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.     

维生素和酮苷生产废水中难降解污染物的溯源研究

研究了维生素和酮苷生产过程中各生产工段排水的生物降解特性,评价了各生产工段对生产废水中难降解有机物的贡献率,追溯了可能的难降解特征污染物。结果表明,维生素生产废水中的难降解物质主要来自W1-1、W1-3、W1-5和W1-6生产工段,甲醛、丁烯酮、醛酮聚合物和吡啶可能是导致生产废水难降解的重要原因;酮苷生产废水中的难降解物质主要来自W2-1、W2-3和W2-7生产工段,氯代有机溶剂和苯环类物质可能是导致生产废水难降解的重要原因。建议根据具体生产工段排水的水质特征,有针对性地进行物化处理,提高废水可生化性。     

MBR技术的发展及应用

介绍了目前MBR的主要类型、膜污染情况、膜清洗方式以及MBR在不同领域的应用情况和工程实例,对MBR技术未来的发展趋势进行了预测。     

Chemisorption and Physical Adsorption Roles in Cadmium Biosorption by Chlamydomonas Reinhardtii

The aim of this study was to investigate the mechanism of cadmium (Cd) adsorbed by microalgae Chlamydomonas reinhardtii (C.reinhardtii). The kinetic and adsorption isotherm of the process could be well described by mathematical models. Chemical modification experiments and Fourier transform infrared spectra indicated that carboxyl and amine groups were the important functional groups for adsorption of Cd. The maximum contribution of physical adsorption in the overall adsorption process was evaluated as 5.5%...     

Synthesis of hybrid carbon nanotubes using Brassica juncea L. application to photodegradation of bisphenol A

Hyperaccumulators contain tubular cellulose and heavy metals, which can be used as the sources of carbon and metals to synthesize nanomaterials. In this paper, carbon nanotubes (CNTs), Cu_0.05Zn_0.95O nanoparticles, and CNTs/Cu_0.05Zn_0.95O nanocomposites were synthesized using Brassica juncea L. plants, and the ultraviolet (UV)-light-driven photocatalytic degradations of bisphenol A (BPA) using them as photocatalysts were studied. It was found that the outer diameter of CNTs was around 50 nm and there were a few defects in the crystal lattice. The synthesized Cu_0.05Zn_0.95O nanocomposites had a diameter of around 40 nm. Cu_0.05Zn_0.95O nanocomposites have grown on the surface of the CNTs and the outer diameter of them was around 100 nm. The synthesized hybrid carbon nanotubes using B. juncea could enhance the efficiency of photocatalytic degradation on BPA. The complete equilibration time of adsorption/desorption of BPA onto the surface of CNTs, Cu_0.05Zn_0.95O nanoparticles, and CNTs/Cu_0.05Zn_0.95O nanocomposites was within 30, 20, and 30 min, and approximately 14.9, 8.7, and 17.4 % BPA was adsorbed by them, respectively. The combination of UV light irradiation (90 min) with CNTs, Cu_0.05Zn_0.95O nanoparticles, and CNTs/Cu_0.05Zn_0.95O nanocomposites could lead to 48.3, 75.7, and 92.6 % decomposition yields of BPA, respectively. These findings constitute a new insight for synthesizing nanocatalyst by reusing hyperaccumulators.     

Removal of sulfamethoxazole and sulfapyridine by carbon nanotubes in fixed-bed columns

Sulfamethoxazole (SMX) and sulfapyridine (SPY), two representative sulfonamide antibiotics, have gained increasing attention because of the ecological risks these substances pose to plants, animals, and humans. This work systematically investigated the removal of SMX and SPY by carbon nanotubes (CNTs) in fixed-bed columns under a broad range of conditions including: CNT incorporation method, solution pH, bed depth, adsorbent dosage, adsorbate initial concentration, and flow rate. Fixed-bed experiments showed that pH is a key factor that affects the adsorption capacity of antibiotics to CNTs. The Bed Depth Service Time model describes well the relationship between service time and bed depth and can be used to design appropriate column parameters. During fixed-bed regeneration, small amounts of SMX (3%) and SPY (9%) were irreversibly bonded to the CNT/sand porous media, thus reducing the column capacity for subsequent reuse from 67.9 to 50.4 mg g^?1 for SMX and from 91.9 to 72.9 mg g^?1 for SPY. The reduced column capacity resulted from the decrease in available adsorption sites and resulting repulsion (i.e., blocking) of incoming antibiotics from those previously adsorbed. Findings from this study demonstrate that fixed-bed columns packed with CNTs can be efficiently used and regenerated to remove antibiotics from water.     

