Formation of iodo-trihalomethanes, iodo-haloacetic acids, and haloacetaldehydes during chlorination and chloramination of iodine containing waters in laboratory controlled reactions

Iodine containing disinfection by-products (I-DBPs) and haloacetaldehydes (HALs) are emerging disinfection by-product (DBP) classes of concern. The former due to its increased potential toxicity and the latter because it was found to be the third most relevant DBP class in mass in a U.S. nationwide drinking water study. These DBP classes have been scarcely investigated, and this work was performed to further explore their formation in drinking water under chlorination and chloramination scenarios. In order to do this, iodo-trihalomethanes (I-THMs), iodo-haloacetic acids (I-HAAs) and selected HALs (mono-HALs and di-HALs species, including iodoacetaldehyde) were investigated in DBP mixtures generated after chlorination and chloramination of different water matrices containing different levels of bromide and iodide in laboratory controlled reactions. Results confirmed the enhancement of I-DBP formation in the presence of monochloramine. While I-THMs and I-HAAs contributed almost equally to total I-DBP concentrations in chlorinated water, I-THMs contributed the most to total I-DBP levels in the case of chloraminated water. The most abundant and common I-THM species generated were bromochloroiodomethane, dichloroiodomethane, and chlorodiiodomethane. Iodoacetic acid and chloroiodoacetic acid contributed the most to the total I-HAA concentrations measured in the investigated disinfected water. As for the studied HALs, dihalogenated species were the compounds that predominantly formed under both investigated treatments.     

碳链延长技术在有机资源回收领域的研究进展

本文综述了碳链延长技术在处理有机废料及碳资源回收领域的优势，梳理了其发展历程为后续研究提供方向指导，阐释了其生化代谢途径中物质转变、能量传递和信号传输等机理，验证了其延长为丁酸、己酸等产物的热力和动力学可行性，总结归纳了其已优化的关键反应参数和已运行的工程试验案例等方面内容.本文为揭示细胞碳链延长机制和应用碳链延长技术于实际废料治理提供理论基础和建议展望.     

Differentiation in low molecular weight organic acids exudation into rhizosphere and their creation in Ulmus laevis Pall organs treated by As – pot experiment

Two-year old Ulmus laevis Pall (U. laevis) seedlings were cultivated in a three-month hydroponic experiment with inorganic (aresenite – As(III) and arsenate – As(V)) and organic (dimethylarsenic acid – DMA(V)) arsenic forms, at 0.06 and/or 0.6?mM concentrations. Further, the profile and content of total low molecular weight organic acids (LMWOAs) were investigated in the rhizosphere, roots and leaves of U. laevis. Obtained results showed that the addition of As(III) or As(V) individually or in a mixture led to increased LMWOAs concentration in the rhizosphere, especially of oxalic and malonic acids, in comparison to the control, while in roots the overall content of the profiled LMWOAs decreased. In both rhizosphere and roots, addition of the DMA(V) form resulted in the inhibition of LMWOAs exudation into the rhizosphere and their creation in plant roots. Leaves were characterised by a higher content of LMWOAs than in the rhizosphere and roots for all experimental systems, where the profile and content of LMWOAs was strictly correlated with the analysed As forms. Our study indicated that creation of LMWOAs in U. laevis organs and their exudation to the rhizosphere could be responsible for the As toxicity tolerance of the plants.     

卤代肉桂酸对羊角月牙藻的急性毒性及3D-QSAR研究

卤代肉桂酸类化合物广泛用于医药、化妆品和除草剂等生产制造,随着使用量的增加,其生态环境健康风险逐渐受到关注。为揭示该类化合物的毒性特征,选择14种卤代肉桂酸作为研究对象,考察了它们对羊角月牙藻的急性毒性效应,并应用三维定量构效相关技术(3D-QSAR)探讨化合物分子结构特征对毒性效应的影响。结果表明,14种卤代肉桂酸类化合物对羊角月牙藻急性毒性的72 h半数效应浓度(72 h-EC50)值在45.88～83.72 mg·L-1范围内,其中4-氯肉桂酸、4-溴肉桂酸等表现出较高毒性效应。3D-QSAR结果表明,该类化合物分子结构的立体场、静电场和疏水场特性对其毒性效应影响显著,在苯环结构上引入体积较大、电负性较弱及疏水性较强的取代基,将导致毒性升高。以上结果将为科学评价卤代肉桂酸类化合物潜在环境健康风险提供基础数据支撑。     

Upgrading VFAs bioproduction from waste activated sludge via co-fermentation with soy sauce residue

