Effect of pre-ozonation on optimized coagulation of a typical North-China source water

Although ozone is widely used as a pre-oxidant before coagulation in water treatment, the effect of pre-ozonation on optimized coagulation for removal of particle and natural organic matter (NOM) is still not fully understood. In this paper, pilot-scale investigation was conducted to examine the impact of pre-ozonation on coagulation for particle and NOM removal. Changes in the particle and NOM distributions were characterized by various methods, including laser light granularity system, particle counter, ultrafiltration, and resin absorbent fractionation. A novel composite flocculant–HPAC was compared with the traditional ferric chloride coagulant in terms of coagulation efficiency under the influence of pre-ozonation. Typical micro-polluted North China surface water was used for pilot coagulation tests. The results show that the effect of pre-ozonation on coagulation is associated with the dosage of ozone, coagulant type, and water contamination characteristics. For FeCl₃, pre-ozonation acts as a coagulation aid at low dosage (1.0 mg L⁻¹ O₃) for turbidity and UV₂₅₄ removal; while at higher dosage (2.0 mg L⁻¹ O₃), pre-ozonation is detrimental to UV₂₅₄ removal although it is still beneficial for turbidity removal. In the case of composite flocculant–HPAC, pre-ozonation demonstrates negligible influence on both turbidity and UV₂₅₄ removal. Ozone can simultaneously aggregate fine particles and break down large ones, making them more mineralized and easier to remove. NOM with intermediate molecular weight and hydrophobic neutral property increases at lower ozone dosage, favoring removal by coagulation. At higher ozone dosages, NOM becomes more hydrophilic and its molecular weight becomes smaller, decreasing NOM removal.     

Monitoring, assessment and modelling using water quality data in the Saale River Basin, Germany

The European Water Framework Directive (WFD) is the overall driver for this environmental study and currently requires the identification of patterns and sources of pollution (monitoring) to support objective ecological sound decision making and specific measures to enhance river water quality (modelling). The purpose of this paper is to demonstrate in a case study the interrelationship between (1) hydrologic and water quality monitoring data for river basin characterization and (2) modelling applications to assess resources management alternatives. The study deals with monitoring assessment and modelling of river water quality data of the main stem Saale River and its principal tributaries. For a period of 6 years the data, which was sampled by Environmental Agencies of the German states of Thuringia, Saxony and Saxony-Anhalt, was investigated to assess sources and indicators of pollution. In addition to the assessment a modelling exercise of the routing of different pollutants was carried out in the lower part of the test basin. The modelling is a tool to facilitate the evaluation of alternative measures to reduce contaminant loadings and improve ecological status of a water body as required by WFD. The transport of suspended solids, salts and heavy metals was modelled along a selected Saale reach under strong anthropogenic influence in terms of contaminants and river morphology between the city of Halle and the confluence with the Elbe River. The simulations were carried out with the model WASP5 which is a dynamic flood-routing and water quality model package developed by the US Environmental Protection Agency.     

Effect of on-site sanitation on groundwater contamination in basaltic environment ’A case study from India

On-site sanitation is increasingly adopted in urban cities in India. The adoption of On-site sanitation system puts the groundwater resources in the vicinity of the system at a greater risk. Microbial contaminants as well as chemical contaminants like Chloride and Nitrate are generated from human waste. These contaminants travel through the medium and ultimately get in contact with the groundwater. Hence, the groundwater sources are vulnerable to nitrate contamination near the On-site sanitation systems. The present study indicates significant Nitrate and Chloride contamination in samples collected close to On-site sanitation systems. The recommended limit set by the Bureau of Indian standards (BIS) limit of 45 mg/l for Nitrate concentration is also exceeded in few samples. The study indicates that Bacterial as well as Nitrate contamination is more in Monsoon as compared to Summer.     

氯离子试纸的研制和应用

根据化学分析原理,经试验选择一定量的显色剂、酸度调节剂、稳定剂等,以层析纸为载体制成氯离子试纸,并对试纸的性能进行了试验,确定其使用方法和储存条件.通过对实际水样的测定,试纸法与国标法比较,结果基本符合,误差在半定量分析允许范围内.     

浅谈氯化物对环境的影响

本文从环境保护角度分析了氯化物对环境的影响。从而提出了制订“气田水中氯化物含量排放标准”的建议，讨论了气田水的处理方法。     

高氯离子废水CODCr测定的方法研究

对CODCr值较低，但氯离子浓度很高的水样中CODCr的测定方法进行了初步研究，比较了稀释法、硝酸银法、硫酸汞加入法各自的优缺点。结果表明，用硝酸银法测定悬浮颗粒物较少的水样中CODCr，既可去除水样中Cl^-的干扰，又可真实地测定CODCr值，同时也不会带来二次污染。     

CuCl2蚀刻液制备CuCl的研究

以氯化钢蚀刻液废液、粗铜粉等为原料,在常温下反应制备氯化亚铜,工艺简便,产品质量好,具有显著的经济效益和环境效益。     

Environmental fate of Ra in cation-exchange regeneration brine waste disposed to septic tanks, New Jersey Coastal Plain, USA: migration to the water table

Fate of radium (Ra) in liquid regeneration brine wastes from water softeners disposed to septic tanks in the New Jersey Coastal Plain was studied. Before treatment, combined Ra (²²⁶Ra plus ²²⁸Ra) concentrations (maximum, 1.54 Bq L⁻¹) exceeded the 0.185 Bq L⁻¹ Maximum Contaminant Level in 4 of 10 studied domestic-well waters (median pH, 4.90). At the water table downgradient from leachfields, combined Ra concentrations were low (commonly ≤0.019 Bq L⁻¹) when pH was >5.3, indicating sequestration; when pH was ≤5.3 (acidic), concentrations were elevated (maximum, 0.985 Bq L⁻¹ - greater than concentrations in corresponding discharged septic-tank effluents (maximum, 0.243 Bq L⁻¹)), indicating Ra mobilization from leachfield sediments. Confidence in quantification of Ra mass balance was reduced by study design limitations, including synoptic sampling of effluents and ground waters, and large uncertainties associated with analytical methods. The trend of Ra mobilization in acidic environments does match observations from regional water-quality assessments.     

南通长江口北支咸潮上溯对水环境的影响

针对长江口北支近20多年来咸潮超常上溯的状况,通过现场调查监测及与文献资料对比,分析了咸潮上溯对水源地供水水质、河口区河道水质和地下水水质的影响。结果表明,长江口北支咸潮上溯对北支水环境影响主要在于入侵时水体中电导率和氯化物浓度急剧升高,一定程度上影响了北支沿线水源地的供水功能。咸潮对现有水质评价体系下的水质类别影响尚不明显,但高氯离子对化学需氧量的测定有明显的干扰。由于受堤围和水闸控制,咸潮期间入江闸门普遍关闭,导致间接水环境影响,主要集中在入海主河道。部分区域咸潮上溯严重时氯化物浓度升高,水质已不能满足农田灌溉需求。北支沿线启东市24%的地下水采样点氯化物浓度已属轻度入侵水,采样区域已属于海水轻度入侵范围。