| With rapid development of economy and serious lack of resources, traditional centralized wastewater treatment system shows more and more drawbacks. By contrast, decentralized system has many advantages. In decentralized wastewater treatment system,key piont is Source Seperation or Source Management. In decentralized system faecal wastewater is separated from ordinary domestic wastewater. Black water treatment is the hotpot in decentralized system, and the methods are manure compositing, septic tank and UASB septic tank, which is most widely used abroad. The research about black water treatment at home and abroad mainly pay close attaintion to improving the reactor and efficiency by stirring, wastewater's well distributing, designing good three phase seperater and so on.This test investigated the treatment of blackwater from classroom building by using an Externally Circular UASB reactor, and the system was operated at 35℃. During the experiment, several index were monitored to check the performance of this system such as pH value, COD, SS, NH4 N, TN,VFA, with the quantity of influent and mixed liquid returning changing. The results indicated that:1. Several index of the raw wastewater such as pH, COD, SS and ammonia nitrogen fluctuated widely. pH value of wastewater was between 7.30 to 8.6, and showed a weak alkaline. This is not conducive to the operation of the reactor, and need to manually adjust the influent pH value. The CODss content of raw water is about 45% of total COD, and this has great effects on high rate anaerobic reactors. But the reactor's ability to loading shock has been strengthened by changing the quantity of reflux.2. During the starting up of reactor, the anaerobic sludge has not been domesticated. if starting reflow, it would disturb the sludge and floatation. That was not good for the stabilization of reactor. When the reactor had stably producted gas, the sludge bed would have short flow or plug flow because of low Vup(velocity of up flow), which resulting in mud flotation. This was bad for the reactor's stabilization. At this time, opening the back flow devices to improve Vup has made removal efficiency increased.3. Inoculating with anaerobic sludge flocs in the UASB reactor, floc sludge granulation has increased by improving upflow velocity through the back flow devices, and, floc sludge has achieved granulation at last.4. Anaerobic reactor formed regular shape of granular sludge, which was black and gray black and dense smooth surface. A large number of filamentous bacteria was wrapping a few cocci and Brevibacterium. The internal of granular sludge is containing a large number of filamentous bacteria, cocci and a small amount of Brevibacterium. Sludge particle size was distributed in the 0.6 0.9mm.5. After the granulation of sludge,the SLR and Vup were 0.15～0.36kgCOD/(kgVSS·d)and 1.16～1.27 m/h respectively, the removal efficiency of COD was better. At the same time, increasing sludge loading of reactor has little effect on gasification efficiency. The average output of CH4 was 183mL when 1gCOD has been removed.6. With fecal coliform as indicator, the reactor mainly depended on the adhesion of sludge to remove pathogens, and the removal efficiency of Pre columri prior pathogen was better than removed by the granular saudge. While the suspended bacteria showed no significant difference. After granulation, HRT and fecal coliform removal was positively correlated. The results indicated that treatment with UASB Blackwater outside the circle, fast and efficient removal of organic matter with the efficient removal of pathogens could not coexist...
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