| Phosphorus recovery from biogas slurry from livestock farms is an important way to solve the contradiction between phosphorus resource shortage and phosphorus pollution.The key factor affecting phosphorus recovery is the content of dissolved orthophosphate in biogas slurry.However,the content of dissolved orthophosphate in biogas slurry is less than 27%,the recovery rate of phosphorus directly recovered is not high,and the recovery is still far from meeting the requirements of standard discharge,which greatly restricts the recovery of phosphorus in biogas slurry.In order to solve this problem,the study takes biogas slurry as the research object.And on the basis of analyzing the form and content of phosphorus from the initial biogas slurry,using inorganic acid/ozone,organic acid/ozone,organic acid//ultrasonic/ozone treatment biogas slurry,in order to realize the biogas slurry is difficult to use state of phosphorus to easy solubility orthophosphate using state transformation,improve the dissolved orthophosphate content,thus improve the biogas slurry,the recovery rate of phosphorus.?1?The analysis of the form and content of phosphorus in the initial biogas slurry shows that dissolved orthophosphate accounts for less than 27%of total phosphorus and has great potential for improvement.The highest content in liquid phase was particulate phosphorus?PP?,which accounted for about 30%of total phosphorus.Soluble reduced phosphorus?RDP?refers to soluble phosphorus except Ortho-P,accounting for about 15%.Exchangeable phosphorus?Ex-P?chemical properties live wave,easy desorption and release potential,accounting for about 20%;The contents of aluminum bound phosphorus?Al-P?,iron bound phosphorus?Fe-P?,calcium bound phosphorus?Ca-P?and remaining phosphorus?Re-P?are low and not easy to transform,which have little effect on the improvement of Ortho-P content.The key to improve Ortho-P content is to start with PP,RDP and Ex-P.?2?The results of biogas slurry treatment with inorganic acid/ozone show that compared with nitrogen and air,ozone can reduce PP and Ex-P content to a greater extent,so as to greatly increase the content of dissolved positive phosphate.The initial pH value of biogas slurry was 6,the amount of ozone was 10 g·h-1,and the oxidation time was 60 min.After aeration,the Ortho-P concentration in biogas slurry increased by 76.12%,and the proportion of dissolved positive phosphate in total phosphorus increased by 20.75%.?3?The results of biogas slurry treatment with organic acid/ozone showed that the conversion of organic acid into biogas slurry was better than that of inorganic acid.The initial pH value was 5,and the Ortho-P concentration increased to 359.99%after 60min of ozonation,accounting for56.12%of the total phosphorus.The anion complexation of tartrate and acid solution of hydrogen ion play an important role in the transformation of phosphorus in biogas slurry.?4?Ultrasonic/organic acid/ozonated biogas slurry treatment test shows that ultrasonic/ozone coordinated treatment of biogas slurry,better than ultrasonic or ozone alone treatment effect;The concentration of Ortho-P increased by 381.15%at the initial pH value of 5,ozonation for 60min,and ultrasound for 360W and 10min,accounting for 58.83%of the total phosphorus.?5?The phosphorus recovery experiment shows that Ortho-P is the most useful phosphorus recovery in biogas slurry.The recovery of phosphorus in biogas slurry can be improved by ultrasonic/organic acid/ozone treatment. |
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