Study on electro-osmotic dewatering of sludge assisted by activated carbon/graphite

doi:10.11949/0438-1157.20230354

Abstract

Abstract:

Using activated carbon, graphite, and their mixtures in different proportions as additives, the mechanism of influence of different proportions of additives on sludge electro-osmotic dewatering performance and filtrate quality (total organic carbon (TOC) content, heavy metal concentration, organic composition, etc.) was studied. The results indicated that both graphite and activated carbon can increase the dewatering performance and conductivity of sludge. Compared with graphite, activated carbon showed the most obvious impact on lowering the moisture content of sludge cake. The optimal dewatering performance was achieved when the dose of carbon materials was set at 5% of dry sludge mass (DS), and the real moisture content of sludge cake was decreased from 46.0%(mass) to 42.2%(mass), while the apparent moisture content was decreased to 41.0%(mass). The addition of activated carbon or graphite can significantly reduce the TOC and heavy metal concentration of cathodic electrodialysis, the effect of activated carbon is the best, and the effect of graphite is the weakest. The TOC content of the cathodic filtrate decreased from 3740.4 mg/L to 2160.0 mg/L when the dose of activated carbon was increased from 0%DS to 20%DS, whereas the concentrations of heavy metals like Cu, Mn, Cr, Ni, Cd, Zn, Hg, and Pb decreased by 57%—100%. The research findings will provide fundamental data support for enhancing sludge electro-dewatering through carbon-containing materials and establish a theoretical foundation for the promotion and application of sludge electro-osmotic dewatering technology.

Key words: electro-osmosis, activated carbon, graphite, sludge dewatering, filtrate, waste treatment, electrochemistry

摘要：

以活性炭、石墨以及两者不同比例的混合物为添加剂，研究了不同配比添加剂对污泥电渗脱水性能以及滤液品质［总有机碳（TOC）含量、重金属浓度、有机物组成等］的影响机理。结果表明，活性炭与石墨都能够提升污泥的脱水性与导电性，其中相较于石墨，单独投加活性炭对泥饼的含水率降低最为明显，当投加量为5%污泥干重（DS）时，脱水效果最优，泥饼真实含水率由无投加时的46.0%（质量）降为42.2%（质量），污泥表观含水率降为41.0%（质量）。活性炭或石墨投加可显著降低阴极电渗滤液的TOC和重金属浓度，其中活性炭效果最优，石墨效果最弱。当活性炭投加量从0%DS增加至20%DS时，阴极滤液TOC含量从3740.4 mg/L降至2160.0 mg/L，而Cu、Mn、Cr、Ni、Cd、Zn、Hg和Pb等重金属元素浓度的降幅为57%~100%。研究成果将为含碳材料强化污泥电渗脱水提供基础数据支撑，并为污泥电渗脱水技术推广应用奠定理论基础。

关键词: 电渗透, 活性炭, 石墨, 污泥脱水, 滤液, 废物处理, 电化学

CLC Number:

X 705

Yuanhao QU, Wenyi DENG, Xiaodan XIE, Yaxin SU. Study on electro-osmotic dewatering of sludge assisted by activated carbon/graphite[J]. CIESC Journal, 2023, 74(7): 3038-3050.

屈园浩, 邓文义, 谢晓丹, 苏亚欣. 活性炭/石墨辅助污泥电渗脱水研究[J]. 化工学报, 2023, 74(7): 3038-3050.

Figures/Tables 12

Table 1 Basic properties of sludge

含水率/%（质量）	pH	电导率/(μS/cm)	灰分（干基）/%（质量）	挥发分（干基）/%（质量）	固定碳（干基）/%（质量）
80.0±0.5	7.2±0.1	1175±50	45.9±0.5	47.8±0.5	6.3±0.5

Fig.1 Electro-osmotic dewatering device1—pressure sensor; 2—thermocouple; 3—sealing apron; 4—ruthenium iridium titanium anode plate; 5—piston; 6—filter cloth; 7—sludge sample; 8—bottom filter plate; 9—stainless steel cathode mesh; 10—beaker; 11—electronic balance; 12—bracket; 13—base; 14—jack; 15—insulating sleeve; 16—metal sleeve; 17—current probe; 18—signal generator; 19—oscilloscope; 20—power amplifier; 21—digital display of pressure value; 22—digital display of temperature; 23—voltmeter

Table 2 The results of pre-experiments

粒径/mm	含水率/%（质量）
<0.056	41.8±0.2
0.056~0.1	41.0±0.2
0.1~0.335	41.3±0.2
0.335~0.5	42.0±0.2
0.5~0.8	42.5±0.2
0.8~1	42.1±0.2

