Characterization of CANON reactor performance and microbial community shifts with elevated COD/N ratios under a continuous aeration mode

COD/N at low ratios (0–0.82) improved N removals of CANON. CANON performance decreased after COD/N up to 0.82. The relative abundance of AOB decreased continuously with increasing COD/N. AOB outcompeted at a high COD load led to CANON failure. The relative abundance of AnAOB decreased and increased with increasing COD/N. The effects of increasing COD/N on nitrogen removal performance and microbial structure were investigated in a SBR adopting a completely autotrophic nitrogen removal over nitrite process with a continuous aeration mode (DO at approximately 0.15–0.2 mg/L). As the COD/N increased from 0.1 to≤0.59, the nitrogen removal efficiency (NRE) increased from 88.7% to 95.5%; while at COD/N ratios of 0.59–0.82, the NRE remained at 90.7%–95.5%. As the COD/N increased from 0.82 to 1.07, the NRE decreased continuously until reaching 60.1%. Nitrosomonas sp. (AOB) and Candidatus Jettenia (anammox bacteria) were the main functional genera in the SBR. As the COD/N increased from 0.10 to 1.07, the relative abundance of Nitrosomonas decreased from 13.4% to 2.0%, while that of Candidatus Jettenia decreased from 35% to 9.9% with COD/N<0.82 then increased to 45.4% at a COD/N of 1.07. Aerobic heterotrophic bacteria outcompeted AOB at high COD loadings (650 mg/L) because of oxygen competition, which ultimately led to deteriorated nitrogen removal performance.     

Impacts of advanced treatment processes on elimination of antibiotic resistance genes in a municipal wastewater treatment plant

The distributions of ARGs were monitored in a WWTP in Harbin during six months. CASS had the best removal efficacy of ARGs compared to other processes in the WWTP. UV disinfection could effectively control the HGT. AGAC significantly remove ARGs and organics due to its high absorption capacity. Combination of ozone and AGAC significantly improve removal of ARGs and organics. Antibiotic resistance genes (ARGs) pose a serious threat to public health. Wastewater treatment plants (WWTPs) are essential for controlling the release of ARGs into the environment. This study investigated ARG distribution at every step in the treatment process of a municipal WWTP located in Harbin for six consecutive months. Changes in ARG distribution involved in two advanced secondary effluent treatment processes, ozonation and granular activated carbon (GAC) adsorption, were analyzed. Biological treatment resulted in the highest ARG removal (0.76–1.94 log reduction), followed by ultraviolet (UV) disinfection (less than 0.5-log reduction). Primary treatment could not significantly remove ARGs. ARG removal efficiency increased with an increase in the ozone dose below 40 mg/L. However, amorphous GAC (AGAC) adsorption with a hydraulic retention time (HRT) of 1 h showed better removal of ARGs, total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) than ozonation at a 60 mg/L dose. UV treatment could efficiently reduce the relative ARG abundance, despite presenting the lowest efficiency for the reduction of absolute ARG abundance compared with GAC and ozone treatments. The combination of ozone and AGAC can significantly improve the removal of ARGs, TOC, TN and TP. These results indicate that a treatment including biological processing, ozonation, and AGAC adsorption is a promising strategy for removing ARGs and refractory organic substances from sewage.     

Membrane-based treatment of shale oil and gas wastewater: The current state of knowledge

• Shale oil and gas production generates wastewater with complex composition. • Membrane technologies emerged for the treatment of shale oil and gas wastewater. • Membrane technologies should tolerate high TDS and consume low primary energy. • Pretreatment is a key component of integrated wastewater treatment systems. • Full-scale implementation of membrane technologies is highly desirable. Shale oil and gas exploitation not only consumes substantial amounts of freshwater but also generates large quantities of hazardous wastewater. Tremendous research efforts have been invested in developing membrane-based technologies for the treatment of shale oil and gas wastewater. Despite their success at the laboratory scale, membrane processes have not been implemented at full scale in the oil and gas fields. In this article, we analyze the growing demands of wastewater treatment in shale oil and gas production, and then critically review the current stage of membrane technologies applied to the treatment of shale oil and gas wastewater. We focus on the unique niche of those technologies due to their advantages and limitations, and use mechanical vapor compression as the benchmark for comparison. We also highlight the importance of pretreatment as a key component of integrated treatment trains, in order to improve the performance of downstream membrane processes and water product quality. We emphasize the lack of sufficient efforts to scale up existing membrane technologies, and suggest that a stronger collaboration between academia and industry is of paramount importance to translate membrane technologies developed in the laboratory to the practical applications by the shale oil and gas industry.     

