewery waste as a carbon source. In the future, water treatment plants designed for water denitrification may utilize a less expensive alternate carbon source than methanol. 

Sakakibara Y, Nakayama T. (2001). A novel multi-electrode system for electrolytic and biological water treatments Electric charge transfer and application to denitrification. 

The treatment of amine-containing scrubbing solutions requires a nitrification/denitrification stage. These treatment steps can also be carried out in an external biological waste water treatment plant. An alternative to discharge is the recovery of the amines. 

Karanasios, K. A., Michailides, M. K., VasiUadou, I. A., Pavlou, S., Vayenas, D. V. (2011). Potable water hydrogenotrophic denitrification in packed-bed bioieactors coupled with a solar-electrolysis hydrogen production system. Desalination and Water Treatment, 55(1—3), 86-96. 

On-Line Monitoring and Control of a Biological Denitrification Process for Drinking-Water Treatment... 

Figure 3 shows the measured concentrations of nitrate, nitrite, and DOC during the denitrification process subjected to different inlet C/N ratios. The system was firstly operated to steady state using an inlet C/N ratio of 1.55. During this initial transient period (approximately 30 hours) both nitrate and nitrite accumulate, after which the concentrations of both pollutants in the treated water drop to values below the maximum admissible ones. The purpose of this preliminary experiment was to simulate the startup of the water treatment plant. 

Online monitoring and control of the biological denitrification process in a cell recyle membrane reactor has been developed and implemented at laboratory scale. The system has been tested with a real groundwater contaminated with nitrate. The results presented in this study show that the C7N ratio is the key parameter to guarantee an efficient denitrification process. A simple feedforward control strategy that adjusts the feed rate of the carbon source to maintain an inlet C/N ratio value of 1.39 is effective at reducing both nitrate and nitrite concentrations in the treated water below the maximum admissible values. Moreover, this control strategy based on the C/N ratio is easy to implement in a water treatment plant and does not increase the complexity of its operation at industrial scale. 

Denitrification is the mechanism by which fixed nitrogen is returned to the atmosphere and is useful in advanced water treatment for the removal of... 

The best H2-prodncer helper bacterinm strains convert the organic material found in dilute waste waters from the food processing industry (sugars and proteins). They are selected becanse in this way, a treatment of polluting waste waters can be linked to the elimination of polluting nitrate contamination. The ability to bring about denitrification... 

In the case of nitrogen, some is transferred to the atmosphere as a consequence of denitrification, which takes place in soils, sewage treatment plants, and natural waters. Some nitrogen is also volatilized as ammonia from animal feedlots. 

Nitrous oxide is important not only as a greenhouse gas but, as discussed in Chapter 12, as the major natural source of NC/ in the stratosphere, where it is transported due to its long tropospheric lifetime (Crutzen, 1970). The major sources of N20 are nitrification and denitrification in soils and aquatic systems, with smaller amounts directly from anthropogenic processes such as sewage treatment and fossil fuel combustion (e.g., see Delwiche, 1981 Khalil and Rasmussen, 1992 Williams et al., 1992 Nevison et al., 1995, 1996 Prasad, 1994, 1997 Bouwman and Taylor, 1996 and Prasad et al., 1997). The use of fertilizers increases N20 emissions. For pastures at least, soil water content at the time of fertilization appears to be an important factor in determining emissions of N20 (and NO) (Veldkamp et al., 1998). 

Nitrite (N02 ) as well as sulfide (H2S/S2 ) removal from waste waters is sometimes performed by ozonation. Both substances react fast with ozone (see Table 3-1). However, it must be emphasized that there are cost-efficient treatment alternatives, e. g. biological denitrification or sulfide removal. 

Denitrification can be limited by carbon availability when O2 is absent and NO3 is abundant. Additions of glucose stimulated denitrification in 11 of 13 agricultural soils that were presumably fertilized (Drury etaL, 1991). Similar observations have been made in water columns (Brettar and Rheinheimer, 1992), marine sediments (Slater and Capone, 1987), river sediments (Bradley et aL, 1995), aquifers (Smith and Duff, 1988 Obenhuber and Lowrance, 1991), wastewater treatment wetlands (Ingersoll and Baker, 1998), and forested wetlands (DeLaune et aL, 1996). Tiedje (1988) proposed that the major influence of carbon on in situ denitrification is to promote anaerobic conditions. 

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