Studies On Rapid Start-up Of UASB Reactor And Performance Optimization Of Modified Version Of UASB

Energy crisis and Environmental pollution are two major obstacles towards sustainable development.With the idea of Ecological Civilization Construction of "Lucid waters and lush mountains are invaluable assets" was arisen in the 19th National Congress of the Communist Party of China,more and more attention has been paid to cleaner production;Moreover,the treatment Technology on wastewater develop rapidly with the publication of ten-measure action plan to tackle water pollution.Upflow Anaerobic Sludge Blanket(UASB)is a biological treatment of wastewater,can not only remove organic matter,but also recovery clean non-polluting,renewable bio-hydrogen energy,to achieve the renewable use of wastewater.In this paper,a biofilm UASB coupling hydrogen production anaerobic system was constructed in the traditional UASB reactor,which is embedded with fiber filler in the suspended sludge layer.The start-up of the modified UASB and the traditional UASB reactor was compared.At the same start-up,the two reactors are activated at a low load of 2 kg/(m3.d)with a low influent concentration of 2000 mg/L.The start-up of two reactors was successfully completed by reducing the volumetric load of HRT with the hydraulic residence time.In order to optimize the operation performance of the coupled system and select reasonable operation parameters,the experiment of increasing load,stabilizing operation and external circulation reflux was carried out.The removal of hydrogen organics and other operating characteristics of the reactor were investigated by increasing the load and stable operation stage.The hydraulic retention time(HRT=6h)remained unchanged,and the influent COD concentration increased from 4000mg/L to 8000mg/L.The hydrogen production,organic matter removal and other operation characteristics reflux could increase the system.The effects of different reflux ratios(R=0,1,2,3)on the operational efficiency was also discussed.The main results are presented as follow:(1)Under the same starting conditions,the volume load of influent COD is 9 kg/(m3.d),HRT is 6 h,the time of the successful start-up of the modified UASB reactor is shorter than that of the traditional UASB reactor,and the modified UASB is activated in 23 d,and the COD removal rate is up to 82%at start-up.The pH value of effluent was stable in 4.8-6.0,ORP lower than-425mV,and the intermediate metabolites in the reactor were degraded by ethanol fermentation,and the microbial community with relatively complete structure was formed in the system.(2)The maximum volumetric load that the modified UASB reactor can withstand is 21 kg/(m3.d),the maximum COD removal rate is 91.5%under the maximum organic load,the maximum yield of hydrogen is 2.27 L/d,the maximum content is 59.3%,the system always keeps ethanol-type leaven,The pH value decreased to 4.2-4.3.It is indicated that increasing the influent COD concentration can increase the volume load of the reactor,improve the utilization rate of the equipment,increase the mass transfer efficiency and promote the formation of a stable anaerobic system.But the high volume load will destroy the stability of the system.(3)To study the effect of different reflux ratios on the performance of the reactor,the results show that the maximum COD removal rate of the reactor is 91.89%,hydrogen can produce 3 L,the highest content is 62.99%,the effluent pH value is stable between 4.1-4.3 and the VFA concentration is not more than 200 mg/L.But the advantages of reflux are not significant in the system.