稻壳粉添加剂提高污泥的脱水效果研究
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摘要
利用农业废弃物稻壳粉能有效提高污泥的脱水性能。该文研究了稻壳粉投加量对污泥脱水性能的影响及调理机理,同时分析稻壳粉调理对污泥滤液和脱水后污泥主要性质的影响,并进行技术经济分析。试验结果表明,稻壳粉的最佳投加量为70%污泥干质量(DS);在最佳调理条件下,与单独投加三氯化铁(FeCl_3,138.09g/kg)相比,污泥比阻降低了59.73%,污泥净产率提高了45.27%,污泥泥饼的含固率从13.99%提高到23.97%;扫描电镜结果表明,稻壳粉调理后的污泥泥饼具有不可压缩性和可渗透性,有利于污泥中水分的脱出;同时,稻壳粉的投加可有效降低滤液浊度和溶解性化学需氧量。因此,利用稻壳粉来调理污泥具有较大的潜力。
At present, finding valuable application of rice husk should be targeted for further research, and how to deal with sewage sludge has become an issue that requires urgent attention. In this study, rice husk flour, an agricultural waste material, was used to condition sludge and enhance sludge dewaterability. The effect of rice husk flour dosage on sludge dewaterability was investigated, and the surface element content and main components of rice husk flour and the microstructure of sludge cakes was investigated to analyze conditioning mechanisms. In addition, the effect of adding rice husk flour on turbidity and soluble chemical oxygen demand(SCOD) of sludge filtrate were also investigated, the advantages of adding rice husk flour for future filtrate treatment were evaluated. Results showed that the dewaterability of sludge conditioned with the rice husk flour and FeCl_3(138.09 g/kg dry solids, DS) was much superior to the sludge conditioned with rice husk flour, and the optimal dosage of rice husk flour was 70%. With the optimal rice husk dosage, the sludge specific resistance to filtration(SRF) decreased by 59.73%, the net sludge solids yield(YN) increased by 45.27%, and the solid content of sludge cake increased from 13.99% to 23.97%, compared with the sludge conditioned with FeCl_3(138.09 g/kg) alone. When the rice husk flour was used to condition sewage sludge combined with FeCl_3(138.09 g/kg), the large cracks were found in the sludge cake easily by an environmental scanning electron microscope(ESEM) and the coefficient of compressibility of sludge cake was decreased to 0.92(the coefficient of compressibility of raw sludge cake and sludge cake conditioned with FeCl_3 alone were 1.21 and 1.08, respectively). So the sludge cake became more incompressible and permeable and the sludge moisture could easily pass through. Therefore, the rice husk flour was proved to play a supportive role as a skeleton builder in the sludge cake for sludge conditioning and dewatering. Surface element contents and zeta potential of rice husk flour tested by an energy-dispersive spectrometry(EDS) and Zetasizer Nano analyzer showed that the stability of sludge colloidal system was not destroyed by charge neutralization, and the sludge particles could not congregate with each other under the treatment with rice husk flour alone, it might be the main reason why adding rice husk flour and FeCl_3 was superior to adding rice husk flour alone for sludge conditioning and dewatering. Moreover, adding rice husk flour could reduce turbidity and SCOD of filtrate(the turbidity decreased from 11.89 NTU to 2.91 NTU and SCOD decreased from 664.87 to 79.93 mg/L, respectively) because the rice husk flour addition might adsorb the pollutants in sludge supernatant. As important indices of water quality, the reduction of turbidity and SCOD was benefited to further filtrate treatment because of the possible significant reduction of difficulty and cost, that is to say that adding rice husk flour as a conditioner aid can also improve the quality of filtrate for further filtrate treatment. Therefore, using rice husk flour to condition sludge is economically feasible and promising.
