Efficiency And Mechanism Of Simultaneous Coupling Ozonation And Biodegradation Technology For Coking Wastewater

Coking wastewater,a typical high toxicity organic wastewater is complex and difficult to degrade.At present,traditional biological treatment is widely used in coking wastewater,but there are some problems like long residence time and persistent organic residue.Although advanced oxidation technology has significant advantages in the treatment of refractory organic matter,it is limited by water conditions and has low mineralization rate.Advanced oxidation-biodegradation near-field coupling technology is a new water treatment technology in recent years.Under the mediation of porous carrier,the biodegradable intermediate product produced by the advanced oxidation reaction on the surface of the carrier is directly degraded or even mineralized by the biofilm inside the carrier,which significantly improves the efficiency of deep mineralization and toxicity reduction of the target wastewater.This study took the lead in constructing ozone oxidation-biodegradation near-field coupling reactor(STOB),studied its behavior and mechanism of treating raw water of actual coking wastewater,clarified the optimization interval of key operating parameters,and proved the degradation mechanism of coking wastewater.It lays an important theoretical foundation for the practical application of STOB technology.First,ozone dose is a key parameter to determine the advanced oxidation efficiency and biological activity maintenance.Compared with other ozone doses,the biomass of the STOB system at 30 mg·(L·h)^-1 was stable with the best bioactivity,the removal of COD with 12 h in STOB was 53%and 27%higher than that of single biological system(B)and single O₃ oxidation system(O₃),total phenol removal was62%and 20%higher,the chroma removal rate could reach 75%.The removal rates of sulfides and cyanide was 72%and 35%respectively,the luminescence inhibition rate of 12 h effluent for Vibrio Qinghaiensis sp.Q67(Q67)decreased by 75%.The results of intermediate product analysis show that,-C=C-double bond substances were removed,blue shift of functional groups such as-C=C-?-C=O,C-H vibrational levels of quinoline,pyridine,benzene and benzene substituents decrease.Molecular weight analysis found that,organic matter greater than 16 KDa is degraded to 10 KDa-15 KDa,even below 1 KDa,the final residue leaves the residue that could not continue to degrade.Secondly,during the biological succession of the STOB system,the Chao1 index and the ACE index increased significantly,and the microbial community abundance and diversity increased.The dominant flora of the STOB system was composed of Comamonas?Truepera?Thauera?Thiobacillus,with an average abundance of 19.3%,14.2%,10.2%and 5.7%,respectively.Meanwhile,there were significant differences in habitat conditions at different locations in porous sponge microspace,the composition of dominant flora was similar,but the proportion of aerobic organisms like Paracoccus decreased significantly at the center of the carrier.The difference of surface and internal microbial species indicated that STOB carrier structure specificity made unit carrier biodiversity and revealed the key role of biodegradation in STOB system.This study discussed the application of STOB system in the field of high concentration coking wastewater treatment,optimizes the optimal ozone dose of STOB system,and analyzes the degradation mechanism and biological response mechanism of coking wastewater in STOB system.It is found that biology plays a key role in coking wastewater treatment and lays a theoretical foundation for the treatment of practical industrial wastewater by STOB system.