| With the large-scale construction of wastewater treatment plant in China, the plants'requirement becomes more and more strict, not only large and medium-sized cities, but also small cities and towns start the construction of wastewater treatment plant. Only the sludge outside transport was considered at quondam sewage treatment factory design and construction, but in actual plant's operation, disposal of sludge (such as the outside transport) became a knotty problem, it even caused much messy and irregular dumpage. Based on the current situation, this study attempted to apply anaerobic reactor of high speed to the experiment of sludge treatment, the Reactor for Improved Integrative Sludge Thickening and Digestion(ISTD) was developed, which can be suitable to our national situation and have the characteristic of higher efficiency, lower invest, convenient management, easy to generalize.This paper mainly covered the hydrodynamic behavior of Improved ISTD Reactor, treatment efficiency and influencing factor at mid-temperature, Biofacies analyses and the degradation model's building-up for organic pollutants.The results of hydrodynamic behavior indicated that all Exit-age Distribution Functions presented secund left normal distribution form, the volume proportion of pusher was bigger than completely mingled, dimensionless variance was 0<σθ2<1, it was tend to 0, Peclet criteria was 3~9, so the flow pattern of Improved ISTD Reactor verged on pushing form. The flow pattern tended to completely mingled with enhanced stirring speeds and verged on pusher form with increasing influent water.The experiment was carried out at TangJiaqiao Wastewater Plant, it adopted inoculation methods and started-up in low organic load (sludge dosage rate was 10%), the set-up process was completed through 30days at about 35℃. The treatment efficiency of Improved ISTD Reactor was carried out under the condition of mid-temperature (about 35℃), stirring time was 4 times/d (40r/min and 30min/time), COD volume load was 0.39~1.87kgCOD/m3?d, the results showed that when the influent sludge water content was about 99.70%, VS/TS was 0.52~0.65, SS was 2.53~4.65g/L, water content of effluent sludge was 89.77%~97.31%, VS/TS was 0.23~0.48, SS of effluent water was 130~1245mg/L, aero-genesis amounts are 8.2~51.0L/d, the sludge specific resistance was 0.88~1.80×1013m/kg, MLSS was 25.5~61.2g/L, COD of effluent water was 159~938mg/L. Among them when the HRT was 3.1~5.0d, volume load was 0.65~1.31KgCOD/m3?d, the sludge water content of Improved ISTD Reactor was 91.91%~94.46%, it was low and the effect of thickening was fine, VS/TS of effluent sludge was 0.27~0.32, organic removal rate was 46.39%~56.88%, it was high and the effect of effluent sludge was fairly good. This was the nicer working condition of Improved ISTD Reactor.Inside the Improved ISTD Reactor, pH value was 6.6~7.0, alkalinity was 700~1200mg/L, VFA was 200~ 450mg/L, the other two targets were mainly within the range that anaerobic digestion should be controlled except that alkalinity was a little small, this indicated that Improved ISTD Reactor had the ability to against shock loads and could meet the requirement of anaerobic digestion. From the anaerobic sludge scanning electronic microscope photograph, we could observe Methanobacterium formicicum, Methanothrix soehngenii, Methanosarcina barkeri and etc., among them filiform bacterium and bacillus were in the majority , it also spread a few cocci, these bacteria basically included all bacterium forms, so it reflected that anaerobic sludge microorganism's ecosystem group and function was steady comparatively.This study built up the sludge bed area and suspension tier's degradation model of Improved ISTD Reactor, and this paper also ascertained the relational expressions of organic substrates'concentration, microorganism's concentration, methane's output and interrelated dynamics constant.
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