以超声波破解剩余污泥为碳源强化污水脱氮
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摘要
针对污水厂生物脱氮碳源不足和剩余污泥难以处置的问题,探讨了利用超声波处理后的剩余污泥作为生物脱氮外加碳源的可行性。研究采用三因素三水平的响应曲面分析法,考察了超声波声能密度、时间和pH对剩余污泥可生化性(BOD_5)的影响,确定了超声波破解剩余污泥的最佳工艺条件。结果表明:在超声波声能密度为2. 0 W/m L,超声波时间为40 min和pH=7. 0的条件下,剩余污泥ρ(BOD_5)为2195 mg/L,增加为原来(88 mg/L)的24. 9倍,大大增强了其可生化性。超声波破解前后剩余污泥的大肠菌群检测结果证明,超声波破解也可将致病菌灭活,使剩余污泥无害化。在以3种剩余污泥产物为外加碳源的反硝化实验中,利用最佳参数条件下处理的剩余污泥为碳源时反硝化效果最好,反应仅进行14 h,ρ(NO_3~--N)从108 mg/L迅速降至3 mg/L,去除率达到95%以上,NH_4~+-N几乎无积累,整个反硝化过程完成仅需24 h,表明采用优化后的超声波预处理条件可以有效提升以剩余污泥为碳源的反硝化效果。
The insufficient carbon source for biological denitrification and difficult disposal of excess sludge are two common problems in wastewater plants. This study explored the feasibility of using excess sludge treated under optimized ultrasonic condition as additional carbon source for biological denitrification. The response surface methodology of three factors and three levels was used to investigate the effects of ultrasound energy density,ultrasonic time and pH on BOD_5. The optimum conditions of ultrasonic treatment for excess sludge were confirmed. The optimum BOD_5 concentration achieved 2195 mg/L at the ultrasonic sound energy density of 2. 0 W/m L,ultrasonic time of 40 minutes and pH of 7. 0,which was 24. 9 times as much as the BOD_5 concentration of untreated sludge. The biodegradability was greatly improved. The detection of the coliforms including E.coli before and after ultrasonic crack showed that these pathogenic bacteria in sludge could be killed by ultrasonic crack,which made the remaining sludge harmless. In the denitrification experiments using three product of the sludge as additional carbon source,denitrification was the best for excess sludge treated under the best parameters. ρ( NO_3~--N) was reduced from 108 to 3 mg/L in only 14 hours. It took only 14 hours to complete the entire denitrification process,and the removal efficiency exceeded 95%. And there was little accumulation of NH_4~+-N. In summary,the optimized ultrasonic pretreatment conditions can effectively enhance the denitrification efficiency of excess sludge as carbon source.
The insufficient carbon source for biological denitrification and difficult disposal of excess sludge are two common problems in wastewater plants. This study explored the feasibility of using excess sludge treated under optimized ultrasonic condition as additional carbon source for biological denitrification. The response surface methodology of three factors and three levels was used to investigate the effects of ultrasound energy density,ultrasonic time and pH on BOD_5. The optimum conditions of ultrasonic treatment for excess sludge were confirmed. The optimum BOD_5 concentration achieved 2195 mg/L at the ultrasonic sound energy density of 2. 0 W/m L,ultrasonic time of 40 minutes and pH of 7. 0,which was 24. 9 times as much as the BOD_5 concentration of untreated sludge. The biodegradability was greatly improved. The detection of the coliforms including E.coli before and after ultrasonic crack showed that these pathogenic bacteria in sludge could be killed by ultrasonic crack,which made the remaining sludge harmless. In the denitrification experiments using three product of the sludge as additional carbon source,denitrification was the best for excess sludge treated under the best parameters. ρ( NO_3~--N) was reduced from 108 to 3 mg/L in only 14 hours. It took only 14 hours to complete the entire denitrification process,and the removal efficiency exceeded 95%. And there was little accumulation of NH_4~+-N. In summary,the optimized ultrasonic pretreatment conditions can effectively enhance the denitrification efficiency of excess sludge as carbon source.
引文
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[25]赵文莉,郝瑞霞,李斌,等.预处理方法对玉米芯作为反硝化固体碳源的影响[J].环境科学,2014,3(35):987-994.
