Changes in organic constituents in river water during incubation

A water sample collected from Tama River in the Tokyo area was incubated 29 days in the dark conditions at 25 ± 3°C to determine the extent and rate of the degradation of organic constituents and changes in their composition. The majority (>95%) of n-alkanes, fatty acids and sterols were degraded, although total organic carbon (TOC) and extractable organic carbon with ethyl acetate (EOC) remained in considerable amounts (>23%). The degradation of organic constituents occurred apparently in two or three steps. The rate constants for the degradation of TOC, EOC, hydrocarbons, fatty acids and sterols for the first step were 0.090, 0.18, 0.082, 1.4 and 0.23 day⁻¹, respectively. The relative abundances of total fatty acids and sterols as carbon in TOC (EOC) decreased remarkably during incubation (0–11 days) from 7.18 to 0.28% and 0.46 to 0.07%, respectively (31.2-2.2% and 2.0-0.6%, respectively), whereas those of hydrocarbons were not significantly changed.     

Comparison of river and canal water dissolved organic matter fluorescence within an urbanised catchment

Recently, growing interest has been shown in the study of canal water quality, yet no research using continuous fluorescence monitoring to characterise dissolved organic matter (DOM) has been performed. This paper evaluated DOM characteristics at hourly resolution. A comparison was made between canal and nearby urban river fluorescence spectra, to emphasise the specific nature of canal water DOM. Results showed that canal water had a significant proportion of microbially derived DOM, while the urban river had a greater proportion of terrestrially derived fractions. The microbial character of canal water DOM originated from the low flow of water, the nutrients predominance and continuous DOM processing. Hence, DOM fluorescence is invariant over a timescale of days, and recreational navigation and precipitation events have no major influence on DOM characteristics. Our results are expected to be applicable to future research on highly regulated freshwater systems for DOM quantity estimation or for water quality models.     

Analytical fractionation of dissolved organic matter in water using on-line carbon detection

A routine method is described for the analytical fractionation of dissolved organic matter (DOM) in natural freshwater and in used waters. The fractionation is based on the different adsorption behaviours of various constituents of the DOM on octadecyl-silica as a function of pH. The DOM is separated into a hydrophilic, an acid and a hydrophobic fraction. The detection is carried out by an on-line carbon detector. The method requires only small water samples (20 ml) with low dissolved organic carbon (DOC) concentrations (1–5 mg Cl⁻¹). The samples can be analysed rapidly with no preconcentration. Fractionation of model compounds and mixtures demonstrates the performance of the method. The application of the method is illustrated by an investigation of the changes of the DOC composition occurring in a longitudinal transect of a river and during the infiltration of river water to groundwater.     

Formation equation of halogenated organic compounds when water is chlorinated

Various halogenated organic compounds are formed by chlorination of water. In this study, formation of organic compounds halogenated from a reagent humic acid and extract of a leaf mold were examined under various conditions. The following overall formation equation was obtained from empirical data under the practical wide range when free chlorine remained.

[TOX]=k_TOX[TOC][Cl₂]_ot^β.

Here, [TOX] is the concentration of total organic halogen after t h in units of mg chlorine per liter; [TOC] and [Cl₂]_o are concentrations of total organic carbon and dosed chlorine in units of mg per liter; k_TOX is the rate constant and and β are parameters. From the values of k_TOX, and β, the character of organic substances i.e. precursor of halogenated organic compounds, in water can be evaluated. The values k_TOX, and β for humic acid are 0.053, 0.28 and 0.13, and the values for extract of the leaf mold are 0.032, 0.36 and 0.15, respectively. The activation energies are 10 kJ mol⁻¹ and 11 kJ mol⁻¹ for the reactions of humic acid and leaf mold extract, respectively.     

环境中金属离子与有机污染物复合污染研究进展

金属离子与有机污染物可通过多种方式同时存在于环境中,形成复合污染。由于金属离子与有机污染物的相互作用,二者的物理化学性质、迁移转化规律以及生态毒性效应都发生了变化,给污染物的水处理过程以及污染物的生态毒性评估带来极大的挑战。综述了环境中金属-有机物复合污染的来源、金属离子与有机污染物之间的相互作用、共存对二者去除效率的影响以及复合污染的生态毒性研究,以期为复合污染的防治与处理工艺研究提供参考。     

Production of lipophilic volatile organohalogen materials during laboratory chlorination of some waste water and polluted river water samples from Yugoslavia

Water chlorination leads to the generation of various halogenated products of natural and waste water organic mater. In natural surface water humic matter usually makes the greatest part of the total organic matter. However, in the river water polluted with various organic wastes, other organic matter is also present in significant concentrations. The investigation of the relationship between the concentration of organic matter in the samples of waste water and heavily polluted river waters in Yugoslavia on one side, and the production of the lipophilic volatile organohalogen materials during the process of their chlorination on the other side is described. The production of the halomethanes and other ECD response materials during the chlorination of water samples in laboratory conditions is compared with the concentrations of organic materials in water samples. From the obtained linear correlation coefficients, possibilities of predicting amounts of organohalides during the chlorination process by using several very simple methods for the organic materials estimation in the investigated water samples are discussed and compared.     

