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821.
采用混凝剂对皮革废水进行混凝处理。对3种无机混凝剂和一种有机混凝剂进行了筛选,研究了pH值和投药量对废水中SS、COD、铬和色度等污染物去除效果的影响。结果表明,当pH值在酸性和中性时,效果不明显;当pH值为碱性时,效果显著。硫酸亚铁、硫酸亚铁+PAM和聚合氯化铝(PAC)+PAM 3种混凝剂组合具有良好的混凝效果,在合适的pH值和投药量下,SS和COD的去除率分别达到80%和30%以上,铬和色度的去除率分别达到95%和50%以上。且硫酸亚铁混凝效果好,成本低,适合小型皮革企业需求。 相似文献
822.
利用具有代表性的三峡地区区域性降水个例,基于WRF模式,在模式下垫面中加入长江水体以及修改局地地形,研究局地环流和气象要素对局地下垫面变化的响应。结果表明:加入长江水体后,不同区域性降水个例空间降水变化上,没有出现明显的降水变化区,表明长江水体对区域局地性降水影响较小;同时加入长江水体和修改地形高度后,空间上降水具有明显的变化,且与修改地形后的降水空间变化较一致,表明局地地形对区域降水空间变化具有重要影响;加入长江水体后,近地面2 m高度相对湿度变化上,不同区域性降水个例表现不一,总体上对局地相对湿度影响较小;近地面2 m温度、地表向上的水汽通量和地表向上的潜热通量均为增加,在局地地形的“喇叭口”效应作用下,长江水体拐弯处增加效应明显 相似文献
823.
824.
Detoxification of Cr(VI) through reduction by organic reductants has been regarded as an effective way for remediation of Cr(VI)-polluted soils. However, such remediation strategy would be limited in practical applications due to the low Cr(VI) reduction rate. In this study, the catalytic effect of two Fe-rich soils (Ultisol and Oxisol) on Cr(VI) reduction by malic acid was evaluated. As the results shown, the two soils could obviously accelerate the reduction of Cr(VI) by malic acid at low pH conditions, while such catalytic effect was gradually suppressed as the increase in pH. After reaction for 48 h at pH 3.2, Oxalic acid was found in the supernatant of Ultisol, suggesting the oxidization of hydroxyl in malic acid to carboxyl and breakage of the bond between C2 and C3. It was also found that the catalytic reactivity of Ultisol was more significant than that of Oxisol, which could be partly attributed to the fact that the amount of Fe(II) released from the reductive dissolution of Ultisol by malic acid was larger than that of Oxisol. With addition of Al(III), the catalytic effect from Ultisol was inhibited across the pH range examined. On the contrary, the presence of Cu(II) would increase the catalytic effect of Ultisol, which was more pronounced with the increase in pH. This study proposed a potential way for elimination of the environmental risks posed by the Cr(VI) contamination by use of the natural soil surfaces to catalyze Cr(VI) reduction by the organic reductant such as malic acid, a kind of organic reductant originating from soil organic decomposition process or plant excretion. 相似文献
825.
滤料粒径对给水曝气生物滤池运行稳定性的影响 总被引:3,自引:1,他引:2
利用给水曝气生物滤池(UBAF)处理刘屋洲水源水,考察了不同陶粒粒径对氨氮、高锰酸盐指数的去除效果以及水头损失变化的影响。结果表明,陶粒3~5 mm的UBAF对氨氮、高锰酸盐指数的去除效果较高,但是其水头损失较大,且反冲洗前后水头损失变化偏大,不利于UBAF稳定运行。陶粒6~10 mm的UBAF运行状况良好,氨氮的去除率为73.8%,高锰酸盐指数的去除率为18.6%,滤池24 h过滤水头损失<0.4 m,反冲洗前后过滤水头损失变化量<5 cm。其出水氨氮和高锰酸盐指数均达到《生活饮用水卫生标准》(GB5749-2006),滤池的水头损失小,反冲洗前后也变化甚微。进一步的实验表明陶粒破碎会导致滤料粒径级配变化,使得水头损失增加。 相似文献
826.
827.