At present, finding valuable application of rice husk should be targeted for further research, and how to deal with sewage sludge has become an issue that requires urgent attention. In this study, rice husk flour, an agricultural waste material, was used to condition sludge and enhance sludge dewaterability. The effect of rice husk flour dosage on sludge dewaterability was investigated, and the surface element content and main components of rice husk flour and the microstructure of sludge cakes was investigated to analyze conditioning mechanisms. In addition, the effect of adding rice husk flour on turbidity and soluble chemical oxygen demand(SCOD) of sludge filtrate were also investigated, the advantages of adding rice husk flour for future filtrate treatment were evaluated. Results showed that the dewaterability of sludge conditioned with the rice husk flour and FeCl_3(138.09 g/kg dry solids, DS) was much superior to the sludge conditioned with rice husk flour, and the optimal dosage of rice husk flour was 70%. With the optimal rice husk dosage, the sludge specific resistance to filtration(SRF) decreased by 59.73%, the net sludge solids yield(YN) increased by 45.27%, and the solid content of sludge cake increased from 13.99% to 23.97%, compared with the sludge conditioned with FeCl_3(138.09 g/kg) alone. When the rice husk flour was used to condition sewage sludge combined with FeCl_3(138.09 g/kg), the large cracks were found in the sludge cake easily by an environmental scanning electron microscope(ESEM) and the coefficient of compressibility of sludge cake was decreased to 0.92(the coefficient of compressibility of raw sludge cake and sludge cake conditioned with FeCl_3 alone were 1.21 and 1.08, respectively). So the sludge cake became more incompressible and permeable and the sludge moisture could easily pass through. Therefore, the rice husk flour was proved to play a supportive role as a skeleton builder in the sludge cake for sludge conditioning and dewatering. Surface element contents and zeta potential of rice husk flour tested by an energy-dispersive spectrometry(EDS) and Zetasizer Nano analyzer showed that the stability of sludge colloidal system was not destroyed by charge neutralization, and the sludge particles could not congregate with each other under the treatment with rice husk flour alone, it might be the main reason why adding rice husk flour and FeCl_3 was superior to adding rice husk flour alone for sludge conditioning and dewatering. Moreover, adding rice husk flour could reduce turbidity and SCOD of filtrate(the turbidity decreased from 11.89 NTU to 2.91 NTU and SCOD decreased from 664.87 to 79.93 mg/L, respectively) because the rice husk flour addition might adsorb the pollutants in sludge supernatant. As important indices of water quality, the reduction of turbidity and SCOD was benefited to further filtrate treatment because of the possible significant reduction of difficulty and cost, that is to say that adding rice husk flour as a conditioner aid can also improve the quality of filtrate for further filtrate treatment. Therefore, using rice husk flour to condition sludge is economically feasible and promising.
引文
[1]Jung D S,Ryou M H,Sung Y J,et al.Recycling rice husks for high-capacity lithium battery anodes[J].Procceedings of The National Academy of Sciences of The United States of America,2013,110(30):12229-12234.
[2]刘斌,顾洁,邱盼,等.稻壳活性炭对水中染料的吸附特性及其回收利用[J].环境科学学报,2014,34(9):2256-2264.Liu Bin,Gu Jie,Qiu Pan,et al.Adsorption characteristics of dye inaqueous solution by activated carbon from rice husks and its recycling[J].Acta Scientiae Circumstantiae,2014,34(9):2256-2264.(in Chinese with English abstract)
[3]Kalderis D,Bethanis S,Paraskeva P,et al.Production of activated carbon from bagasse and rice husk by a single-stage chemical activation method at low retention times[J].Bioresource Technology,2008,99(15):6809-6816.
[4]王秋菊,刘峰,常本超,等.稻壳深施改良苏打碱土理化性质长期效应[J].农业工程学报,2018,34(2):147-152.Wang Qiuju,Liu Feng,Chang Benchao,et al.Long-term effect of deep application of rice husk improving physical and chemical properties of soda alkaline soil[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(2):147-152.(in Chinese with English abstract)
[5]Zhang Panyue,Wan Tian,Zhang Guangming.Enhancement of bio-sludge gravitational thickening with weak ultrasound[J].International Journal of Environmental Science and Technology,2012,9(2):287-296.
