页岩气增产采出水处理方法研究

针对页岩气增产采出水易起泡,难以平稳蒸发脱盐的问题,利用"预处理+多效蒸发"处理方法,对井站两种不同性质的采出水进行中试,连续监测各工艺单元处理后水质及蒸发出水水质。结果表明:通过破乳混凝、催化氧化、电荷中和及除硬等步骤,能够完全消除泡排水起泡性;中试稳定运行7d,两种泡排水蒸发出水水质稳定,COD浓度<55mg/L,NH4^+-N浓度<18mg/L,满足GB 8978-1996《污水综合排放标准》一级标准;Cl^-浓度<21mg/L,满足DB 51/190-1993《四川省水污染物排放标准》要求。     

Comparative genotoxicity of water processed by three drinking water treatment plants with different water treatment procedures

• Genotoxicity of substances is unknown in the water after treatment processes. • Genotoxicity decreased by activated carbon treatment but increased by chlorination. • Halogenated hydrocarbons and aromatic compounds contribute to genotoxicity. • Genotoxicity was assessed by umu test; acute and chronic toxicity by ECOSAR. • Inconsistent results confirmed that genotoxicity cannot be assessed by ECOSAR. Advanced water treatment is commonly used to remove micropollutants such as pesticides, endocrine disrupting chemicals, and disinfection byproducts in modern drinking water treatment plants. However, little attention has been paid to the changes in the genotoxicity of substances remaining in the water following the different water treatment processes. In this study, samples were collected from three drinking water treatment plants with different treatment processes. The treated water from each process was analyzed and compared for genotoxicity and the formation of organic compounds. The genotoxicity was evaluated by an umu test, and the acute and chronic toxicity was analyzed through Ecological Structure- Activity Relationship (ECOSAR). The results of the umu test indicated that biological activated carbon reduced the genotoxicity by 38%, 77%, and 46% in the three drinking water treatment plants, respectively, while chlorination increased the genotoxicity. Gas chromatograph-mass spectrometry analysis revealed that halogenated hydrocarbons and aromatic compounds were major contributors to genotoxicity. The results of ECOSAR were not consistent with those of the umu test. Therefore, we conclude that genotoxicity cannot be determined using ECOSAR .     

Adsorption characteristics of ciprofloxacin onto g-MoS2 coated biochar nanocomposites

• The g-MoS₂ coated composites (g-MoS₂-BC) were synthesized. • The coated g-MoS₂ greatly increased the adsorption ability of biochar. • The synergistic effect was observed for CIP adsorption on g-MoS₂-RC700. • The adsorption mechanisms of CIP on g-MoS₂-BC were proposed. The g-MoS₂ coated biochar (g-MoS₂-BC) composites were synthesized by coating original biochar with g-MoS₂ nanosheets at 300°C(BC300)/700°C (BC700). The adsorption properties of the g-MoS₂-BC composites for ciprofloxacin (CIP) were investigated with an aim to exploit its high efficiency toward soil amendment. The specific surface area and the pore structures of biochar coated g-MoS₂ nanosheets were significantly increased. The g-MoS₂-BC composites provided more π electrons, which was favorable in enhancing the π-π electron donor-acceptor (EDA) interactions between CIP and biochar. As a result, the g-MoS₂-BC composites showed faster adsorption rate and greater adsorption capacity for CIP than the original biochar. The coated g-MoS₂ nanosheets contributed more to CIP adsorption on the g-MoS₂-BC composites due to their greater CIP adsorption capacity than the original biochar. Moreover, the synergistic effect was observed for CIP adsorption on g-MoS₂-BC700, and suppression effect on g-MoS₂-BC300. In addition, the adsorption of CIP onto g-MoS₂-BC composites also exhibited strong dependence on the solution pH, since it can affect both the adsorbent surface charge and the speciation of contaminants. It was reasonably suggested that the mechanisms of CIP adsorption on g-MoS₂-BC composites involved pore-filling effects, π-π EDA interaction, electrostatic interaction, and ion exchange interaction. These results are useful for the modification of biochar in exploiting the novel amendment for contaminated soils.     

