砂,纤维球,纤维球-砂过滤效果的比较

通过过滤实验从过滤周期、水头损失及比沉积量三个方面对砂、纤维球和纤维球-砂滤床的过滤效果进行了比较.实验结果证实了纤维球-砂滤料的优越性。      

黄河泥沙对某些重金属离子的特性吸附及影响因素研究

黄河水在河南境内含沙量巨大,所携带的泥沙粒子对重金属离子的作用关系到河水的自净作用。以泥沙粒子的ξ电位测定为主要手段,研究了泥沙粒子对Ｃｒ、Ｃｕ、Ｍｎ、Ｃｄ离子的特性吸附及某些因素对吸附的影响。结果表明:不同重金属离子被吸附程度不同;泥沙表面的有机物层阻碍吸附;而溶液的盐度增大,温度升高均不利于吸附,且各离子受影响的程度不同。      

Application and appreciation of chemical sand fixing agent-poly (aspartic acid) and its composites

The sand fixing agent-poly (aspartic acid) (PASP) and its composites were applied in the field by two forms (spraying around by PASP solution and PASP powder directly). It was found that the sand fixing effect in powder form was not as good as in solution form, but it was more practical in dry region. It needed 9, 6 and 7 days for PASP, xanthan gum-PASP (X2) and ethyl cellulose-PASP (E3) to attain the maximal mechanical strength after they were applied, respectively. The sand fixing effect decreased when the material was subjected to repeated hydration-dehydration cycles and the material had no negative influence on plant growth. The PASP and its composites had water-retaining ability and could reduce the water evaporation.     

Total and Leachable Heavy Metals in Muddy and Sandy Sediments of Egyptian Coast Along Mediterranean Sea

The assessment of marine pollution due to metals was made for surficial sediments sampled from 20 sites along Mediterranean coast of Egypt. The samples were dried, acid digested and analyzed for leachable and total heavy metal contents (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) by flame atomic absorption spectrophotometer (air–acetylene) with deuterium background correction. Evaluation of the heavy metals pollution status was carried out using enrichment factors (EFs), the effect range-low (ERL) and the effect range-median (ERM). The study showed high concentrations of Cd, Co, Pb, Ni and moderate concentrations of Cr, Cu and Mn were contaminated in the sediments of studied sites. The results of Spearman correlation, factor and cluster analysis of the heavy metals analyzed in the collected sediment were discussed. The main source of contamination is the offshore oil field and industrial wastes, which arise due to the ineffective and inefficient operation equipments, illegal discharge and lack of supervision and prosecution of offenders.     

Vegetation succession and lichen diversity on dry coastal calciumpoor dunes and the impact of management experiments

The negative impact of grass and moss encroachment on the botanical diversity of West European coastal dunes attracted increasing attention in the 1990s. This paper focuses on moss encroachment during primary succession in the xeroseries. Until the mid-1970s, vegetation types rich in species of the lichen generaCladonia andCladina were found on the fixed,Corynephorus canescens-dominated, so-called grey dunes all over the island of Terschelling, The Netherlands. In addition, species ofHypogymnia, Parmelia andUsnea, which usually grow on trees, occurred here terrestrially on moss carpets or bare sand. These vegetation types are still present on the Noordsvaarder, a nature reserve in the western part of the island. They occur on parts of seven dune ridges parallel to the coast and form a chronosequence in which age increases with distance from the sea. Our study found the highest lichen diversity on the second and third dune ridges in a stage of primary succession that can be assigned to theViolo-Corynephoretum. The changes from lichen-rich to moss-dominated stadia were significantly related to soil development and acidification in connection with the ageing of the dune soil. The superficial cutting of sods in moss-encroached vegetation appeared to be unsuccessful as a management technique for restoring the biodiversity of cryptogams. Our findings suggest that the best option for maintaining lichen vegetation in theViolo-Corynephoretum is the blow-in of sand with a subneutral or neutral pH from reactivated and natural blowouts or from foredunes, with increasing lime content respectively. Nomenclature: Van der Meijden (1990) for higher plants; Touw & Rubers (1989) for mosses; Purvis et al. (1992) for lichens. A set of lichen specimens has been deposited at the herbarium of Dr. A. Aptroot (C.B.S. Baarn) — herbarium code ABL (Taxon 44: 258).     