SSR addition upgraded VFAs production from WAS. Structure modification by pretreatments led to performance distinctions. Distinctions in microbial community was observed by pretreatments selection. Up to 0.49‒0.65 billion €/year of market value potential was preliminary estimated. Conditioning of extra carbon sources has been widely reported to facilitate fermentation of waste activated sludge (WAS). Soy sauce residue (SSR) was a relatively untapped carbon source for sludge conditioning. This batch study aimed to evaluate the possible implementation of SSR for volatile fatty acids (VFAs) production from WAS. To upgrade the bioavailability of feedstock, three typical pretreatment methods were conducted, i.e., ammonium hydroxide (AH), sulfuric acids (SA) and thermal assisted alkaline (TA). AH pretreated test (AH-PT) outperformed due to a relatively strong structure decomposition of cellulosic materials as revealed by infrared spectroscopic analysis and crystal index. As a result, performed a high hydrolysis rate of 4449 mg COD/d, 1.12-1.23-fold higher than that in TA and SA pretreated tests (TA-PT and SA-PT), and 7.8-fold higher than that in the Control test. Meanwhile, a volatile fatty acids (VFAs) contribution of 401.2 mg COD/g SSR∙L and a maximum acidification rate of 3.59 d^-1 was recorded, with a high sum proportion of mall molecular acetic and propionic 82.2%, 11% ‒70% increase over the other three tests. Besides, speciation process characterized with functional genus differentiation was identified by microbial diversity and distribution investigation and canonical correspondence analysis (CCA). Finally, a potential market value of 0.49‒0.65 Billion €/year was preliminary estimated, showing promise of resource recovery from both WAS and SSR instead of extensive disposal.     

污泥产短链脂肪酸微生物的研究进展

厌氧消化系统微生物是生物降解有机物工艺的核心。系统综述了厌氧消化产短链脂肪酸的微生物种类及其种类间的代谢关系,重点阐述了污泥中基质、温度、p H值、碳氮比和污泥停留时间等因素对污泥厌氧消化产短链脂肪酸微生物的生物多样性、优势种群及产物的影响,介绍了促进污泥厌氧发酵产短链脂肪酸微生物活性的研究进展,展望了通过调控主要影响因素实现对厌氧消化系统微生物优势种群的控制。     

三峡大坝建成后长江河流表层沉积物中有机物组成与分布特征

利用气相色谱法对2009年长江河流(干流和主要支流)表层沉积物样品中的正构烷烃(n-alkanes)和脂肪酸(fatty acids)进行测定和分析,结合粒度、OC%、δ13C等参数,研究样品中有机质的组成和分布特征,并对其来源及影响因素,特别是三峡大坝对其的影响进行了初步分析.结果显示,长江表层沉积物粒度组成主要以粉砂(45.8%)和砂(41.4%)为主,OC%值为0.08~1.99%, OC 的δ13C值为-31.9‰~-21.4‰.正构烷烃含量以干重计为0.71~13.69 μg/g,以OC计为0.05~1.99mg/g.脂肪酸含量以干重计为2.77~32.52μg/g,以OC计为0.16~40.58mg/g,其中饱和脂肪酸含量最多,含量最少的是支链脂肪酸.水动力分选、粒径是控制支流沉积有机质含量与分布的重要因素.干流中下游较上游具有丰富的水生植物源贡献,并且降解程度低.三峡大坝对陆源有机质的输送和改造具有重要影响.     

两种挥发性有机酸的浓度比值对生物除磷的影响

在序批式反应器(SBR)中,研究了废水中2种挥发性脂肪酸(VFAs)丙酸/乙酸的浓度比值对生物除磷(EBPR)的影响.结果表明,突然增加丙酸/乙酸浓度比值,导致短时间内系统生物除磷的效果变差;但经过一段时间的驯化后,除磷效果明显变好,溶解正磷酸盐(SOP)的去除效率比改变丙酸/乙酸的浓度比值前提高10%左右.进一步研究表明,除磷效率得到显著提高的原因主要是SBR2系统较低的二次磷释放量.     

红球菌PR-1菌株破乳性能研究

利用乳化剂Span 80配制出一种稳定的煤油-水乳浊液作为模型乳浊液,进而从大港油田废水中筛选出1株破乳能力较强的红球菌PR-1.该菌株培养液在55℃下8h可以使模型乳浊液完全破乳,且在实验条件下比化学破乳剂DGF-01具有更强的破乳活性.研究发现,乳浊液的破乳为线性增长过程,冻融和高压灭菌对其破乳能力没有影响,菌体细胞是破乳的主要活性成分,经超声波破碎及有机溶剂处理后其破乳活性显著降低.菌体表面有很强的疏水性,其对烃的粘附率为84%,碳链长度范围在C₂₇～C₅₄的枝菌酸类物质是保持菌体细胞完整性和疏水性的关键,其对细胞的破乳活性也至关重要.PR-1菌株发酵液用于原油乳状液的破乳具有操作方便,破乳率高,应用面广,无毒无害等优点,且能完全脱出J9-19原油乳状液中的水,因此可作为原油乳状液或油田采出水的破乳剂.