Fig.2 Water content of sewage sludge (a), filtrate content of cathode and anode (b) and pH of filtrate (c) from electro-osmotic dewatering with different percentage of additives, and energy consumption change curve (d)

Fig.3 Flowrate of cathodic filtrate

Fig.4 Influence of dosage of activated carbon and graphite on the current of sludge during electro-osmotic dewatering

Fig.5 Effect of carbon materials on sludge temperature

Fig.6 Effect of carbon material on the voltage between the two sides of sludge cake

Fig.7 TOC values of cathodic filtrate from sludge electro-osmotic dewatering

Fig.8 3D-EEM spectra of cathodic filtrate [(a)—(e)], and variation of fluorescence intensity with additives [(g), (f)]

Fig.9 Heavy metal contents in cathodic filtrate

Fig.10 Morphology of anode [(a)—(e)] and cathode [(f)—(j)] surfaces of sludge cake

References 33

1	戴晓虎. 我国污泥处理处置现状及发展趋势[J]. 科学, 2020, 72(6): 30-34, 4.
	Dai X H. Applications and perspectives of sludge treatment and disposal in China[J]. Science, 2020, 72(6): 30-34, 4.
2	Kacprzak M, Neczaj E, Fijałkowski K, et al. Sewage sludge disposal strategies for sustainable development [J]. Environmental Research, 2017, 156: 39-46.
3	Yang G, Zhang G M, Wang H C. Current state of sludge production, management, treatment and disposal in China[J]. Water Research, 2015, 78: 60-73.
4	Grobelak A, Czerwińska K, Murtaś A. General considerations on sludge disposal, industrial and municipal sludge[M]//Industrial and Municipal Sludge. Amsterdam: Elsevier, 2019: 135-153.
5	Qian X, Zhou X Q, Wu J D, et al. Electro-dewatering of sewage sludge: influence of combined action of constant current and constant voltage on performance and energy consumption[J]. Science of the Total Environment, 2019, 667: 751-760.
6	Mahmoud A, Olivier J, Vaxelaire J, et al. Electrical field: a historical review of its application and contributions in wastewater sludge dewatering[J]. Water Research, 2010, 44(8): 2381-2407.
7	Rao B Q, Wang G Q, Xu P. Recent advances in sludge dewatering and drying technology[J]. Drying Technology, 2022, 40(15): 3049-3063.
8	Wei Y J, Zhou X Q, Zhou L, et al. Electro-dewatering of sewage sludge: effect of near-anode sludge modification with different dosages of calcium oxide[J]. Environmental Research, 2020, 186: 109487.
9	王晗. 电渗法在污泥脱水领域应用的影响因素[J]. 中国环保产业, 2022(11): 37-39, 42.
	Wang H. Factors influencing the application of electroosmosis in the field of sludge dewatering[J]. China Environmental Protection Industry, 2022 (11): 37-39, 42.
10	同帜, 王瑞露, 曹秉帝, 等. 炭材料调理改善活性污泥脱水性能的影响机制[J]. 环境工程学报, 2018, 12(7): 2094-2105.
	Tong Z, Wang R L, Cao B D, et al. Mechanism of carbon conditioning for improving dewatering performance of activated sludge[J]. Chinese Journal of Environmental Engineering, 2018, 12(7): 2094-2105.
11	Mahmoud A, Hoadley A F A, Conrardy J B, et al. Influence of process operating parameters on dryness level and energy saving during wastewater sludge electro-dewatering[J]. Water Research, 2016, 103: 109-123.
12	Deng W Y, Lai Z C, Hu M H, et al. Effects of frequency and duty cycle of pulsating direct current on the electro-dewatering performance of sewage sludge[J]. Chemosphere, 2020, 243: 125372.
13	Liu C Y, Zhou X Q, Zhou L, et al. Enhancement of sludge electro-dewatering by anthracite powder modification[J]. Environmental Research, 2021, 201: 111510.
14	Cao B D, Wang R L, Zhang W J, et al. Carbon-based materials reinforced waste activated sludge electro-dewatering for synchronous fuel treatment[J]. Water Research, 2019, 149: 533-542.
15	Dong Y T, Yuan H P, Ge D D, et al. A novel conditioning approach for amelioration of sludge dewaterability using activated carbon strengthening electrochemical oxidation and realized mechanism[J]. Water Research, 2022, 220: 118704.
16	国家质量监督检验检疫总局,国家标准化管理委员会. 煤的工业分析方法: [S]. 北京: 中国标准出版社, 2008.
