稻壳基活性炭的制备及其对亚甲基蓝吸附的研究

以稻壳为原料,采用K2CO3活化法和H3P04活化法制备了比表面积为1312m^2／g和682m^2／g的活性炭,通过扫描电子显微镜（SEM）、X-射线衍射仪（XRD）对样品进行了表征,并将孔隙发达的活性炭样品用于对亚甲基蓝的吸附,结果表明,K2CO3活化法制备的活性炭样品具有更多的微孔结构;随着亚甲基蓝溶液初始浓度的增加、活性炭吸附时间的延长,亚甲基蓝的去除率呈现逐渐降低和逐渐增大的变化规律,当pH值为6时,活性炭对亚甲基蓝的吸附效果最佳;稻壳基活性炭对亚甲基蓝的吸附等温线符合Langmuir模型,Qm最高可达476．2mg／g;热力学参数△G^0△H^0和△S^0均为负值,表明稻壳基活性炭对亚甲基蓝的吸附是一个自发的放热反应。     

Mutagenicity, genotoxicity and carcinogenic risk assessment of indoor dust from three major cities around the Pearl River Delta

The mutagenicity and genotoxicity of workplace dust including commercial office, secondary school, shopping mall, hospital, electronics factory and manufacturing plant in Hong Kong and settled house dust from Hong Kong, Shenzhen and Guangzhou were measured. Results indicated that indoor dust contained both frameshift and base pair substitution mutagens. Dust from manufacturing plant showed highest mutagenic potency on TA98±S9 and TA100±S9 activation, whereas, electronics factory showed highest genotoxicity with and without S9 activation. TA100 (-S9) mutagenic potency was significantly correlated with genotoxicity expressed as SOSIP (-S9) of workplace dust (r(2)=0.37, p<0.01). The total PAHs concentration of settled house dust from PRD ranged from 1.63 to 29.2μg/g. Linear regression analyses indicated that the PAHs likely accounted for about 45% of the TA98 with S9 mutagenic activity of workplace dust. TA98 (-S9) mutagenicity (r(2)=0.27, p<0.05) and SOSIP (-S9) of house dust (r(2)=0.41, p<0.01) were both significantly correlated with the number of inhabitants in the house. To achieve a more accurate cancer risk assessment, the oral bioaccessibility of B(a)A, Chry, B(b+k)F, B(a)P, D(ah)A and I(cd)P in different dust ranging from 1.3% to 17% was taken into account. Risk assessments indicated that about 26% of house dust samples resulted in unacceptable cancer risk (>1×10(-6)) for preschool children.     

Bioaugmented sulfate reduction using enriched anaerobic microflora in the presence of zero valent iron

Biological sulfate reduction was evaluated in batch and continuous reactors that were inoculated with enriched microflora cultivated from sulfate laden medium. Heterotrophic sulfate-reducing bacteria (SRB) principally reduced the sulphate when the chemical oxygen demand was sufficient. The heterotrophic SRB in the enriched microflora could not efficiently reduce sulphate at T<33 °C and/or pH<6.0. However, when 200 mg L(-1) of zero valent iron (ZVI) was added to the reactor, the sulphate reduction rate was increased by 15% while the inhibition of the SRB activity occurred at T<25 °C or pH<4.5, broader than those noted for non-ZVI systems. In batch tests, the autotrophic SRB reduced 95% of 1500 mg L(-1) sulphate in <50h at 15 °C when the substrate was amended with 8 gL(-1) ZVI. In continuous up-flow anaerobic multiple bed reactor tests conducted to evaluate the remediation of sulphate in acid mine runoff, ZVI enhanced the activity of SRB, resulting in a 61% reduction of 20.8 gL(-1) sulphate when the reactor was operated at 25 °C and pH 2.6 with a hydraulic remain time of 96 h.     

