杀虫双生产废水的预处理研究

研究杀虫双生产废水的预处理工艺，对碱性废水采用减压蒸馏法脱盐，馏出比1／3，真空度40kPa,10次循环蒸馏，脱盐率达77％，馏出液的可生化性好，可直接生物处理，酸性废水，尾气吸收废水经混合调碱处理后，CODcr去除率达75％，BODs/CODcr由原水的0．08提高至0．36，各股废水预处理后混合，经7d间歇生化处理的CODcr去除率达68％。     

中空纤维膜器处理含铀(VI)废水的研究

在中空纤维膜器中研究了二（2－乙基己基）磷酸（HDEHP＿煤油膜萃取含铀（Ⅵ）废水。实验表明，HDEHP－煤油膜萃取铀（Ⅵ）的萃取率随萃取时间的增加而增加；当水相pH大于2时，水相酸度对速率影响较小，当水相pH小于2时，随着水相pH的提高，速率明显上升；提高水相流速可提高膜萃取率；当有机相HDEHP浓度小于0.01mol/L时，随着HDEHP浓度的提高萃取率上升，当大于0.01mol/L后，其浓度改变对萃取率影响不大。温度和有机相流速对膜萃取率影响较小。     

平片膜生物反应器中膜污染特性的实验研究

采用聚偏氟乙烯平片膜生物反应器 ,通过测定不同运行条件下的水通量研究其污染特性 ,重点考察了运行时间、操作压力、曝气状况对膜污染的影响。实际结果表明 ,在曝气量为 3m3 h、操作压力为 0 .0 2MPa条件下运行 6h后 ,膜水通量从2 4 0mL min·m2 降至 5 5mL min·m2 ,下降率超过 77%。     

热泵蒸馏应用于橡胶助剂废水预处理的研究

橡胶助剂废水属于难处理的工业废水，尤其是CBS（N－环己基－2－苯并噻唑次磺酰胺，英文名N－cyclohexy1-2-benzoth-iazole sulfonamide，简称Accelerator CBS)生产废水的COD达40000mg/L，并且含有杂环类有害化合物，难降解，难生化。经过絮凝沉淀、化学氧化、电化学法、吸附法等实验方法，处理效果都不是十分理想。采用热泵蒸馏技术对橡胶促进剂CBS的废水进行预处理实验，可使CBS废水的COD从40000mg/L降至1600mg/L，结果表明，该技术设备简单，投资少，操作方便，运行成本低，并能达到较理想的预处理效果。     

Enhanced solar still productivity using transparent walls with an integral trough and organic porous absorber material

This experimental work has been conducted to compare the performance of the modified stills with that of the conventional still. Three modified stills (S1, S2, and S3) and conventional still (S4) were fabricated, each with 0.5 m² of the basin area. S1 and S3 had transparent double glass walls with air in between acting as insulation, whereas S2 has a single transparent wall. S4 has insulated plywood walls painted black from inside. A mixture of coco peat and charcoal was used in S1, S2, and S3, whereas there was no basin material for S4. Experiments were conducted by changing the water quantity in the solar still ranging from 5 to 10 kg. Maximum distillate output of 5.46 l/m²-d was obtained for S2, whereas it was 3.80 l/m²-d for S4 for an average solar radiation intensity of 675 W/m² (24.3 MJ/m²-d). Use of transparent walls with troughs to collect condensate increased the condenser area by 78.4%. The distillate water cost per liter was estimated as Rs. 0.86 (0.013 US$) and Rs. 1.61 (0.025 US$) for S2 and S4, respectively. Energy payback time for S2 was estimated as 4 months. Theoretical and experimental values showed that there is a significant loss of incoming solar radiation due to wall shadow.     

Advanced treatment of municipal wastewater by nanofiltration: Operational optimization and membrane fouling analysis

Municipal sewage from an oxidation ditch was treated for reuse by nanofiltration (NF) in this study. The NF performance was optimized, and its fouling characteristics after different operational durations (i.e., 48 and 169 hr) were analyzed to investigate the applicability of nanofiltration for water reuse. The optimum performance was achieved when transmembrane pressure = 12 bar, pH = 4 and flow rate = 8 L/min using a GE membrane. The permeate water quality could satisfy the requirements of water reclamation for different uses and local standards for water reuse in Beijing. Flux decline in the fouling experiments could be divided into a rapid flux decline and a quasi-steady state. The boundary flux theory was used to predict the evolution of permeate flux. The expected operational duration based on the 169-hr experiment was 392.6 hr which is 175% longer than that of the 48-hr one. High molecular weight (MW) protein-like substances were suggested to be the dominant foulants after an extended period based on the MW distribution and the fluorescence characteristics. The analyses of infrared spectra and extracellular polymeric substances revealed that the roles of both humic- and polysaccharide-like substances were diminished, while that of protein-like substances were strengthened in the contribution of membrane fouling with time prolonged. Inorganic salts were found to have marginally influence on membrane fouling. Additionally, alkali washing was more efficient at removing organic foulants in the long term, and a combination of water flushing and alkali washing was appropriate for NF fouling control in municipal sewage treatment.     