[6]何艳华,蒋志坚,宋联,等.粉煤灰替代石灰进行污泥深度脱水的中试研究[J].环境工程学报,2017,11(4):2447-2451.He Yanhua,Jiang Zhijian,Song Lian,et al.Pilot-scale study on deep dewatering process of sewage sludge by fly ash and quicklime[J].Chinese Journal of Environmental Engineering,2017,11(4):2447-2451.(in Chinese with English abstract)
[7]姚尚安,孙同华,瞿赞,等.污泥深度机械脱水的优化研究[J].环境科学与技术,2014,37(3):126-131.Yao Shang’an,Sun Tonghua,Qu Zan,et al.Optimization research of mechanical dewatering of sludge with high pressure[J].Environmental Science&Technology,2014,37(3):126-131.(in Chinese with English abstract)
[8]莫群青,邵立明,吕凡,等.纤维调理对污水厂污泥脱水性能的影响[J].四川环境,2015,34(4):27-31.Mo Qunqing,Shao Liming,Lv Fan,et al.Effect of fiber conditioning on sewage sludge dewaterability[J].Sichuan Environment,2015,34(4):27-31.(in Chinese with English abstract)
[9]Qi Ying,Thapa K B,Hoadley A F A.Application of filtration aids for improving sludge dewatering properties:Areview[J].Chemical Engineering Journal,2011,171(2):373-384.
[10]Wu Boran,Su Lianghu,Dai Xiaohu,et al.Development of montmorillonite-supported nano CaO2 for enhanced dewatering of waste-activated sludge by synergistic effects of filtration aid and peroxidation[J].Chemical Engineering Journal,2017,3077:418-426.
[11]Wu Yan,Zhang Panyue,Zeng Guangming,et al.Enhancing sewage sludge dewaterability by a skeleton builder:Biochar produced from sludge cake conditioned with rice husk flour and FeCl3[J].ACS Sustainable Chemistry&Engineering,2016,4(10):5711-5717.
[12]Khalid N,Rahman A,Ahmad S,et al.Adsorption behavior of rice husk for the decontamination of chromium from industrial effluents[J].Journal of Radioanalytical and Nuclear Chemistry,1999,240(3):775-781.
[13]王晓萌,王鑫,杨明辉,等.铝、铁、钛3种金属盐基混凝剂调理污泥的性能比较[J].环境科学,2018,39(5):2274-2282.Wang Xiaomeng,Wang Xin,Yang Minghui,et al.Sludge conditioning performance of polyaluminum,polyferric,and titanium xerogel coagulants[J].Environmental Science,2018,39(5):2274-2282.(in Chinese with English abstract)
[14]Li Yifu,Yuan Xingzhong,Wu Zhibin,et al.Enhancing the sludge dewaterability by electrolysis/electrocoagulation combined with zero-valent iron activated persulfate process[J].Chemical Engineering Journal,2016,303:636-645.
[15]吴炜,安莹,唐建国,等.聚硅硫酸铁改善活性污泥过滤脱水性能研究[J].环境工程,2018,36(5):68-72.Wu Wei,An Ying,Tang Jianguo,et al.Enhancement of waste activated sludge dewatering performance with polymeric ferric silicate sulfate[J].Environmental Engineering,2018,36(5):68-72.(in Chinese with English abstract)
[16]骆丽宁,王丽娟,杨敏,等.氧化-铁盐絮凝联合对调理改善污泥脱水性能的影响[J].环境工程学报,2018,12(2):630-637.Luo Lining,Wang Lijuan,Yang Min,et al.Combined effects of oxidation and iron coagulation on sludge co-conditioning and dehydration performance[J].Chinese Journal of Environmental Engineering,2018,12(2):630-637.(in Chinese with English abstract)
[17]Rebhun M,Zall J,Galil N.Net sludge solids yield as an expression of filterability for conditioner optimization[J].Journal(Water Pollution Control Federation),1989,61(1):52-54.
[18]Ning Xunan,Luo Haijian,Liang Xiujuan,et al.Effects of tannery sludge incineration slag pretreatment on sludge dewaterability[J].Chemical Engineering Journal,2013,221:1-7.