Transformation of 4-nonylphenol isomers during biosolids composting

4-Nonylphenol, a degradation intermediate of commercial surfactant and known endocrine disruptor, has been frequently detected at levels up to several thousand microgl(-1) in surface waters and up to several hundred mgkg(-1) (dry weight) in soil and sediment samples. Large quantities of 4-NP can be quickly sorbed by the organic rich solid phase during wastewater treatment and are concentrated in biosolids, a possible major source for 4-NP in the environment. Microbial transformation in culture studies followed different mechanisms for different 4-NP isomers, which have different estrogenic activity. Composting is a process of solid matrix transformation where biological activity is enhanced by process control. This approach has been used successfully in remediation of contaminated soils and sludges. In this study, the transformation kinetics of 4-NP and its isomers were characterized during biosolids composting. Five distinctive 4-NP isomer groups with structures relative to alpha- and beta-carbons of the alkyl chain were identified in biosolids. Composting biosolids mixed with wood shaving at a dry weight percentage ratio of 43:57 (C:N ratio of 65:1) removed 80% of the total 4-NP within two weeks. At this biosolids/wood shaving ratio (B:WS), the transformation of total 4-NP and its isomers followed second-order kinetic. Higher B:WS ratios yielded significantly slower 4-NP transformation which followed first-order kinetic. Isomers with alpha-methyl-alpha-propyl structure transformed significantly slower than those with less branched tertiary alpha-carbon and those with secondary alpha-carbon, suggesting isomer-specific degradation of 4-NP during biosolids composting.     

陕北地区北洛河上游石油开发对水环境的影响

陕北是我国重要能源基地,随着陕北地区油气大规模的开采,资源勘探开发对区域环境带来的影响日趋严重,北洛河上游石油开发区内水质恶化,水体功能降低等问题非常突出.通过对北洛河上游地表水采样测试分析,并根据国家标准采用单因子污染指数进行评价,结果显示六价铬、硫酸盐、COD、NH3-N、挥发酚、石油类在集油站、井场、个别污水偷排处超标情况较严重,在河岸有大量原油污染物沉积.在部分地区河水的氯化物含量较高,除本地区地质条件因素之外,油层水的排入也有一定影响.并且由于春冬季河水流量减少,河流自净能力下降,枯水期的污染程度大幅度上升.     

Y型内混双级雾化喷嘴流量特性研究

对自行设计的 Y 型内混双级雾化喷嘴进行了实验研究,分析了不同喷嘴尺寸对喷嘴流量特性的影响.对比了压缩空气与过热蒸气做雾化介质的不同.通过测量喷嘴内混室压力,拟合出了供气压力-内混室压力曲线,并通过实验测量和校核,得到工质流景系数的表达式,对喷嘴设计有指导作用.     

Simulations of the impacts of building height layout on air quality in natural-ventilated rooms around street canyons

Numerical simulations were conducted to investigate the effects of building height ratio (i.e., HR, the height ratio of the upstream building to the downstream building) on the air quality in buildings beside street canyons, and both regular and staggered canyons were considered for the simulations. The results show that the building height ratio affects not only the ventilation fluxes of the rooms in the downstream building but also the pollutant concentrations around the building. The parameter, outdoor effective source intensity of a room, is then proposed to calculate the amount of vehicular pollutants that enters into building rooms. Smaller value of this parameter indicates less pollutant enters the room. The numerical results reveal that HRs from 2/7 to 7/2 are the favorable height ratios for the regular canyons, as they obtain smaller values than the other cases. While HR values of 5/7, 7/7, and 7/5 are appropriate for staggered canyons. In addition, in terms of improving indoor air quality by natural ventilation, the staggered canyons with favorable HR are better than those of the regular canyons.     

A laboratory study of microalgae-based ammonia gas mitigation with potential application for improving air quality in animal production operations

