可用于水体污染控制的氨氮转化菌筛选及部分降解特性的实验研究

从南京禄口水产养殖基地淡水鱼塘取淤泥作为分离菌株的土源,采用选择性富集培养法,从中分离到能以硫酸铵为氮源的菌株7株,对7个菌株进行氨氮降解实验,它们氨氮转化率分别为14.8%、19.7%、53.4%、94.2%、29.1%、63.5%和41.7%,其中AN-4菌株的转化率最高且生长良好。通过AN-4菌株16S rRNA基因序列分析以及生理生化方法,鉴定此菌株为克雷伯氏菌属(Klebsiellasp.)。对菌株AN-4转化氨氮的特性及温度、pH值、氨氮初始浓度和菌株接种量对其氨氮转化率的影响研究,结果表明,菌株AN-4降解氨氮的最适条件为:温度为30℃和pH值为8.0;当氨氮初始浓度为30mg/L时,AN-4菌株在24 h内的氨氮降解率可达85%以上,且能耐受高达200 mg/L的氨氮浓度;AN-4活化菌液浓度为108cfu/mL,当接种量为3×106cfu/mL时,AN-4菌株在24 h内的氨氮降解率为87.75%。综合上述结果,符合淡水养殖水环境条件,说明AN-4菌株适合在水产养殖中应用,为将菌株AN-4应用于水产养殖环境修复提供了理论依据。     

厌氧氨氧化ASBR中亚硝氮和氨氮降解规律研究

采用生物膜ASBR反应器,研究了厌氧氨氧化反应过程中亚硝氮与氨氮降解速度的变化规律。结果表明,降解过程主要分为2个阶段:速度上升期(0~30 min)和速度下降期(30~150 min)。一阶指数衰减模型的模拟结果表明,20 min以后亚硝氮、氨氮降解速度逐渐减少,亚硝氮降解速度始终高于氨氮降解速度,但是两者差值随时间逐渐减少。     

厌氧-好氧接触氧化处理汽车脱脂废水研究

采用厌氧UASB-好氧接触氧化工艺对汽车脱脂废水进行连续处理实验研究。结果表明,在脱脂废水进水COD浓度为6 000 mg/L,厌氧水力停留时间为3.4 d,好氧水力停留时间为2.5 d条件下,COD总去除率平均为93%,厌氧段平均值为38%。厌氧段可以提高出水的可生化性,厌氧-好氧接触氧化工艺效果要明显优于好氧工艺。     

氧化镁烟气脱硫反应特性研究

利用实验室规模的鼓泡式反应装置,对比了碳酸钙、氧化镁和氧化镁/硫酸镁脱硫剂的反应活性,证实脱硫液中高浓度硫酸镁的存在是保证镁法脱硫效率高于钙法的重要因素,并考察了硫酸镁浓度、脱硫剂(氧化镁)浓度、烟气量、SO2浓度和吸收液温度等因素对脱硫效率的影响。结果表明,脱硫反应可以根据pH分为2个不同阶段;反应过程中脱硫效率随着硫酸镁浓度的增加而显著升高;烟气量增加将会导致脱硫效率有所下降;入口SO2浓度升高,脱硫效率下降;氧化镁浓度、温度对脱硫效率影响不显著。结合实验现象进行推断,氧化镁脱硫的反应过程受SO2在气液两相界面的传质扩散和其水解产物在液相的扩散控制。     

连续流反应器中培养好氧颗粒污泥的运行效能研究

在连续流完全混合反应器(CSTR)中,采用不同进水方式,以乙酸钠作为碳源配制的人工配水作为原水,对好氧颗粒污泥的运行效能进行了试验研究。研究表明,采用不同进水方式运行的2个反应器在颗粒污泥出现后,运行效能差别不大;好氧颗粒污泥反应器运行高效稳定,在水力停留时间为1.5h、COD容积负荷为1.0kg/(m3·d)的条件下,对COD、TP、NH4+-N和TN的去除率分别为90%、85%、95%和60%,并具有明显的脱氮除磷效果;反应器中存在同步硝化反硝化现象。     

