| "Sustainable development"and"energy saving and emission reduction"are the guiding thought and important principle for the study and development of wastewater treatment technique, nowadays. The following contents were studyed by integrating of EGSB reactor technique and BAF reactor technique, batch experiment, molecule biology determination, theoretic argumentation and the research of model: the kinetic characteristics, mechanism and influencing factors of anaerobic ammonium oxidation, methanogenesis and denitrification; ammonia oxidation characteristics and kinetics of ammonia oxidizer mixed culture under the conditions of O2 and trace NO2 mixed gasses; the characteristics of integration with EGSB reactor technique and BAF reactor technique for wastewater treatment. It provided important and scientific data conveniently for developing this technique with integration of the aerobic ammonium oxidation, anaerobic ammonium oxidation, methanogensis and denitrification, which could be of capability to save energy and organic substances requirements under the conditions of simultaneous removal of COD and ammonium at high loadings. The results were given as follows:①Granular sludge was formed in two EGSB reactors inoculated with aerobic activated sludge and anaerobic activated sludge after the start-up operation of 120d and 60d,respectively. The effluent COD concentration about 40 mg/L and COD removal efficiency up to 80% were obtained with the influent flux 10 mL/min, inner recycle flux 180 mL/min, COD concentration 180 mg/L, the organic loading rate up to 1.728 kgCOD/(m3.d) and the sludge loading rate 0.19 kgCOD/(kgMLSS.d). The temperature was controlled between 32℃and 35℃, pH at 6.8～7.2, redox potential below -340mV, HRT 4.2h, the up-velocity 4.86m/h and the flocculant (aluminium potassium sulfate) 80mg/L. The formation of the granular sludge was accelerated. Results demonstrated that up-velocity,flocculant and the type of sludge affected the formation of granular sludge.The start-up of the reactor which was inoculated with aerobic sludge was succeeded if the loading rate was controlled rationally in low strength COD.②Anaerobic ammonium oxidation, methanogensis and denitrification were integrated after 240 d with adding nitrite and ammonium in EGSB reactor. The pH was controlled between 7.5 and 8.3, redox potential at -40 mV～-150 mV and temperature at 32℃～35℃in the reactor;HRT and the up-velocity were controlled as same as start-up. The organic loading rate (OLR) was 4.8 kgCOD/(m3.d) and 2.88 kgCOD/(m3.d), the sludge loading rate (SLR) was 0.55 kgCOD/(kgMLSS.d) and 0.33 kgCOD/(kgMLSS.d), COD removal efficiency was 85% and 76%, the ammonium nitrogen removal efficiency was 35% and 20%,the nitrite nitrogen was both 99.9% and the total nitrogen was 67% and 59% in EGSB1# and EGSB2#, respectively. Results demonstrated that pH, temperature, DO, redox potential, nitrite and COD affected the integration of anaerobic ammonium oxidation bacteria, Methanogenesis bacteria and denitrification bacteria and the characteristic of granular sludge in EGSB reactor.③The anaerobic ammonium oxidation activity about 9.84×10-4 mg NH4+-N/(mgMLSS.h) or 12.9×10-4 mgNO<sup>2-N/(mgMLSS.h) was obtained by measuring the simultaneous consumption of ammonium and nitrite under anoxic conditions. A new anammox bacterial species, denominated as anaerobic ammonium-oxidizing Planctomycete cquenviron-1, was discovered by 16S-rRNA based molecule biology determination.