| The anaerobic ammonium oxidation(anammox) process is a promising alternative in biological nitrogen removal field with advantages of high-efficiency, cost-efficiency and environment friendly, and have tempting application prospect. But the anammox bacterium are very sensitive to temperature and this defect influence its practical application. This paper aimed to investigate the performance of moderate high-temperature(≥40 oC) anammox process, the effect of temperature shock to the mesophilic anammox process, and to summarize appropriate strategies of controlling salinity in the thermophilic anammox system. The main results in this study are as follows:(1) The mature mesophilic anammox granule was selected as inoculums to start the thermophilic anammox reactor with one-step heating mode, and unstable system was to revealed. The results of sequence batch reactor(SBR) test found the effluent NO2--N concentration was below 5 mg L-1, and removal efficiency of NH4+-N and NO2--N were 78.1 % and 98.8 %, respectively. A minimum temperature of inhibiting the specific anammox activity(SAA) was 45 oC, in this regard, when during the fourth cycle of SBR operational period, the effluent NO2--N concentration was below 91.6 mg L-1 which is near to the threshold value of NO2--N inhibiting. In the continuous flow trial at 40 oC, the addition of influent substrate concentrations and diminution of hydraulic retention time(HRT) were choosed to exploit the reactor proficiency. The phase of HRT diminution sustained 141 d, when the HRT was decreased from 12 h to 1.12 h, the nitrogen load rate(NLR) was increased from 1.08 kg m-3 d-1 to 11.7 kg m-3 d-1, nitrogen removal rate(NRR) was changed from 1.02 kg m-3 d-1 to 9.9 kg m-3 d-1 correspondingly. The modified Stover-Kincannon model and Second-order kinetic model were both appropriate to predict the nitrogen removal performance. Moreover, the trial of the substrate augment was not successful.(2) Based on one-factor shock of high-temperature, this research contents were including two- or three-factors shock of high-temperature, low-temperature, nitrogen load increasement. Comparised with the low-temperature shock, the high-temperature shock gave rise to a longer recovery time of reactor performance. The results was fond that when the reactor suffered with 55 oC shock, the maximum effluent NO2--N concentration was 182.8 mg L-1, inhibition time was 47.5 h, recovery time was approximate 10 d, and SAA was decreased from 163 mg N g-1VSS d-1 to 70 mg N g-1VSS d-1, which affected the reactor performance severely. After the long-time shock, the reactor performance was not bad when it was suffered with composite shock, and it was showed that the effect of composite shock was lower than one-factor shock. Moreover, extracellular polymeric substance(EPS) increased, and Heme c content was decreased during impact phase.(3) This study revealed the vital role of salinity to anammox bacterium(An AOB) thermotolerance. The aim of batch test was to analyze the short effect of salinity to the thermophilic anammox process. It is indicated that proper salt content could promote the SAA and the optimal value were 5 g L-1、8 g L-1Na Cl, which enhanced the SAA 76.6 %、77.5 % at 40 oC, 16.5 %、53.4 % at 47.5 oC. The result of pre-exposure time and endurance time test was shown that facilitation of salinity was dependent with the continuous supply of salt. The continuous flow test investigated the long-term effect by raising temperature gradually. Comparised with the control group, the SAA value was more bigger, settling property of sludge was more well, and EPS content was even more during the test group. However, Heme c content in the test group was less than the value of control group, and it was concluded that the SAA was non-corresponding with Heme c content. Furthermore, modified Arrhenius model was applied to account activation energy of thermophilic anammox, the value of R0 R1 were-41.5 kg mol-1 and-35 kg mol-1, respectively. |
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