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631.
混凝法深度处理废纸造纸废水实验研究 总被引:4,自引:2,他引:2
按照烧杯实验方法,重点考察了pH值、混凝剂种类和投加量等因素对生化处理后废纸造纸废水混凝处理效果的影响。实验结果表明:PAC作为混凝剂,PAM作为助凝剂联合处理该废水时,能够取得较好的去浊率、SS、色度和COD去除率。混凝沉淀最佳运行条件为:废水pH为6.5,含铝量10%的PAC和2 g/L的PAM投加量分别为1 mL/L、0.5 mL/L,浊度从35 NTU降低到1 NTU,去除率达97.1%,SS从30 mg/L降低到7 mg/L,去除率达76.7%,色度从64倍降低到18倍,去除率达71.9%,COD从95 mg/L降低到44.8 mg/L,去除率可达52.8%,取得了较好的去除效果,达到国家造纸废水新排放标准限值。 相似文献
632.
面对计算机行业的飞速发展,产品生产企业在不断创新技术的同时,也需要持续了解国家对产品节能认证及测试的最新标准,已满足产品节能的新要求。本文简述新旧版计算机节能认证技术规范的主要差异,运用实例比对阐述标准的使用,帮助企业更好的理解新版标准的实施。 相似文献
633.
634.
635.
根据语言测试的发展历程,指出了语言测试在外语教学过程中发挥的作用。当前高职英语测试存在学期测试与等级测试脱节、测试模式陈旧、形式单一、等级测试题型死板等问题。结合高职英语教学现状和学生素质水平,对高职英语的常规测试模式提出改革,构建了形成性评价与终结性评价相结合、重技能、寓考于乐的高职英语的新测试体系。 相似文献
636.
我国安全培训机构分布现状分析 总被引:6,自引:3,他引:3
周刚林 《中国安全生产科学技术》2009,5(2):129-132
为了解现有安全培训机构分布状况,对当前全国3813家机构有关信息进行了统计分析。分析结果表明:安全培训机构建设已经进入了规范提高阶段,当前安全培训机构合理利用了各类资源,但四级安全培训机构定位尚不明确。建议充分发挥四级机构作用,建立安全培训机构地域分布合理的判定标准。 相似文献
637.
638.
NEBS认证,是电信网络设备进入北美地区电信网络的通行证。本文把获取NEBS认证的全过程划分为三个阶段,即准备阶段、设计阶段和实施阶段,并论述了各阶段的关键要点。首先,在准备阶段对NEBS进行了介绍,简要分析了NEBS认证的主要标准,同时指出运营商的特殊要求的重要性。接着分析了在设计阶段应该注意的技术点,如空间尺寸要求、电源输入、接地、防火、地震等。最后,讨论了认证测试阶段面临的困难,并强调了认证前摸底测试的重要性及必须具备足够的耐心。 相似文献
639.
本文以气候环境试验方法对试验参数的要求为出发点,提出气候环境试验设备性能确认的原则。同时,扼要介绍气候环境试验设备性能确认相关标准的一些问题。 相似文献
640.
Kocí V Ocelka T Dragoun D Vit M Grabic R Sváb M 《Environmental science and pollution research international》2007,14(2):94-101
Background, Aim and Scope
The article is focused on dioxin, furan, PCB and organochlorine pesticide monitoring in the surface waters of the Central
European, protected natural reserve Krivoklatsko, under the UNESCO programme Man and Biosphere. Persistent compounds are presently
transported via different means throughout the entire world. This contamination varies significantly between sites. This raises
the question of what constitutes the naturally occurring background levels of POPs in natural, unpolluted areas, but which
are close to industrialised regions. Information of real background POP contamination can be of high value for risk assessment
management of those sites evidently polluted and for the defining of de-contamination limits.
Preserved areas should not be seen as isolated regions in which the impacts of human activities and natural factors are either
unexpected or overlooked. Every ambient region, even those protected by a law or other means, are still closely connected
to neighbouring human developed and impacted areas, and are therefore subject to this anthropogenic contamination. These areas
adjacent to natural reserves are sources of diverse substances, via entry of air, water, soil and/or biota. After an extended
period of industrial activities, organochlorine pollutants, even those emitted in trace concentrations have reached detectable
levels. For future research and for the assessment of environmental changes, present levels of contamination would be of high
importance. This work publishes data of the contamination with organochlorine pollutants of this natural region, where biodiversity
and ecological functions are of the highest order.
Materials and Methods:
Semipermeable membrane devices (SPMDs) were utilised as the sampling system. SPMDs were deployed in two small creeks and one
water reservoir selected in the central part of the Krivoklatsko Natural Reserve, where it could be expected that any possible
contamination by POPs would be lowest. The exposed SPMDs were analysed both for chemical contents of POPs and for toxicity
properties. The chemical analyses of dibenzo-dioxins, dibenzo-furans, PCBs and OCPs were analysed by GC/MS/MS on GCQ or PolarisQ
(Thermoquest). Toxicity bioassays were performed on the alga Desmodesmus subspicatus, bacteria Vibrio fischeri and crustacean
Daphnia magna. All toxicity data were expressed as the effective volume Vtox. Vtox is a toxicity parameter, the determination
of which is independent of SPMD deployment time and pre-treatment dilution (unlike, for example, the EC50 of the SPMD extract).
Results:
The following chemical parameters were monitored: 1) tetra, penta, hexa and hepta dibenzo-p-dioxins and furans; 2) all those
detectable from tri- through deca-polychloriated biphenyls (PCBs) and 3) a group of organochlorine pesticides: hexachlorobenzene
and isomers of hexachlorocyclohexane, DDE, DDD and DDT. The concentrations of dioxins and furans on the assessed sites varied
from under detection levels up to 7 pg.l-1; PCBs were detected in a sum concentration up to 2.8 ng.l-1; and organochlorine
pesticides up to 346 pg.l-1. The responses of bioassays used were very low, with the values obtained for Vtox being under
0.03 l/d.
Discussion:
Toxicity testing showed no toxicity responses, demonstrating that the system used is in coherence with the ecological status
of the assessed sites. Values of Vtox were under the critical value – showing no toxicity. The PCA of chemical analysis data
and toxicity responses resulted in no correlations between these two groups of parameters. This demonstrated that the present
level of contamination has had no direct adverse effects on the biota.
Conclusions:
The concentration values of six EPA-listed, toxic dioxins and sums of tetra-hepta dioxins; nine EPA toxic dibenzofurans and
the sums of tetra-hepta bibenzofurans are presented together with all tri-deka PCBs and organochlorine pesticides (alfa-,
beta-, gama-, delta-HCH, HCB, opDDE, ppDDE, opDDD, ppDDD, opDDT, ppDDT). These values represent possible current regional
natural background values of these substances monitored within the Central European region, with no recorded adverse effects
on the freshwater ecosystem (up until the present time).
Recommendations and Perspectives:
Assessment of dioxins, furans and other organochlorine compounds within natural reserves can be important for the monitoring
of human-induced impacts on preserved areas. No systematic monitoring of these substances in areas not directly affected by
industry has generally been realised. There is a paucity of data of the presence of any of these substances within natural
regions. Further monitoring of contamination of both soil and biota by dioxins and furans in preserve regions is needed and
can be used for future monitoring of man-made activities and/or accidents.
Semipermeable membrane devices proved to be a very good sampling system for the monitoring of trace concentrations of ambient
organochlorine compounds. Toxicity evaluation using the Vtox concept demonstrated that those localities assessed expressed
no toxicity. 相似文献