Identification of close relationship between atmospheric oxidation and ozone formation regimes in a photochemically active region

Understanding ozone (O₃) formation regime is a prerequisite in formulating an effective O₃ pollution control strategy. Photochemical indicator is a simple and direct method in identifying O₃ formation regimes. Most used indicators are derived from observations, whereas the role of atmospheric oxidation is not in consideration, which is the core driver of O₃ formation. Thus, it may impact accuracy in signaling O₃ formation regimes. In this study, an advanced three-dimensional numerical modeling system was used to investigate the relationship between atmospheric oxidation and O₃ formation regimes during a long-lasting O₃ exceedance event in September 2017 over the Pearl River Delta (PRD) of China. We discovered a clear relationship between atmospheric oxidative capacity and O₃ formation regime. Over eastern PRD, O₃ formation was mainly in a NO_x-limited regime when HO₂/OH ratio was higher than 11, while in a VOC-limited regime when the ratio was lower than 9.5. Over central and western PRD, an HO₂/OH ratio higher than 5 and lower than 2 was indicative of NO_x-limited and VOC-limited regime, respectively. Physical contribution, including horizontal transport and vertical transport, may pose uncertainties on the indication of O₃ formation regime by HO₂/OH ratio. In comparison with other commonly used photochemical indicators, HO₂/OH ratio had the best performance in differentiating O₃ formation regimes. This study highlighted the necessities in using an atmospheric oxidative capacity-based indicator to infer O₃ formation regime, and underscored the importance of characterizing behaviors of radicals to gain insight in atmospheric processes leading to O₃ pollution over a photochemically active region.     

高浓度硫化染料染色废水的处理与综合利用

采用混凝气浮－内电解－接触氧化组合工艺处理高浓度硫化染料染色废水，生产运行结果表明：S^2-、COD、BOD5和色度的去除率分别为近100％、94％左右、92．5％－94．8％、96％－100％，处理后出水的各项污染指标均符合国家排放标准，并且实现了部分回用。该处理工艺设备简单、系统运行稳定、投资少、操作方便，具有一定的推广应用价值。     

厌氧氨氧化颗粒污泥快速培养及其抑制动力学

为实现厌氧氨氧化颗粒污泥(ANAMMOX granular sludge,AGS)的快速培养,采用上流式厌氧污泥床(up-flow anaerobic sludge bed,UASB)工艺,在添加少量絮状厌氧氨氧化污泥(flocculent ANAMMOX sludge,FAS)的反应器内填充生物流离球作为填料,对ANAMMOX的启动及FAS的颗粒化进行研究.同时利用Haldane模型研究AGS的基质抑制动力学特性.结果表明,利用生物流离球作为填料,实现了ANAMMOX的启动,总氮去除率达85%以上,总氮容积负荷为0. 72 kg·(m3·d)-1,并在127 d内成功培养出直径1. 0～3. 0 mm的AGS.动力学研究表明,反应器内AGS对氨和亚硝酸盐的最大反应速率分别为1. 46 kg·(kg·d)-1和1. 76 kg·(kg·d)-1,半抑制速率分别是852. 2 mmol·L-1和108. 2 mmol·L-1.与絮状污泥相比,AGS能承受更高的氨和亚硝酸盐抑制浓度,并保持较高的反应速率.采用含有海绵的生物流离球作为填料,能有效加速反应器的启动,加快AGS的形成,对厌氧氨氧化工艺的实际运行具有积极的意义.     

