Utilization of a biosurfactant foam/nanoparticle mixture for treatment of oil pollutants in soil

Oil contamination has become a primary environmental concern due to increased exploration, production, and use. When oil enters the soil, it may attach or adsorb to soil particles and stay in the soil for an extended period, contaminating the soil and surrounding areas. Nanoparticles have been widely used for the treatment of organic pollutants in the soil. Surfactant foam has effectively been employed to remediate various soil contaminants or recover oil compounds. In this research, a mixture of biosurfactant foam/nanoparticle was utilized for remediation of oil-contaminated soil. The results demonstrated that the biosurfactant/nanoparticle mixture and nitrogen gas formed high-quality and stable foams. The foam stability depended on the foam quality, biosurfactant concentration, and nanoparticle dosage. The pressure gradient change in the soil column relied on the flowrate (N₂ gas + surfactant/nanoparticle mixture), foam quality, and biosurfactant concentration. The optimal conditions to obtain good quality and stable foams and high oil removal efficiency involved 1 vol% rhamnolipid, 1 wt% nanoparticle, and 1 mL/min flowrate. Biosurfactant foam/nanoparticle mixture was effectively used to remediate oil-contaminated soil, whereas the highest treatment efficiency was 67%, 59%, and 52% for rhamnolipid biosurfactant foam/nanoparticle, rhamnolipid biosurfactant/nanoparticle, and only rhamnolipid biosurfactant, respectively. The oil removal productivity decreased with the increase of flowrate due to the shorter contact time between the foam mixture and oil droplets. The breakthrough curves of oil pollutants in the soil column also suggested that the foam mixture’s maximum oil treatment efficiency was higher than biosurfactant/nanoparticle suspension and only biosurfactant.

     

The modelling of trichloroethene photodegradation in Brij 35 surfactant by two-stage reaction.

Various clean-up technologies have been developed for the removal and/or destruction of trichloroethene (TCE) in the subsurface. Surfactant-aided soil washing followed by photodegradation could be a promising approach to such a task. The modelling of TCE photodegradation by UV in Brij 35 surfactant micelles is therefore investigated. Two stages of TCE degradation are observed in surfactant Brij 35 systems. A lag phase is observed at the commencement of the degradation, but the duration of the lag phase is significantly reduced as the initial pH increases. As the overall decay of TCE is also found to be faster at higher pH levels, it is suggested that the free radical reaction is dominant at high pH levels, and the formation of lag phases is mainly due to the deficiency of free radicals at lower pH levels. Since the period of the lag phase gradually decreases with the increase of initial pH level, and the two pseudo first-order reaction constants (one for the lag phase and one for the subsequent fast decay) for TCE decay in both stages are also pH dependent, a non-steady-state mathematical model is developed for the prediction of TCE photodegradation in Brij 35 solutions, in which the remaining fraction of TCE (C/C0) in the system can be determined at any instant by using a simple parameter of the initial system pH.     

我国粮食安全保障中改善农业环境的途径

本文分析了我国粮食安全及粮食持续生产所依托的农业环境状况。从我国粮食生产状况与经济发展水平看,全国粮食生产处于结构性过剩与低水平安全中,区域性粮食安全与不安全并存;耕地资源、水资源以及农民的经济收入状况等均不容乐观,加之自然灾害加重,粮食生产的环境成本将随之增加,这将影响我国未来粮食安全。为此,本文提出了走农业集约化道路是解决我国粮食安全与改善环境的基本途径。     

树脂吸附-Fenton试剂氧化法处理水杨醛生产废水

采用树脂吸附-Fenton试剂氧化法处理水杨醛生产废水。XF-01树脂和XF-02树脂静态吸附水杨醛生产废水时,COD去除率均在85％以上,挥发酚去除率均高于90％。XF-02树脂对水杨醛生产废水的处理效果更佳。动态吸附随废水流量增大,吸附出水的COD和挥发酚质量浓度均增加。适宜的废水流量为15BV,树脂的最佳脱附温度为80℃。在连续4批的吸附-脱附实验中,吸附出水的平均COD约为1200mg／L,平均挥发酚质量浓度小于10mg／L。在Fenton试剂氧化中,铁屑和铁粉的催化效果差别很小,都好于FeSO4·7H2O。以铁屑为催化剂、H2O2溶液加入量为1％时,氧化出水的COD小于150mg／L,挥发酚质量浓度小于0．5mg／L。     

Enhanced sludge solubilization by microbubble ozonation

A microbubble ozonation process for enhancing sludge solubilization was proposed and its performance was evaluated in comparison to a conventional ozone bubble contactor. Microbubbles are defined as bubbles with diameters less than several tens of micrometers. Previous studies have demonstrated that microbubbles could accelerate the formation of hydroxyl radicals and hence improve the ozonation of dyestuff wastewater. The results of this study showed that microbubble ozonation was effective in increasing ozone utilization and improving sludge solubilization. For a contact time of 80 min, an ozone utilization efficiency of more than 99% was obtained using the microbubble system, while it gradually decreased from 94% to 72% for the bubble contactor. The rate of microbial inactivation was obviously faster in the microbubble system. At an ozone dose of 0.02 g O₃ g⁻¹ TSS, about 80% of microorganisms were inactivated in the microbubble system, compared with about 50% inactivation for the bubble contactor. Compared to the bubble contactor, more than two times of COD and total nitrogen, and eight times of total phosphorus content were released from the sludge into the supernatant by using the microbubble system at the same ozone dosage. The application of microbubble technology in ozonation processes may provide an effective and low cost approach for sludge reduction.     