Ammonia gas emission is a major concern in concentrated animal production operations. It not only reduces the manure value as fertilizer due to nitrogen loss, but also has considerable environmental consequences for both animals and ecosystem. In this work, a microalgae culture system was developed as an ammonia gas bioscrubber to reduce ammonia gas emission. The green algae Scenedesmus dimorphus was grown in a flat-panel photobioreactor aerated with ammonia-laden air. A continuous culture was performed at different operational conditions including dilution rate (D = 0.05, 0.1, 0.2, and 0.3 day^?1), ammonia gas loading rate (9.4, 19.3, 28.9, 39.9, 55.6 mg/L-day), and medium pH (5, 6, 7, and 8). The alga culture at 0.1 day^?1 dilution rate, 39.9 mg/L-day ammonia gas loading rate, and pH 7 resulted in the highest cell density and biomass productivity. In order to provide a wide spectrum evaluation of the algae-based ammonia mitigation system, four parameters were determined, including ammonia removal rate, overall ammonia gas removal efficiency, cellular ammonia consumption rate, and cell yield based on ammonia input. Depending on the operational conditions used, the maximum values of those four evaluative parameters were 50.92 ± 2.91 mg/L-day of ammonia removal rate, 94.90 ± 1.87% of ammonia removal efficiency, 0.0597 ± 0.0024 g NH₃/g cell-day of cellular ammonia consumption rate, and 19.40 ± 2.52 g cell/g NH₃ of cell yield based on ammonia. It was also found that the majority of nitrogen in the ammonia gas was assimilated by the algal cells. At D = 0.1 day^?1, 39.9 mg/L-day of ammonia gas loading rate and pH 7, algal biomass assimilated 98.6% of nitrogen contained in the ammonia gas input, with less than 5% of inlet ammonia gas was exhausted after the algal treatment.

Implications: This study demonstrated the effectiveness of using microalgae for mitigating ammonia gas emission from animal production operations. The results enabled us to better understand the mechanisms of ammonia assimilation by microalgae, the engineering design parameters for the process scale up, and the economic viability of the system. Eventually, it will lead to a novel, alternative method for mitigating ammonia gas emission from concentrated animal operations while producing biomass as high-quality feed ingredient.     

温度对阶段培养法建立高盐生物系统的影响

腌制废水具有高有机物、含盐量高(7%左右)等特点,废水可生化性在0.4左右,其处理的最大难点在于生化性较差影响正常生物方法的处理和生化段高盐生物系统的建立;本实验主要针对水解酸化工艺,考察了利用阶段培养法建立高盐生物系统的效果及温度对高盐生物系统的影响,实验结果表明,在中温((28±2)℃)下利用阶段培养法可以建立良好的高盐生物系统,对含盐量在5.5%左右的腌制废水处理效果良好,废水B/C由0.4提高为0.6左右,COD去除率为23.81%,微生物活性温度在28.11 mg/L,挥发性脂肪酸(VFA)为34 mmol/L。     

Effects of biochar addition on greenhouse gas emissions and microbial responses in a short-term laboratory experiment

Biochar application to soil has drawn much attention as a strategy to sequester atmospheric carbon in soil ecosystems. The applicability of this strategy as a climate change mitigation option is limited by our understanding of the mechanisms responsible for the observed changes in greenhouse gas emissions from soils, microbial responses, and soil fertility changes. We conducted an 8-wk laboratory incubation using soils from PASTURE (silt loam) and RICE PADDY (silt loam) sites with and without two types of biochar (biochar from swine manure [CHAR-M] and from barley stover [CHAR-B]). Responses to addition of the different biochars varied with the soil source. Addition of CHAR-B did not change CO and CH evolution from the PASTURE or the RICE PADDY soils, but there was a decrease in NO emissions from the PASTURE soil. The effects of CHAR-M addition on greenhouse gas emissions were different for the soils. The most substantial change was an increase in NO emissions from the RICE PADDY soil. This result was attributed to a combination of abundant denitrifiers in this soil and increased net nitrogen mineralization. Soil phosphatase and N-acetylglucosaminidase activity in the CHAR-B-treated soils was enhanced compared with the controls for both soils. Fungal biomass was higher in the CHAR-B-treated RICE PADDY soil. From our results, we suggest CHAR-B to be an appropriate amendment for the PASTURE and RICE PADDY soils because it provides increased nitrogen availability and microbial activity with no net increase in greenhouse gas emissions. Application of CHAR-M to RICE PADDY soils could result in excess nitrogen availability, which may increase NO emissions and possible NO leaching problems. Thus, this study confirms that the ability of environmentally sound biochar additions to sequester carbon in soils depends on the characteristics of the receiving soil as well as the nature of the biochar.