Removal of Cu2+ and dye from wastewater using the heavy metal precipitant N,N-bis-(dithiocarboxy)piperazine

We found that a new heavy metal precipitant, disodium N,N-bis-(dithiocarboxy)piperazine, both precipitates Cu²⁺ ions removes the dye from wastewater. The precipitation was based on a coordination polymerization reaction while the removal of the dye could be mainly attributed to an hydrophobic adsorption at pH 7.     

Short-term impact of reservoir impoundment on the patterns of mercury distribution in a subtropical aquatic ecosystem, Wujiang River, southwest China

Surveys on pre- and post-impoundment total mercury concentrations in water, seston and fish were conducted during 2007–2008 in the Wujiang River, southwest China. Compared with the pre-impoundment, total mercury in the reservoir and downstream water rapidly increased by 164–303 % during the first half year of flooding, and then decreased by 61.7–62.2 % after 9 months of flooding. However, total mercury in seston from the reservoir and downstream generally declined. There was no significant difference in the total mercury between reservoir fish with different habitat preference and feeding habit. We find that fish tissue mercury concentration significantly increased threefold after flooding, and the increasing rate is lower than those in subarctic and temperate reservoirs. The pre- and post-impoundment fish samples exceeding the Chinese hygienic standard for tolerances of mercury in foods increased from 1.3 to 17.4 %. Long-term monitoring of fish mercury level in Wujiang River should be undertaken to ensure local food security.     

塔中油田硫酸盐还原菌恶性繁殖机理分析＊

硫酸盐还原菌等的恶性繁殖使油田生产管线设施腐蚀破坏、结垢堵塞,注入地层后对油层造成伤害。研究发现,塔中油田联合站水体可检测SRB菌数高达2.5×104个/mL,注水管垢含FeS高达29.8%,属硫酸盐还原菌恶性繁殖代谢产物。塔中油田水系统各主要环节中硫酸盐还原菌和硫化氢含量与油田水处理工艺特点密切相关,其中塔中油田联合站完全密闭的水处理压力流程是造成该站硫酸盐还原菌恶性繁殖的主要原因。实验表明,前端适度曝氧、添加H2O2等氧化性杀菌剂和300mg/L冲击式加药等都是抑制硫酸盐还原菌的有效方法。     

放空尾气回收技术在塔中油田的应用

塔中油田为解决油气生产过程中排放的放空尾气给油田节能环保工作带来的压力,采用移动撬装天然气处理装置回收放空尾气技术。大量放空尾气经脱硫、脱水、脱烃、增压后,再利用CNG罐车拉运至尾气回收站回收利用。尾气回收利用技术的实施节约了大量天然气,降低了油气田开发对环境的影响。     

Heavy metal speciation in various types of fly ash from municipal solid waste incinerator

Fly ash (FA) from municipal solid waste incinerators has been known as hazardous waste, which is mostly because of the high content of heavy metal and dioxins. Besides the content, the form of the heavy metals in fly ash is also very important, because it is tightly related with the leaching behavior of fly ash in diverse circumstances. To evaluate the environment potential risk of fly ash, the Tessier chemical extraction method was adopted. In this study, four kinds of fly ash were examined, one sample from China (CFA) and the other three from Japan (RFA, CaFA and NaFA). Five metal elements were detected and they were Ni, Cr, Cd, Pb, and Cu. The result of total heavy metals’ concentration showed CFA has the lowest content. As to the Tessier chemical extraction experiments, the results show that Cd, Pb, and Cu have higher leaching risk in the environment than other heavy metals. The result of leaching test experiment showed that the more exchangeable speciation of Cd, Cr and Pb in FA, the more it could leach out in natural environment.     

稻田保护性耕作的生态效应研究进展与发展建议

首先阐述了保护性耕作的国内外发展现状,指出我国保护性耕作存在的主要问题：关键技术创新研究不够,具有中国南方特色的稻田保护性耕作制度、模式及其技术体系尚未形成;与南方独特的自然地理条件、复杂的稻田耕作制度相匹配的保护性耕作机具研究亟待加强;技术推广保障体系薄弱,适合农村实际的推广机制有待进—步探索。其次,从土壤理化性状、土壤生物学特性、节能减排效应和病虫害生态调控等4方面综述了稻田保护性耕作的生态效应最新研究进展。最后,针对我国南方稻区特别是西南丘陵山区稻田保护性耕作的发展提出了3点建议：加大政策扶持力度,建立政策优惠、财政补贴、生态补偿等多元化长效投入机制;重点开展技术攻关,深入研究中稻-再生稻优质、高产、高效保护性耕作关键技术;丘陵山区稻田周年高效农作制度创新与配套保护性耕作技术,以及以水旱轮作为中心的稻田保护性耕作技术节能减排效应的技术机理;进一步强化现有技术集成,扩大技术成果的示范,加快技术成果向生产力的转变。     