厌氧氨氧化菌活性恢复及富集培养研究

为了防止微生物流失,向厌氧序批式反应器(ASBR)中投加纤维膜(无纺布)作为厌氧氨氧化菌的载体,而使ASBR改为厌氧序批式生物膜反应器(ASBBR),研究了厌氧氨氧化菌活性恢复及富集培养过程中氮负荷提高对ASBBR的影响。经过23d的培养,厌氧氨氧化菌的活性恢复到原有的水平,然后提高TN容积负荷培养厌氧氨氧化菌。至132d时,反应器TN容积去除负荷达到了2.060kg/(m3·d)。整个过程中NH4+-N和NO2--N去除率一直保持在98%以上。当厌氧氨氧化菌活性恢复后,NH4+-N、NO2--N消耗量与NO3--N生成量之比最终趋于一定值(1.00∶1.30∶0.25)。在培养过程中,污泥颜色逐渐由灰色变为红棕色,最终变为浅红色。结果表明,反应器运行很稳定,NH4+-N、NO2--N出水浓度非常低,在短时间内能提高到较高的容积去除负荷。可见,ASBBR很适合厌氧氨氧化菌的富集培养。     

Polybrominated diphenyl ethers and their methoxylated metabolites in anchovy (<Emphasis Type="Italic">Coilia</Emphasis> sp.) from the Yangtze River Delta,China

Background, aim, and scope  

Polybrominated diphenyl ethers (PBDEs) and their metabolites are toxic to animals, and concentrations of the PBDEs metabolites can exceed those of the parent materials. But no information was available on concentrations of PBDEs metabolites in the lower Yangtze River in the region around Jiangsu Province of China, which is heavily urbanized and industrialized area. The aims of this study were to determine whether PBDEs and their methoxylated PBDEs (MeO-PBDEs) were accumulated in Coilia sp. in this area and to investigate the potential sources for these two kinds of brominated organic pollutants.     

Carbon/nitrogen ratio as a major factor for predicting the effects of organic wastes on soil bacterial communities assessed by DNA-based molecular techniques

Background, aim, and scope  

Current Australian legislation permits the beneficial application of grease trap waste (GTW) to agricultural soil, viewing it as a beneficial source of organic matter and soil conditioner containing no/low amounts of metals or pathogenic organisms. However, little is known about the influence of GTW on soil bacterial community. A field experiment was established at Menangle in south western Sydney in Australia to quantitatively assess the impacts of different types (GTW CO and GTW CL) and amounts of GTW application on the soil bacterial community and diversity. Furthermore, a municipal solid waste (MSW) compost was simultaneously examined to compare against the other organic wastes. Knowledge about the shifts in microbial community structure and diversity following the applications of organic wastes could help to evaluate the ecological consequences on the soil and thus to develop sound regulatory guidelines for the beneficial reuse of organic wastes in agricultural lands.     

Ferrate(VI) enhanced photocatalytic oxidation of pollutants in aqueous TiO<Subscript>2</Subscript> suspensions

Background, aim and scope  

Photocatalytic oxidation using UV irradiation of TiO₂ has been studied extensively and has many potential industrial applications, including the degradation of recalcitrant contaminants in water and wastewater treatment. A limiting factor in the oxidation process is the recombination of conduction band electrons (e ⁻ _cb) with electron holes (h_vb⁺) on the irradiated TiO₂ surface; thus, in aqueous conditions, the presence of an effective electron scavenger will be beneficial to the efficiency of the oxidation process. Ferrate (FeO₄²⁻) has received much recent attention as a water treatment chemical since it behaves simultaneously as an oxidant and coagulant. The combination of ferrate [Fe(VI)] with UV/TiO₂ photocatalysis offers an oxidation synergism arising from the Fe(VI) scavenging of e ⁻ _cb and the corresponding beneficial formation of Fe(V) from the Fe(VI) reduction. This paper reviews recent studies concerning the photocatalytic oxidation of problematic pollutants with and without ferrate.     

A method of detecting carbonyl compounds in tree leaves in China

Background, aim, and scope  

Carbonyl compounds have been paid more and more attention because some carbonyl species have been proven to be carcinogenic or a risk for human health. Plant leaves are both an important emission source and an important sink of carbonyl compounds. But the research on carbonyl compounds from plant leaves is very scarce. In order to make an approach to the emission mechanism of plant leaves, a new method was established to extract carbonyl compounds from fresh plant leaves.