Identifying factors that influence soil heavy metals by using categorical regression analysis: A case study in Beijing,China

A method was proposed to identify the main influence factors of soil heavy metals. The influence degree of different environmental factors was ranked. Parent material, soil type, land use and industrial activity were main factors. Interactions between some factors obviously affected soil heavy metal distribution. Identifying the factors that influence the heavy metal contents of soil could reveal the sources of soil heavy metal pollution. In this study, a categorical regression was used to identify the factors that influence soil heavy metals. First, environmental factors were associated with soil heavy metal data, and then, the degree of influence of different factors on the soil heavy metal contents in Beijing was analyzed using a categorical regression. The results showed that the soil parent material, soil type, land use type, and industrial activity were the main influencing factors, which suggested that these four factors were important sources of soil heavy metals in Beijing. In addition, population density had a certain influence on the soil Pb and Zn contents. The distribution of soil As, Cd, Pb, and Zn was markedly influenced by interactions, such as traffic activity and land use type, industrial activity and population density. The spatial distribution of soil heavy metal hotspots corresponded well with the influencing factors, such as industrial activity, population density, and soil parent material. In this study, the main factors affecting soil heavy metals were identified, and the degree of their influence was ranked. A categorical regression represents a suitable method for identifying the factors that influence soil heavy metal contents and could be used to study the genetic process of regional soil heavy metal pollution.     

不同菌糠生物炭对水体中Cu2+、Cd2+的吸附性能

以菌糠废弃物为原料,采用限氧裂解法在500℃条件下制备香菇菌糠、猴头菇菌糠和平菇菌糠生物炭(LEBC、HEBC和POBC).利用SEM、XRD和FTIR等方法对吸附剂进行了表征;通过吸附动力学、等温吸附、生物炭酸化实验探究了3种菌糠生物炭去除水溶液中Cu~(2+)、Cd~(2+)的效果及机理.结果表明,在溶液初始pH 2—3时,3种菌糠生物炭对溶液中Cu~(2+)、Cd~(2+)的吸附量急剧增加.LEBC、HEBC、POBC对Cu~(2+)、Cd~(2+)的吸附符合准二级动力学模型,对Cu~(2+)的吸附速率分别为10.15×10~(-3)、7.08×10~(-3)、0.69×10~(-3) mg·g~(-1)·min~(-1),对Cd~(2+)的吸附速率分别为6.53×10~(-3)、5.19×10~(-3)、0.26×10~(-3) mg·g~(-1)·min~(-1).不同浓度下LEBC、HEBC、POBC对Cu~(2+)的吸附符合Langmuir模型,最大吸附量依次为56.74、11.98、77.32 mg·g~(-1);而Cd~(2+)的吸附符合Freundlich模型,最大吸附量依次为74.26、36.49、70.2 mg·g~(-1).LEBC在较短的时间内能达到较大的吸附量,可作为去除水体中Cu~(2+)、Cd~(2+)的优质吸附剂.XRD和FTIR等分析结果表明生物炭对Cu~(2+)、Cd~(2+)的吸附机制包括物理吸附、阳离子-π作用、官能团络合及沉淀.3种生物炭经酸化处理后,对Cu~(2+)、Cd~(2+)的吸附能力显著下降,表明生物炭中碳酸盐引起的Cu~(2+)、Cd~(2+)表面沉淀在吸附过程中起重要作用.     

