Study On Hybrid Subsurface-flow Constructed Wetlands In The Fairy Town

Generally there are little flow and complex quality characteristics at sewagetreatment in China small towns.And its difficult for operation and management in thesearea.If use traditional sewage treatment process for small towns,there are high technicalrequirements, complex operation. Its economic and the management level limited, sodoes not suitable. The operation cost of ordinary wastewater treatment technology morethan Constructed wetlands technology, having clear advantage of beautiful landscapeand facility operation management, but there are also some disadvantages：need hugeground, easy jam harden, low dissolved oxygen and get season climate effectremarkable etc. Then existing of the shortcomings of the constructed wetland, designeda "VBFW/HSFW constructed wetlands" patent technology （patent number is200510057047.2ZL）, used in Sichuan, Yunnan and Chongqing, in which the western ofChina.This is a loading research of the technology in the field of fairy town. The researchstarted, using natural inoculation in ChongQing fairy town at October2010. Theactivity experiment start by natural flow not special method. After the completion of thestart, trying to ascertain the working regulation of the autumn，according to the designof the hydraulic loading. And then to ascertain the operating conditions of the winter,spring and summer gradually. The research indicate that the flow between320and1030m³·d^-1，the inflow of concentration of COD,ammonia-N, TN and Tp during29.5-58mg·L^-1,10^-33mg·L^-1,13.5-38.8mg·L^-1,0.7-2.8mg·L^-1respectively. Andaccording the working condition to operating， the outflow of concentration ofCOD,ammonia-N, TN and Tp during6.3-15.5mg· L^-1,2.8-9.8mg· L^-1,10.8-21.5mg· L^-1,0.3-0.9mg· L^-1， loading are77.5%,72.4%,40.1%,68.4%respectively.Indicates that removal of organics and ammonia-N has reach the first levelA criteria specified Discharge Standard of Pollutants for Municipal WastewaterTreatment Plant （GB18918-2002） The results from systems treating wastewatersclearly indicate that the outflow of TN and TP，reach the first level B criteria specifiedDischarge Standard of Pollutants for Municipal Wastewater Treatment Plant （GB18918-2002）.The loading rate of COD, ammonia-N, TN and Tp in VBFW constructed wetlandduring33.3%-54.5%，7.1%-37.5%，-1.1%-14.3%，-6.8%-56.3%respectively， when organic and hydraulic load were respective25-103.9×10^-3kg/（m²·d）,0.078-0.178m³/m²·h.Then research the HSFW constructed wetland indicate that theloading rate of COD,ammonia-N, TN and Tp during26%-44.6%，35%-61.9%，-22.9%-33.6%，14.7%-64.7%, additioning4.1-11.1×10^-3kg/（m²·d）of organic loadand0.0248-0.0417m³/m²·h hydraulic load.Removal of TN and TP are limited primaryby lack of dissolved oxygen in filtration beds and also caused by low temperature butnot strong.Research of dissolved oxygen indicated that the oxygen increment is1.65mg/L,when the current through to the complex oxygen channel at the distance of7m.Calamus is more suitable for this constructed wetland than reeds and wicks. HSFWconstructed wetland have jammed，after operated one year, recoveryed by vent, washand idle two weeks.At last, the expense of operation is1.07yun/m³in this system,but it’s about labour and asset depreciation cost mainly.