过滤器处理含聚采油污水滤料流失及改进技术研究

为解决石英砂过滤器处理聚驱污水过程中出现的滤料板结、反冲洗憋压、滤料流失问题,通过对石英砂过滤器进行了改造,利用搅拌装置破碎滤饼层,经现场测试,搅拌式石英砂过滤器反冲洗压力由原来的0.27~0.46Mpa降低到0.12~0.16 Mpa,滤料流失得以解决。在来水含油和悬浮固体平均41 mg/L和21 mg/L,总滤后水质含油达到5.8 mg/L以下,出水悬浮固体3.2 mg/L。油和悬浮固体去除率分别提高85%和86%。     

小型砂滤池在废水处理中的应用

本文通过湿式除尘后的废水治理及工程实例,探讨了小型砂滤池在废水处 理中应用的可行性。     

Vegetation development in coastal foredunes in relation to methods of establishing marram grass (Ammophila arenaria)

In coastal foredunes marram grass (Ammophila arenaria) is used to stabilize windblown sand. The development of traditionally plantedAmmophila into a more natural foredune vegetation may take 5 – 10 yr. For economic reasons, traditional planting may be replaced by alternative techniques such as planting seeds or disk-harrowing rhizome fragments. In this paper, we compare the initial vegetation development of traditionally planted stands with stands established from seeds and from rhizomes. The experiments were conducted on an artificial foredune originating from dredged sea sand. The total experimental area covered more than 100 ha and the vegetation development was studied for 6 yr. The data were analysed bya priori grouping of plant species according to their ecology, as well as by Principal Components Analysis (PCA) and Redundancy Analysis (RA) of the percentage ground cover per plant species. Comparing ecological groups of plants showed that all planting methods delivered equal numbers of plant species that are indicative for coastal dunes. PCA and RA showed that methods based on the use of rhizome material resulted in a higher percentage cover of clonal perennials (Calammophila baltica, Festuca rubra ssp.arenaria, Carex arenaria andCirsium arvense) than the traditionally planted stands and the stands obtained from seeds. The latter two were characterized by the dominance of annuals, bi-annuals and (mostly nonrhizomatous) perennials. Initially, the rates of succession were highest in the stands obtained from rhizomes. However, after 3 – 6 yr there were no differences between the various stands. During the first four years, the percentage cover by rhizomatous foredune plants developed faster than that of annuals, bi-annuals and perennials. After 6 yr, the latter contributed almost as much to the percentage cover as the clonal species. Nomenclature: van der Meijden et al. (1990) for plant species. The plant species were classified into ecological groups according to van der Meijden et al. (1991) and Mennema et al. (1980).     

沙滤器回洗水薄膜过滤法

介绍了荷兰新近研究成功的适用于处理沙粒过滤器回洗水的XIGA薄膜法,及其参数、工作原理、适用条件和经济效益。     

导热性能对浸油沙层闪点、燃点的影响研究

研究了浸油沙层的导热性能对浸油沙层闪点和燃点的影响。选用柴油作为燃料液体,铜粉和沙子的混合物代表沙层,浸油沙层的导热系数由混合物中的沙子和铜粉比例控制。实验结果表明,浸油沙层的导热性能对其着火特性有重要影响。不加铜粉时,存在一个使混合物的闪点与燃点最小的沙油质量比。随着铜粉添加量的增加,闪点与燃点的最小值点逐渐消失。这可能是加入细铜粉使混合物的表面平整造成的。在最小点后,随铜粉添加量的增加,也就是随混合物的导热性能的改善,混合物的闪点与燃点增大。但当沙子与铜粉的质量比达到1：1时,闪点与燃点随沙油质量比的变化出现了一个最大值,之后闪点和燃点随沙油质量比的增加而降低。这些现象的出现可能是导热能力、毛细现象和混合物内部的空隙三者共同作用的结果。