Study On Internal Circulation Degassing Anaerobic Reactor Quick Start-up And Gas Production Effect On Granular Sludge Settlement

At present,as researchers continuous studies in the field of sewage treatment,anaerobic biological treatment has gradually become a research hotspot because of its low operating cost,good biodegradability,and less residual sludge.However,anaerobic reactors often have problems such as long startup time,difficulty in forming granular sludge,and easy loss of sludge,which severely restrict the further application of anaerobic reactors.Therefore,this test trial-produces a new type of anaerobic reactor,and proposes a modification plan for the above-mentioned problems of the traditional anaerobic reactor,so that it has excellent mass transfer effect,can be quickly started,has degassing ability,and can effectively avoid sludge loss.In order to provide reference for actual engineering and research and development of new reactors.This is mainly divided into three parts.First,the internal circulation degassing anaerobic reactor was started up using fruit and vegetable wastewater as feed water to investigate the operation effect of the reactor;then the physical and chemical properties of the granular sludge in the reactor were explored.,Explore the influencing factors that affect its production and growth;finally use the mature granular sludge in the reactor to carry out the clear water column and nutrient column sedimentation test to explore the effect of gas production on the sedimentation performance of the granular sludge.The main test results and conclusions are as follows:(1)The test only took 22 days to complete the initial start-up.After the start-up,primary granular sludge appeared in the reactor,and the COD removal rate could be stabilized above 85%;it reached 11.4 kg COD/(m~3·d)on the 67th day.The design load,the various indicators of the reactor are good;the limit load of the reactor can reach15.8kg COD/(m~3·d),and the maximum gas production rate can reach 20L/d.It shows that the internal circulation degassing reactor has the advantages of fast start-up speed and strong impact resistance,and has completed the design goal.(2)The appearance of granular sludge changed significantly after domestication.As granular sludge gradually matured,the proportion of large and medium-sized granular sludge(particle size>1.5mm)increased significantly;the mechanical strength of granular sludge increased from 59%to 85%,indicating that the reactor is operating well;VSS reached 20mg/L at the end of the reactor operation,VSS/TSS=85%,indicating that the reactor can maintain a higher sludge concentration.(3)The nutrient column sedimentation test shows that gas production has a significant impact on the sedimentation rate of granular sludge with a particle size of1～2mm.The granular sludge with a particle diameter of 1.5～2mm is combined with the clear water column in the nutrient column.The maximum speed settlement difference is-27m/h.The reason for this phenomenon is that the lifting effect of the bubbles increases the resistance and buoyancy of the granular sludge when it sinks,and this effect is particularly obvious for the medium-sized granular sludge,so the reactor is equipped with a degassing system.It is very necessary to prevent the loss of granular sludge.