[19]黄绍松,梁嘉林,张斯玮,等.Fenton氧化联合氧化钙调理对污泥脱水的机理研究[J].环境科学学报,2018,38(5):1906-1919.Huang Shaosong,Liang Jialin,Zhang Siwei,et al.Acomprehensive mechanism for deeply dewatering sludge using Fenton's reagent with lime[J].Acta Scientiae Circumstantiae,2018,38(5):1906-1919.(in Chinese with English abstract)
[20]Zhang Hao,Yang Jiakuan,Yu Wenbo,et al.Mechanism of red mud combined with Fenton's reagent in sewage sludge conditioning[J].Water Research,2014,59C:239-247.
[21]邓云,陈建国,徐卫东.稻壳粉吸附铅、镉离子能力研究[J].环境科学与技术,2016,39(S2):146-149.Deng Yun,Chen Jianguo,Xu Weidong.Study on adsorptive performance of plumbum,cadmium ions by rice husk[J].Environmental Science&Technology,2016,39(S2):146-149.(in Chinese with English abstract)
[22]万云雷,韩红霞,高梦祥.稻谷吸附特性及安全水分研究[J].食品科技,2015,40(12):124-127.Wan Yunlei,Han Hongxia,Gao Mengxiang.Moisture adsorption characteristics and safe moisture of rice[J].Food Science and Technology,2015,40(12):124-127.(in Chinese with English abstract)
[2]刘斌,顾洁,邱盼,等.稻壳活性炭对水中染料的吸附特性及其回收利用[J].环境科学学报,2014,34(9):2256-2264.Liu Bin,Gu Jie,Qiu Pan,et al.Adsorption characteristics of dye inaqueous solution by activated carbon from rice husks and its recycling[J].Acta Scientiae Circumstantiae,2014,34(9):2256-2264.(in Chinese with English abstract)
[3]Kalderis D,Bethanis S,Paraskeva P,et al.Production of activated carbon from bagasse and rice husk by a single-stage chemical activation method at low retention times[J].Bioresource Technology,2008,99(15):6809-6816.
[4]王秋菊,刘峰,常本超,等.稻壳深施改良苏打碱土理化性质长期效应[J].农业工程学报,2018,34(2):147-152.Wang Qiuju,Liu Feng,Chang Benchao,et al.Long-term effect of deep application of rice husk improving physical and chemical properties of soda alkaline soil[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(2):147-152.(in Chinese with English abstract)
[5]Zhang Panyue,Wan Tian,Zhang Guangming.Enhancement of bio-sludge gravitational thickening with weak ultrasound[J].International Journal of Environmental Science and Technology,2012,9(2):287-296.
[6]何艳华,蒋志坚,宋联,等.粉煤灰替代石灰进行污泥深度脱水的中试研究[J].环境工程学报,2017,11(4):2447-2451.He Yanhua,Jiang Zhijian,Song Lian,et al.Pilot-scale study on deep dewatering process of sewage sludge by fly ash and quicklime[J].Chinese Journal of Environmental Engineering,2017,11(4):2447-2451.(in Chinese with English abstract)
[7]姚尚安,孙同华,瞿赞,等.污泥深度机械脱水的优化研究[J].环境科学与技术,2014,37(3):126-131.Yao Shang’an,Sun Tonghua,Qu Zan,et al.Optimization research of mechanical dewatering of sludge with high pressure[J].Environmental Science&Technology,2014,37(3):126-131.(in Chinese with English abstract)
[8]莫群青,邵立明,吕凡,等.纤维调理对污水厂污泥脱水性能的影响[J].四川环境,2015,34(4):27-31.Mo Qunqing,Shao Liming,Lv Fan,et al.Effect of fiber conditioning on sewage sludge dewaterability[J].Sichuan Environment,2015,34(4):27-31.(in Chinese with English abstract)
[9]Qi Ying,Thapa K B,Hoadley A F A.Application of filtration aids for improving sludge dewatering properties:Areview[J].Chemical Engineering Journal,2011,171(2):373-384.