Comparison of surface emissions and subsurface distribution of cis- and trans-1,3-dichloropropene and chloropicrin in sandy field beds covered with four different plastic films

The purpose of this study was to conduct a field study at a Florida field site on surface emissions and subsurface distribution of cis-and trans-1,3-dichloropropene (1,3-D) and chloropicrin (CP) in raised beds injected with Telone C35 with four replications. A total of 16 beds were applied with Telone C35 by chisel injection and covered with four different plastic films, 4 beds for each film. Each bed was installed with five 20-cm long soil pore air probes and a surface air collection pan at arbitrarily locations along the length of each bed for sampling soil pore air and surface air, respectively, for analysis of the three biologically active compounds, cis- and trans-1,3-D and CP. We found that average concentrations of the three compounds at 20-cm depth among the beds covered with four different plastic films generally were not statistically different. Among the four beds covered with the same plastic film, average concentrations of the three compounds were statistically different only in the four metallic PE covered beds at 5 and 24 hours after injection. Volatilization rates of the three compounds among the beds covered with four different plastic films, with the exception of CP at 48 hours after injection, were not statistically different. It appeared that initial upward diffusion and volatilization flux were influenced by solar radiation. Initial subsurface concentrations of the three compounds and volatilization flux, especially cis-1,3-D, were greater in the beds on the east side of the field than that in the beds on the west side of the field. Whether or not difference in initial subsurface concentrations of the compounds between east side beds and west side beds may influence fumigant efficacy remains to be determined.     

江苏省一次典型沙尘污染过程分析

2021年4月16日至4月18日江苏省经历了一次受沙尘影响的重污染过程.本次过程沙源地为蒙古国中南部及中国内蒙古中西部地区,在蒙古气旋后部西北大风影响下,沙尘气团自西北向东南影响了中国多个省市和地区.江苏省自16日起逐渐受到沙尘过程影响,苏北城市ρ(PM10)从凌晨开始迅速升高,浓度最高达569μg/m3,空气质量达严...     

Cooling suits, physiological response, and task performance in hot environments for the power industry.

Heat stress on workers working outdoors in the power industry may result in fatigue and deterioration in task performance. This research collected and analyzed data on task performance of workers working indoors and outdoors with and without a cooling suit. The task performance was compared on the basis of heart rate, oxygen consumption, tympanic temperature, subjective responses, productivity, and error rates. Based on One-Way Analysis Of Variance (ANOVA) results, a significantly lower estimated working oxygen consumption was observed (p < .001) when the cooling suit was worn. The productivity was higher while workers wore the cooling suit as compared to no cooling suit (p = .011) whereas the error rates were significantly lower (p < .001). Also a significantly lower self-reported discomfort was observed in the neck and shoulders while working wearing the cooling suit (p = .004). This study concluded that wearing a cooling suit while working outdoors was associated with physiological benefits as well as improved task performance of the study participants.     

Variations in the chemical properties of landfill leachate

Landfill leachates were collected and their chemical properties analyzed once every two months over a ten-month period from the Gin Drinkers' Bay (GDB) and Junk Bay (JB) landfills. The contents of solids, and inorganic and organic components fluctuated considerably with time. In general, the chemical properties of the two leachates correlated negatively (P<0.05) with the amounts of rainfall prior to the sampling periods. However, magnesium and pH of the leachates remained relatively constant with respect to sampling time. The JB leachate contained higher average contents of solids and inorganic and organic matter than those of GDB with the exception of trace metals. Trace metals were present in the two leachates in trace quantities (<1.0 mg/liter). The concentrations of average ammoniacal nitrogen were 1040 and 549 mg/liter, while chemical oxygen demand (COD) values were 767 and 695 mg/liter for JB and GDB leachates, respectively. These results suggest that the leachates need further treatment before they can be discharged to the coastal waters.     

Marine oil spill contingency planning

According to the practice researching and formulating “The Oil Spill Contingency Plan of south Chinese Sea”,this paper analyses and discusses the structure,functions and main contents of marine oil spill contingency planning,programs the organizing and commanding system and emergency response system,and advances the planning and researching method to coordinate comprehensively and to design practically the detailed emergency response steps until to formulate the ease operating programs for the plan implementation(PPI) and the PPI to apply high-techniques supporting emergency administrations and response.