<abstract xmlns="http://www.w3.org/1999/xhtml">

In this paper, two iron salts, ferrous chloride (FeCl2) and ferric chloride (FeCl3), are directly added into an aeration tank for phosphorus removal, and their effects on the biochemical system are studied; the water quality parameters such as pH and alkalinity are also investigated. The extent of influence of the added iron salts on the pH and alkalinity of aerated solutions is demonstrated to be FeCl3 > FeCl2. When the dosage of iron ions is 20 mg/L, the decrease in pH and alkalinity caused by FeCl3 is 0.5 and 65 mg/L, which is higher than FeCl2 by 2% and 26%. The initial phosphorus removal effect of FeCl2 is worse than that of FeCl3, but after continued aeration and oxidation, the phosphorus removal effect of FeCl2 can be improved; however, the final phosphorus removal effect is basically the same as that of FeCl3 added directly. The results show that FeCl2 is preferred when iron salt is added directly into the aeration tank to remove phosphorus. The proposed scheme can reduce the effect of iron salts on the alkalinity of the biochemical system on the premise of ensuring the phosphorus removal effect of the system, and is conducive to ensuring the stable operation of the biochemical system.
</abstract>

In this paper, two iron salts, ferrous chloride (FeCl2) and ferric chloride (FeCl3), are directly added into an aeration tank for phosphorus removal, and their effects on the biochemical system are studied; the water quality parameters such as pH and alkalinity are also investigated. The extent of influence of the added iron salts on the pH and alkalinity of aerated solutions is demonstrated to be FeCl3 > FeCl2. When the dosage of iron ions is 20 mg/L, the decrease in pH and alkalinity caused by FeCl3 is 0.5 and 65 mg/L, which is higher than FeCl2 by 2% and 26%. The initial phosphorus removal effect of FeCl2 is worse than that of FeCl3, but after continued aeration and oxidation, the phosphorus removal effect of FeCl2 can be improved; however, the final phosphorus removal effect is basically the same as that of FeCl3 added directly. The results show that FeCl2 is preferred when iron salt is added directly into the aeration tank to remove phosphorus. The proposed scheme can reduce the effect of iron salts on the alkalinity of the biochemical system on the premise of ensuring the phosphorus removal effect of the system, and is conducive to ensuring the stable operation of the biochemical system.

Research on the effects of ferric salt added into aeration tank for phosphorus removal on biochemical system

School of Environmental and Municipal Engineering

Department of Information Technology, Faculty of Computing and Information Technology

Applied Mathematics and Nonlinear Sciences

This work is licensed under the Creative Commons Attribution 4.0 International License.

In this paper, two iron salts, ferrous chloride (FeCl2) and ferric chloride (FeCl3), are directly added into an aeration tank for phosphorus removal, and their...

Experimental device	Type
Digital electronic analytical balance	AUY220
Precise PH meter	PHS-3C
Vacuum extractor	MC-600D
Stirrer used in coagulation test	ZR4-6
Magnetic stirrer	MS7-H550-Pro
Silent air pump	AP9903A
UV spectrophotometer	UVmini-1240

Test I		Initial pH	The pH after aeration

	Pure water	6.4	6.3
	Tap water	7.7	8.3

Test II		Initial pH	The pH after filling in CO₂	The pH after aeration

	Pure water	6.2	5.3	6.4

Research on the effects of ferric salt added into aeration tank for phosphorus removal on biochemical system

Published Online: Nov 10, 2021

Page range: 281 - 290

Received: May 25, 2021

Accepted: Jul 23, 2021

DOI: https://doi.org/10.2478/amns.2021.2.00041

Keywords
iron salt, aeration tank, pH, alkalinity, total phosphorus

© 2021 Xie Jingliang et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Main instrument table for testing.

Pure water test.

Research on the effects of ferric salt added into aeration tank for phosphorus removal on biochemical system

Published Online: Nov 10, 2021

Page range: 281 - 290

Received: May 25, 2021

Accepted: Jul 23, 2021

DOI: https://doi.org/10.2478/amns.2021.2.00041

Keywordsiron salt, aeration tank, pH, alkalinity, total phosphorus

© 2021 Xie Jingliang et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Main instrument table for testing.

Pure water test.

Keywords
iron salt, aeration tank, pH, alkalinity, total phosphorus