[Inhibition of Internal Phosphorus Release in the Black-Odor Channel Under Different Adding Methods of CaO₂]

The inhibition of sedimentary phosphorus(P) was investigated under the CaO₂ with 3 addition ways. The overlying water and sediments came from a black-odor channel in S City. The results showed that the value of pH and DO in the overlying water increased under the 3 addition ways of CaO₂. Under the condition of injection, the DO concentration of the overlying water was lower than that of the covering condition, which indicated that the injection could delay the oxidation of CaO₂ and be favor of creating the micro-oxidation environment in the sediment. The concentrations and the trend of TP and DIP in the overlying water were similar under the injection and covering, which were lower than that in the mixing condition. However, under the covering condition, the DIP concentration in the pore water was the highest, reaching up to 120.33-142.18 times, compared with the injection condition. Noticeably, the DIP in the pore water and the overlying water was lower, indicating that the addition of CaO₂ could inhibit the release of sedimentary P. This was attributed to the micro-oxidation environment. The sedimentary P fractions also confirmed this. The explanation may be that the addition of CaO₂ accelerated the mineralization of organophosphate and the formation of Fe-Al/P and Ca-P, which enhanced the retention of sedimentary P.