Reconsidering the quantitative analysis of organic carbon concentrations in size exclusion chromatography

The evaluation of the molecular size distribution of natural organic matter (NOM) in aquatic environments via size exclusion chromatography (SEC) is important for the understanding of environmental processes such as nutrient cycling and pollutant transport as well as of technical water treatment processes. The use of organic carbon (OC) detectors has become popular in recent studies due to improved availability and quantification possibilities, which supposedly are superior to those of ultraviolet (UV) detectors. A set of 12 NOM samples was used to demonstrate the limitations of online OC detection (OCD) when analyzing complex aquatic organic matter. A novel evaluation approach for SEC data is introduced by combining the information from UV absorbance (UVA) and OCD chromatograms as well as offline total OC (t-OC) and dissolved OC-specific UVA (SUVA) measurements. It could be shown that about 70% of certain OC components were not detected with the OCD system used in this study. For the investigated samples, these types of carbon accounted for up to 72% of the t-OC, i.e. for such NOM samples quantification by OCD is not possible or at least highly questionable. The addition of an oxidant improved the overall oxidation efficiency only slightly. Most likely NOM that predominantly consists of polysaccharides and features a nominal molecular weight of 150 kg/mol or more was responsible for low OCD yields. For future applications, a further improvement of the OCD system would be worthwhile so that quantitative analytical data on the molecular size distribution of NOM and its structural characteristics such as the SUVA distribution can be obtained.     

Assessment of the surface water quality in Northern Greece

The application of different multivariate statistical approaches for the interpretation of a large and complex data matrix obtained during a monitoring program of surface waters in Northern Greece is presented in this study. The dataset consists of analytical results from a 3-yr survey conducted in the major river systems (Aliakmon, Axios, Gallikos, Loudias and Strymon) as well as streams, tributaries and ditches. Twenty-seven parameters have been monitored on 25 key sampling sites on monthly basis (total of 22,350 observations). The dataset was treated using cluster analysis (CA), principal component analysis and multiple regression analysis on principal components. CA showed four different groups of similarity between the sampling sites reflecting the different physicochemical characteristics and pollution levels of the studied water systems. Six latent factors were identified as responsible for the data structure explaining 90% of the total variance of the dataset and are conditionally named organic, nutrient, physicochemical, weathering, soil-leaching and toxic-anthropogenic factors. A multivariate receptor model was also applied for source apportionment estimating the contribution of identified sources to the concentration of the physicochemical parameters. This study presents the necessity and usefulness of multivariate statistical assessment of large and complex databases in order to get better information about the quality of surface water, the design of sampling and analytical protocols and the effective pollution control/management of the surface waters.     

Applicability of light absorbance and fluorescence as measures of concentration and molecular size of dissolved organic carbon in humic Lake Tjeukemeer

Ultrafiltration results of humic Lake Tjeukemeer water demonstrated that light absorbance at 250 nm (E250), fluorescence (λ_ex = 365 nm; λ_em = 470 nm) (F), and concentration of dissolved organic carbon (DOC) vary with the molecular size (5–200 nm) of the dissolved organic matter. The ratio of the ultrafiltered organic fractions increased with decreasing molecular size of the DOC. However, under field conditions this ratio failed to predict molecular size distribution.These results limit the applicability of E250 and F as measures of molecular size and concentration of DOC. However, E250 measurements can be made rapidly and easily, and so are useful in estimating (30%) concentrations of DOC in humic waters.     

Timing of organic carbon release from mountain pine beetle impacted ponderosa pine forests in South Dakota

The decay of mountain pine beetle (MPB) (Dendroctonus ponderosae) affected ponderosa pine (Pinus ponderosa) forests has increased organic carbon (OC) loading within the Rapid Creek watershed in the Black Hills of South Dakota, with total OC (TOC) concentrations up to 6.2 mg L^?1 observed in 2015. The impacts of large‐scale tree mortality on water quality were delayed. OC concentrations in the watershed correlated with recent MPB impact stage progression. Regional ponderosa pine forests that were 3 and 6 years after MPB infection (grey and snagfall phases) exhibited increased OC loading within the Rapid Creek watershed. A better understanding of regional watershed response patterns for MPB tree mortality may assist with mitigating ancillary water quality impacts.     

