【正文】 業(yè)出版社，2001中國(guó)市政工程華北設(shè)計(jì)研究院主編：：中國(guó)建筑工業(yè)出版社，2001[9].《給水排水》，2000[11]于爾捷，中國(guó)建筑工業(yè)出版社，1996[13]高俊發(fā)，化學(xué)工業(yè)出版社，2003[15]，化學(xué)工業(yè)出版社，200257外文資料翻譯Oxidation ditches 1. Introduction Oxidation ditch and continuous circular aeration tank, deformation is one of the activated sludge process. Oxidation ditch sewage treatment technology is successfully developed by the Dutch in the 1950 s and health engineering. Put into use in the Netherlands for the first time since 1954. Due to its good effluent water quality, steady operation, convenient management and other technical characteristics, has been widely used both at home and abroad in domestic sewage and industrial wastewater treatment. The types of the oxidation ditch has been widely applied at present include: pass, oxidation ditch, the Carrousel oxidation ditch, Mr. Bell oxidation ditch, T oxidation ditch, three groove type oxidation ditch, and the integration of DE type oxidation ditch and oxidation ditch. The oxidation ditch because of the differences on the structure and operation, so each has its characteristics. This paper will mainly introduce Carrousel’s structure, the mechanism of the oxidation ditch, the existence question and its latest development. 2. The structure of Carrousel oxidation ditch Carrousel oxidation ditch is DHV Company developed in 1967 by the Dutch. On the basis of the original Carrousel oxidation ditch DHV EIMCO it’s patented in the United States Company and created the Carrousel 2000 System, realizes the higher requirements of biological denitrification and phosphorus removal function. By far the world has more than 850Carrousel oxidation ditch and Carrousel 2000 System is running. Carrousel oxidation ditch with directional control of aeration and agitation device, the mixture transfer horizontal velocity, which was stirring the mixture of circulating in the oxidation ditch channels closed. Oxidation ditch has special hydraulic flow state, therefore, has the characteristics of both the pletely mixed reactor and has the characteristic of push flow reactor, groove exists obvious dissolved oxygen concentration gradient. Oxidation ditch cross section is rectangular or trapezoidal, plane shape is oval, more groove depth is generally ~ m, width depth ratio is 2:1, also have a depth of up to 7 m, ditch water an average speed of m/s. Oxidation ditch aeration mixing equipment have surface aerator, aeration brush or turntable, jet aerator, catheter type aerator and riser type aerator etc., also used underwater driver in recent years. 3. The mechanism of Carrousel oxidation ditch Carrousel oxidation ditch sewage treatment principle The original Carrousel oxidation ditch process with reflux sludge sewage directly into the oxidation ditch System. Dissolved oxygen in surface aerator make mixture the DO concentration increased to about 2 ~ 3 mg/L. Under the condition of the fully mixed oxygen, get enough dissolved oxygen to remove BOD microbial。s share of the activated sludge phosphorus content is 4% of the dried sludge quantity, 11% of the quality of heterotrophic bacteria, but when sludge in sludge age more than 15 d maximum phosphorus content significantly decreased, but cannot meet the maximum phosphorus removal effect. So blindly extend sludge age (for example, 20, 25 d, 30 d d) is not necessary, appropriate within 8 ~ 15 d choose. At the same time, high nitrate concentration and low substrate concentration of phosphorus removal process. 4. Carrousel Moseley oxidation ditch existing problems and solutions Though Carrousel Moseley oxidation ditch have effluent water quality is good, strong ability to resist impact load, high efficiency of nitrogen removal and sludge is stable, power consumption province, easy to automatic control, etc. However, in the actual operation process, a series of problems still exist. Sludge bulking problem When carbohydrates in the waste water is more, N, P content in imbalance, low pH, high oxidation ditch in sludge load, dissolved oxygen concentration, dredge not free and easy to sludge bulking caused by filamentous bacteria sex。 Such as sludge loading is too high, can improve the MLSS, in order to adjust the load, when necessary to stop water, boring exposure for a period of time。 PH value is too low, but adding the lime to adjust。t effectively remove it pletely, part of the oil concentration in the sludge, turn the brush oxygen filling mixing, produce a large number of bubbles。t well control the residence time in the second pond, easy cause lack of oxygen, produce sludge upfloating decay。 In addition, the oil content in the waste water is too large, the sludge may carry oil to rise. After sludge floating water shall be suspended, break or removal of the sludge, ascertain the reason, adjust the operation. Sludge settle ability is poor, can dosing coagulant or inert material, improve the precipitation。 Such as the sludge particles small can decrease the aerator speed。 Sludge decay is found, should increase air, and clean up mud, hydraulic conditions and try to improve in the pool. And uneven velocity of sludge deposition problem In Carrousel Moseley oxidation ditch, for its unique mixing and processing results, the mixture must be circulating in the groove at a certain velocity. It is generally believed that the minimum flow rate should be m/s, the average velocity of sedimentary does not occur should be ~ m/s. Oxidation ditch aeration equipment generally brush turn for aeration and aeration rotary brush turns the submerged depth of 250 ~ 300 mm, submerged depth of the wheel is 480 ~ 530 mm. With oxidation ditch depth ( ~ m), pared to brush only 1/10 ~ 1/12 of the water depth, turntable also accounts for only 1/6 ~ 1/7, so the oxidation ditch caused by upper flow velocity is larger (about ~ m, or even more), and at the bottom of the flow rate is small (especially in depth below twothirds or 3/4,