Lewatit S 100 in Drinking Water Treatment for Ammonia Removal

Several nitrogenous compounds, including ammonia, nitrite and nitrate, are frequently present in drinking water and in various types of agricultural, domestic and industrial wastewaters (Metcalf & Eddy, 1991). This necessitates the upgrading of technological schemes, and a search for cost effective and environment friendly methods for removal of ammonia, nitrite, and nitrate. According to the instruction of the European Community Council (CCE) of 15 July 1980, the maximum permissible level of ammonium in drinking water is 0.5 mg/l. Methods for removal of nitrogenous compounds proposed by previous investigators have included air stripping, nitrification/denitrification using fixed or fluidized bed biological reactors and ion exchange. One of the common processes for drinking water treatment applied in recent times is an ion exchange process. Removal of ammonia from water has been investigated by many researchers (Gaspard and Martin, 1983; Hlavay et al., 1983; Vokáčová, et al., 1986; Hódi et al., 1995; Booker et al., 1996; Beler Baykal and Akca Guven, 1997; Cooney et al., 1999). A simple comparison of ammonia removal by both natural and a synthetic material was attempted by (Haralambous et al. 1992). Jörgensen, (1976) wrote in his paper that ammonia removal from wastewater was examined during treatment in a laboratory glass column with a diameter of 20 mm, containing 200 ml of ion exchange material of the following type: 1) a strong acidic cation exchanger on a sodium form (Lewatit 500 A); 2) a strongly acidic cation exchanger on a hydrogen form (Lewatit 500 A); 3) clinoptilolite on a sodium form; 4) an artificial zeolite; 5) sulfonated lignocelluloses on a sodium form; 6) a weak acidic cation exchanger on a sodium form (Lewatit 69 MP); 7) a weak acidic cation exchanger on a hydrogen form (Lewatit 69MP). The results show that out of ion exchangers 1–7 only 2, 3 and 7, and perhaps also 6 give satisfactory results. The objective of our work is to treat drinking water spiked with NH4 +


Introduction
Several nitrogenous compounds, including ammonia, nitrite and nitrate, are frequently present in drinking water and in various types of agricultural, domestic and industrial wastewaters (Metcalf & Eddy, 1991).This necessitates the upgrading of technological schemes, and a search for cost effective and environment friendly methods for removal of ammonia, nitrite, and nitrate.According to the instruction of the European Community Council (CCE) of 15 July 1980, the maximum permissible level of ammonium in drinking water is 0.5 mg/l.Methods for removal of nitrogenous compounds proposed by previous investigators have included air stripping, nitrification/denitrification using fixed or fluidized bed biological reactors and ion exchange.One of the common processes for drinking water treatment applied in recent times is an ion exchange process.Removal of ammonia from water has been investigated by many researchers (Gaspard and Martin, 1983;Hlavay et al., 1983;Vokáčová, et al., 1986;Hódi et al., 1995;Booker et al., 1996;Beler Baykal and Akca Guven, 1997;Cooney et al., 1999).A simple comparison of ammonia removal by both natural and a synthetic material was attempted by (Haralambous et al. 1992).Jörgensen, (1976) wrote in his paper that ammonia removal from wastewater was examined during treatment in a laboratory glass column with a diameter of 20 mm, containing 200 ml of ion exchange material of the following type: 1) a strong acidic cation exchanger on a sodium form (Lewatit 500 A); 2) a strongly acidic cation exchanger on a hydrogen form (Lewatit 500 A); 3) clinoptilolite on a sodium form; 4) an artificial zeolite; 5) sulfonated lignocelluloses on a sodium form; 6) a weak acidic cation exchanger on a sodium form (Lewatit 69 MP); 7) a weak acidic cation exchanger on a hydrogen form (Lewatit 69MP).

Physical description of the system
Fig. 1 shows an experimental apparatus consisting of a column with the following characteristics: Internal diameter = 20 mm, containing approximately 50 ml of exchanger, at a volumetric flow rate of 8.7 ml min -1 , which is equivalent to 10.5 bed volumes (BV) per hour, particle-size of material = 0.3-1.2mm.A glass screen supported the Lewatit in the column.

Analysis
All analyses were made according to standard methods (APHA, see Greenberg et al., 1992).Ammonia was determined by Nessler methods using a spectrophotometer (Model Hach DR/2000).Calcium and magnesium were determined by the EDTA titrimetric method.