长江下游区域水源突发性污染应急供水处理

对长江下游区域水源突发性污染状况和产生的原因进行了分析,针对不同的突发性污染物类型提出相应的应急处理措施,以期为长江下游区域供水企业应对突发性水污染事件和安全供水提供技术支持和知识储备。     

陕西地下水水质污染与修复管理

对地下水分类、化学特性、污染途径、污染物类型作了简要介绍,通过对地下水污染的调查,对其进行了监测,并详细阐述了地下水的一系列修复方法,从而及时有效地做好地下水修复工作。     

黄河流域水污染分析及保护措施

对黄河流域水资源污染及其污水排放现状进行了介绍,在此基础上,分析了黄河流域废污水排放情况、水质污染程度、污染物的组成等情况,并提出水资源的保护措施。     

Reducing the concentration of assimilable organic carbon (AOC) in treated drinking water

This study focuses on reducing the concentration of assimilable organic carbon (AOC) in treated drinking water. Experiments were conducted to evaluate the efficiency of AOC removal by biological activated carbon filters (BACF) in a pilot-scale system. The measured values of AOC in treated drinking water were approximately 59.0 ± 8.6 μg acetate-C/L. The results show that BACFs reduce the total concentration of AOC. The concentration of AOC primarily indicates microbial growth in a water supply network, and the amount of AOC in the water is significantly reduced after BACF treatment. After BACF treatment, the removal of AOC was approximately 58% after 40 min of empty-bed contact time. An AOC empirical equation was established by determining the relationship between water quality parameters, such as total organic carbon, dissolved organic carbon, UV₂₅₄, ammonia nitrogen, and total phosphorous.     

供水管网二次污染的成因与防治措施

从内因和外因两方面分析了造成供水管网二次污染的原因,并从提高管网水质稳定性和加强管网改造及维护管理两方面提出了改善管网水质的措施,以保证城市供水系统的安全运行。     

北方某城市给水管网水质生物稳定性研究

以我国东北某市市政给水管网为研究对象,采用AOC和BDOC指标共同评价了管网水的生物稳定性。研究结果表明：管网水中AOC为39—379μg/L,BDOC为0．8～2．8mg／L,属于生物略不稳定的饮用水;随着管网的延长,水中的AOC和BDOC浓度总体上处于降低趋势,余氯浓度对AOC和BDOC浓度的变化均有较大影响;冬、夏两季节,管网水中AOC占BDOC的比例分别为5．8％和6．2％。     

Incidence of yeasts in coastal sea water of the Attica Peninsula, Greece

Coastal sea water from 15 locations around the Attica peninsula, Greece were collected and analysed for the presence of yeasts on three occasions during 1984. Yeast cell densities ranged from 30 to 1020 CFU 50 ml⁻¹. There was a marked increase in yeast cell densities during the summer months. A total of 30 yeast species were recorded, single sampling stations yielding from 8 to 27 species. Qualitative differences between sites were consistent throughout the sampling period. Potentially pathogenic species, often in high numbers, were recorded from many stations, the most common being Rhodotorula spp, Candida spp, and Torulopsis glabrata. Among isolates of Candida albicans, serotype B occurred significantly more frequently than serotype A.     

Attenuation of total organic carbon and unregulated trace organic chemicals in U.S. riverbank filtration systems

There is increasing concern regarding the presence of unregulated trace organic chemicals in drinking water supplies that receive discharge from municipal wastewater treatment plants. In comparison to conventional and advanced drinking water treatment, riverbank filtration represents a low-cost and low-energy alternative that can attenuate total organic carbon (TOC) as well as trace organic chemicals (TOrC). This study examined the role of predominant redox conditions, retention time, biodegradable organic carbon, and temperature to achieve attenuation of TOC and TOrC through monitoring efforts at three full-scale RBF facilities in different geographic areas of the United States. The RBF systems investigated in this study were able to act as a reliable barrier for TOC, nitrogen, and certain TOrC. Temperature (seasonal) variation played an important role for the make-up of the river water quality and performance of the RBF systems. Temperatures of less than 10 °C did not affect TOC removal but resulted in diminished attenuation of nitrate and select TOrC.     

Mechanistic and kinetic evaluation of organic disinfection by-product and assimilable organic carbon (AOC) formation during the ozonation of drinking water

Ozonation of drinking water results in the formation of low molecular weight (LMW) organic by-products. These compounds are easily utilisable by microorganisms and can result in biological instability of the water. In this study, we have combined a novel bioassay for assessment of assimilable organic carbon (AOC) with the detection of selected organic acids, aldehydes and ketones to study organic by-product formation during ozonation. We have investigated the kinetic evolution of LMW compounds as a function of ozone exposure. A substantial fraction of the organic compounds formed immediately upon exposure to ozone and organic acids comprised 60-80% of the newly formed AOC. Based on experiments performed with and without hydroxyl radical scavengers, we concluded that direct ozone reactions were mainly responsible for the formation of small organic compounds. It was also demonstrated that the laboratory-scale experiments are adequate models to describe the formation of LMW organic compounds during ozonation in full-scale treatment of surface water. Thus, the kinetic and mechanistic information gained during the laboratory-scale experiments can be utilised for upscaling to full-scale water treatment plants.     

南海饮用水水源突发性污染应急处理系统的研发和建立

针对水源突发性污染频发的现状,开发和建立了南海饮用水水源突发性污染应急处理系统。在对北江水源地存在的污染物进行调查分析并确定目标污染物的基础上,研究了目标污染物的应急去除技术,建立水源水质预警系统和水厂应急强化处理系统。介绍了项目实施的技术思路以及取得的主要技术成果,可为同行业其他企业提供参考。