Lu Zai-Liang, Li Jiu-Yu, Jiang Jun, Xu Ren-Kou
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Huan Jing Ke Xue. 2012 Oct;33(10):3585-91.
Biochars were prepared from wastewater sludge from two wastewater treatment plants in Nanjing using a pyrolysis method at 300, 500 and 700 degrees C. The properties of the biochars were measured, and their amelioration effects on the acidity of a red soil and environmental risk of application of sludge biochars were examined to evaluate the possibility of agricultural application of wastewater sludge biochars in red soils. Results indicated that incorporation of both sludge and sludge biochar increased soil pH due to the alkalinity of sludge and sludge biochar, and the mineralization of organic N and nitrification of ammonium N from wastewater sludge induced soil pH fluctuated during incubation. The amelioration effects of biochars generated at 500 and 700 degrees C on the soil were significantly greater than that of sludge significantly. Sludge and sludge biochar contain ample base cations of Ca2+, Mg2+, K+ and Na+ and thus incorporation of sludge and sludge biochar increased the contents of soil exchangeable base cations and decreased soil exchangeable aluminum and H+. Contents of heavy metals in sludge biochars were greater than these in their feedstock sludge, while the contents of Cu, Pb, Ni and As in sludge biochars were lower than the standard values of heavy metals were wastewater sludge for agricultural use in acid soils in China except for Zn and Cd. The contents of available forms of heavy metals in the biochars generated from sludge from Chengdong wastewater treatment plant was lower than these in the corresponding sludge, suggesting that pyrolysis proceed decreased the activity of heavy metals in wastewater sludge. After 90-day incubation of the soil with sludge and sludge biochar, the differences in the contents of soil available heavy metals were not significant between the biochars and their feedstock sludge from Jiangxizhou wastewater treatment plant, and the contents in the treatments with biochars added was lower than these in the treatments with the corresponding sludge from Chengdong wastewater treatment plant for most of heavy metals. It can be concluded that the biochars from wastewater sludge could be used as soil amendments to adjust soil acidity. Application of sludge biochars did not increase activity and availability of heavy metals compared with direct incorporation of the sludge.
采用热解方法，在300、500和700摄氏度下，以南京两座污水处理厂的废水污泥为原料制备生物炭。测定了生物炭的性质，研究了其对红壤酸度的改良效果以及污泥生物炭施用的环境风险，以评估废水污泥生物炭在红壤中农业应用的可能性。结果表明，由于污泥和污泥生物炭的碱性，添加污泥和污泥生物炭均提高了土壤pH值，且废水污泥中有机氮的矿化和铵态氮的硝化作用导致培养期间土壤pH值波动。500和700摄氏度下生成的生物炭对土壤的改良效果显著大于污泥。污泥和污泥生物炭含有丰富的Ca2+、Mg2+、K+和Na+等碱性阳离子，因此添加污泥和污泥生物炭增加了土壤交换性碱性阳离子含量，降低了土壤交换性铝和H+含量。污泥生物炭中重金属含量高于其原料污泥，而除锌和镉外，污泥生物炭中铜、铅、镍和砷的含量低于中国酸性土壤农业用废水污泥重金属标准值。城东污水处理厂污泥制备的生物炭中重金属有效态含量低于相应污泥，表明热解过程降低了废水污泥中重金属的活性。用污泥和污泥生物炭培养土壤90天后，江西洲污水处理厂生物炭及其原料污泥之间土壤有效重金属含量差异不显著，且添加生物炭处理中大多数重金属含量低于城东污水处理厂相应污泥处理。可以得出结论，废水污泥生物炭可作为土壤改良剂来调节土壤酸度。与直接施用污泥相比，施用污泥生物炭不会增加重金属的活性和有效性。
