臭氧氧化对奶牛场沼液中磷形态转化的影响

为了提高沼液磷的回收效果,研究了曝气种类和曝气条件对奶牛场沼液磷形态转化的影响。结果表明:在参考曝气条件下,与氮气和空气相比,臭氧能更大程度地降低颗粒态磷和交换态磷含量,并大幅度提升溶解性正磷酸盐含量。臭氧曝气的优选条件为沼液初始pH值为6、臭氧发生量为10 g·h~(-1)、氧化时间为60 min,曝气后沼液中溶解性正磷酸盐浓度提高了76.12%,溶解性正磷酸盐占总磷比例提升20.75%。臭氧氧化可以促进颗粒态磷和交换态磷向溶解性正磷酸盐转化,从而促进沼液磷的回收。

Effect of ozone oxidation on phosphorus speciation transformation in dairy biogas slurry

With the rapid development of large-scale livestock and poultry breeding, outputs of biogas slurry are increasing. However, most large-scale farms are located in the suburbs of cities, so it is difficult to find sufficient farmland to absorb the biogas slurry. Moreover, there is a large amount of phosphorus in biogas slurry, and its direct discharge may lead to eutrophication of water bodies. Phosphorus is an extremely scarce and non-renewable resource, and the recovery of phosphorus from biogas slurry can effectively alleviate the combined problems of phosphorus resource shortage and phosphorus pollution aggravation, which is closely related to the content of dissolved orthophosphate in biogas slurry. In order to increase the content of dissolved orthophosphate, phosphorus species and contents in biogas slurry from a dairy farm in Banan District, Chongqing, were determined. The effects of the initial pH of biogas slurry, aeration type, ozone amount, and oxidation time on the speciation transformation of phosphorus were studied. It was found that the ratio of dissolved orthophosphate to total phosphorus in the initial biogas slurry was 26.29%, and that of particulate and exchangeable phosphorus was 37.76%, indicating that particulate and exchangeable phosphorus have the potential to be transformed into dissolved orthophosphate. Compared with nitrogen and air, ozone oxidation could lead to larger decreases in particulate and exchangeable phosphorus contents and could greatly enhance the content of dissolved orthophosphate under reference aeration conditions. The optimal conditions for ozone aeration were also obtained; i.e., an initial pH of biogas slurry was 6, an ozone amount of 10 g·h^-1, and an oxidation time of 60 min. After ozone aeration, the concentration of dissolved orthophosphate in biogas slurry increased to 76.12%, and the ratio of dissolved orthophosphate to total phosphorus improved to 20.75%. Ozone oxidation can promote the transformation of particulate and exchangeable phosphorus into dissolved orthophosphate, thus promoting the recovery of phosphorus from biogas slurry.