Research And Debugging Of Nitrogen Excess In Wastewater Treatment In Chemical Parks

The sewage treatment plant in Lanzhou New District Chemical Industry Park is in the stage of trial operation and commissioning.Each process section is basically operating normally,but there is a problem that the effluent ammonia nitrogen and total nitrogen do not meet the standard.Therefore,this paper will be oriented to solve this problem,systematically study the problem of nitrogen exceeding the standard and put forward debug scheme.The main conclusions are as follows.（1）The organic nitrogen in the sewage treatment plant in the park mainly includes triethylamine,nitrobenzene,aniline,nitrile,hydrazine hydrate,acetonitrile,pyridine,DMF,etc.Nitrogen is degraded,including Fenton oxidation,micro-electrolysis,catalytic oxidation,and ozone oxidation;chemical wastewater has a high organic nitrogen content and has a significant removal effect,while domestic sewage has a low organic nitrogen content and an insignificant removal effect.The main reason is the lack of advanced oxidation technology.（2）In the iron-carbon micro-electrolysis method,the optimal volume ratio of iron-carbon to wastewater is 1:2,the optimal p H is 3,and the optimal reaction time is120 min;the optimal n（H2O2）:n（Fe2+）ratio of Fenton method is 5:1.The maximum dosage of hydrogen peroxide（H2O2）is 21.25 m L/L,the initial optimal p H is 3.5,and the CODCr removal rate can reach 60.03%.The pretreatment process can not only effectively reduce COD,but also help the operation of the subsequent biochemical system to achieve the standard treatment of ammonia nitrogen and total nitrogen.（3）After debugging,the following rules were mainly found: iron-carbon and Fenton systems help to accelerate the conversion of organic nitrogen into ammonia nitrogen;ozone oxidation,as an advanced oxidation process,helps to stably remove ammonia nitrogen in water when the p H range is 8.0 8.7,The treatment effect can reach 44%,and the ozone oxidation method can be used as the final control measure for ammonia nitrogen;compared with total nitrogen,ammonia nitrogen will be degraded first,and the denitrification effect will be significantly improved after 3months of biochemical process debugging;When the aeration rate is too large（5 mg/L 7 mg/L）,the sludge will disintegrate and the sludge concentration will decrease.（4）In order to ensure the discharge of nitrogen-containing wastewater up to the standard,debugging is carried out on the following points: control the upstream water quality,ensure that the front-end inlet water meets the design standards and the water quality fluctuation is small;ensure that the p H of the biochemical system is between8.0 and 8.5,and the dissolved oxygen in the good maintenance stage Between 4 mg/L and 6 mg/L,it is beneficial to the degradation of ammonia nitrogen in chemical wastewater;adding high-quality carbon source sodium acetate,increasing the internal reflux ratio greater than 200% is beneficial to the removal of total nitrogen in the biochemical system.