Research On Productive Experiment Of EBF Integrated Equipment For Rural Domestic Wastewater Treatment

With the development of rural economy,increasingly pollution caused by the disorderly emissions and increase of wastewater discharge.Due to the backwardness of rural infrastructure construction in China,there is short of imperfect wastewater collection system and wastewater treatment facilities,domestic wastewater discharged to surrounding rural areas finally results in pollution of nearby water sources,it has become a major factor for the eutrophication of lakes and the pollution of underground water.According to the particularity of rural sewage treatment,it is suggested to adopt miniaturization and highly-integrated equipment with high treatment efficiency,convenient operation and management and less energy consumption can meet the demands of the development of rural areas.The EBF integrated equipment developed from floating-media expanded-bed biological filter is found suitable for wastewater treatment in rural areas.It shows extraordinary performance in nitrogen and phosphorus removal with higher organic load,smaller floor space,higher automation level,and the ability to realize unattended operation.On the basis of EBF integrated equipment,the productive test is conducted to study start-up of the integrated equipment and analyzes backwash characteristics of filter tanks at various levels;the best operation condition is determined by the influence of water hydraulic loading,internal reflux ratio and gas water ratio on the effects of the equipment handling,through stable operation of the reactor under optimal working conditions,the analysis of the removal effect of COD_cr,NH₄⁺-N,TN and SS by EBF integrated equipment;study on its strengthening effect in removing nitrogen and phosphorus,and treatment effect of the equipment when it is applied to treatment of high ammonia and nitrogen wastewater at turnpike service zones.The equipment adopt two-stage continuous water inlet and natural biofilm formation.After 25 days of biofilm cultivation,the removal rate of COD_cr can reach more than 85%,the removal rate of NH₄⁺-N can reach above 90%,and the removal rate of TN can reach 55%.The change of water hydraulic load,reflux ratio and gas water ratio will affect the denitrification effect of the system,the removal efficiency of COD_cr,NH₄⁺-N,TN decreased with increasing water hydraulic load;when the reflux ratio is adjusted to 100%,the equipment shows the highest TN removal efficiency;the removal efficiency of COD_crr and TN increased with increasing gas water ratio at the beginning,and then decreased,and the outlet concentration of NH₄⁺-N will be continuously reduced;when the water hydraulic load is3m³/?m²·h?and gas water ratio is 4:1,together with reflux ratio is 100%,under this running condition,the removal rate for COD_cr,NH₄⁺-N,TN and SS could respectively achieve 86.4%,91.5%,57.8%and 95.2%.The primary anoxic filter tank is used the remove TN and COD_crr and the secondary aerobic filter tank is used to remove NH₄⁺-N.Applying the carbon source before the third stage denitrifying filter column,choosen sodium acetate as carbon source,at C/N=3.5,the concentration of the effluent TN met the emission standards at the national level A.Adding phosphorus removal agents in third stage anoxic filter,the running state of the system shows that when the AlCl₃ was 50mg/L,the removal efficiency of TP in the third stage filter could reach 84.6%and without much influence on removal efficiency of COD_cr and SS.When applied to treatment of high ammonia and nitrogen wastewater at turnpike service zones,the integrated equipment operates in a two-state A/O model,and adding sodium carbonate to supplement the alkalinity of aerobic zone.When the gas water ratio is 5:1,together with reflux ratio is 300%,under this running condition,the removal of COD_cr,NH₄⁺-N,TN and SS performed well,with the removal rate 86.8%,90.3%,63.9%and 86.4%,respectively.