Study On Strengthened Ecological Floating Bed For Advanced Treatment Of Effluents From Municipal Wastewater Treatment Plant

In order to improve the nitrogen?N?and phosphorus?P?removal performance of traditional ecological floating bed?EFB?for advanced treatment of effluent from urban wastewater treatment plants?WWTPs?with low C/N,the carbon source?CS?and reed biochar substrate?RBS?derived from reed straw powder were manufactured and introduced into EFB.In this study,the slow-release performance of CS and P adsorption mechanism of RBS were studied by static experiment and adsorption kinetics experiment,respectively.Based on pollutants removal efficiency and high-throughput sequencing,the mechanisms of CS and RBS in the process of advanced treatment of effluent from a WWTP by EFBs was clarified.The main conclusions were as follows:?1?The novel slow-release CS prepared with reed straw as the main raw material exhibited good carbon release performance,which could maintain a stable release rate of4.5 mg COD/g within 15 days.And,the release amounts of total nitrogen?TN?and total phosphorus?TP?from CS were extremely low,which would not damage the water quality.?2?The adsorption behavior of RBS fitted pseudo-second-order adsorption kinetic equation better?R2>0.99?,and the theoretical adsorption capacity calculated by pseudo-second-order adsorption kinetic equation was similar to the actual adsorption capacity obtained from the experiment,which further verified that chemical adsorption was the main mechanism for removing P in water by RBS.?3?The average TN removal efficiency of the EFB with the CS increased by about57.6%,and the removal efficiency of ammonia nitrogen?NH₄⁺-N?decreased slightly.The removal efficiency of COD gradually increased,which was eventually higher than that of EFB without CS.Besides,the TN concentration?1.06 mg/L?in the effluent of the EFB with CS could finally meet the level of Class IV in the Environmental Quality Standards for Surface Water in China?GB 3838-2002?.Besides,after the addition of RBS,the average removal efficiency of TP in the EFB increased by around 46.7%,and the concentration of TP?0.09 mg/L?in the effluent finally reached the level of Class?in the Environmental Quality Standards for Surface Water in China.?4?The results of high-throughput sequencing showed that adding RBS and CS significantly changed the microbial community structure and species diversity in EFBs.The relative abundances of genera involved in nitrification and denitrification such as Pseudomonas,Rhodobacter,Hydrogenophaga,Bradyrhizobium,Acinetobacter and Thiobacillus markedly increased in EFBs with RBS and CS.