Effects of Al3+ on pollutant removal and extracellular polymeric substances (EPS) under anaerobic,anoxic and oxic conditions

The highest removal efficiencies of COD and TN were achieved under 10 mg/L of Al³⁺. The highest TP removal efficiency occurred under 30 mg/L of Al³⁺. EPS, PS and PN concentrations increased with the addition of Al³⁺. Sludge properties significantly changed with the addition of Al³⁺. Aluminum ions produced by aluminum mining, electrolytic industry and aluminum-based coagulants can enter wastewater treatment plants and interact with activated sludge. They can subsequently contribute to the removal of suspended solids and affect activated sludge flocculation, as well as nitrogen and phosphorus removal. In this study, the effects of Al³⁺ on pollutant removal, sludge flocculation and the composition and structure of extracellular polymeric substances (EPS) were investigated under anaerobic, anoxic and oxic conditions. Results demonstrated that the highest chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies were detected for an Al³⁺ concentration of 10 mg/L. In addition, the maximal dehydrogenase activity and sludge flocculation were also observed at this level of Al³⁺. The highest removal efficiency of total phosphorus (TP) was achieved at an Al³⁺ concentration of 30 mg/L. The flocculability of sludge in the anoxic zone was consistently higher than that in the anaerobic and oxic zones. The addition of Al³⁺ promoted the secretion of EPS. Tryptophan-like fluorescence peaks were detected in each EPS layer in the absence of Al³⁺. At the Al³⁺ concentration of 10 mg/L, fulvic acid and tryptophan fluorescence peaks began to appear, while the majority of protein species and the highest microbial activity were also detected. Low Al³⁺ concentrations (<10 mg/L) could promote the removal efficiencies of COD and TN, yet excessive Al³⁺ levels (>10 mg/L) weakened microbial activity. Higher Al³⁺ concentrations (>30 mg/L) also inhibited the release of phosphorus in the anaerobic zone by reacting with PO₄^3-.     

Municipal wastewater treatment in China: Development history and future perspectives

The history of China’s municipal wastewater management is revisited. The remaining challenges in wastewater sector in China are identified. New concept municipal wastewater treatment plants are highlighted. An integrated plant of energy, water and fertilizer recovery is envisaged. China has the world’s largest and still growing wastewater sector and water market, thus its future development will have profound influence on the world. The high-speed development of China’s wastewater sector over the past 40 years has forged its global leading treatment capacity and innovation ability. However, many problems were left behind, including underdeveloped sewers and sludge disposal facilities, low sustainability of the treatment processes, questionable wastewater treatment plant (WWTP) effluent discharge standards, and lacking global thinking on harmonious development between wastewater management, human society and the nature. Addressing these challenges calls for fundamental changes in target design, policy and technologies. In this mini-review, we revisit the development history of China’s municipal wastewater management and identify the remaining challenges. Also, we highlight the future needs of sustainable development and exploring China’s own wastewater management path, and outlook the future from several aspects including targets of wastewater management, policies and technologies, especially the new concept WWTP. Furthermore, we envisage the establishment of new-generation WWTPs with the vision of turning WWTP from a site of pollutant removal into a plant of energy, water and fertilizer recovery and an integrated part urban ecology in China.     

