| In this paper,modified constructed rapid infiltration systems were constructed to study the treatment effect and removal mechanism of phosphorus-containing wastewater.The phosphorus removal effect of phosphorus-containing wastewater prepared with different phosphorus sources in the constructed rapid infiltration system with different fillers was investigated.The removal mechanism of organophosphorus and inorganic phosphorus in the modified constructed rapid infiltration system was analyzed through high throughput and enzyme analysis.Taking the actual wastewater from tofu production as the object,this paper studied the effect of a constructed rapid infiltration system on the removal of main pollutants in the wastewater from tofu production,analyzed the transformation path of phosphorus in the influent stage and the drying stage,and studied the treatment mechanism of modified constructed rapid infiltration system on the wastewater from the perspective of enzymology and microecology.The conclusion is as follows:（1）In the study on filler selection of the modified constructed rapid infiltration system,the adsorption capacity of biochar on COD and NH4+-N is greater than that of calcium carbonate powder,calcium carbonate particles,and river sand,and calcium carbonate powder has the best adsorption effect on TP.（2）Biochar and calcium carbonate powder were used as fillers to construct rapid infiltration columns（C column and G column）to treat wastewater from different phosphorus sources.The COD removal effect of C column is due to that of G column.The TP removal effect of G column on organic phosphorus source wastewater is better than that of C column,and the TP removal effect on inorganic phosphorus source wastewater is not significantly different.The biochemical degradation of COD and the conversion of organic phosphorus to inorganic phosphorus in wastewater are mainly carried out in the upper layer of the filler.Phosphorus is removed by reacting with Ca,Fe,Al,and other elements contained in the filler to become solidified phosphorus.Solidified phosphorus removal includes Ca HPO4,iron-aluminum-bound phosphorus,slow-acting calcium-bound phosphorus,etc.The curing rate of P in G column was higher than that in the C column,and the curing P content of each column showed a downward trend.There were gasification phosphorus removal methods in column C and column G,and the instantaneous concentrations of phosphine detected in the upper fillers of column G and column C were 0.28 mg/m3 and 0.11 mg/m3,respectively.（3）In the study of the effect of modified constructed rapid infiltration systems in the treatment of tofu production wastewater,the average removal rates of COD,TP,and NH4+-N in column F（biochar and calcium carbonate mixture）were 97%,99.8%,and99.2%,respectively,when the hydraulic load was 0.11 m3/（m2·d）.When the hydraulic load is increased to 0.21 m3/（m2·d）,the average removal rates of COD,TP,and NH4+-N of the F column are 97.35%,98.75%,and 99.7%.The concentration ratio of pollutants removed by the sampling port of column F1#is higher than that of other sampling ports,and the removal of pollutants is mainly carried out in the upper packing.The curing treatment of phosphorus in the system is mainly carried out in the upper layer.The system’s phosphorus forms are mainly calcium-bound phosphorus and iron-aluminum-bound phosphorus.There is a gasification way to remove phosphorus in the percolation system,and the maximum concentration of PH3 in the system is 0.4 mg/m3.（4）The enzyme activity of the packing related to phosphorus treatment showed that the activities of NADH enzyme,alkaline phospholipase,and dehydrogenase in the upper,middle,and lower layers of the packing in column C and column G were all higher than those in the original packing,and the activities of the three enzymes in the upper packing were significantly higher than those in the middle and lower layers.In the system,the enzyme activities of alkaline phosphatase and acid phosphatase in the upper layer of the filler were significantly higher under the condition of an organophosphorus source than that under the condition of an inorganic phosphorus source,and their activities were related to the concentration of organic phosphate.The mineralization of organic phosphate was mainly carried out in the upper layer of the filler,and the higher alkaline phosphatase and acid phosphatase in the upper layer of the filler participated in the mineralization of organic phosphate in the process of percolation.In the process of tofu production wastewater treatment,the activities of NADH enzyme,acid phosphatase,alkaline phosphatase,and dehydrogenase in the upper packing of the F column were higher than those in other packing layers.The four enzymes decreased from top to bottom in the system.Compared with the original packing layers,the activity of NADH enzyme,alkaline phosphatase,and dehydrogenase was improved.After a stable operation,the activity of alkaline phosphatase and acid phosphatase in the packing material increased,indicating that the conversion trend of organophosphorus to inorganic phosphorus in the fast-infiltration process was accelerated,which was also conducive to the production of PH3.The trend of the activity of the four enzymes in the F column was basically consistent with the trend in the C column and the G column.（5）High throughput sequencing was used to study the microecology of the fillers after the treatment of organophosphorus and inorganic phosphorus wastewater by C-column and G-column.A total of 17 phyla,42 orders,and 78 genera were detected in the samples.The main dominant bacteria groups are Proteobacteria,Bacteroidetes,and Candidatus＿Saccharibacteria.The dominant bacteria order were Sphingomonadales,Rhodobacterales,Burkholderiales,and Enterobacteriales.At the genus level,the dominant bacteria were Aeromicrobium,Pseudomonas,Sphingomonas,etc.Under the condition of inorganic phosphorus,the main phosphorus accumulation bacteria were Acinetobacter,Decloromonas,Pseudomonas,Subdivision3＿genera＿incertae＿sedis,Taueria,and so on.Under the condition of organophosphorus,the main phosphorus-accumulating bacteria are Acinetobacter,Bacillus,Pseudomonas,Arthrobacter,and so on.Sphingomonas,Terrimonas,and Aeromicrobium can play a good role in the mineralization of organophosphorus.The relative abundance of Sphingomonas and Terrimonas all increased significantly under organophosphorus conditions,while Aeromicrobium had a high abundance under organophosphorus sources,but was not detected under inorganic phosphorus sources.Azotobacter,Clostridium＿sensu＿stricto,and unclassified＿Enterobacteriaceae are associated with the generation of PH3,Under organophosphorus conditions,the relative abundance of Azotobacter and unclassified＿Enterobacteriaceae obviously decreases,and under the condition of the organic phosphorus as the phosphorus source is not conducive to the generation of PH3.The results of high-throughput sequencing showed that the microbial communities on the filler of treated tofu production wastewater were divided into 16 bacteria,41bacteriales and 79 genera.The main dominant bacteria are Proteobacteria,Acidobacteria,Actinobacteria and Firmicutes.On order level,Actinomycetales,Bacillales and Burkholderiales were the dominant bacteriales.The dominant bacteria genera were Sphingomonas,Arthrobacter and Acinetobacter,etc.At the genus level,the main bacteria related to COD degradation were Saccharibacteria＿incertae＿sedi,Terrimonas and Sphingomonas.Armatimonadetes＿gp5,cupriavidus and Pirellula were the key bacterial groups for nitrogen treatment in the system.The bacteria related to phosphorus treatment are Acinetobacter,Pseudomonas,Arthrobacter and Plexomonas.Azotobacter,Clostridium＿sensu＿stricto,unclassified＿Enterobacteriaceae mainly related with the PH3,has a higher abundance in the system,the system has a potential of PH3.The key bacteria groups of phosphorus treatment in column F were basically the same as those in column C and column G. |
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