生物炭来源溶解性有机质的化学性质及其氯化反应活性

CHEMICAL PROPERTIES AND CHLORINATION REACTIVITY OF BIOCHAR-DERIVED DISSOLVED ORGANIC MATTER

刘雨蕙

11930306

硕士

材料工程

王俊坚

2021-05-24

2021-05-24

南方科技大学

深圳

生物炭因其良好的土壤改良效能被广泛投放到田间，而生物炭来源溶解性有机质（biochar-derived dissolved organic matter，BDOM）与天然溶解性有机质一样，可成为流域内消毒副产物的前体物，但BDOM的溶出能否会影响周围受纳水体的水质未成定论。原料和热解温度是影响BDOM化学性质的重要因素，探究不同来源和不同热解温度影响下BDOM的化学性质与氯反应活性，有助于评估生物炭的使用对流域水安全的影响。结合光谱分析、氯化试验和毒性试验，我们分析了源自6种常用的原料（富碳原料：松针、小麦秸秆和核桃壳；富氮原料：苜蓿、污泥和猪粪）、分别在3个热解温度（300，500和700 °C）下制成的18种生物炭的BDOM的光学性质和消毒副产物的生成潜力及其毒性。此外，选取小麦秸秆（植物基）和污泥（非植物基）BDOM进行28天的微生物降解，模拟溶解性有机质在环境中的降解，评估降解后的化学性质、消毒副产物生成潜力和产物毒性的变化。 研究结果表明，热解温度的升高会改变生物炭的溶解性有机碳的释出量，增加BDOM的芳香性和腐殖化程度。BDOM生成的消毒副产物主要是三卤甲烷。消毒副产物的生成潜力主要与生物炭的原料有关，富氮原料生物炭（0.05 ~7.80 µg-卤乙腈/g-生物炭）比富碳原料生物炭（0.02~0.57 µg-卤乙腈/g-生物炭）具有更高的卤乙腈的生成潜力。300 °C热解的污泥BDOM来源的消毒副产物混合物急性毒性最高（1.71±0.04 mg-Zn2+/L）。BDOM中不稳定的、低分子量的物质在微生物降解后，被优先分解或转化成了更稳定的芳香族物质。降解后三卤甲烷的生成潜力增大（从8.33~50.25到17.24~278.03 µg/mg-DOC），而水合氯醛（从0.22~6.61到0.09~2.60 µg/mg-DOC）和卤代酮（从0.05~0.49到0.00~0.45 µg/mg-DOC）的生成潜力减小。小麦秸秆BDOM的氯化产物急性毒性在降解后降低，而污泥BDOM的氯化产物急性毒性略有升高，然而两者降解后的氯化产物均不足以引起基因毒性。综上，BDOM的光学性质与氯反应性受到热解温度、生物炭原料和微生物降解过程的影响。其中，污泥生物炭是这些生物炭中具有较高使用风险的生物炭。本研究从BDOM的化学性质入手，通过分析化学性质与消毒副产物生成潜力及其毒性的联系，为流域内生物炭应用的环境风险提供一定参考依据。

Biochar is widely used in the fields due to its good soil amendment effect. However, the biochar-derived dissolved organic matter (BDOM), like the natural organic matter, can be important terrestrial precursor of disinfection by-products (DBPs). But whether BDOM will affect the water quality of the surrounding watershed remains unknown. R­aw materials and pyrolysis temperature are expected to be important factors that affect the properties of BDOM. Therefore, exploring the properties of BDOM from different sources and pyrolysis temperatures will help evaluate the impact of biochar application in watersheds on drinking water safety. Here, we prepared 18 different kinds of biochars from 6 common raw materials (carbon-rich materials: pine needle, wheat straw and walnut shell; nitrogen-rich materials: alfalfa, sludge and pig manure) pyrolyzed under 3 temperatures (300, 500 and 700 °C). We analyzed the optical properties, the DBPs formation potential and toxicity of the DBPs mixture for these 18 kinds of BDOM. In addition, we conducted 28-day microbial degradation experiments on the BDOM from wheat straw (plant base) and sludge (non-plant base) biochar to simulate the changes in chemical properties, the DBPs formation potential and toxicity of DBPs mixture after microbial degradation.Results showed that the increase in pyrolysis temperature led to the changes in the quantity of BDOM and the increases in aromaticity and humification of BDOM. The main DBPs after chlorination were trihalomethanes (THMs). The formation potential of DBPs highly depended on the raw materials of biochar. The BDOM of nitrogen-rich material biochar (0.05­~7.80 µg-HAN/g-Biochar) had a higher potential for the formation of HANs than that of carbon-rich material biochar (0.02~0.57 µg-HAN/g-Biochar). The DBPs mixture from chlorinated sludge-derived BDOM (300 °C) had the highest acute toxicity (1.71±0.04 mg-Zn2+/L).The labile and low-molecular-weight substances in BDOM were preferentially decomposed or converted into more stable aromatic substances after microbial degradation. After degradation, the formation potential of THMs of BDOM increased (from 8.33~50.25 to 17.24~278.03 µg/mg-DOC), while the formation potential of chloral hydrate (CHD, from 0.22~6.61 to 0.09~2.60 µg/mg-DOC) and halogenated ketones (HKTs, from 0.05~0.49 to 0.00~0.45 µg/mg-DOC) decreased. The acute toxicity of the DBPs mixture from chlorinated BDOM derived from wheat straw decreased after degradation, while that from chlorinated sludge-derived BDOM increased slightly. However, none of the DBPs mixtures showed genotoxicity after microbial degradation.Overall, the optical properties and chlorine reactivity of BDOM were affected by pyrolysis temperature, raw materials and microbial degradation process. Among these biochars, sludge biochars had a relatively high risk of use. This study linked the BDOM chemical properties, the DBPs formation potential of BDOM, and the toxicities of the DBPs mixtures, which will provide a reference for biochar application in watersheds.

生物炭 溶解性有机质 光谱特征 消毒副产物 毒性

biochar dissolved organic matter spectroscopic characteristics disinfection by-products toxicity

中文

独立培养

南方科技大学

刘雨蕙. 生物炭来源溶解性有机质的化学性质及其氯化反应活性[D]. 深圳. 南方科技大学,2021.