电化学氧化预处理垃圾渗滤液的可行性研究

文章采用电化学氧化技术预处理渗滤液,在以钛涂钌铱为阳极、不锈钢为阴极,极板距离1.5cm,电流密度60mA/cm2,不外加电解质的情况下,电解120min,渗滤液的COD去除率达到48.6%,NH4+离子浓度去除率达53.6%,BOD5/COD比值由0.15提高到0.38,达到了较好的预处理效果。     

Fenton试剂加硫酸处理高浓度含酚废水的研究

研究了硫酸、Fenton试剂对酚的催化降解作用，证实了硫酸与Fenton试剂对酚的催化降解具有协同作用。H_2SO_4－Fenton试剂对高浓度含酚废水的处理结果说明，在Fenton试剂中加入硫酸可大大增加其对酚的降解能力。与单独的Fenton试剂法比较，当H_2O_2∶COD（重量比）＜0．8时，本法对COD≥14000mg／L含酚废水COD去除率可提高40％以上，对高浓度含酚废水具有很好的处理效果。     

Acid Orange 7 degradation using methane as the sole carbon source and electron donor

• AO7 degradation was coupled with anaerobic methane oxidation. • Higher concentration of AO7 inhibited the degradation. • The maximum removal rate of AO7 reached 280 mg/(L·d) in HfMBR. • ANME-2d dominated the microbial community in both batch reactor and HfMBR. • ANME-2d alone or synergistic with the partner bacteria played a significant role. Azo dyes are widely applied in the textile industry but are not entirely consumed during the dyeing process and can thus be discharged to the environment in wastewater. However, azo dyes can be degraded using various electron donors, and in this paper, Acid Orange 7 (AO7) degradation performance is investigated using methane (CH₄) as the sole electron donor. Methane has multiple sources and is readily available and inexpensive. Experiments using ¹³C-labeled isotopes showed that AO7 degradation was coupled with anaerobic oxidation of methane (AOM) and, subsequently, affected by the initial concentrations of AO7. Higher concentrations of AO7 could inhibit the activity of microorganisms, which was confirmed by the long-term performance of AO7 degradation, with maximum removal rates of 8.94 mg/(L·d) in a batch reactor and 280 mg/(L·d) in a hollow fiber membrane bioreactor (HfMBR). High-throughput sequencing using 16S rRNA genes showed that Candidatus Methanoperedens, affiliated to ANME-2d, dominated the microbial community in the batch reactor and HfMBR. Additionally, the relative abundance of Proteobacteria bacteria (Phenylobacterium, Pseudomonas, and Geothermobacter) improved after AO7 degradation. This outcome suggested that ANME-2d alone, or acting synergistically with partner bacteria, played a key role in the process of AO7 degradation coupled with AOM.     

基于SBR反应器的ANAMMOX工艺的启动运行

采用SBR反应器,接种好氧硝化污泥,在142 d内于较高负荷下成功启动了厌氧氨氧化反应器.反应器总氮容积负荷(以N计)为0.43 kg/m3·d,总氮去除率最高达到93.3%,平均为80.5%;氨氮和亚硝酸盐氮的去除率最高达到93.9%和99.8%,平均去除率为81.2%和85.7%.在稳定运行阶段,氨氮去除量、亚硝酸盐氮去除量、硝酸盐氮生成量三者之间的比值为1:1.38:0.18.反应器启动过程中,出水、进水pH差值的变化趋势由负到正,然后稳定在一定范围内;且污泥性状有较大变化,污泥中微生物所占比率有所提高,整个反应器中适应厌氧氨氧化运行方式的菌种增殖较快.     

Quantity and activity of ammonia-oxidizing archaea and bacteria and their contribution to ammonia oxidation in farmland soil of Qinghai-Tibet Plateau北大核心CSCD

