Prior to technical establishment of a simple and easy advanced sewage treatment, simulteneous adsorptive removal of P and N in waste water associated with eutrophication of water was investigated.
Zeolite/Aluminum-flock composite material (Zeo/Al-flock composite material) was used as the adsorbent which was prepared by treating natural zeolite with aluminum salt (Al-salt). Clinoptilolite (TOYORAITO-Z) was used as the natural zeolite and such natural zeolite as an experimental material was also low cost. It was purchased from TOYOROZAI (OSAKA). Al
2 (SO
4)
3 was also used as Al-salt.
Zeo/Al-flok composite material was prepared as followed ; Four grams of the zeolite particle controlled with diameters ranging from 0.074 mm to O. 125 mm was added into 500 ml of 4.0 × 10
-2 M Al
2 (SO
4)
3 solution, and they was neutralized with 2. 0 M Na
2CO
3 solution. The suspension obtained was filtrated, and the precipitates were washed and dried for 3 hours at 105°C. The weight ratio, betwee such zeolite and Al-flock as the precipitates yielded was 5 : 1, respectively.
Simulteneous adsorption of P and N with the Zeo/Al-flock composite material obeyed the Freundlich's adsorption formula and the adsorpabilities (especially an adsorpability of P) were superior to those of the other materials prepared for this investigation. The adsorpabilities of P and N with the composite material were 16 mg-PO
43-/adsorbent 1 g and 5 mg-NH
4+/adsorbent 1 g.
The simultenous adsorpabilities of P and N with the Zeo/Al-flock composite material were affected by behaviours of Al
3+, OH- and SO
42- used for the preparation. Such the chemical composition as a stable intermediate formation of the Al-flock complex produced at pHs ranging from 4. 5 to 5. 25 was analyzed from a weight of Al-flock complex yielded or Al
3+ content used for the complex and so on. The composition was calculated as [A15 (OH) 9 (SO4) 3] n (n=1, 2, 3, …). But at the final point (pH = 6. 7) the composition was calculated to be changed from [Al
5 (OH)
9 (SO
4)
3]
n to [Al
2 (OH)
4 (SO
4)]
n (n = 1, 2, 3, …).
Some merits of such the Zeo/A1-flock composite material as a pollutant removal reagent were an use of low cost material (natural zeolite) and a simplification of the treatment process which the composite material would be directly used as a filter medium. We expect the composite material would be practically used as the material for the simple and easy advanced treatment.
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