Study On Phosphorus And Ammonia Simultaneous Removal From Tail Water Of Urban Sewage Plant

One of the main factors of eutrophication of water body is the excess discharge of nitrogen and phosphorus. An effectively way to prevent eutrophication is further purification of the tail water of urban sewage plant. In this paper, hydrous ferric oxides loaded zeolite (Fe-Zeolite) and ferric and manganese binary oxides loaded zeolite (FMBO-Zeolite) were synthesized by in-situ precipitation method and used for ammonia (NH4+) and phosphorus (PO43-) adsorption removal. The adsorption behavior and mechanism of ammonia and phosphorus on the surface of the modified zeolites were systematically studied. Based on the dynamic operation results, a set of process design was provided and aimed at phosphorus and ammonia adsorption removal from tail water of urban sewage plant.Based on batch experiment results, the adsorption capacities of Fe-Zeolite and FMBO-Zeolite for phosphorus was 32 and 41 times higher than that of the natural zeolite, while the adsorption capacity for ammonia of the two zeolites were similar to that of the natural zeolite within a wide pH range. SiO32-and AsO43- would cause negative effect for phosphorus removal. Pseudo-second-order kinetic model gave a good fit for ammonia and phosphorus uptake by Fe-Zeolite and FMBO-Zeolite. The adsorption data of Fe-Zeolite and FMBO-Zeolite for phosphorus were well fitted by the Langmuir isotherm model and the Freundlich model, and the maximum adsorption capacity reached 2.92 mg/g and 3.70 mg/g, respectively. The adsorption data of Fe-Zeolite and FMBO-Zeolite for ammonia were well fit by the Freundlich isotherm model, and the maximum adsorption capacity reached 16.85mg/g (Fe-Zeolite) and 17.84 mg/g (FMBO-Zeolite), respectively. The adsorption process of Fe-Zeolite and FMBO-Zeolite for ammonia and phosphorus was spontaneous and endothermic process.To the simulation tail water with ammonia and phosphorus initial concentration of 15 mg/L and 1 mg/L, both Fe-Zeolite and FMBO-Zeolite could effectively remove ammonia and phosphorus simultaneously and the solution pH had no clear change. After saturation, the adsorption columns could be regenerated in-situ easily and effectively. The removal efficiency of phosphorus was increased after regeneration, while regeneration has no clear negative effect on ammonia removal.A set of process design based on Fe-Zeolite or FMBO-Zeolite adsorption filter combined with sand filter was provided for ammonia and phosphorus simultaneous removal from tail water of urban sewage plant. The influent and effluent concentrations of ammonia and phosphorus were 15 to 1 mg/L and 1 to 0.4 mg/L, respectively, and the maximum treatment capacity of the process was 6000 m3/d.