Dewaterability enhancement and heavy metals immobilization by pig manure biochar addition during hydrothermal treatment of sewage sludge
Hydrothermal treatment (HTT) of sewage sludge (SS) with pig manure biochar (PMB) addition at 160–200 °C was conducted in this study. The effects of PMB addition on the dewaterability of SS and the speciation evolution, leaching toxicity, and potential ecological risk of heavy metals were investigated. The results showed that the solid contents of the filter cakes after adding PMB increased from 20.24%, 24.03%, and 28.69% to 21.57%, 27.69%, and 32.91% at 160, 180, and 200 °C, respectively, compared with traditional HTT of SS. Furthermore, PMB could reduce the bioavailable fractions of Cr, Ni, As, and Cd in the filter cakes obtained at 160 and 180 °C compared with the theoretical value. The leaching toxicity of heavy metals in the filter cakes after adding PMB decreased significantly at 160 and 180 °C and the potential ecological risk index (RI) declined from 62.13 and 44.83 to 55.93 and 42.11, respectively. The obtained filter cake had low potential ecological risk when used in the environment. The mechanisms on the improvement of the dewaterability and heavy metals immobilization were related that PMB acted as the skeleton builder providing the outflow path for free water and implanting heavy metals into SS structure. And the optimal results were obtained at 180 °C during HTT of SS with PMB addition. This work provides a novel and effective method for the treatment of SS.
KeywordsSewage sludge Hydrothermal treatment Pig manure biochar Dewaterability Heavy metals Skeleton builder
Pig manure biochar
European Community Bureau of Reference
Toxicity characteristic leaching procedure
This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA23020500), the Natural Science Foundation of Fujian Province (2019J01135), the China-Japanese Research Cooperative Program (2016YFE0118000), the Industry Leading Key Projects of Fujian Province (2015H0044), the Scientific and Technological Major Special Project of Tianjin City (16YFXTSF00420) and the Key Project of Young Talent of the Institute of Urban Environment, Chinese Academy of Sciences (IUEZD201402).
- Antonkiewicz J, Pełka R, Bik-Małodzińska M, Żukowska G, Gleń-Karolczyk K (2018) The effect of cellulose production waste and municipal sewage sludge on biomass and heavy metal uptake by a plant mixture. Environ Sci Pollut R 25:31101–31112. https://doi.org/10.1007/s11356-018-3109-5 CrossRefGoogle Scholar
- Jin JW, Li YN, Zhang JY, Wu SC, Cao YC, Liang P, Zhang J, Wong MH, Wang MY, Shan SD, Christie P (2016) Influence of pyrolysis temperature on properties and environmental safety of heavy metals in biochars derived from municipal sewage sludge. J Hazard Mater 320:417–426. https://doi.org/10.1016/j.jhazmat.2016.08.050 CrossRefGoogle Scholar
- Li CX, Wang XD, Zhang GY, Yu GW, Lin JJ, Wang Y (2017) Hydrothermal and alkaline hydrothermal pretreatments plus anaerobic digestion of sewage sludge for dewatering and biogas production: bench-scale research and pilot-scale verification. Water Res 117:49–57. https://doi.org/10.1016/j.watres.2017.03.047 CrossRefGoogle Scholar
- Li CX, Wang XD, Zhang GY, Li J, Li ZW, Yu GW, Wang Y (2018a) A process combining hydrothermal pretreatment, anaerobic digestion and pyrolysis for sewage sludge dewatering and co-production of biogas and biochar: Pilot-scale verification. Bioresour Technol 254:187–193. https://doi.org/10.1016/j.biortech.2018.01.045 CrossRefGoogle Scholar
- Suanon F, Chi QQ, Yang XY, Wang HJ, Rashid A, Asefi B, Mama D, Yu CP, Sun Q (2018) Diagnosis and ecotoxicological risk assessment of 49 elements in sludge from wastewater treatment plants of Chongqing and Xiamen cities, China. Environ Sci Pollut R 25:29006–29,016. https://doi.org/10.1007/s11356-018-2888-z CrossRefGoogle Scholar
- Wang T, Sun HW, Ren XH, Li B, Mao HJ (2017) Evaluation of biochars from different stock materials as carriers of bacterial strain for remediation of heavy metal-contaminated soil. Sci Rep 7(12114). https://doi.org/10.1038/s41598-017-12503-3
- Wu Y, Zhang PY, Zeng GM, Ye J, Zhang HB, Fang W, Liu JB (2016) Enhancing sewage sludge dewaterability by a skeleton builder: biochar produced from sludge cake conditioned with rice husk flour and FeCl3. ACS Sustain Chem Eng 4:5711–5717. https://doi.org/10.1021/acssuschemeng.6b01654 CrossRefGoogle Scholar
- Yu GW, Wang Y, Zhang X, Tang XD, Li J, Yu Z, Wang XD, You FT (2016) Influence of sludge and sludge biochar on the transfer of available heavy metals in soil. J Solid Waste Technol Manage 42:814–823Google Scholar
- Zhai YB, Chen HM, Xu BB, Xiang BB, Chen Z, Li CT, Zeng GM (2014) Influence of sewage sludge-based activated carbon and temperature on the liquefaction of sewage sludge: yield and composition of bio-oil, immobilization and risk assessment of heavy metals. Bioresour Technol 159:72–79. https://doi.org/10.1016/j.biortech.2014.02.049 CrossRefGoogle Scholar