④The kinetic characteristics of anaerobic ammonium oxidation,methanogenesis and denitrification inoculated with the granular sludge from EGSB reactor, in which anaerobic ammonium oxidation, methanogenesis and denitrification were integrated, were investigated by batch experiment,respectively. The kinetic parameters of anaerobic ammonium oxidation were determined, where the maximum anaerobic ammonium oxidation rate was 6.65×10-3 mg NH+4-N/(mgMLSS.h), the half saturate coefficient of ammonium nitrogen and nitrite nitrogen were 87.1 mg/L and 15.39 mg/L,respectively;inhibition coefficient of ammonium nitrogen and nitrite nitrogen were 1123 mg/L and 159.5 mg/L,respectively.The kinetic parameters of methanogenesis were determined, where the maximum specific degradation rate, half saturation constant and yield coefficient were 0.158 mgCOD/(mgVSS·h), 464 mgCOD/L and 0.254 mL CH4/mgCOD respectively. The kinetic parameters of denitrification were determined, where the maximum denitrification rate, half saturation constant of NO-2-N and COD were 0.0069 mg NO2--N/(mgMLSS.h), 2.26 mg NO2--N/L and 4.72 mgCOD/L respectively.The rates of anaerobic ammonium oxidation, methanogenesis and denitrification in coupling experiments of them all decreased.⑤The effect of trace NO2 on anaerobic ammonium oxidation, methanogenesis and denitrification was investigated by batch experiment. Trace NO2 apparently enhanced the anaerobic ammonium oxidation, the kinetic parameters of anaerobic ammonium oxidation were kept invariable, the function for NO2 apparently to enhance ammonium oxidation was suggested using the Haldane based model. The parameters were estimated, where the half saturate coefficient of NO2 was 2570 mg/m3, inhibition coefficient of NO2 was 3.9 mg/m3, the maximum enhanced rate coefficient was 48.79, the basic rate coefficient was 0.0188.The methanogenesis and denitrification kinetics could be described using uncompetitive inhibition model. The maximum NaAc removal rate, NaAc half saturation constant and NO2 inhibition coefficient in methanogenesis were 0.149 mgCOD/mgVSS·h, 396 mgCOD/L and 231 mg NO2/ m3,respectively. The maximum nitrite removal rate, half saturation constant of NO2--N and NO2 inhibition coefficient in denitrification were 0.006865/h, 0.1 mg NO2--N/L and 1530 mg NO2/m3,respectively. The most of NOX in the experiment was lost.⑥The effect of trace NO2 on integrating anaerobic ammonium oxidation, methanogenesis and denitrification was investigated by batch experiment. The kinetic parameters of anaerobic ammonium oxidation were kept invariable, the function for NO2 apparently to enhance ammonium oxidation was suggested using the Haldane based model. The parameters were estimated, where the half saturate coefficient of NO2 was 1960 mg/m3, inhibition coefficient of NO2 was 8.2 mg/m3, the maximum enhanced rate coefficient was 30.55, the basic rate coefficient was 0.0314 . The methanogenesis and denitrification kinetics the integration system could be described using uncompetitive inhibition model. The maximum NaAc removal rate, NaAc half saturation constant and NO2 inhibition coefficient in methanogenesis were 0.15 mgCOD/mgVSS·h, 395 mgCOD/L and 623 mg NO2/m3 ,respectively. The maximum nitrite removal rate, half saturation constant of NO2--N and NO2 inhibition coefficient in denitrification were 0.00685 /h, 0.214 mg NO2--N /L and 22400 mg NO2/m3,respectively. Most of the NOX in the experiment was lost.The rates of methanogenesis and denitrification in the coupling experiments of them were decreased. When NO2 was lower than 50 ppm, the rate of anaerobic ammonium oxidation in the coupling experiments of them was smaller than it in the separate experiment, but larger when NO2 was higher than 50 ppm.