RESEARCH ON DEEP DENITRIFICATION AND DENITRIFICATION TECHNOLOGY IN MOVING BED BIOFILM REACTOR (MBBR) OF REFINERY WASTEWATER

Due lo the shortage of water resources in some northern cities in China, water pollution and water crises caused by insufficient water resources have severely restricted social and economic development and the improvement of people's living standards. Especially in the petrochemical industry, it is very important to recycle wastewater after treatment. In this paper, a moving bed biofilm reactor (MBBR) is used to study the deep denitrification of the effluent from the secondary sedimentation tank of a refinery in Hebei Province in northern China under continuous flow experimental conditions, and the feasibility of the deep denitrification process is analyzed. The results show that, if MBBR uses the effluent of the first-level aeration tank as the inlet water, the external carbon source and controlling the carbon-to-nitrogen ratio is4~5. And the hydraulic retention time in the anoxic section is 4h, the deep denitrification effect is efficient and stable. The total nitrogen removal rate is 78.85±11.25%, and the nitrate nitrogen removal rate is as high as 93.07±3.18%. When the effluent of the primary aeration tank is introduced into acid-base neutralization wastewater (volume ratio 300:13), the total nitrogen removal rate still reaches 79.60±0.18%, the nitrate nitrogen removal rate is 94.86±1.20%, and the total nitrogen mass concentration of the effluent are less than 3mg/L. At the same time, the experimental analysis of TN and NO3-N in the influent concentration are 2.25±6.36mg/L, 16.70±5.99mg/L (stage I) and 36.83±2.11mg/L, 30.37±1.83mg/L (stage II), respectively. Under the conditions, the MBBR treatment has a deep denitrification effect. Compared with the stage I) process, the removal rate of stage II is increased by 2.16% and 3.30%, respectively. Overall, the increase in the removal rate is not large.