Study On The Key Technology And Mechanism Of Oil Sludge Wastewater Treatment By Biological Method

With the large-scale exploitation of oil,a large amount of waste oil sludge is produced,and the oil sludge contain a large amount of crude oil.Collecting and recovering the waste oil sludge are the effective way for the recovery of oil resource,but the oil sludge wastewater will be generated in the process,which contains chemicals additive,toxic and hazardous substances in the soil,and a large amount of chemicals and difficult-to-separable fine-grained components added during the recovery of the oil,and these components increased the difficulty of the purification of the wastewater greatly.The keys of oil sludge wastewater treatment were discussed through the laboratory's study and the trial operation of the pilot plant,and the laboratory's study includes two parts:the treatment of oil sludge waste water by biofilm method and by sequential batch activated sludge process(SBR).At the same time,the acclimation mechanism of microorganism in the reaction system was studied by high-throughput sequencing technology,and the GC-MS analysis technology were used to study the degradation mechanism of organic pollutants in wastewater.The main results were described as follows:(1)The treatment of coagulated oil sludge wastewater by anaerobic-aerobic biofilter,which was inoculated with the active sludge from on-site pilot plant,oyster shell and ceramsite were used as filter meterials in this research.The result showed that oyster shell biofilter is superior to ceramsite biofilter in terms of stability and treatment effect.When the influent COD is about 1042 mg/L and HRT of biofilter is 168 h,the total removal of COD,NH3-N and TOC were about 71%,89%and 70%for oyster shell biofilter.The COD removal of anaerobic part of oyster shell biofilter and ceramsite biofilter were 33%-41%.The results indicated that the anaerobic biofilter have a good performance on the removal of COD.(2)The results of the treatment of oil sludge wastewater by SBR reactor showed that at low temperature,when the dosage of glucose in the reactor was 100 mg/L,HRT was 10 d,the dosage of influent was 1 L/d.and the influent COD and ammonia nitrogen were 420.7-597.8 mg/L and 6.8-12.9 mg/L,respectively,the SBR reactor can perform stably on the 12 d and continue to day 30.The removal of COD and ammonia nitrogen were 28%and 51%,respectively.It can be seen that the SBR reactor perform badly on the COD and ammonia nitrogen removal at lower temperature.The reactor stopped to add glucose after 35 d,the influent COD and ammonia nitrogen values were 418.1-491.8 mg/L and 8.5-20.4 mg/L,respectively,and the COD removal rate of the reactor is about 10%,the removal rate of ammonia nitrogen was 0-25%.It can be speculated that that the microorganisms use the glucose as carbon sources,aided by organic components in the wastewater.(3)There were several kinds of functional microbial were detected in the sludge samples of anaerobic-aerobic biological filter before and after acclimation,such as Thauera,Exiguobacterium,Sphingobium herbicidovorans,Trichococcus,Hyphomicrobium,Anaerolineaceae and so on.Exiguobacterium play a key role in the degradation of environmental pollutants.Thauera have a function of denitrification.Sphingobium herbicidovorans can degrade herbicide.Trichoococcus can degrade phenol.Hyphomicrobium can remove NH3-N.Anaerolineaceae can degrade alkanes.The abundance of Trichococcus,Desulfobacter postgatei-2ac9,Anaerolineaceae increased after anaerobic acclimation of oyster shell biofilter and ceremsite biofilter.The abundance of Exiguobacterium increased after anaerobic acclimation of oyster shell biofilter,but decreased after anaerobic acclimation of ceremsite biofilter.The abundance of Hyphomicrobium decreased after anaerobic acclimation of oyster shell biofilter and ceremsite biofilter.The abundance of Trichococcus,Sphingomonas herbicidovorans,Thiothrix-caldifontis,Thauera increased after aerobic acclimation of oyster shell biofilter and ceremsite biofilter.The abundance of Exiguobacterium increased after aerobic acclimation of ceremsite biofilter,but decreased after aerobic acclimation of oyster shell biofilter.The results showed that biofilter acclimation would help the enrichment of functional bacteria.(4)The different influent loads have significant influence on the the bacterial community richness and diversity of SBR reactor at low temperature,but few on the Archaea community.Some functional bacteria can resist the low temperature and grow,but the abundance of some genus like Exiguobacterium,Simplicispira and Trichococcus decreased for the low temperature.It is indicated that the decrease of the abundance of Exiguobacterium,Simplicispira and Trichococcus result in the bad performance of NH3-N removal.(5)The seed sludge of the pilot plant was took from the aerobic tank of Daqing chemical wastewater treatment plant,and treating the oil sludge waste water aid by the fermented flour.The results showed that the aerobic tank of pilot plant can perform normally at long hydraulic retention time(30-150 d).The pilot plant can perform normally after 100 d,and the MLSS of aerobic tank is about 2500 mg/L in the late period.The COD concentration in the effluent of the second settling tank of the pilot plant is about 145.0-382.6 mg/L,failed to meet the allowable emission limit of the national secondary discharge standard.The pH and NH3-N of the effluent were about 7.5 and 1.5-2.5 mg/L,can meet the allowable emission limits of the national second-class emission standards.