This study evaluates four policy options to secure the water supply needed for wetland conservation in Qixinghe--a national wetland nature reserve in China--using four criteria: cost effectiveness, probability of success in achieving the water-saving goal, political feasibility, and farmer acceptance. This multi-criteria analysis framework reveals the ecological, economic, and socio-political trade-offs for policymakers when choosing among the four policy options. Results suggest that upgrading irrigation infrastructure in the area surrounding the wetland (Option I) is the most politically feasible option, but it is the second best option in terms of cost effectiveness. Constructing a dam to store and control floodwater (Option II) is the most reliable for achieving the water-saving goal. It is also the farmers' most favored strategy. But this option is the least cost effective and receives little support from local governments. Promoting farmers' adoption of water-saving practices (Option III) is the most cost effective, but it is less reliable for achieving the water-saving goal than Options I or II. Converting paddy crops to dry-land crops (Option IV) is politically infeasible and least reliable for achieving the water-saving goal. The overall ranking of the four options is determined using the policymakers' revealed weights on the four criteria. Option I is ranked first, followed by Options II, III, and IV. 相似文献
828.
以广州市最大补水人工景观湖白云湖水生态系统构建示范区为对象,利用综合污染指数评价了以沉水植被构建为主的修复措施对示范区水体水质改善的影响,并应用因子分析法对各水质指标和生态因子之间的相互关系进行了研究。综合污染分析结果表明,恢复沉水植物后,示范区水体各项污染物浓度大幅降低,水质从V-劣V类提高到III-IV类,水体综合污染状态由严重污染改善为轻污染。因子分析显示,10项水质指标可划分为四类主因子来反映水质状况,其中,第一主因子主要反映水体营养盐指数,第二主因子反映水体有机污染指数,第三主因子反映温度变化对水质的影响,第四主因子反映水体的酸碱度;综合评分结果说明了生态系统构建后水质综合评分可大幅降低,且月评分结果呈现温度越高、水质越优的特点,水体特征呈现向草型水体发展的趋势。上述结果表明,水生态系统构建可有效改善示范区水质,是保障城市河道补水水源安全的有效方法。 相似文献
829.
荆州市浅层地下水环境质量综合评价与分区 总被引:3,自引:0,他引:3
通过实地调查荆州市浅层地下水环境,合理选择评价指标集(16项),分别采用模糊数学综合评价法和F值法对该浅层地下水环境质量进行综合评价,分析对比两种方法的评价结果,对浅层地下水环境进行分区和污染分析。评价结果表明:浅层地下水环境质量不容乐观,整体状况较差。浅层地下水中主要超标组分为Fe、Mn、NO-3、NO-2、As、Ba等,对比分析荆州市2006~2011年主要超标组分的平均含量,可知6 a来,Fe、Mn、NO-2的平均含量均超过地下水Ⅲ类水质标准,NO-3、As、Ba的平均含量虽然均未超过地下水Ⅲ类水质标准,但其平均含量呈现随着年份递增的趋势。浅层地下水环境质量分区结果显示:严重区面积为2 623 km2约占305%,较严重面积为1 33128 km2约占1548%,合格区面积为3 07192 km2约占3572%,较好区面积为1 5738 km2仅占183%。浅层地下水环境质量在很大程度上不仅受当地特有的区域原生地质环境影响,还与人类活动有密切关系 相似文献
830.
Huaidong He Zhihong Ye Danjing Yang Junlan Yan Li Xiao Ting Zhong Ming Yuan Xinde Cai Zhanqiang Fang Yuanxiao Jing 《Chemosphere》2013,90(6):1960-1965
Microbe-assisted phytoremediation has been considered as a promising measure for the remediation of heavy metal-polluted soils. In this study, a metal-tolerance and plant growth-promoting endophytic bacterium JN6 was firstly isolated from roots of Mn-hyperaccumulator Polygonum pubescens grown in metal-contaminated soil and identified as Rahnella sp. based on 16S rDNA gene sequence analysis. Strain JN6 showed very high Cd, Pb and Zn tolerance and effectively solubilized CdCO3, PbCO3 and Zn3(PO4)2 in culture solution. The isolate produced plant growth-promoting substances such as indole-3-acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic deaminase, and also solubilized inorganic phosphate. Based upon its ability in metal tolerance and solubilization, the isolate JN6 was further studied for its effects on the growth and accumulation of Cd, Pb and Zn in Brassica napus (rape) by pot experiments. Rape plants inoculated with the isolate JN6 had significantly higher dry weights, concentrations and uptake of Cd, Pb and Zn in both above-ground and root tissues than those without inoculation grown in soils amended with Cd (25 mg kg?1), Pb (200 mg kg?1) or Zn (200 mg kg?1). The isolate also showed a high level of colonization in tissue interior of rapes. The present results demonstrated that Rahnella sp. JN6 is a valuable microorganism, which can cost-effectively improve the efficiency of phytoremediation in soils contaminated by Cd, Pb and Zn. 相似文献