| Internal circulation anaerobic reactor,hereinafter referred to as IC reactor,is a kind of high efficient anaerobic bioreactor developed from up-flow anaerobic sludge bed UASB,it is considered to be the most representative of the third generation of anaerobic reactors.Water distribution system,heavy sludge discharge and reactor circulation system are regarded as Key structure in many components of IC reactor because of their significant effects on reactor's operating load and efficiency.The existing key structure mainly has problems like no-uniform of water distribution,dead zone,severe calcification of reactor and cannot discharge heavy sludge effectively,insufficient circulation,poor buffer ability and loss of biological sludge.Therefore,it is of theory and practical significance to the optimization researches of reactor's key structure to achieve long-term stable and efficient operation of IC reactor.(1)On basis of comparison and analysis of design idea,structure form,mixing mechanism at kinds of water distribution systems,combining with technologies of rotational flow water distribution and water distribution under big resistance,a set of reactor graded and multilayered rotational water flow distribution system is designed to improve the uniformity of water distribution,avoid water distribution dead zone.This makes the sludge bed in a fluidized state that can enhance mixture degree of waste water with granular sludge and finally effectively strengthened the mass transfer and reaction process.(2)A set of heavy sludge separation and discharge system is designed in reference with the theory of hydro cyclone slag after done some researches on heavy sludge formation mechanism.Also,a cylindrical sludge collected groove is installed at the bottom of this device so that heavy sludge can effectively be collected regularly and discharge timely.(3)Optimize circulation system hydraulic conditions of IC reactor on basis of expanded granular sludge bed and Solid fluidization technology main ideas.Thus a set of standpipe is added,which is designed specially in function on basis that overflow outlet from the top and recirculation water with sludge at the bottom.In this way,the external loop system of IC reactor is formed.Thus,the liquid level rising velocity can be improved and make its stability at high load range 5~8m/h,concentration of granular sludge in effluent is 5ml/L or less,mixing degree of the matrix and stable operation ability of the reactor are guaranteed.(4)In order to detect the uniformity of water distribution,heavy sludge discharge result,flow pattern and mass transfer effect,COD removal rate and operational stability,here built a test reactor in laboratory scale on basis of main optimization ideas on key structure.Operation state shows that uniformity of water distribution are significantly improved,no dead zone exist,separation and discharge of heavy sludge from reactor are successful,reactor matrix between mass transfer is obvious.When considering to comprehensive evaluation system index of reactor operation,it achieved 80% of COD removal rate,0.2kgCOD/(kgVSS·d)of Sludge loading,30kgCOD/(m~3·d)of volume loading,around 5mmol/L in effluent VFA,All indicating that reactor running in good condition.Finally,this article provides an engineering rebuilt and application project for an old structure type IC reactor in which new structure after optimization is the first adopted in China.The operation data and infrared thermal imaging detection showing that the updated rebuilt achieved expected effect.Uniformity of water distribution was improved,pre-existing calcification and heavy sludge discharge problems were solved,obtained the uniform temperature field more than 90%,mass transfer effect is better,reactor operation are stable and efficient,COD removal rate increased by 10 percentages compared with original design value.Hence this provides a new reference on the research,Optimization and application for IC anaerobic reactor. |
PDF Full Text Request