基于SD-ABMS方法的航空应急医疗转运任务仿真系统

为解决我国航空应急医疗转运演练成本高昂及我国航空医疗转运任务执行机理相关研究不足的问题,依据真实的医疗转运场景,抽象出病患、飞行员、医护、机务、医院负责人、安保、环境等共16种Agent和详细的医疗转运流程;使用ABMS方法对各Agent的离散行为及Agent间的协同行为进行建模,使用SD方法对各Agent的连续行为进行建模, 从微观视角刻画并实现航空应急医疗转运任务仿真模型,并基于Anylogic实现航空应急医疗转运任务系统可视化原型。研究结果展示了航空应急医疗转运任务执行机理,可降低相关演练成本,也可为航空应急医疗转运实时任务评估提供支持。     

AA-HPA-AMPS阻垢剂最佳合成条件研究

通过溶液聚合方法,以丙烯酸、丙烯酸羟丙酯、2-丙烯酰胺-2-甲基丙磺酸为单体,以过硫酸铵为引发剂,合成AA-HPA-AMPS聚合物。固定聚合物浓度为4mg/L,分别考查反应时间、反应温度(X1)、引发剂用量(X2)、单体配比(X3)对聚合物阻CaCO3垢性能的影响,并设计了正交实验,得出聚合物在90℃、引发剂用量为13.5%、M(AA)∶M(HPA)为7∶3时,阻CaCO3垢率最高为80.9%。为探究此聚合物是否有更高的阻垢性能,应用多元回归分析对正交实验结果进行分析及验证,聚合物阻CaCO3垢效率y与各影响因素x之间基本满足y=-146.825+16.25x2,最佳聚合条件为X2=14.5,y为90.20%。     

腐殖酸活性组分及其比例对紫色潮土中铅形态转化和有效性演变动态的影响

腐殖酸(HAs)是制约土壤铅赋存形态与活性的重要因素.本研究通过室内模拟实验,结合化学连续提取形态分级方法,探讨HAs活性组分(胡敏酸,HA;富里酸,FA)添加量及其比例(HA/FA比)对紫色潮土中铅赋存形态、有效性变化动态的影响.结果表明:(1)外源铅进入土壤经60d转化平衡后,土壤中交换态、残渣态铅降低,铁锰氧化物结合态、有机结合态铅增加,碳酸盐结合态铅变化不明显.(2)紫色潮土以交换态铅和碳酸盐结合态铅对有效铅贡献最大,HA通过降低碳酸盐结合态而对土壤铅产生钝化作用,FA则通过增加交换态和碳酸盐结合态而活化土壤铅;随着HAs用量的增加,钝化或活化作用越强.当HAs用量为3%C时,添加HA的土壤碳酸盐结合态铅较对照降低13.4个百分点,有效铅相应降低14.19%;添加FA的土壤交换态铅较对照增加13.59个百分点,碳酸盐结合态铅增加2.15个百分点,有效铅较对照相应增加4.09倍.FA(1%C)是土壤铅活化的突变点,当FA1%C时,土壤铅活化百分率增加了14%,土壤铅活性和生物有效性显著增大.(3)等量HAs(1%C)条件下,当HA/FA比≥7/3时,促进土壤铅向低活性的有机结合态和残渣态转化,HAs对土壤铅表现为钝化作用,而当HA/FA比≤5/5时,则表现为活化作用.     

Heat loss analysis: An approach toward the revival of parabolic dish type solar cooker

Present work investigates a noble approach toward the heat loss analysis of parabolic dish type solar cooker. Various experiments have been done on cooking pot to get the input parameter for calculation purposes. Cooking pot was kept at the focus of a parabolic dish type concentrator and repeated experiments have been done to measure solar radiation intensity (direct and Indirect) using a pyrometer, temperature at the focus of parabolic dish using a thermocouple and air velocity using hot wire anemometer to investigate the heat losses from the cooking pot. In the present article, a numerical approach has been performed to define the new parameter called performance index of the cooking pot which decides how the useful energy of working fluid inside the cooking pot approaches concentration ratio of the parabolic dish type solar cooker. The present analysis shows that the performance index varies from 15.45 to 17.66 and efficiency varies from 85.83% to 98.10% with the time of the day.     

站场伴生气减排回收工艺研究与应用

针对部分油田站场因伴生气量低造成的燃烧排放或无效放空的生产现状,研制了一种基于双U型管气液分离、气体过滤、阀前调压稳压和止回阀的组合式回收装置。对组合式回收装置进行了功能测试,并在17座站场现场应用,供气系统压力平稳,加热炉正常运行,实现了低气油比站场伴生气100%回收利用,有利于油田安全环保、节能减排与清洁生产。