Experimental Investigation On Sludge Disruption For Organics Release In AOH Process Using A Hydrocyclone And Its Industrial Application

Activated sludge process,exactly presented 100 years ago is still at the heart of current sewage treatment technology in the world and was difficult to treat the bio-refractory industrial wastewater with high concentration accompanying with large volume of generated surplus activated sludge.Aiming at the refinery wastewater in 2.28 million tons per year refinery units in Sinopec Zhenhai Refining&Chemical Company,the relationship between hydrocyclone turbulence,sludge floc movement,soluble COD and quinloine was investigated by comutation fluid mechanics(CFD),three-dimensional synchronous high-speed motion analyzer(S-HSMA),scanning electron microscope(SEM),laser light scattering(LLS)and three-dimensional excitation emission matrix fluorescence spectrophotometer(3D-EEM).The improved anoxic-aerobic-hydrocyclone process(AOH)and large-scale hydrocyclones were developed for the improvement of 100m~3/h A/O reactor.All the conclusions and progresses was showed as follow.(1)A ?35 mm and ?25 mm hydrocyclone was developed for sludge disruption.The sludge flocs movement in ?35 mm,as well as the relationship between sludge flocs and wastewater were measured by S-HSMA and simulated by FLUENT.The simulated sludge floc exhibited high speed self rotation with maximal speed of 1550 rad/s out of the hydrocyclone free vortex and forced vortex.The organic compounds were desorbed from the porous activated sludge flocs,which caused to the decrease of sludge floc median diameter from 78.8?m to 15.8-23.3?m.The ratio of SCOD to TN in mixed liquid recirculation(MLR)was increased from 2.96 to 4.7-5.8 and the specific oxygen ultilization rate(SOUR)was enhanced by 7.2 ±0.9%.The microbial activity involved in denitrification,including of NAR and NIR,was increased by 15.1%and 17.6%.respectively.CFD results showed that the velocity profiles fitted the conventional curves in ?35 mm hydrocyclone.The pressure on axial section decreased from the wall to the central,which subsequently led to the dissolved oxygen(DO)from the wastewater.Maximal DO removal efficiency reached 61.8%by hydrocyclone with the optimal operation parameters.(2)A 50 L/h AOH reactor,2 L/h A~2OH reactor and sludge disintegration apparatus were built to measure its sludge disruption efficiency and the other accompanied characteristics.An exhaustive investigation on treated activated sludge and A/O effluents was conducted in batch and continuous operation tests.The A/O process operated in the mode of hydrocyclone-treated MLR,compared with in the conventional mode,resulted in a 15.6%higher TN removal,and the other effluent parameters remained stable.Effect of hydrocyclone disruption on the bioadsorption and biodegradability of quinoline was further investigated based on the configuration and microstructure measurement.Microscope and SEM results showed that the updated floc interfaces and cleaned floc channels,which benefited to the mass transfer and adsorption of compounds.LLS and 3D-EEM further demonstrated that the expended EPS configuration and looser structure,which was favored for pollution capture in sludge.The adsorption rate of COD and quinoline was significantly improved which was in according with the configuration and microstructure measurement.The A~2OH process received 32.7%more quinolone adsorption and 17.0%decrease of quinoline in effluent from synthesis degassing wastewater relative to the A~2O process.Hydrocyclone was innovatively used to disintegrate the surplus activated sludge followed by anaerobic digestion,which was assessed by SCOD solubilization,methane production and economic analysis.Combined hydrocyclone pretreatment,which lasted 80 minutes,included hydrocyclone treatment throughout and alkaline treatment from 50th min to 80th min and involves sludge disruption and subsequent microorganism cell destruction,resulted in 3689 mg/L soluble chemical oxygen demand(SCOD)release.The optimal combined pretreated sludge also exhibited VFA accumulation of 639 mg/L and 134.3 mL CH4/gTS methane production.The optimal combined sludge pretreatment,with net costs of ?341.2 per ton of TS,is assessed to be a cost-effective process.(3)A ?100 mm hydrocyclone was developed according to the equal proportion enlargement of?035 mm hydrocyclone.The ?100 mm hydrocyclone,with optimal capacity of 11.7 m~3/h,showed 107.2%increase of SCOD,9.3%increase of SOUR and 44.0%less residual DO in pilot-scale experiments,which caused to 11.7%more nitrate removal efficiency.The AOH process was developed for the improvement of 100 m~3/h A/O reactor in Sinopec Zhenhai Refining&Chemical Company.The improved A/O reactor achieved stability after acclimatization for 4.5 month.With hydrocyclone pressure drop of 0.043 MPa,the AOH process received 19.7 mg/L less COD and 11.4%higher TN removal efficiency relative to the A/O process,which met the GB31570-2015.