1、 外文资料翻译 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 Netherland
2、s 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
3、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 op
4、eration, so each has its characteristics. This paper will mainly introduce Carrousels 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 Du
5、tch. On the basis of the original Carrousel oxidation ditch DHV EIMCO its 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
6、 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
7、 state, therefore, has the characteristics of both the completely 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 gener
8、ally 2.5 4.5 m, width depth ratio is 2:1, also have a depth of up to 7 m, ditch water an average speed of 0.3 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
9、in recent years. 3. The mechanism of Carrousel oxidation ditch 3.1 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 concentra
10、tion increased to about 2 3 mg/L. Under the condition of the fully mixed oxygen, get enough dissolved oxygen to remove BOD microbial； at the same time, nitrate and nitrite, ammonia was oxidized to at this point, the mixture in aerobic condition. By aeration zone in the downstream of the aerator, wat
11、er turbulence state into a state of advection, maintained at a minimum velocity of flow, ensure that activated sludge in a suspended state ( 0.3 m/s) average velocity. Microbial oxidation process consumes dissolved oxygen in water, until the value to zero in the DO, mixture in hypoxia state. 3. The
12、CD method and application widely in the large-span tunnel, the CRD construction method in this System, BOD degradation is a continuous process, nitrification and denitrification occurred in the same pool. Because of the limitation of structure of the oxidation ditch can be effective for BOD, but pho
13、sphorus removal denitrification ability is limited. 3.2 Carrousel Moseley oxidation ditch the influence factors of biological nitrogen removal Influence factors of phosphorus removal from Carrousel Moseley oxidation ditch is primarily a sludge age, nitrate concentration and substrate concentration.
14、Research shows that when the total sludge age of 8 10 d, the lions 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 c
15、annot 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 oxidatio
16、n 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 ope
17、ration process, a series of problems still exist. 4.1 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 bacteri
18、a sex； Non filamentous bacteria mainly in wastewater sludge bulking sludge load at high temperature is low. Microbial load is high, the bacteria absorb a large amount of nutrients, because of the low temperature, metabolic speed is slow, product storage on a large amount of high viscosity polysaccha
19、ride substances, the adhered on the surface of the activated sludge in the water increase greatly, SVI value is very high, the formation of sludge bulking. Aiming at the cause of sludge bulking, can adopt different countermeasures: caused by a lack of oxygen, high water temperature, can increase air
20、 or cut into the water to lighten the load, or decrease the MLSS (control sludge return flow), reduce oxygen demand； 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； Can be adjusted by adding th
21、e nitrogen fertilizer, phosphate fertilizer, mixture of nutrient balance (BOD5: N: P = 100:5)； PH value is too low, but adding the lime to adjust； Chlorine bleaching powder and liquid (0.3% 0.6% in dry sludge dosing), inhibit filamentous fungi reproduction, combined with water sludge bulking control. 4.2 Bubble problem