Ammonia oxidation, the first and rate-limiting step of nitrification, is mainly performed by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). However, the activities of AOA and AOB in soil and their relative contribution to ammonia oxidation are unclear, and whether there is a significant correlation between the quantity of AOA and AOB and the ammonia oxidation rate is also controversial. In this study, quantitative PCR combined with acetylene (C2H2) and 1-octyne inhibition methods were used to determine the quantity and activity of AOA and AOB in wheat, highland barley, and oilseed rape soils in Nyingchi, Lhatse, Sangzhuzi, and Sangri counties on the Qinghai-Tibet Plateau. The results showed that the quantity of AOB ((2.34 ± 0.84) ×105 - (2.65 ± 1.07) ×106 copies g-1 dry soil) was significantly higher than that of AOA ((0.20 ± 0.10) ×104 - (4.02 ± 0.39) ×104 copies g-1 dry soil) in all the soil samples. Soil pH was the key factor affecting the quantity of AOB, and the total phosphorus and ammonium nitrogen in soil were the key factors affecting the quantity of AOA. The rates of ammonia oxidation in the farmland soils of Lhatse (2.42 ± 0.73 mg kg-1 d-1) and Sangzhuzi (3.24 ± 1.15 mg kg-1 d-1) were significantly higher than those in the soils of Nyingchi (1.17 ± 0.43 mg kg-1 d-1) and Sangri counties (0.88 ± 0.57 mg kg-1 d-1). The rates of ammonia oxidation in the farmland soils of Lhatse and Sangzhuzi were dominated by AOB, while those in the farmland soils of Nyingchi and Sangri counties were dominated by AOA. For crops, the ammonia oxidation rates of wheat and oilseed rape soils in all four regions were significantly higher than those of highland barley soil, whereas the activity of AOA and AOB was not influenced by crops. The ratio of nitrogen to phosphorus was the key factor influencing AOA activity, whereas soil pH and total carbon were the main factors influencing AOB activity. Additionally, the quantities of AOA and AOB were not significantly correlated with the total ammonia oxidation rates and AOA and AOB activity. Overall, our study suggests that both AOA and AOB play important roles in ammonia oxidation in farmland soils of the Qinghai-Tibet Plateau. Moreover, it is unreliable to predict the activity of AOA and AOB and their relative contribution to ammonia oxidation directly based on their number of amoA genes, and the activity of AOA and AOB should be directly and accurately measured. These results are important for understanding ammonia nitrogen removal processes, slowing nitrate loss, and reducing the emission of the greenhouse gas nitrous oxide in the farmland ecosystem of the Qinghai-Tibet Plateau. © 2022 Science Press. All rights reserved.     

Semi-closed synthesis of nitrogen and oxygen Co-doped mesoporous carbon for selective aqueous oxidation

Heteroatom-doped meso/micro-porous carbon materials are conventionally produced by harsh carbonization under an inert atmosphere involving specific precursors, hard/soft templates, and heteroatom-containing agents. Herein, we report a facile synthesis of N and O co-doped meso/micro-porous carbon (NOMC) by template-free carbonization of a small-molecule precursor in a semi-closed system. The semi-closed carbonizaiton process yields hydrophilic NOMCs with large surface area in a high yield. The porous structure as well as the elemental composition of NOMCs can be modulated by changing the holding time at a particular temperature. NOMCs as metal-free heterogeneous catalysts can selectively oxidize benzyl alcohol and its derivatives into aldehydes/ketones with>85％conversion in aqueous solution, which is much higher than that of the control sample obtained in tube furnace (21％conversion), mainly due to their high N content, high percentage of pyridinic N, and large surface area. The presence of O-containing moieties also helps to improve the hydrophilicity and dispersion ability of catalysts and thus facilitates the mass transfer process during aqueous oxidation. The NOMC catalysts also dispayed excellent activity for a wide range of substrates with a selectivity of>99％.     

氧化-微絮凝-高速过滤应用于再生水生产的研究

以中国北方缺水地区污水再生利用为目标,采用常规滤料双层过滤探讨高速微絮凝、氧化过滤再生水处理技术,试验通过不同的滤料级配、滤层厚度的对比试验;采用3种混凝剂和3种助凝剂做筛选试验,发现采用1#混凝剂,HFO助凝剂做絮凝氧化剂效果较理想,得出高速微絮凝氧化过滤工艺处理城市污水厂二级出水的工艺是可行的。试验装置的滤池单位面积周期产水量为50m3/(m2.h),最佳工艺条件下出水浊度去除率为92.21%,平均浊度为0.889NTU;COD去除率为55.58%,平均为22.33mg/L;PO34--P去除率为84%,平均为0.135mg/L;色度去除率为80.7%,平均为1.45度,完全符合GB/T18920-2002《城市污水再生利用城市杂用水质》要求。