Removal of Ammonia from Wastewater

The solution of the problem is a process with two different operating pressures as shown inFig. 11.1-4 (Wunder 1990). In the first colunm (p, = 1 bar) pure water is recovered as bottoms. The lowest feasible condensation temperature at the top is approximately 45°C, which is equivalent to an ammonia concentration of 20 wt%. This overhead fraction is compressed (in liquid state) to 20 bar and fed into colunrn C-2 for further fractionation. The overhead fraction of C-2 is pure ammonia (20 bar, 45°C). The bottom fraction, which is limited by the available steam (maximum 

However, large recycle streams within processes are disadvantageous since they increase operating and investment costs. For economic reasons recycle streams have to be as small as possible. In this process, the concentration of the bottom fraction of column C-2 has to be much lower than that of the overhead fraction of column C-2. The following mass balance holds  

Equation (11.1-1) makes it clear that the concentration x 2 has to be significantly lower than the concentration. This condition is met when the bottom tempera- 

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Adequate ventilation is necessary for aH process lines to ensure worker safety. Electroless copper baths must have good ventilation to remove toxic formaldehyde vapors and caustic mist generated by the hydrogen evolution reactions and air sparging. Electroless nickels need adequate ventilation to remove nickel and ammonia vapors. Some states and municipalities requite the removal of ammonia from wastewaters. A discussion of printed circuit board environmental issues and some sludge reduction techniques is avaHable (25). 

In 2002, Membrana GmbH in Wuppertal, Germany, installed a TMCS pilot plant to test the removal of ammonia from wastewater with the purpose of reducing wastewater disposal costs at the manufacturing plant. In the first step, a system utilizing two 6 x 28 Liqui-Cel Contactors (2x1 system... 

ELM removal of ammonia from wastewater has been studied considerably (2,5). Table Vin shows a typical ELM system for the ammonia removal (59). Ammonia can be removed from 1200 mg/L down to 6 mg/L with an extraction efficiency of 99.5%. 

Nitrification, followed by denitrification, is an important process in the removal of nitrogen from wastewaters. Removal of the nitrogenous constituents helps to minimize the toxicity of the water and to reduce its oxygen demand. The removal of nitrogenous material commences when the sewage is formed and almost all the urea is decomposed to ammonia and carbon dioxide. The toxic ammonia in a waste is first nitrified to nitrite and nitrate by aerobic biological processes and then denitrified anaerobically to molecular nitrogen. 

Nitrification followed by denitrification is arguably the most effective technique for the removal of nitrogen from wastewater. The first step is an essentially complete conversion of ammonia and organic nitrogen to nitrate under strongly aerobic conditions, achieved by more extensive than normal aeration of the sewage ... 

This reaction is used to remove pollutant ammonia from wastewater. However, problems can arise from chlorination of organic wastes. Typical of such by-products is chloroform, produced by the chlorination of humic substances in water. 

Chevron s WWT (wastewater treatment) process treats refinery sour water for reuse, producing ammonia and hydrogen sulfide [7783-06-04] as by-products (100). Degassed sour water is fed to the first of two strippers. Here hydrogen sulfide is stripped overhead while water and ammonia flow out the column bottoms. The bottoms from the first stripper is fed to the second stripper which produces ammonia as the overhead product. The gaseous ammonia is next treated for hydrogen sulfide and water removal, compressed, and further purified. Ammonia recovery options include anhydrous Hquid ammonia, aqueous Hquid ammonia, and ammonia vapor for incineration. There are more than 20 reported units in operation, the aimual production of ammonia from this process is about 200,000 t. 

We have previously described ammonia removal with zeolites. However, the development of new methods capable of effective and total ammonia removal from wastewater are extremely attractive in this regard, the ion-exchange removal of ammonia with a Dowex HCR-S ion-exchange resin has been carried out [79],... 

Type 1. In this case the mass transfer rate through the membrane phase is increased by incorporating a stripping agent in the internal phase which reacts with the solute yielding a membrane insoluble product. Examples of this system are extraction of weak acids or bases from wastewater such as phenol removal by NaOH solution as the internal phase [3-8] and removal of ammonia by H2SO4 solution as the internal phase [9-10]. 

Acid or base can be used as an internal phase or stripping phase for ELM process depending upon solute to be extracted, for example, Cahn and Li [3] used NaOH solution as the internal phase for phenol removal from wastewater. H2SO4 solution was used as the internal phase for removal of ammonia [4-8]. The solute extraction rate also increases with an increase in the amount of internal reagent present in the emulsion. 

In this context, a new autotrophic member of the order Planctomycetales was isolated earlier and identified which possessed the Anammox pathway [22]. The process of Anammox has to be considered to be one of the most innovative technological advances in removal of ammonia nitrogen from wastewater. 

Liao PH, Chen A, Lo KV (1995) Removal of nitrogen from swine manure wastewaters by ammonia stripping. Bioresour Technol 54 17-20... 

Wastewater Treatment. Potential applications in wastewater treatment include the removal of heavy metals (Zn, Cd, Cu, Pb, and Hg), arsenic, acids (acetic acid and nitrophenols), and bases (ammonia) from wastewater streams. For the removal of heavy metals from wastewaters in metallurgical and incineration plants, Marr and... 

Although the removal of all heavy metals is generally needed for wastewater treatment, selective extraction of Zn , Cd , and Ni " was performed by Shiau and Jung (25). Their results show that the order of the degree of extraction is Zn > Cd > Ni for a low pH value of the external feed phase. However, at the high pH value with the presence of ammonia in the feed phase, the order is reversed to hfi > Cd > Zn. Recently, selective separation of palladium from wastewater of high iron concentration was conducted by Kakoi et al. (55). 

Ammonium Ion Removal. A fixed-bed molecular-sieve ion-exchange process has been commercialized for the removal of ammonium ions from secondary wastewater treatment effluents. This application takes advantage of the superior selectivity of molecular-sieve ion exchangers for ammonium ions. The first plants employed clinoptilolite as a potentially low cost material because of its availability in natural deposits. The bed is regenerated with a lime-salt solution that can be reused after the ammonia is removed by pH adjustment and air stripping. The ammonia is subsequentiy removed from the air stream by acid scmbbing. 

Conventional wastewater treatment techniques consist of physical/chemical treatments, including oil separation, dissolved gas flotation, and ammonia distillation (for removal of free cyanides, free sulfides, and ammonia) followed by biological treatment (for organics removal) and residual ammonia nitrification. Almost all residuals from coke-making operations are either recovered as crude byproducts (e.g., as crude coal tar, crude light oil, ammonium sulfate, or other sulfur compounds)... 

Reforming is a relatively clean process. The volume of wastewater flow is small, and none of the wastewater streams has high concentrations of significant pollutants. The wastewater is alkaline, and the major pollutant is sulfide from the overhead accumulator on the stripping tower used to remove light hydrocarbon fractions from the reactor effluent. The overhead accumulator catches any water that may be contained in the hydrocarbon vapors. In addition to sulfides, the wastewater contains small amounts of ammonia, mercaptans, and oil. 

Arnold, D.W. Wolfram, W.E. Ammonia removal and recovery from fertilizer complex wastewaters. In Proceedings of 30th Industrial Waste Conference, Purdue University, Lafayette, IN, 1975 Vol. 30, 760-767. 

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