Hydrothermal carbonization of sewage sludge: The effect of feed-water pH on fate and risk of heavy metals in hydrochars

2016 ◽  
Vol 218 ◽  
pp. 183-188 ◽  
Author(s):  
Yunbo Zhai ◽  
Xiangmin Liu ◽  
Yun Zhu ◽  
Chuan Peng ◽  
Tengfei Wang ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Feed Water ◽  
Water Ph

scholarly journals The Migration and Transformation of Heavy Metals in Sewage Sludge during Hydrothermal Carbonization Combined with Combustion

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Meng Liu ◽  
Yufeng Duan ◽  
Kagiso Bikane ◽  
Liang Zhao
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Residence Time ◽  
Combustion Process ◽  
Hydrothermal Carbonization ◽  
Positive Influence ◽  
Arsenic Compounds ◽  
Weakly Bound ◽  
Residual Rate ◽  
Leaching Risk

The migration and transformation behaviors of heavy metals (HMs), including Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb, during the hydrothermal carbonization (HTC) of sewage sludge (SS) were investigated. The immobilization of HMs during the combustion of solid residual (SR) produced from HTC of SS was also analyzed. With increasing HTC temperature and residence time, the majority of HMs (except As) accumulated in the SR. The residual rate of As in the SR decreased from 73.95% to 56.74% when the residence time was increased from 1h to 3h and reduced significantly from 73.95% to 37.48% when the temperature increased from 220°C to 280°C, implying that numerous arsenic compounds dissolved into liquid phase products. Although the HTC process has a positive influence on the transformation of HMs from weakly bound fractions to the more stable fractions, the exchangeable and reducible fractions of Mn, Zn, As, and Cd in the SR were still high. In addition, the leached amounts of Zn and As were high (14.61 and 6.16 mg/kg, respectively) and showed a high leaching risk to the environment. An increase in HTC temperature and residence time led to an increase of the residual rate of HMs in the combustion residual of SR, implying that the HTC process promotes the stabilization of HMs in the combustion process.

Effect of hydrothermal carbonization on migration and environmental risk of heavy metals in sewage sludge during pyrolysis

2018 ◽  
Vol 247 ◽  
pp. 282-290 ◽  
Author(s):  
Tingting Liu ◽  
Zhengang Liu ◽  
Qingfu Zheng ◽  
Qianqian Lang ◽  
Yu Xia ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Environmental Risk ◽  
Hydrothermal Carbonization

scholarly journals Influence of Acids and Alkali as Additives on Hydrothermally Treating Sewage Sludge: Influence on Phosphorus Recovery, Yield, and Energy Value of Hydrochar

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 618
Author(s):  
Vicky Shettigondahalli Ekanthalu ◽  
Satyanarayana Narra ◽  
Jan Sprafke ◽  
Michael Nelles
Keyword(s):  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Negative Influence ◽  
Proximate Analysis ◽  
Phosphorus Recovery ◽  
Feed Water ◽  
Temperature Dependent ◽  
Heating Value ◽  
Management Processes ◽  
Sewage Sludge Management

The high moisture content present in sewage sludge hinders the use of sewage sludge in incineration or energy application. This limitation of moisture present in sewage sludge can be obviated by using the hydrothermal carbonization (HTC) process. In sewage sludge management, the HTC process requires less energy compared to other conventional thermo–chemical management processes. The HTC process produces energy-rich hydrochar products and simultaneously enables phosphorus recovery. This study investigates the influence of organic acids, inorganic acid, and alkali as additives on phosphorus transformation, yield, proximate analysis and the heating value of subsequently produced hydrochar. The analysis includes various process temperatures (200 °C, 220 °C, and 240 °C) in the presence of deionized water, acids (0.1 M and 0.25 M; H2SO4, HCOOH, CH3COOH), and alkali (0.1 M and 0.25 M; NaOH) solutions as feed water. The results show that phosphorus leaching into the process-water, hydrochar yield, proximate analysis, and the heating value of produced hydrochar is pH- and temperature-dependent, and particularly significant in the presence of H2SO4. In contrast, utilization of H2SO4 and NaOH as an additive has a negative influence on the heating value of produced hydrochar.

Predicted Solution Phase Forms of Heavy Metals in Sewage Sludge‐Treated Soils

1982 ◽  
Vol 11 (2) ◽  
pp. 182-186 ◽  
Author(s):  
W. E. Emmerich ◽  
L. J. Lund ◽  
A. L. Page ◽  
A. C. Chang
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Solution Phase
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