| The kitchen waste fermentation wastewater is derived from the moisture contained in the kitchen waste itself and the wastewater generated after the anaerobic fermentation treatment of the kitchen waste,which has a low C/N ratio,high concentration of ammonia nitrogen and organic matter,and poor biodegradability.It contains a lot of refractory biodegradable organic matter,is rich in oil and protein,and has relatively large fluctuations in water quality.How to achieve efficient and low-cost treatment of kitchen waste fermentation wastewater is the key to preventing secondary pollution caused by kitchen waste treatment.When processing nitrogen-containing wastewater,the short-range nitrification and denitrification technology has the strength of saving consumption of aeration and carbon source addition,and is suitable for wastewater with high ammonia nitrogen concentration and low C/N ratio.When used as pre-treatment or post-treatment,Fenton oxidation can efficiently remove refractory biodegradable organic substances,highly improve the biodegradability of wastewater,and has the strengths of easy operation and low cost.In this paper,the SBR reactor is used as a short-range nitrification and denitrification reactor,the combined Fenton oxidation system is used to denitrify and degrade organic waste in the kitchen waste fermentation wastewater,and the key influencing factors of each unit are investigated.Thus,the paper provides a reference for engineering application of stable and cost-effective denitrification.1 In this paper,after 273 cycles of operation,the average ammonia nitrogen removal rate reached 88.94%and the average nitrite nitrogen accumulation rate reached85.29%in the stable operation period,by simulating wastewater to start short-range nitrification to achieve enrichment of ammonia oxidizing bacteria in a short period of time,and controlling the operating parameters pH between 7.5?8.0,reaction temperature of about 30?,DO between 0.5?1mg/L.Thus,the short-term nitrification stage of the treatment of kitchen waste fermentation wastewater was successfully achieved.When doing research into the influencing factors of the short-range nitrification stage,it is concluded that the optimal operating parameters of the short-range nitrification stage are pH=7.5,DO=0.8mg/L,and temperature of 30?.When studying the change of the specific ammonia oxidation rate of the reaction system under different DO,it was found that when the DO reaches the threshold of the reaction system,continuing to increase the aeration amount will not greatly increase the specific ammonia oxidation rate of the reaction system.When DO=0.8mg/L,it reached63.59mg NH4+-N·g-1MLSS·d-1.At pH=7.5,the effect of different free ammonia concentrations on the specific ammonia oxidation rate of the reaction system was found.When the initial free ammonia concentration of the reaction system was about36.27mg/L,the specific ammonia oxidation rate can maintain a high value.In actual engineering application,it is recommended to adjust the pH to 7.5±0.2 according to the change of ammonia nitrogen concentration in the influent.2 Under the condition of keeping the operating parameters of the short-term nitrification stage unchanged,increasing the anoxic agitation for 5h,and using the method of gradually increasing the nitrite nitrogen concentration of the influent,we successfully domesticate the denitrifying sludge in the SBR.After 39 cycles of domestication,nitrified effluent achieves a total nitrogen removal rate that is almost stable at about 93%.After that,the concentration of nitrite nitrogen in the influent is not diluted any more,and the continuous and stable operation of shortcut nitrification and denitrification is realized.In the reaction system,the removal rate of total nitrogen is kept at around 89.64%,the average concentration of total nitrogen in the effluent is120.57mg/L,and the removal rate of COD is 80.78%.The study on the change of pH in the stable period shows that there is a certain correlation between the change of pH and the variation of shortcut nitrification and denitrification process.And that can be used as an indicator to assist in judging whether various response stages are completed in engineering application.This study shows that the best carbon source dosage(calculated by COD)is 4000mg/L in denitrification stage.And it has certain feasibility to use the fermentation wastewater of kitchen waste as the additional carbon source.3 The orthogonal level experiment of Fenton oxidation system shows that the order of importance of each influencing factor of Fenton oxidation is as follows:hydrogen peroxide dosage>ferrous sulfate dosage>reaction time>pH.The optimum operating conditions were pH=3,reaction time 90min,hydrogen peroxide 5ml/L,ferrous sulfate 32ml/L.In the optimum conditions,the removal rate of COD reaches 78.34%.The system can reduce the total nitrogen of effluent to70.37?226.18mg/l,COD concentration to 194.78mg/L,chroma less than 11 times and B/C to 0.4,which greatly improves the biodegradability of effluent. |
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