Identifying the major fluorescent components responsible for ultrafiltration membrane fouling in different water sources

Three-dimensional fluorescence excitation–emission matrix(EEM) coupled with parallel factor analysis(PARAFAC) was performed for a total of 18 water samples taken from three water sources(two lakes and one wastewater treatment plant(WWTP) secondary effluent),with the purpose of identifying the major ultrafiltration(UF) membrane foulants in different water sources. Three fluorescent components(C1, C2 and C3) were identified,which represented terrestrially derived humic-like substances(C1), microbially derived humic-like substances(C2), and protein-like substances(C3). The correlations between the different fluorescent components and UF membrane fouling were analyzed. It was shown that for the WWTP secondary effluent, all three components(C1, C2 and C3) made a considerable contribution to the irreversible and total fouling of the UF membrane.However, for the two lakes, only the C3 exhibited a strong correlation with membrane fouling, indicating that the protein-like substances were the major membrane foulants in the lake waters. Significant attachment of C1, C2 and C3 to the UF membrane was also confirmed by mass balance analyses for the WWTP secondary effluent; while the attachment of C1 and C2 was shown to be negligible for the two lakes. The results may provide basic formation for developing suitable fouling control strategies for sustainable UF processes.     

Inherently Safer Design for low-temperature process during depressurization: An industrial case study

The exploitation of a low-quality gas field with high CO₂ concentration is more viable through liquid CO₂ produced from cryogenic distillation technology. Despite the bright potential of the technology, there are deficiencies in handling high concentration of CO₂ at low temperature and high pressure during the blowdown condition. This study focuses on the CO₂ blowdown at a cryogenic pilot plant designed to manage high concentrations of CO₂ in the feed gas, high pressures, and low temperatures. A comprehensive design review and risk assessment using Inherent Safer Design (ISD) indexes were carried out in this study. The ISD was performed to identify the current risk level, and the critical parameters that may cause solid CO₂ formation in the piping or equipment as well as to identify mitigation measures to avoid the temperature to drop below the CO₂ freezing point during blowdown. The present findings confirmed that the initial pressure and temperature, as well as CO₂ concentration are key parameters towards significant impact on blowdown conditions. Therefore, the reduction of the feed gas pressure from 80 bar to 70 bars has minimized the Joule Thomson (JT) effect during blowdown and avoided the CO₂ solid formation in the system. Moreover, the relocation of the blowdown valve at the downstream heater resulted in a higher final temperature above the CO₂ freezing point. The ISD indexes confirmed that the cryogenic facilities are inherently safer during blowdown with the mitigation measures adopted.     

Dehydration of ethanol with different salts in a packed distillation column

This work aimed the evaluation of a saline extractive distillation for the ethanol production. A thermodynamic model was used to predict the influence of the salts in the liquid–vapor equilibrium of the system water–ethanol and inside the packed column. The experiments were done in a distillation unit, with an internal diameter of 5.9 cm and a packing section with 37 cm of height, packed with raschig rings with 0.73 cm of characteristic inner made of glass. All the bottom and top samples were analyzed by refractive index. Two synthetic charges with the same composition of ethanol that are produced in the refinery (0.02 and 0.25 mol.L^-1) were distilled under atmospheric pressure. Sodium chloride, calcium chloride, potassium acetate, calcium nitrate and a mixture of sodium and potassium acetates were added to the synthetic charges and the results were compared to the experiments already done without the presence of the salts, revealing the ethanol enrichment in the top product of the distillation unit, for all the systems analyzed. Another charge from the refinery, known as load of wine without yeast, was evaluated and the results indicated the same behavior, enriching the ethanol with the application of the saline extractive distillation.     

Recent improvements in oily wastewater treatment: Progress, challenges, and future opportunities

Oily wastewater poses significant threats to the soil, water, air and human beings because of the hazardous nature of its oil contents. The objective of this review paper is to highlight the current and recently developed methods for oily wastewater treatment through which contaminants such as oil, fats, grease, and inorganics can be removed for safe applications. These include electrochemical treatment, membrane filtration, biological treatment, hybrid technologies, use of biosurfactants, treatment via vacuum ultraviolet radiation, and destabilization of emulsions through the use of zeolites and other natural minerals. This review encompasses innovative and novel approaches to oily wastewater treatment and provides scientific background for future work that will be aimed at reducing the adverse impact of the discharge of oily wastewater into the environment. The current challenges affecting the optimal performance of oily wastewater treatment methods and opportunities for future research development in this field are also discussed.