Feedforward control for nitrogen removal in a pilot-scale anaerobic-anoxic-oxic plant for municipal wastewater treatment

To improve the efficiency of nitrogen removal with lower energy consumption, the study of feedforward control was carried out on a pilot-scale anaerobic-anoxic-oxic (AAO) plant for the treatment of municipal wastewater. The effluent qualities of the pilot plant under different control strategies were investigated. The results indicated that the change of external recycle was not a suitable approach to regulate the sludge concentration of plug-flow reactors; adjusting the aeration valve and dissolved oxygen set-point according to ammonia load could overcome the impact of influent fluctuation; and the denitrification potential could be estimated based on the transit time of anoxic zone and the relative content of carbon resource entering the anoxic zone. Simple feedforward control strategies for aeration and internal recycle were subsequently proposed and validated. The nitrogen removal was successfully improved in the pilot plant. The effluent total nitrogen had decreased by 29.9% and was steadily controlled below 15 mg·L^-1. Furthermore, approximately 38% of the energy for aeration had been saved.     

Hydrolytic Degradation of PPDO/PDLLA Blends Containing the Compatibilizer PLADO

The poly(para-dioxanone) (PPDO)/poly poly (dl-lactide) (PDLLA) blends containing various contents of compatibilizer (0, 1, 3, 5, 10 %) were prepared by solution co-precipitation, which were dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) to form 10 % wt/vol solutions. Then in vitro hydrolytic degradation of PPDO/PDLLA blends containing poly (dl-lactide-co-para-dioxanone) (PLADO) as the compatibilizer was studied by the changes of weight loss, water absorption, thermal properties, surface morphology and mechanical properties of samples in phosphate buffered saline (pH 7.44) at 37 °C for 8 weeks. During the degradation, the weight loss and water absorption increased significantly for all blends, whereas hydrolysis rate of blends varied with the blend composition. The samples’ glass transition temperature decreased notably, while the degrees of crystallinity increased. Compared with uncompatibilized PPDO/PDLLA blends, PPDO/PDLLA blends with compatibilizer exhibited higher hydrolysis rate. The results suggested that the compatibilizer (PLADO) accelerated the hydrolysis rate of PPDO/PDLLA blends during the degradation.     

Selectivity of Nano Zerovalent Iron in In Situ Chemical Reduction: Challenges and Improvements

Nano zerovalent iron (nZVI) is a promising remediation technology utilizing in situ chemical reduction (ISCR) to clean up contaminated groundwater at hazardous waste sites. The small particle size and large surface area of nZVI result in high reactivity and rapid destruction of contaminants. Over the past 20 years, a great deal of research has advanced the nZVI technology from bench‐scale tests to field‐scale applications. However, to date, the overall number of well‐characterized nZVI field deployments is still small compared to other alternative remedies that are more widely applied. Apart from the relatively high material cost of nZVI and questions regarding possible nanotoxicological side effects, one of the major obstacles to the widespread utilization of nZVI in the field is its short persistence in the environment due to natural reductant demand (NRD). The NRD for nZVI is predominantly due to reduction of water, but other reactions with naturally present oxidants (e.g., oxygen) occur, resulting in situ conditions that are reducing (high in ferrous iron phases and H₂) but with little or no Fe(0). This article reviews the main biogeochemical processes that determine the selectivity and longevity of nZVI, summarizes data from prior (laboratory and field) studies on the longevity of various common types of nZVI, and describes modifications of nZVI that could improve its selectivity and longevity for full‐scale applications of ISCR. © 2016 Wiley Periodicals, Inc.     

中国降水量区域变化稳定性研究

利用中国气象中心160站点的实际观察资料,对中国半个世纪的降水变化进行了系统分析,发现中国的夏季降水变化稳定性有显著的纬度与海拔效应:纬度越高,方差值越小,降水变化的幅度也越小,稳定性越大;从海拔来看,海拔越高,降水稳定性越好,降水量的变化稳定性与海拔是成反相关关系.除过受区域水汽来源稳定性的影响,主要受全球降水稳定性的分布规律所制约;在海拔上,降水量稳定性的分布,除过受水汽来源影响外,还与水汽凝结的高度效应有一定的关系.