⑦The mixed ammonium oxidizer culture was enriched from normal activated sludge in SBR reactor, in which the pH was controlled between 7.8 and 8.2 ,DO between 0.8 and 1.0 mg/L and temperature at 30±2℃. The experimentation was carried out through synthetic wastewater,in which the initial NH4+-N was 50 mg/L and was increased up to 250 mg/L gradually by the step of 50 mg/L.The MPN test was run every 15 days to characterize the enrichment of ammonium oxidizer.The concentration of the ammonium oxidizer culture increased by 300 times after the cultivation for 120 days. The results of batch experiment indicated that pH, DO and temperature had significant influence on the enrichment of aerobic ammonia oxidation bacteria. During the enrichment cultivation, pH, DO and temperature were the key factors, FA and nitrous acid could be properly controlled to inhibit the growth of nitrite oxidation bacteria, but not the ammonia oxidation bacteria.⑧The biomass yield coefficient of 0.2119 mg COD produced/mg NH4+-NOD (or 0.7268 mg COD/mg NH4+-N)and the maximum specific ammonium nitrogen consumption rate of 0.1 mg NOD/(mg COD.h)(or 0.0292 mg N/(mg COD.h)) for autotrophic aerobic ammonia oxidation bacteria were obtained from batch respirometry. The kinetics of aerobic ammonia oxidation was established by adding 24μM NaN3 to the sequence batch reactor. The kinetic parameters were determined, where the half saturate coefficient of NH4+-N was 18.38 mg NOD/L (or 5.36 mg NH4+-N/L) and the half saturate coefficient of DO was 0.494 mg/L.⑨The kinetics of the NO2-dependent ammonia oxidation was developed for ammonia oxidizer mixed culture when there was no molecular oxygen in the batch tests. The kinetic parameters were determined, where the half saturate coefficient of NO2 was 0.821μmol/L, inhibition coefficient of NO2 concentration was 1.721μmol/L, the maximum ammonium oxidation rate was 0.144 mgNOD/(mgCOD·h). After adding 2%O2 to trace NO2, the ammonium oxidation rates increased obviously. The maximum ammonium oxidation rate, 0.198 mgNOD/(mgCOD·h) occurred under the condition of the mixed gasses containing 2%O2 and 50 ppm NO2. Under the condition of mixed gasses containing 21%O2 and trace NO2, the ammonium oxidation rates further increased greatly. The maximum ammonium oxidation rate, 0.477 mgNOD/(mgCOD·h) occurred under the condition of 21%O2 and 100 ppm NO2 in the mixed gas, which is 3 times higher than the general aerobic ammonium oxidation rate. The function for NO2 apparently to enhance ammonium oxidation was suggested. The kinetic models of ammonium oxidation under the conditions of O2 and trace NO2 mixed gasses was developed. The model was validated by the results of ammonium oxidation experiments under the conditions of the mixed gasses containing 2%O2 and trace NO2. The mechanism for NO2 to enhance ammonium oxidation under the conditions of O2 and trace NO2 mixed gasses was discussed.⑩COD removal and aerobic ammonium oxidation were performed in BAF reactor filled with expanded clay.After the start-up operation of 20d, the effluent COD concentration below 30 mg/L ,ammonium nitrogen below 0.1 mg/L ,nitrite nitrogen 45.55 mg/L and nitrate nitrogen 4.18 mg/L were obtained with the influent ammonium nitrogen concentration about 50 mg/L, COD concentration about 100 mg/L and inner recycle ratio 200% in BAF reactor. Bigger or smaller inner recycle ratio was unsuitable for running of BAF reactor.⑾The aerobic ammonium oxidation,anaerobic ammonium oxidation, methanogensis and denitrification were coupled in the integration of EGSB reactor technique and BAF reactor technique. The removal efficiency of total nitrogen was 80.6% and COD concentration was below 40 mg/L, ammonium nitrogen below 1 mg/L, nitrite nitrogen 4.3 mg/L, nitrate nitrogen 2.56 mg/L in the effluent under the performance conditions of influent flux 13 mL/min,ammonium nitrogen concentration 50 mg/L , COD concentration 500 mg/L and outer recycle ratio 200%. Because of application for EGSB-BAF system, the removal rate of total COD, total nitrogen and total ammonium nitrogen were 1.7122 (kg/m3.d), 0.1363 (kg/m3.d) and 0.1632 (kg/m3.d) ,respectively; it can saved 0.2405 (kg O2/m3.d) and 0.1775 (kg COD /m3.d), received 554.94(L CH4 /m3.d).
|
PDF Full Text Request