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801.
在利用渗透反应格栅技术修复地下水氨氮污染过程中,掌握氨氮在不同介质环境中的转化规律及存在形态对多介质渗透反应格栅中各介质作用及氮转化过程的控制十分重要.针对进水氨氮浓度约10 mg/L的模拟地下水,以天然河沙、释氧材料、斜发沸石及海绵铁为反应介质,设计了一套多介质渗透反应格栅模拟氨氮在各介质环境中的转化及归宿.结果表明,在天然河沙层,氨氮优先被河沙吸附固定,但去除量有限(△C<1.5 mg/L),氨氮主要以离子态溶于模拟地下水.在好氧沸石层,氨氮经沸石吸附及生物硝化协同作用几乎被完全去除,该层出水氨氮浓度低于0.01 mg/L,且氮主要存在形态为硝酸盐氮(C=10~26.6 mg/L).在铁厌氧层,部分硝酸盐氮经海绵铁化学还原和生物反硝化作用,分别被转化为氨氮(△C=2~9.5 mg/L)和氮气(△C<8 mg/L),其余硝酸盐氮以离子态继续存留于模拟地下水. 相似文献
802.
To sufficiently utilize chemically active species and enhance the degradation rate and removal efficiency of toxic and biorefractory organic pollutant para-chlorophenol (para-CP), the introductions of iron metal ions (Fe2+/Fe3+) into either pulsed discharge plasma (PDP) process or the PDP process with TiO2 photo-catalyst were tentatively performed. The experimental results showed that under the same experimental condition, the degradation rate and removal efficiency of para-CP were greatly enhanced by the introduction of iron ions (Fe2+/Fe3+) into the PDP process. Moreover, when iron ions and TiO2 were added together in the PDP process, the degradation rate and removal energy of para-CP further improved. The possible mechanism was discussed that the obvious promoting effects were attributed to ferrous ions via plasma induced Fenton-like reactions by UV light irradiation excited and hydrogen peroxide formed in pulsed electrical discharge, resulting in a larger amount of hydroxyl radicals produced from the residual hydrogen peroxide. In addition, the regeneration of ferric ions to ferrous ions facilitates the progress of plasma induced Fenton-like reactions by photo-catalytic reduction of UV light, photo-catalytic reduction on TiO2 surface and electron transfer of quinone intermediates, i.e. 1,4-hydroquinone and 1,4-benzoquinone. 相似文献
803.
804.
在分析广东省湛江市东海岛的区域水文地质特征及地下水开发利用特点的基础上,构建了地下水入海排泄量估算模型,以估算地下水入海排泄量和携带入海的营养盐量。结果表明,估算得到的2009年东海岛地下水入海排泄总量为133.8×104m3,其中携带入海的营养盐总量为5 157.98kg,地下水的携带入海成为近岸海域陆域营养盐入海排泄的主要途径;研究区位于沿海地带的砂堤砂地潜水分布区以及位于海岸地带的湛江组浅部潜水—微承压水含水层分布区等局部地段,存在地下水入海排泄量的低值区,可能存在海水入侵风险。 相似文献
805.
806.
Estimation of Nitrogen and Phosphorus in Effluent from the Striped Catfish Farming Sector in the Mekong Delta,Vietnam 总被引:1,自引:0,他引:1
In this study an attempt is made to estimate nitrogen and phosphorus discharged to the environment from the striped catfish
(Pangasianodon hypophthalmus) farming sector in the Mekong Delta (8°33′–10°55′N, 104°30′–106°50′E), South Vietnam. The sector accounted for 687,000 t
production in 2007 and 1,094,879 t in 2008, with over 95% of the produce destined for export to over 100 countries. Commercial
and farm-made feeds are used in catfish farming, currently the former being more predominant. Nitrogen discharge levels were
similar for commercial feeds (median 46.0 kg/t fish) and farm-made feeds (median 46.8 kg/t fish); whilst, phosphorus discharge
levels for commercial feeds (median 14.4 kg/t fish) were considerably lower than for farm-made feeds (median 18.4 kg/t fish).
