Abstract
In this paper, two iron salts, ferrous chloride (FeCl
) and ferric chloride (FeCl
), 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 FeCl
> FeCl
. When the dosage of iron ions is 20 mg/L, the decrease in pH and alkalinity caused by FeCl
is 0.5 and 65 mg/L, which is higher than FeCl
by 2% and 26%. The initial phosphorus removal effect of FeCl
is worse than that of FeCl
, but after continued aeration and oxidation, the phosphorus removal effect of FeCl
can be improved; however, the final phosphorus removal effect is basically the same as that of FeCl
added directly. The results show that FeCl
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.