Specification of the material
Lewatit S100 was the material used for the investigation.Lewatit S100 is a synthetic resin ion exchanger of the Na-type.It is a strongly acid cationic ion exchange resin.Acta Polytechnica Vol.41 No. 1/2001 Lewatit S100 in Drinking Water Treatment for Ammonia Removal H. M. Abd El-Hady, A. Grünwald, K. Vlčková, J. Zeithammerová Ammonium nitrogen is the most important form of nitrogen that can cause excessive algal growth and stimulate eutrophication in surface water.The purpose of this study is to investigate the possibility of removing ammonium from drinking water by means of an ion exchange process.Polymeric Lewatit S100 material (particle-size 0.3-1.2mm) was used.The breakthrough capacity was determined by dynamic laboratory investigations and the concentration of regenerant solution (5 and 10 % NaCl) was investigated.The concentration of ammonium ion inputs in the tap water that we used were 10, 5 and 2 mg NH 4 + l -1 and down to levels below 0.5 mg NH 4 + l -1 .The experimental results show that the breakthrough capacity was very small at ammonium concentration 2 mg NH 4 + l -1 compared to its breakthrough capacity at ammonium concentration 10 mg NH 4 + l -1 .There was no difference between regeneration by 10 and 5 % NaCl.We conclude that the use of Lewatit S100 is an attractive and promising method for ammonium concentration greater than 5 mg NH

System operation parameters
The first experiment was carried out to see the exhaustion performance of Lewatit S100 using distilled water spiked at 10 mg NH 4 + l -1 concentration.Then we applied tap water containing Ca +2 = 60 mg l -1 and Mg +2 = 12 mg l -1 .The concentrations of ammonium input were 10, 5 and 2 mg NH 4 + l -1 as (NH 4 Cl) and down to levels below 0.5 mg l -1 .
In the regeneration phase, we used 5.0% NaCl at a volumetric flow rate of 8.7ml min -1 , which is equivalent to 10.5 bed volumes (BV) per hour and then 10% NaCl.After regeneration, the excess Cl -was removed from the Lewatit S100 by distilled water.This washing was repeated until visual tests with AgNO 3 revealed zero chloride.

Breakthrough capacity
Within the scope of this work, the results from the first experiment using distilled water indicated that the volume of water treated till breakthrough, defined as 0.5 mg l -1 in NH 4 + , was 2570 BV (128.5 l), and the breakthrough capacity was 1.356 mol l -1 for NH 4 + = 10 mg l -1 .
Fig. 2 shows that for tap water containing calcium and magnesium ions, the breakthrough capacity and the volume of water treated till NH 4 + breakthrough were 0.156, 0.085, 0.0317 mol l -1 and 295 BV (14.75 l), 340 BV (17 l), 380 BV (19 l), respectively.These values indicate that tap water produces a lower breakthrough capacity than distilled water, due to the presence of other ions, especially ions with a polyvalent charge in water, such as Ca +2 and Mg +2 .
Fig. 3 shows that, for tap water, the evaluation of practical capacity exchange is a function of the entering concentration of NH 4 + .These results reveal that the breakthrough capacity is lower by approximately 0.55 and 0.2 times at NH 4 + = 5 and 2 mg l -1 , respectively, than the breakthrough capacity at NH 4 + = 10 mg l -1 .Thus, Lewatit S100 can remove ammonium ions very quickly with a higher breakthrough capacity at initial ammonia concentration of more than 5 mg l -1 .
Comparing the results summarized in Table 1, it can be seen that the calcium elimination from solution of 10 mg l -1 NH 4 + was higher than the other solution of 5 mg l -1 and 2 mg l -1 .Magnesium was elimination from all ammonium solution with the same rate.

Regeneration effects
The elution curves (Fig. 4) indicate no difference between regeneration by (10 and 5%) NaCl solution.Table 2 shows that 29 BV (1.45 l) of on NaCl solution is sufficient for ammonium elution using Lewatit S100.These results reveal that Lewatit S100 is slightly more economical when using 5% NaCl for regeneration.

Conclusions
The experimental results indicate that Lewatit S100 as a cation exchanger can remove ammonium ions very quickly.Higher breakthrough capacity was found at an initial ammonium ion concentration of more than 5 mg/l compared to 2 mg.The calcium elimination was lower at an ammonium ion concentration of 10 mg/l.No difference between regeneration by 10 and 5% NaCl was observed.We conclude that the use of Lewatit S100 is an attractive and promising method for ammonium concentration greater than 5 mg NH 4 + l -1 and till 10 mg

Table 1 :
Results of experiments

Table 2 :
Elution of ammonia