摘要
污泥热解过程中,辅料是影响热解产物性质的主要因素之一.本文研究了添加废弃生物质辅料——稻壳(0、25%、50%)对污泥炭性质、结构和重金属含量、生物有效性及生态风险的影响.实验结果表明,稻壳添加比例为50%时,污泥炭产率及其H/C和O/C比均为最小值,而其pH值和比表面积均达到最大值,污泥炭芳香化程度明显提高.同时,添加稻壳致污泥炭所含重金属存于生物有效态的含量显著降低.通过RAC风险评估,稻壳添加比例为25%时,较原污泥,污泥炭中Cu、Zn、Mn和Ni 4种元素风险水平均有不同程度的减小,而当添加比例为50%时,污泥炭中除Cu元素以外,其余各重金属风险等级均为低风险或无风险.表明污泥与稻壳共热解可有效降低污泥中重金属潜在生态风险水平,且当稻壳添加比例为50%时处理效果最优,本研究结果为污泥与稻壳资源化和无害化利用提供了理论依据.
Auxiliary materials may dramatically influence the characteristic properties of the final product through the pyrolysis of sewage sludge. This paper studied the effects of the addition of rice husk(0, 25% and 50%), a kind of agricultural wastes,on the characteristics including structure and heavy metal contents as well as their bioavailability and relevant ecological risk. The results show that the biochar production rate and ratio of H/C reached the lowest point when the addition dosage of husk was 50%, however, the pH value and total surface area got the maximum values. The addition of rice husk significantly improved the aromatic degree of biochar compared with no husk addition control. Meanwhile, the addition of husk led to a remarkable reduction of the bioavailable heavy metals fractions in the sludge biochar. According to RAC risk assessment, there was no risk level variation of Pb and Ni among the raw sewage sludge, the sludge biochar and the sludge-husk co-pyrolyzed biochar. When the addition rate of rice husk was 25%, the risk level of Cu and Mn was reduced to the middle-risk level from the high-risk level, and Zn and Ni was reached to the low-risk level compared to the raw sludge. When the proportion of risk husk reached to 50%, the risk of Mn declined to the low level. It is shown that the co-pyrolysis of sludge and rice husk could effectively reduce the potential ecological risk level of heavy metals in sludge, and the optimal addition rate of risk husk was 50%. The results of this study may provide theoretical basis for the recycling and harmless utilization of sludge and rice husk.
引文
Cao Y C, Paw?owski A. 2013. Sewage sludge-to-energy approaches based on anaerobic digestion and pyrolysis: Brief overview and energy efficiency assessment[J]. Renewable and Sustainable Energy Reviews, 16: 1657-1665
Chen T, Huang Q, Gao D, et al. 2003. Heavy metal concentrations and their decreasing trends in sewage sludges of China[J]. Acta Scientiae Circumstantiae, 23: 561-569
程伟凤, 李慧, 杨艳琴, 等. 2016. 城市污泥厌氧发酵残渣热解制备生物炭及其氮磷吸附研究[J]. 化工学报, 67 (4): 1541-1548
Dai J, Thierry B, James H R, et al. 2004. Heavy metal accumulation by two earthworm species and its relationship to total and DTPA-extractable metals in soils[J]. Soil Biology and Biochemistry, 36: 91-98
董丽华,李亚男,常素云,等.2009. 沉积物中重金属的形态分析及风险评价[J]. 天津大学学报, 42 (12): 1112-1117
Evita A, George B, Dimitrios K, et al. 2013. Biochar production by sewage sludge pyrolysis[J]. Journal of Analytical and Applied Pyrolysis, 101: 72-78
Hakanson L. 1980. An ecological risk index for aquatic pollution control.a sedimentological approach[J]. Water Research, 14: 975-1001