4种人工湿地基质对马拉硫磷的吸附特性

通过基质对马拉硫磷的等温吸附和吸附动力学实验,研究天然土壤、煤渣、沸石、砾石对马拉硫磷的吸附特性,为人工湿地处理含马拉硫磷废水提供理论依据.结果表明:马拉硫磷浓度为2.25 ～ 90 mg/L条件下,Langmuir和Freundlich方程均能较好地拟合4种基质对马拉硫磷的等温吸附过程,并且Freundlich方程的拟合效果要好于Langmuir方程.马拉硫磷的理论饱和吸附量大小依次为天然土壤(9.9304 mg/g)＞煤渣(1.6173 mg/g)＞沸石(0.6039 mg/g)＞砾石(0.3965 mg/g).4种基质对马拉硫磷的缓冲能力大小依次为天然土壤＞煤渣＞沸石＞砾石,即当进水马拉硫磷浓度波动较大时,作为湿地基质天然土壤使人工湿地系统维持稳定出水水质的能力最强.马拉硫磷浓度为4.5 mg/L条件下,吸附动力学模型Elovich方程能较好地拟合4种基质对马拉硫磷的吸附动力学特征,说明4种基质对马拉硫磷的吸附是表面吸附和内部扩散吸附共同作用的结果.因此,天然土壤和煤渣适宜作为处理含马拉硫磷废水的人工湿地基质.     

Annual variations of odor concentrations and emissions from swine gestation, farrowing, and nursery buildings

To obtain annual odor emission profiles from intensive swine operations, odor concentrations and emission rates were measured monthly from swine nursery, farrowing, and gestation rooms for a year. Large annual variations in odor concentrations and emissions were found in all the rooms and the impact of the seasonal factor (month) was significant (P < 0.05). Odor concentration was low in summer when ventilation rate was high but high in winter when ventilation rate was low, ranging from 362 (farrowing room in July) to 8934 (nursery room in December) olfactory unit (OU) m(-3). This indicates that the air quality regarding odor was significantly better in summer than that in winter. Odor emission rate did not show obvious seasonal pattern as odor concentration did, ranging from 2 (gestation room in November) to 90 (nursery room in April) OU m(-2) sec(-1); this explains why the odor complaints for swine barns have occurred all year round. The annual geometric mean odor concentration and emission rate of the nursery room was significantly higher than the other rooms (P < 0.05). In order to obtain the representative annual emission rate, measurements have to be taken at least monthly, and then the geometric mean of the monthly values will represent the annual emission rate. Incorporating odor control technologies in the nursery area will be the most efficient in reducing odor emission from the farm considering its emission rate was 2 to 3 times of the other areas. The swine grower-finisher area was the major odor source contributing 53% of odor emission of the farm and should also be targeted for odor control. Relatively positive correlations between odor concentration and both H2S and CO2 concentrations (R(2) = 0.58) means that high level of these two gases might likely indicate high odor concentration in swine barns.     

水力条件对复合人工湿地处理城市受污染河水效果的影响

通过对水力负荷、水力停留时间等水力条件的控制,观察其对复合垂直上行流人工湿地处理城市受污染河水效果的影响.一年多来的运行结果表明:水力条件对复合垂直上行流人工湿地去除其他污染物的影响显著,但对总氮去除的影响不大.水力停留时间的延长可提高总磷、氨氮、COD的去除效果;随着水力负荷的增加,总磷、氨氮、COD去除率都有所增加...     

O3-BAC组合工艺深度净化MBR出水的中试研究

采用臭氧-生物活性炭(O3-BAC)组合工艺对某工业园区再生水厂MBR出水进行了深度净化的中试研究,主要考察了组合工艺各节点对常规指标的处理效果.结果表明,臭氧投加量约3 mg/L(H2O)、臭氧接触塔接触时间为30min、活性炭滤池空床接触时间(BECT)为15 min时,O3-BAC组合工艺能有效去除水中色度、浊度...