[2]李雄伟,李俊,李冲,等.我国污泥处理处置技术应用现状及发展趋势探讨[J].中国给水排水,2016,32(16):26-31.
[3] Zawieja I,Wolny L. Ultrasonic disintegration of sewage sludge to increase biogas generation[J]. Chemical&Biochemical Engineering Quarterly,2013,27(4):491-497.
[4]晏鹏,毛建红,曾荣辉,等.剩余污泥碳源化特性及利用途径研究[J].中国给水排水,2013,29(23):27-31.
[5]李高朋.高压均质强化剩余污泥水解酸化及水解酸化液作反硝化碳源研究[D].北京:北京林业大学,2016.
[6] Saha M,Eskicioglu C,Marin J. Microwave,ultrasonic and chemomechanical pretreatments for enhancing methane potential of pulp mill wastewater treatment sludge[J]. Bioresour Technology,2011,102(17):7815-7826.
[7] Jin Pei,Hong Yao. Comparison of ozone and thermal hydrolysis combined with anaerobic digestion for municipal and pharmaceutical waste sludge with tetracycline resistance genes[J].Water Research,2016,99:122-128.
[8]王晓霞,吕树光,邱兆富,等.超声波处理、热处理及酸碱调节对剩余污泥溶解效果的对比研究[J].环境污染与防治,2010,32(8):56-61.
[9]蒋建国,张妍,张群芳,等.超声波对污泥破解及改善其厌氧消化效果的研究[J].环境科学,2008,29(10):2815-2819.
[10] Zielewicz E. Effects of ultrasonic disintegration of excess sewage sludge[J]. Topics in Current Chemistry,2016,374(5):1-26.
[11]王怡,刘潘,彭党聪.剩余污泥的超声处理及资源化利用研究[J].中国给水排水,2010,26(23):20-23.
[12] Le N T, Julcour-Lebigue C, Delmas H. Ultrasonic sludge pretreatment under pressure[J]. Ultrasonics Sonochemistry,2013,20(5):1203-1210.
[13]张自杰.排水工程(下册)[M]. 4版.北京:中国建筑工业出版社,2000.
[14]李小平.剩余污泥的超声处理及资源化利用[D].广西:广西大学,2013.
[15]李瑞.地下水硝酸盐污染原位生物修复模拟装置研发及其性能研究[D].北京:中国地质大学(北京),2015.
[16]胡一帆,杨昌柱,但锦锋,等.人工神经网络在膨胀颗粒污泥床反应器中的应用[J].环境工程,2017,35(增刊1):184-188.
[17] Xu Juan,Sheng Guo-Ping,Luo Hong-Wei,et al. Evaluating the influence of process parameters on soluble microbial products formation using response surface methodology coupled with grey relational analysis[J]. Water Research,2011,45(2):674-680.
[18]国家环境保护总局.水和废水监测分析方法[M]. 4版.北京:中国环境科学出版社,2002:211-268.
[19]王芳,王凯,樊赟,等. Easy Test~(TM)测试片:准确性更高、适用性更广———微生物快速检测新产品[J].食品安全导刊,2010(6):40-41.
[20]郭璇.超声技术对给水厂污泥絮体作用机理的数值模拟与试验研究[D].北京:北京工业大学,2016.
[21]郑蕾,田禹,孙德智. pH值对活性污泥胞外聚合物分子结构和表面特征影响研究[J].环境科学,2007,28(7):1507-1511.
[22]林彩华,许如苏,曾梅锦,等. SN标准和3M Petrifilm法检测水产品卫生指标菌的比较[J].中国卫生检验杂志,2006,16(10):1218-1219.
[23] Glass C, Silverstein J. Denitrification kinetics of high nitrate concentration water p H effect on inhibition and nitrite accumulation[J]. Water Research,1998,32(3):831-839.
[24]艾小凡,王鹤立,陈祥龙.地下水硝酸盐污染生物修复中的亚硝态氮积累研究[J].环境工程,2014,32(1):33-36.
[25]赵文莉,郝瑞霞,李斌,等.预处理方法对玉米芯作为反硝化固体碳源的影响[J].环境科学,2014,3(35):987-994.