Hossain M K, Strezov V, Chan K Y, et al. 2011. Influence of pyrolysis temperature on production and nutrient properties of wastewater sludge biochar[J]. Journal of Environmental Management, 92: 223-228
Huang H J, Yuan X Z. 2016. The migration and transformation behaviors of heavy metals during the hydrothermal treatment of sewage sludge[J]. Bioresource Technology, 200: 991-998
黄小河, 张守玉, 杨靖宁, 等. 2017. 准东煤高温燃烧过程中含钙矿物质的转化规律[J]. 化工学报, 68(10):3906-3911
Jin J, Li Y, Zhang J, et al. 2016. Influence of pyrolysis temperature on properties and environmental safety of heavy metals in biochars derived from municipal sewage sludge[J]. Journal of Hazardous Materials, 320: 417-426
Jin J, Wang M, Cao Y, et al. 2017. Cumulative effects of bamboo sawdust addition on pyrolysis of sewage sludge: Biochar properties and environmental risk from metals[J]. Bioresource Technology, 228: 218-226
金俊伟, 2017. 热解及添加生物质辅料对污泥中重金属的固定效应及生态风险评价[D].杭州:浙江农林大学
Kinga B, Anna M, Zofia P S. 2016. The urgent need for risk assessment on the antibiotic resistance spread via sewage sludge land application[J]. Environment International, 87: 49-55
李楠, 单保庆, 唐文忠, 等. 2013. 稻壳活性炭制备及其对磷的吸附[J]. 环境工程学报, 7 (3):1024-1028
林贵英, 陈伟, 刘文质, 等. 2017. 热解温度对稻壳生物炭特性的影响[J]. 沈阳农业大学学报, 48 (4): 456-461
吕娟, 王明峰, 蒋恩臣, 等. 2017. 不同热解温度下稻壳炭的理化特性分析[J]. 可再生能源, 35 (10): 1448-1453
单彩霞. 2016. DTPA浸提法测定土壤中Cu、Zn的含量[J]. 河南水利与南水北调, (8): 100-101
佘跃心, 李锦柱, 曹茂柏, 等. 2016. 稻壳灰及掺稻壳灰混凝土应用研究进展述评[J]. 混凝土, (6): 57-62
Shi W S, Liu C G, Shu Y J, et al. 2013. Synergistic effect of rice husk addition on hydrothermal treatment of sewage sludge: Fate and environmental risk of heavy metals[J]. Bioresource Technology, 149: 496-502
Sing K P, Mohan D, Singh V K, et al. 2005. Studies on distribution and fractionation of heavy metals in Gomtiriver sediments--a tributary of the Ganges, India[J]. Journal of Hydrology, 312: 14-27
孙海勇, 2015. 市政污泥资源化利用技术研究进展[J]. 洁净煤技术, 21: 91-94
王会方, 於朝广, 王涛, 等. 2016. 硅缓解植物重金属毒害积累的研究进展[J]. 云南农业大学学报 (自然科学), 31 (3): 528-535
许振岚, 陈红. 2010. 城市污泥人工土壤中重金属生物有效性及综合毒性研究[J]. 浙江大学学报 (理学版), 37 (3): 300-305
Yuan H R, Lu T, Huang H Y, et al. 2015. Influence of pyrolysis temperature on physical and chemical properties of biochar made from sewage sludge[J]. Journal of Analytical and Applied Pyrolysis, 112: 284-289
Zhang B, Xiong S, Xiao B, et al. 2011. Mechanism of wet sewage sludge pyrolysis in a tubular furnace[J]. International Journal of Hydrogen Energy, 36: 355-363
张辰, 王逸贤, 谭学军, 等. 2017. 城镇污水处理厂污泥处理稳定标准研究[J]. 给水排水, 53 (9): 137-140
Zhang H, Wang X, Deng X, et al. 2013. Characteristics and nutrient values of biochars produced from giant reed at different temperatures[J]. Bioresource Technology, 130: 463-471
Zhang J, Wang M Y, Wu S C, et al. 2016. Land use affects soil organic carbon of paddy soils: empirical evidence from 6280 years BP to present[J]. Journal of Soils and Sediments, 16: 767-776
郑凯琪, 王俊超, 刘姝彤, 等. 2016. 不同热解温度污泥生物炭对Pb2+、Cd2+的吸附特性[J]. 环境工程学报, 10 (12): 7277-7282