Influence of water quality on plankton in tropical ponds: A multivariate analysis approach

Plankton are highly sensitive to environmental changes, therefore being excellent water indicators. This study was conducted to classify water and sediment quality characteristics and different genera of phytoplankton and zooplankton in three ponds. The prominent water and sediment quality characteristics responsible for the occurrence of phytoplankton and zooplankton were also studied. The nutrient pollution factor is mainly responsible for the abundance of Cyanophyceae and for reduction in Rotifera, Cladocera, Copepoda and Ostracoda. The organic pollution factor is responsible for the abundance of Bacillariophyceae and Protozoa. The products of mineralization have more influence on the decreased Chlorophyceae. Thus, it is essential to control the disposal of pollutants into the study pond system.     

干旱地区高盐纳污坑塘水生态修复——以阿拉尔氧化塘为例

针对干旱地区污染水体修复及资源化利用的关键问题,以新疆阿拉尔纳污坑塘生态修复及景观提升项目为例,探索不同水生态修复技术在干旱地区高盐水体水环境修复中的应用效果。通过前期调研、方法研究和技术论证,提出“控源截污、水质提升、活水循环、生态修复”的技术路线,阿拉尔氧化塘内废水采用“改性沸石原位修复+微生物降解+水生植被种植+曝气增氧”的协同技术体系改善水质,实现水生态系统的恢复和水体自净能力的提升。工程全面实施后,氧化塘内水体总磷、氨氮、化学需氧量、色度和总氮的去除率分别达80.73%、58.55%、62.63%、87.06%和68.61%,水体黑臭现象消失,生态效益显著,对我国西北干旱地区的水环境修复和水资源利用具有较强的示范作用。     

Modelling of coliform removal in 186 facultative and maturation ponds around the world

The paper presents a very extensive evaluation of the coliform decay in facultative and maturation ponds, based on data from 186 different ponds in the world. The ponds encompass a very wide diversity in terms of physical and operating conditions, covering most situations encountered in practice. The median values for the coliform removal efficiencies were 1.8 log units (98% removal) for primary facultative ponds, 1.0 log units for secondary facultative ponds (90% removal) and 1.2 log units (94% removal) for each maturation pond in the series. Two equations to be used for design purposes were derived for estimating the die-off coefficient K(b) (dispersed flow, 20 degrees C) in facultative and maturation ponds. The first equation led to a slightly better fitting with the observed logarithm of the effluent coliform concentrations (R2 = 0.874), and related K(b) with the pond detention time t and depth H (K(b) = 0.682 H(-1.286) t(-0.103)). The other equation also led to a satisfactory fitting (R2 = 0.845), but was slightly simpler, depending only on the pond depth (K(b) = 0.549 H(-1.456)).     

Single-stage and advanced absorption heat transformers operating with lithium bromide mixtures used to increase solar pond's temperature

Mathematical models of single-stage and advanced absorption heat transformers operating with the water/lithium bromide and water/Carrol™ mixtures were developed to simulate the performance of these systems coupled to a solar pond in order to increase the temperature of the useful heat produced by solar ponds. Plots of coefficients of performance and gross temperature lifts are shown against the temperatures of the heat supplied by the solar pond. The results showed that the single-stage and the double absorption heat transformer are the most promising configuration to be coupled to solar ponds. With single-stage heat transformers it is possible to increase solar pond's temperature until 50°C with coefficients of performance of about 0.48 and with double absorption heat transformers until 100°C with coefficients of performance of 0.33.     

Baseline study of methane emission from anaerobic ponds of palm oil mill effluent treatment

The world currently obtains its energy from the fossil fuels such as oil, natural gas and coal. However, the international crisis in the Middle East, rapid depletion of fossil fuel reserves as well as climate change have driven the world towards renewable energy sources which are abundant, untapped and environmentally friendly. Malaysia has abundant biomass resources generated from the agricultural industry particularly the large commodity, palm oil. This paper will focus on palm oil mill effluent (POME) as the source of renewable energy from the generation of methane and establish the current methane emission from the anaerobic treatment facility. The emission was measured from two anaerobic ponds in Felda Serting Palm Oil Mill for 52 weeks. The results showed that the methane content was between 35.0% and 70.0% and biogas flow rate ranged between 0.5 and 2.4 L/min/m(2). Total methane emission per anaerobic pond was 1043.1 kg/day. The total methane emission calculated from the two equations derived from relationships between methane emission and total carbon removal and POME discharged were comparable with field measurement. This study also revealed that anaerobic pond system is more efficient than open digesting tank system for POME treatment. Two main factors affecting the methane emission were mill activities and oil palm seasonal cropping.     

