鸟粪石法回收养猪废水中氮磷时产物的组分与性质研究

Components and particle properties of products recovered from swine wastewater by struvite recovery

为了探究鸟粪石法回收养猪废水中氮磷时产物的组分与性质,利用傅里叶红外光谱(FTIR)、X射线衍射(XRD)和物料衡算,分析了不同工艺条件下回收产物的化学组分,利用扫描电镜-能谱(SEM-EDS)和激光粒度仪表征了不同条件下回收产物的形貌、粒度和元素组成.结果表明:各条件下废水中PO43-P去除率均超过93%,而NH4+-N去除率在28%左右;回收产物中主要为棒状鸟粪石(MgNH4PO·46H2O)晶体,同时还存在少量磷酸钙(Ca3(PO4)·2xH2O,ACP)和氢氧化镁(Mg(OH)2)等无定形颗粒;回收的鸟粪石纯度最高为87.72%,颗粒体积平均粒径最大为110μm;鸟粪石纯度和颗粒粒度与反应液pH和进水PO34-P浓度相关,反应液pH由8.5±0.2升至9.5±0.2,鸟粪石纯度降低,粒度减小;进水PO43-P浓度由55.29mg·L-1升至81.98mg·L-1,鸟粪石纯度增大,粒度减小.

In order to explore the components and the properties of the products recovered from swine wastewater by struvite recovery, Fourier transform infrared spectroscopy （FTIR）, X-ray diffraction （XRD）, and mass balance were utilized to analyse the chemical composition of recycled products under different process conditions, and Scanning electron microscope-Energy dispersive spectrometry （SEM-EDS） and a laser particle size analyzer were used to detect their morphology, particle size and elemental composition. The results showed that the removal efficiency of phosphorous was over 93% under all experimental conditions and the removal efficiency of ammonium was about 28%. The recovered products were mostly rod-like struvite crystals, while there were still a small amount of calcium phosphate （ Ca3 （ PO4 ） 2· xH2 O） and magnesium hydroxide （ Mg（OH） 2 ） in amorphous structure. The highest purity of recovered struvite was 87.72% and the average particle size of products was 110 p^m. The purity and the particle size of products were both related to the pH of reaction as well as the influent orthophosphate concentration. The pH of the reaction mixture rising from 8.5 ±0. 2 to 9.5 ±0. 2 resulted in the decrease of the purity and the particle size of struvite. When the orthophosphate concentration increased from 55.29 mg. L - 1 to 81.98 mg- L ~ , the purity of struvite was improved, while the particle size of struvite decreased.