SPRR工艺回收养猪废水营养元素研究

Nutrients Recovery by SPRR Process from Piggery Wastewater

采用磷酸铵镁(MAP)结晶法,研究序批式磷回收反应器(SPRR)从养猪废水厌氧消化液中回收营养元素的能力,初步确定了SPRR反应器的运行参数,考察了废水组成对反应器运行效果的影响。结果表明,在废水pH=8.5时,SPRR工艺能够有效富集MAP晶体,单个运行周期仅3.6h;养猪废水中适量投加Mg盐能使MAP产量提高约10.5%～11.6%;考虑经济成本,当养猪废水仅用于营养元素回收时,可不投加Mg盐。SPRR工艺可直接从养猪废水厌氧消化液中高效回收营养元素,具有广阔的应用前景。

When adopting the crystallization technology of magnesium ammonium phosphate （MAP） for P recovery from high strength wastewater, fluid bed reactor is usually viewed as the most common choice. However, due to its poor hydrodynamics conditions, masses of MAP particles can not remain in the reactor but flow out the system with the effluent, which result in lower recovery efficiencies of phosphorus. For improving these recovery efficiencies, a new kind of sequencing-batch phosphorus recovery reactor （SPRR）, which can accelerate the separation efficiencies of MAP particles from water, was designed. The nutrients recovery potential of SPRR from anaerobic digestion effluent of piggery wastewater was studied. Primary operational parameters of the SPRR were determined, and the influences of pollution components on the MAP crystallization were investigated. The results show that only through 3.0 h aeration stage, the anaerobic digestion wastewater can offer appropriate conditions for MAP crystallization. A running cycle of this SPRR including five stages, namely influent stage, pH increase stage, MAP crystal stage, MAP precipitation stage, effluent stage, it can be finished only in 3.6 h. The addition of Mg^2＋ could improve MAP production by 10.5%-11.6%; however, considering the cost of nutrients recovery, it is not necessary to add Mg^2＋ salt. Except some ions, such as NH4^＋, PO4^3- and Mg^2＋, the rest pollution components in anaerobic digestion effluent of piggery wastewater did not signifieandy restrain MAP formation. In conclusion, this kind of SPRR has a broad application future as a high-efficiency installation for direct nutrients recovery from anaerobic digestion effluent of the piggery wastewater.