Research On The Inhibition And Mechanism Of Chiloroteracyline On Completely Autotrophic Nitrogen-removal Over Nitrite

CANON(completely autotrophic nitrogen removal over nitrite) is a novel biological denitrification process, which can save2/3of the oxygen and all the organic carbon source, compared with the traditional process. Therefore it has broad development prospects. However, due to the anaerobic ammonia oxidation bacteria are sensitive to outside environment, such as substrate, heavy metal, non-toxic or toxic organic matters can become inhibition factors. Due to the residual antibiotic in antibiotic wastewater containing would inhibits the CANON process functional microorganism, hampered the CANON process in the application of antibiotic wastewater denitrification treatment. This topic centers on researching on chlorotetracycline (CTC)’s inhibition on intricate film activated sludge (IFAS)-CANON reactor, and functional microorganism’s response concentration and the changes of community diversity. The main results are as follows:(1)Started up a CANON reactor. Different forms of seed sludge were inoculated, the optimized operating conditions were used, the temperature was controlled at32±1℃, DO0.1-0.4mg/L, pH8.2-8.4, which effectively limited the ammonia nitrogen conversion rate of AOB, and raised the ammonia nitrogen conversion rate of ANAMMOX bacteria. After67days, total nitrogen removal rate had reached0.69kg N/(m3·d), and total nitrogen removal rate had reached80.7%, the reactor had realized the CANON performance stability.(2) Batch experiment was conducted to study the short-term inhibition effects on CANON functional microorganism. Within20mg/L CTC, it had almost no inhibition after12h, but within800mg/LCTC, total activity of functional microorganism was lost after12h. Under the same concentration of chlortetracycline, the shorter exposure time, the lower inhibition degree of functional microorganism. In this experiment, the half inhibition concentration of CTC was870.79mg/L,498.24mg/L,324.47mg/L,278.91mg/L with the exposure time of2h,4h,8h,12h.(3) Long-term inhibition of CANON reactor was studied. The influent included60mg/L CTC, the reactor is not obvious inhibits at the first10days, but the reactor performance was rapidly deteriorated, total nitrogen removal rate in16days reactor by62.7%. Low concentration CTC cannot restore the reactor performance. However, AOB bacteria could restore its activity in the presence of20mg/L CTC, easy to cause excessive accumulation of NO2-in effluent. To further reduce the aureomycin concentration in the water to0mg/L, the reactor performance was still not recovered. After long-term inhibition, the recovery strategies was discussed, through regulating the inhibitor concentration, the substrate load, the DO concentration and sludge seeding. After54days recovery, the reactor total nitrogen removal rate recovered to0.12kg N/(m3·d).(4)During the long-term inhibition, CANON reactor functional microorganism’s bacteria morphology and abundance was studied. Scanning electron microscope (SEM) results showed that the main morphology of microorganism in biofilm was ball, the main morphology of microorganism in particles was ball, spiral, and short rod,and the main morphology of microorganism of the floe was spiral and short rod when the CANON reactor’s performance was stable. After long-term inhibition, the phenomenon of the cell membrane rupture was observed in all three form sludge. Real-time fluorescent quantitative PCR method was used for the major functional microorganisms-AOB and ANAMMOX bacteria, and found that the ANAMMOX bacteria mainly exists in granular sludge and biological membrane, while the relative abundance in the floc sludge is low; In the process of CANON reactor from start to stable, the relative abundance of ANAMMOX bacteria in granular sludge and biological membrane was increased, and the relative abundance of AOB in the floc sludge significantly was increased; during and after chlortetracycline inhibition, the relative abundance of ANAMMOX of granular sludge and biofilm was reduced, the relative abundance of the AOB of floc sludge was reduced as well.