Reactor Design For Coking Wastewater And Study On Its Water Treatment Process

Coking wastewater is a kind of mixed wastewater collected from all stages of treatment process,which has the characteristics of high pollutant concentration,complex composition,poor toxic and harmful biodegradability,and difficult to treat.The existing pre-anaerobic processes such as A/O are used to treat coking wastewater,while the toxic substances in the anaerobic unit cannot be degraded quickly,which leads to the poor effect of the anaerobic process.Therefore,it is necessary to use multi-stage series or coupling other processes in engineering applications for coking wastewater treatment.By preaerobic process such as O/H/O in the treatment of coking wastewater,the primary aerobic pool will consume most of the organic matter(about 92%),then the carbon source is insufficient in the subsequent section of denitrification.The one of the operation mode is going beyond plus a denitrification treatment of reflux mode of operation,the cost of these process is very high.At the same time,aerobic pool also faces a big bubble,the problem such as "sludge".However,other combined processes and membrane processes are limited by operating conditions and water quality characteristics of coking wastewater,and can only be used as advanced treatment sections for engineering applications.Therefore,it is of great significance to explore a method that can avoid the toxic inhibition of coking wastewater,coupled with a variety of denitrification pathways,and make full use of the internal carbon source/electron donor’s carbon to development the self-purification biochemical pathways for denitrification and apply it to the actual wastewater treatment process,which can solve the treatment problem of coking wastewater.In this paper,a mixed fluidized bed reactor with a variety of dissolved oxygen environment gradient was designed based on the operation data and literature research results.Then,the flow field of the reactor was simulated and optimized by COMSOL 5.5 software.In order to strengthen the denitrification function of the reactor,a new lightweight ceramic material was prepared,which was both an electron donor and a biological carrier.The performance of the carrier was determined by various characterization methods.Then,the reactor and carrier were applied to the actual treatment process of coking wastewater.By comparing with the traditional fluidized bed,the denitrification and carbon removal performance of the reactor was analyzed.On the basis of the above work,the community structure and function of different regions in the mixed fluidized bed reactor were analyzed by16 S rDNA.Research shows that:(1)the reactor with water quality characteristics of coking wastewater,and dissolved oxygen flow field distribution are more uniform and reasonable,and out of the water pollutants degradation process in different areas of the hydraulic retention time is more conform to the law of biological treatment.Under the premise of without changing the stay time change residence time for different segments of the dissolved oxygen,the reactor can adapt to a variety of water quality and condition;(2)The new lightweight ceramic material prepared is a good microbial carrier,which has a short start-up time and a large amount of membrane in the treatment of coking wastewater.At the same time,it can provide electron donors for denitrification and promote the deep denitrification effect of the reactor.(3)The actual operation results show that the COD removal performance of the mixed fluidized bed is similar to that of the traditional aerobic fluidized bed,but the removal efficiency of total nitrogen and ammonium nitrogen has been greatly improved,which are93.1±2.7% and 84.6±1.8%,respectively.Mixed fluidized bed can effectively promote ammonification,nitrification and denitrification in the process of denitrification.(4)According to the analysis of microbial data,there are obvious differences in the structure and function of microbial community between traditional aerobic fluidized bed and mixed fluidized bed,and there are also great differences in the structure and function of microbial community between each dissolved oxygen interval of mixed fluidized bed sludge.The analysis showed that the main nitrification bacteria in the primary dissolved oxygen zone were Blastocatellaceae(1.1%relative abundance),Burkholderiaceae(1.27%)and Algoriphagus(2.79%).Planctomicrobium in the secondary oxygen-soluble region may be involved in the process of microbial apoptosis.Alteromonadales,Azospira,Desulfomicrobium may be the bacteria that carry out denitrification with low price iron and other elements as electron donors in the anaerobic and anoxic zone.