Based on the median nutrient discharge levels for commercial feeds, striped catfish production in the Mekong Delta discharged
31,602 t N and 9,893 t P, and 50,364 t N and 15,766 t P in 2007 and 2008, respectively. However, the amount of nutrients returned
directly to the Mekong River may be substantially less than this as a significant proportion of the water used for catfish
farming as well as the sludge is diverted to other agricultural farming systems. Striped catfish farming in the Mekong Delta
compared favourably with other cultured species, irrespective of the type of feed used, when the total amounts of N and P
discharged in the production of a tonne of production was estimated. 相似文献
807.
Pulp and paper mills are one of the major effluent generating industries in the world. In most cases, mill effluent (treated or raw) is discharged back into a river, creek, stream or other water body; resulting in negative environmental impacts, as well as social concerns, among the downstream users. Pulp and paper mill effluent management, which could result in zero discharge into downstream water bodies, would present the best management option to address socio-environmental concerns. This paper presents such an effort aimed at closing the water cycle by using treated effluent from the mill to irrigate forage and fodder crops for producing animals feed. The treated effluent is delivered from the mill through gravity into a winter storage dam of 490ML capacity. For irrigation applications on 110ha of farmland, which is 42% of the total farmland, the water is pumped from the winter storage dam to five individual paddocks with Centre Pivot (CP) irrigators and one rectangular paddock with a Soft Hose Travelling (SHT) irrigator. From October 2001 to June 2006, a total of 2651mm of wastewater was applied at the farm. The impact assessment results, obtained from field monitoring, investigations and analysis, indicated that the closed water cycle effluent management strategy described had resulted in a lessening of the impact on water resources usually associated with paper mills. However, social attitudes to the use of crops that have been irrigated with recycled waters and the resulting impact on market value of the produce may still be a major consideration. 相似文献
808.
Efficient environmental management calls for the consideration of multiple pollutants, for which two main types of transferable discharge permit (TDP) program have been described: separate permits that manage each pollutant individually in separate markets, with each permit based on the quantity of the pollutant or its environmental effects, and weighted-sum permits that aggregate several pollutants as a single commodity to be traded in a single market. In this paper, we perform a mathematical analysis of TDP programs for multiple pollutants that jointly affect the environment (i.e., interactive pollutants) and demonstrate the practicality of this approach for cost-efficient maintenance of river water quality. For interactive pollutants, the relative weighting factors are functions of the water quality impacts, marginal damage function, and marginal treatment costs at optimality. We derive the optimal set of weighting factors required by this approach for important scenarios for multiple interactive pollutants and propose using an analytical elasticity of substitution function to estimate damage functions for these scenarios. We evaluate the applicability of this approach using a hypothetical example that considers two interactive pollutants. We compare the weighted-sum permit approach for interactive pollutants with individual permit systems and TDP programs for multiple additive pollutants. We conclude by discussing practical considerations and implementation issues that result from the application of weighted-sum permit programs. 相似文献
809.
810.
水电站的建设会造成坝址下游河段减水,对水环境和水生生物造成不利影响,因此电站生态流量的确定和泄放措施的可行性对于维护河流生态环境至关重要。以硕曲河去学水电站为例,基于可行性研究阶段提出的生态流量泄放措施方案,采用数学模型和理论分析方法,从生态流量取水水温、泄洪洞事故条件下生态流量保证率以及水资源的合理高效利用等方面进一步对生态流量泄放方案进行了优化比选。提出的优化方案提高了生态流量取水口的布置高程,在泄洪洞之外单独布置生态泄放系统,并增设生态流量发电机组等。对比分析表明,该优化方案在改善生态流量的下泄水温、提高生态流量泄放保证率、合理高效利用水能资源等方面具有较大优势。本研究为水电工程中生态流量泄放措施保障等方面提供了科学依据和技术参考。 相似文献