[10]Wu Boran,Su Lianghu,Dai Xiaohu,et al.Development of montmorillonite-supported nano CaO2 for enhanced dewatering of waste-activated sludge by synergistic effects of filtration aid and peroxidation[J].Chemical Engineering Journal,2017,3077:418-426.
[11]Wu Yan,Zhang Panyue,Zeng Guangming,et al.Enhancing sewage sludge dewaterability by a skeleton builder:Biochar produced from sludge cake conditioned with rice husk flour and FeCl3[J].ACS Sustainable Chemistry&Engineering,2016,4(10):5711-5717.
[12]Khalid N,Rahman A,Ahmad S,et al.Adsorption behavior of rice husk for the decontamination of chromium from industrial effluents[J].Journal of Radioanalytical and Nuclear Chemistry,1999,240(3):775-781.
[13]王晓萌,王鑫,杨明辉,等.铝、铁、钛3种金属盐基混凝剂调理污泥的性能比较[J].环境科学,2018,39(5):2274-2282.Wang Xiaomeng,Wang Xin,Yang Minghui,et al.Sludge conditioning performance of polyaluminum,polyferric,and titanium xerogel coagulants[J].Environmental Science,2018,39(5):2274-2282.(in Chinese with English abstract)
[14]Li Yifu,Yuan Xingzhong,Wu Zhibin,et al.Enhancing the sludge dewaterability by electrolysis/electrocoagulation combined with zero-valent iron activated persulfate process[J].Chemical Engineering Journal,2016,303:636-645.
[15]吴炜,安莹,唐建国,等.聚硅硫酸铁改善活性污泥过滤脱水性能研究[J].环境工程,2018,36(5):68-72.Wu Wei,An Ying,Tang Jianguo,et al.Enhancement of waste activated sludge dewatering performance with polymeric ferric silicate sulfate[J].Environmental Engineering,2018,36(5):68-72.(in Chinese with English abstract)
[16]骆丽宁,王丽娟,杨敏,等.氧化-铁盐絮凝联合对调理改善污泥脱水性能的影响[J].环境工程学报,2018,12(2):630-637.Luo Lining,Wang Lijuan,Yang Min,et al.Combined effects of oxidation and iron coagulation on sludge co-conditioning and dehydration performance[J].Chinese Journal of Environmental Engineering,2018,12(2):630-637.(in Chinese with English abstract)
[17]Rebhun M,Zall J,Galil N.Net sludge solids yield as an expression of filterability for conditioner optimization[J].Journal(Water Pollution Control Federation),1989,61(1):52-54.
[18]Ning Xunan,Luo Haijian,Liang Xiujuan,et al.Effects of tannery sludge incineration slag pretreatment on sludge dewaterability[J].Chemical Engineering Journal,2013,221:1-7.
[19]黄绍松,梁嘉林,张斯玮,等.Fenton氧化联合氧化钙调理对污泥脱水的机理研究[J].环境科学学报,2018,38(5):1906-1919.Huang Shaosong,Liang Jialin,Zhang Siwei,et al.Acomprehensive mechanism for deeply dewatering sludge using Fenton's reagent with lime[J].Acta Scientiae Circumstantiae,2018,38(5):1906-1919.(in Chinese with English abstract)
[20]Zhang Hao,Yang Jiakuan,Yu Wenbo,et al.Mechanism of red mud combined with Fenton's reagent in sewage sludge conditioning[J].Water Research,2014,59C:239-247.
[21]邓云,陈建国,徐卫东.稻壳粉吸附铅、镉离子能力研究[J].环境科学与技术,2016,39(S2):146-149.Deng Yun,Chen Jianguo,Xu Weidong.Study on adsorptive performance of plumbum,cadmium ions by rice husk[J].Environmental Science&Technology,2016,39(S2):146-149.(in Chinese with English abstract)
[22]万云雷,韩红霞,高梦祥.稻谷吸附特性及安全水分研究[J].食品科技,2015,40(12):124-127.Wan Yunlei,Han Hongxia,Gao Mengxiang.Moisture adsorption characteristics and safe moisture of rice[J].Food Science and Technology,2015,40(12):124-127.(in Chinese with English abstract)