Research On The Denitrification And Phosphorus Removal Efficiency And Bacterial Community Structure Of Water-supply Sludge-based Ceramsite Biological Filter

The"Water Pollution Prevention and Control Action Plan"issued by the State Council has raised the standard discharge of municipal tail water from sewage treatment plants.Therefore,sewage treatment plants urgently need to be upgraded to meet the new discharge standards.In this study,the deep denitrification and dephosphorization process werecoupled into a synchronous deep denitrification and dephosphorization process.The deep denitrification process uses the denitrification filter process,and the deep dephosphorization useed feedwater sludge with iron and aluminum salts.In this study,water supply sludge was used to prepare ceramsite,and the effect of ceramsite to remove PO₄^3--P and NO₃^--N was studied.Ceramsite was used as the main filler in the denitrification biological filter to study the removal efficiency of nitrogen and phosphorus and the distribution of the microbial community in the filter.And got the following conclusions:(1)In order to study the removal effect of water supply sludge-based ceramsite on PO₄^3--P and NO₃^--N,the preparation process was determined to be 15%kaolin dosage,sintering temperature and sintering time of 1150?10 min,respectively.The effect of adsorption temperature on the adsorption capacity of ceramsite was studied,and the results showed that the adsorption capacity of ceramsite to PO₄^3--P increased with the rose of adsorption temperature while the adsorption capacity of NO₃^--N decreased with the increase of adsorption temperature.The adsorption performance of ceramsite was fitted with adsorption kinetics and isothermal adsorption model.The fitting results showed that the adsorption of ceramsite to PO₄^3--P and NO₃^--N was more in line with the quasi-second-order kinetics and Langmuir isotherm model.(2)In order to study the denitrification and phosphorus removal efficiency of the ceramsite-based biofilter for water sludge,the operating parameters of the biofilter were optimized.The results indicated that the total nitrogen(TN)removal rate was 93.8%,the chemical oxygen demand(COD)removal rate was 59.0%,and the total phosphorus(TP)removal rate was 3.4%under the conditions of hydraulic retention time(HRT)at 0.5 h;In addition,the removal rate of TN and COD was 79.9%and 67.0%,respectively under the conditions that carbon-to-nitrogen ratio(C/N)is 2:1.the backflushing method was a combination of air washing and water washing,and the backwashing parameters were as follow:the air flushing intensity was controlled at s about 7?9 L/(m²·s),the water flushing intensity was maintained at 3.23 L/(m²·s),and the air washing for 10 min followed by the water washing for 5 min.(3)In order to study the effect of iron salt on the enhanced phosphorus removal of biological filters,an experiment of iron salt enhanced phosphorus removal was carried out.It iswas determined that the concentration of Fe³⁺added is 0.56 mg/L,and the TP concentration of effluent is about 0.30 mg/L,and it does not affect the denitrification and COD degradation efficiency of the filter.In order to study the microbial species and community changes in the filter,16S r DNA high-throughput sequencing technology was used,and the results showed that the relative abundance and diversity of microorganisms in the filter were stable.At the phylum level,Proteobacteria was the dominant flora while at the genus level,Brevundimonas is the dominant flora at the genus level,among which Desulfovibrio and Rhodobacteraceae are The bacterial flora for denitrification in the filter;Hyphomicrobium,Methylophilaceae,etc.are the bacterial flora that degrade COD in the filter.Micrococcaceae and Bosea are microorganisms that can produce siderophores,and can use the Fe³⁺added in the denitrification filter to meet the needs of microbial growth.