	General Administration of Quality Supervision, Inspection and Quarantine, Standardization Administration of the People's Republic of China. Proximate analysis of coal: [S]. Beijing: Standards Press of China, 2008.
17	国家市场监督管理总局, 国家标准化管理委员会. 纳米技术碳纳米管粉体电阻率四探针法: [S]. 北京: 中国标准出版社, 2021.
	State Administration for Market Regulation, Standardization Administration of the People's Republic of China. Nanotechnology—Resistivity of carbon nanotube powder—Four probe method: [S]. Beijing: Standards Press of China, 2021.
18	国家质量监督检验检疫总局. 高绝缘电阻测量仪(高阻计)检定规程: [S]. 北京: 中国计量出版社, 2004.
	General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China. Verification Regulation of High Insulation Resistance Meters: [S]. Beijing: China Metrology Publishing House, 2004.
19	中华人民共和国建设部. 城市污水处理厂污泥检验方法: [S]. 北京: 中国标准出版社, 2006.
	Ministry of Construction of the People's Republic of China. Determination method for municipal sludge in wastewater treatment plant: [S]. Beijing: Standards Press of China, 2006.
20	Cao B D, Zhang W J, Du Y J, et al. Compartmentalization of extracellular polymeric substances (EPS) solubilization and cake microstructure in relation to wastewater sludge dewatering behavior assisted by horizontal electric field: effect of operating conditions[J]. Water Research, 2018, 130: 363-375.
21	Citeau M, Larue O, Vorobiev E. Influence of salt, pH and polyelectrolyte on the pressure electro-dewatering of sewage sludge[J]. Water Research, 2011, 45(6): 2167-2180.
22	Clayton S A, Scholes O N, Hoadley A F A, et al. Dewatering of biomaterials by mechanical thermal expression[J]. Drying Technology, 2006, 24(7): 819-834.
23	Lv H, Liu D G, Zhang Y L, et al. Effects of temperature variation on wastewater sludge electro-dewatering[J]. Journal of Cleaner Production, 2019, 214: 873-880.
24	Weber K, Stahl W. Influence of an electric field on filtration in a filter press[J]. Chemical Engineering & Technology: Industrial Chemistry-Plant Equipment-Process Engineering-Biotechnology, 2003, 26(1): 44-48.
25	Weber K, Stahl W. Improvement of filtration kinetics by pressure electrofiltration[J]. Separation and Purification Technology, 2002, 26(1): 69-80.
26	Bergins C, Berger S, Strauß K. Dewatering of fossil fuels and suspensions of ultrafine particles by mechanical/thermal dewatering[J]. Chemical Engineering & Technology, 1999, 22(11): 923-927.
27	Navab-Daneshmand T, Beton R, Hill R J, et al. Impact of Joule heating and pH on biosolids electro-dewatering[J]. Environmental Science & Technology, 2015, 49(9): 5417-5424.
28	Hu S G, Hu J P, Sun Y F, et al. Simultaneous heavy metal removal and sludge deep dewatering with Fe (Ⅱ) assisted electrooxidation technology [J]. Journal of Hazardous Materials, 2021, 405: 124072.
29	王瑞露, 刘相汝, 曹秉帝, 等. 炭材料强化污泥电脱水效果及同步燃料化处理[J]. 中国环境科学, 2018, 38(11): 4120-4129.
	Wang R L, Liu X R, Cao B D, et al. Carbon material reinforced sludge electric-dewatering synchronous fuel treatment[J]. China Environmental Science, 2018, 38(11): 4120-4129.
30	Rao B Q, Su J G, Xu J, et al. Coupling mechanism and parameter optimization of sewage sludge dewatering jointly assisted by electric field and mechanical pressure[J]. Science of the Total Environment, 2022, 817: 152939.
31	Li Y L, Liu L, Li X R, et al. Influence of alternating electric field on deep dewatering of municipal sludge and changes of extracellular polymeric substance during dewatering[J]. Science of the Total Environment, 2022, 842: 156839.
32	李亚林, 刘蕾, 张毅, 等. 电渗透/Fe-过硫酸盐氧化协同强化污泥深度脱水[J]. 化工学报, 2016, 67(9): 4013-4019.
	Li Y L, Liu L, Zhang Y, et al. Coordination of electro-osmotic and Fe-persulfate oxidation process on sewage sludge deep-dewatering[J]. CIESC Journal, 2016, 67(9): 4013-4019.
33	Barton W A, Miller S A, Veal C J. The electrodewatering of sewage sludges[J]. Drying Technology, 1999, 17(3): 498-522.

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