硝酸钾卤水盐田蒸发质量分数分布模型及优化

新疆罗布泊天然硝酸钾卤水进行多级盐田蒸发除盐时,各级盐田中目标产物硝酸盐质量分数的分布及盐田的级数对硝酸盐收率有很大影响.本文通过物料衡算和相图推导,建立了以硝酸根损失量为函数,以盐田级数、各级质量分数分布为自变量的数学模型,并结合实际生产数据,通过优化,获得了不同盐田级数卤水质量分数分布规律,确定新疆罗布泊硝酸钾卤水应采用三到四级盐田滩晒,同时讨论了盐田级数和沉积盐夹带液相量对硝酸钾损失的影响.     

水力旋流器在德兴铜矿4#尾矿库的应用

４＃尾矿库是我国第一座采用两段分级中线法机械筑坝的大型尾矿库,本文介绍了４＃尾矿库水力旋流器的设计和现场使用情况,并对今后水力旋流器的正常生产提出了几点建议。     

The distribution and macrofauna of ponds in stretches of an alpine floodplain differently impacted by hydrological engineering

The purpose of this study was to describe the impact of hydrological engineering on distribution, morphology and macrofaunal community composition of ponds in an alpine floodplain. The study was conducted in 1995 with the study sites being located on the Isar floodplain (Bavaria, Germany). The density of ponds was highest in a bypassed section of the floodplain with a residual flow regime and unrestricted peak floods (up to 40 ponds per river kilometre). In a channelized section and downstream of a reservoir, density was much lower. In 1995, about one third of the ponds were removed by floods or dried out in summer. About the same fraction was generated as a result of flood events. The composition of the macroinvertebrate and vertebrate faunas of 59 ponds was investigated. Cluster analysis classified the ponds into four groups. One of the faunal types was limited to ponds generated by the 1995 floods, where only a few predominantly rheophilic species occurred. The other types represented older successional stages and were inhabited by more species‐rich faunas composed mainly of Odonata, Heteroptera and Coleoptera. In the channelized stretch of the Isar floodplain, and downstream of the reservoir only a single pond was generated by the 1995 floods; this caused a lower abundance and diversity of pond types. Copyright © 1999 John Wiley & Sons, Ltd.     

Seasonal Operation of Ponds for Chemical Precipitation of Wastewater

Wastewater precipitation ponds (fellingsdams) are conventional stabilization ponds adapted to cold climate by the use of chemical precipitation to attain sufficient removal efficiency of impurities, primarily phosphorus. The objective with this investigation was to study the influence of an interruption of the dosage of coagulant during summer periods at two fellingsdam systems (Orrviken and Lockne) in the middle of Sweden. The investigation took place over two years characterized by unusual precipitation conditions; 2001 was intense in precipitation whereas summer 2002 represented a dry season. The results showed that there is a potential to utilize the summer biological activity in fellingsdams. At Orrviken the effluent quality measured as organic matter and phosphorus in the effluent was just slightly above the values that were reached by chemical precipitation. At Lockne the performance was lower. The organic matter reduction at Orrviken in the summers of 2001 and 2002 were 71 and 67%, respectively, compared to previous years using precipitant when the average was 78%. At Lockne, however, the values in the summers of 2001 and 2002 were 36 and 18%, respectively, compared to previous years using precipitant when the average was 55%. The phosphorous reduction at Orrviken in the summers of 2001 and 2002 were 85 and 89%, respectively, compared to previous years using precipitant when the average was 95%; at the Lockne plant, the phosphorous reduction during the summers of 2001 and 2002 were 60 and 66%, respectively, compared to the previous years' average of 86%. The nitrogen reduction varied considerably over the two summer periods. The reduction at Orrviken was 13% in 2001 and 58% in 2002; the reduction at Lockne was 13% in 2001 and 33% in 2002. Reference values of nitrogen reduction during normal operations were not available.     

多级盐田滩晒硝酸钠矿浸取液时浓度分布模型及优化

天然硝酸钠矿浸取液在进行多级盐田日晒除盐时,各级盐田中目标产物硝酸钠浓度的分布及盐田的级数对硝酸钠收率有很大影响。本文通过物料衡算和相图推导,建立了以硝酸钠收率为函数,以盐田级数、各级浓度分布为自变量的数学模型, 并结合实际生产数据,以硝酸钠在盐田中的损失量为目标函数,利用MatLab优化工具进行优化。研究结果表明:盐田级数越多,硝酸钠的损失越少,但四级以后,损失减少不大,综合考虑确定天然硝酸钠矿浸取液应采用3-4级盐田滩晒,同时获得了不同盐田级数时卤水浓度分布规律;如果各级盐田中沉积盐夹带液相量比例相同,则该比例大小对各级盐田中的浓度、析盐量和蒸发量分布没有影响,但对硝酸钠收率的影响很大。