2008—2018年黄山市酸雨污染特征变化趋势分析

采用2008—2018年黄山市酸雨监测数据,阐述了黄山市酸雨变化特征及成因。结果表明:黄山市降水pH在5.0左右徘徊;酸雨频率在2017年以前均处于高位,以2017年为拐点,下降到最低值(35.7%)。总体上,黄山市酸雨污染情况正在得到改善,但形势依然严峻。SO2-₄和NO-₃的当量浓度之比从2013年的4.09下降到2018年的1.10;SO₂和NO_x排放量逐年减少,但是幅度不同,NO_x排放量下降幅度不大,致使NO_x对酸雨的贡献有增加的趋势;酸雨类型由硫酸型转变为硫酸型和硝酸型并重,机动车排放对酸雨污染的贡献已不可忽视。对黄山市降水中的碱性离子中和能力进行分析发现,黄山市起主要中和作用的离子为NH⁺₄和Ca²⁺。将黄山市降水与其他地区降水进行对比发现,黄山市降水受到的中和作用强于东南地区,但弱于北方地区。     

一株氧化亚铁硫杆菌的筛选及生长条件研究

从广东省大宝山矿区尾矿中分离纯化得到一株嗜酸细菌,对其进行DNA提取和16S rRNA扩增后测序,将测序结果与国际基因数据库Genbank中已有相关菌株序列进行相似性比对后,发现该菌株与氧化亚铁硫杆菌(Acidithiobacil-lus ferrooxidans)Tf-49菌位于系统发育树的同一分支中,二者相似度高达99%以上,确定其为氧化亚铁硫杆菌并命名为DBS-8菌。另外,通过设计5因素4水平的正交实验,研究了接种量、培养温度、硫酸铵浓度、初始pH和初始亚铁浓度对该菌株生长状况的影响。结果表明适宜该菌株生长的最佳初始条件为:20%的接种量、3.0 g/L硫酸铵、9.0 g/L初始亚铁、pH=2.0和28℃培养,各初始条件对细菌生长影响的顺序为:pH初始亚铁浓度接种量温度硫酸铵浓度。     

活性炭纤维载体生物膜法处理洗车废水研究

为了实现洗车废水的循环使用,进行了以聚丙烯腈基活性炭纤维(PAN-ACF)为生物膜载体处理洗车废水的实验研究。以LAS、COD和NH3-N等指标考察了活性炭纤维生物膜反应器对洗车废水的处理效果。结果表明:在常温下、pH=6.5~7,当进水流量在30 mL/min时,反应器达到最佳运行参数,活性炭纤维载体生物膜法对LAS、COD和NH3-N等的去除率分别达到了97%、80%和60%。出水水质完全达到《生活杂用水水质标准》(CJ/T48-99)中洗车用水主要水质指标的规定。此外,实验表明PAN-ACF作为生物膜载体具有很好的生物亲和性和再生性。     

膜生物反应器中同步硝化反硝化机制及影响因子探讨

通过膜生物反应器的连续运行,研究了DO、C/N比、F/M和pH等影响因子对膜生物反应器同步硝化反硝化的影响,并对其影响机制进行了分析。实验结果表明,DO、C/N比、F/M和pH是同步硝化反硝化效果的重要影响因子;膜生物反应器中pH值的变化在7左右,DO为0.8 mg/L,C/N比为10,F/M在0.15~0.36 kg COD/(kg MLSS.d)之间时能发生比较好的同步硝化反硝化现象。     

Ca5（AsO4）3OH的溶解度与稳定性研究

通过在不同pH值,温度等条件下Ca5（AsO4）3OH的溶解,确定其稳定存在的pH值范围,得出它的溶度积和生成的自由能（ΔG0f）。结果表明,Ca5（AsO4）3OH在水中的溶解度和稳定范围与pH和温度有关,在酸性条件下（初始pH=2）它的溶解度较大,而且在水中的溶解度随着温度的升高而降低。利用PHREEQC程序计算确定Ca5（AsO4）3OH的溶度积为10-40.86,生成自由能ΔG0f为-5 063.53 kJ/mol。利用JADE5软件计算得到其晶格参数a=b=9.696,c=6.967和晶胞体积为567.304 3。