Typical Water Sources Research Articles

Characterisation of the formation of halobenzoquinone disinfection by-products in typical water sources at different water quality stages

As an emerging class of uncontrolled disinfection by-products, halobenzoquinones (HBQs) are 3 to 4 orders of magnitude more cytotoxic and genotoxic than regulated disinfection by-products.

Non-Single Charge Ions Effect on Reverse Electrodialysis Technology for Salinity Gradient Power Generation

Salinity Gradient Power (SGP), also known as Blue Energy, is gaining attention in the recent years due to its global availability and renewable nature [1,2]. SGP is based on the physico-chemical potential existing when two water streams of different salinity are mixed. The most important and well-known technology to harvest the SGP energy is the Reverse Electrodialysis (RED), which converts the blue energy into electricity through ion exchange membranes (IEMs). Usually, seawater has been targeted as high concentrated solution and river water as low concentrated solution. Nevertheless, other water bodies are possible, for example, industrial brine solutions, groundwater or treated urban wastewater streams. The presence of the non-single charge ions presents in common water streams can affect power performance due to an increase in the internal resistance of the system [3,4], and thus their effects need to be thoroughly studied.This work aims to model the RED performance providing a robust and comprehensive mathematical tool to predict power output under real conditions. The model takes into account different variables (flowrate and temperature), the RED system characteristics (effective area, thickness of both membranes and spacers and number of cell pair) as well as different scenarios in term of streams composition. In this sense, the concentration of the main compounds presents in the typical water sources was studied achieving different correlations as function of the cationic or anionic type of membrane.For this purpose, electrochemical impedance spectroscopy (EIS) technique was employed to measure the resistance of IEMs in contact with NaCl solution including mixtures of non-single charge ions (Ca2+, Mg2+, SO4 2-) in order to find suitable mathematical correlations to be integrated into the mathematical model [1]. EIS measurements were performed by placing the membranes in a nylon cell system previously submerged in the different solutions for seven days to ensure impregnation.The results obtained were validated with different experimental conditions in terms of water composition. Theoretical and experimental results fit well with errors below 5%, showing that the presence of divalent ions has a negative effect on power performance due to the increase in membrane resistance in comparison to pure NaCl solutions. Nevertheless, the maximum decay in power output, for a wide range of real scenarios studied, was not higher than 16%, which can still be considered acceptable. Acknowledgements: The authors want to acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through the projects: CTQ2015-66078-R, and CTM2017-87850-R. This research is also being supported by the Project “HYLANTIC”-EAPA_204/2016, which is co-financed by the European Regional Development Fund in the framework of the Interreg Atlantic program.

Study on the risk assessment and forewarning model of groundwater pollution

In the purview of groundwater pollution, a rational exploitation, utilization, protection, and risk assessment of groundwater has become an important means of groundwater management and pollution prevention. Xiashan Economic Zone of Weifang City which is located in the central region of the Shandong Peninsula, China, has been chosen to investigate the risk assessment of pollution by heavy metals (Pb, Cr, Cd, and Hg) permeating into groundwater periodically through the soil layers or the vadose zone. This study deals with the risk assessment and forewarning model of groundwater pollution by the use of comprehensive risk index method along with GIS overlay analysis and groundwater pollution forewarning system. Soil samples (n = 988) and water samples (n = 327) from groundwater resources of Xiashan Economic Zone and eight major factors, i.e., runoff factor, overburden strata factor, atmospheric precipitation factor, pollutant source type, pollutant generation quantity, pollutant release possibility, water yield from aquifers, and groundwater conservation district, have been thoroughly studied. Based on data analysis and study, groundwater pollution risk assessment zonation map and groundwater forewarning distribution map were established. The results show that the distribution area accounting for 3.07% of the total area is of medium warning with high risk of pollution. Mainly spread on both banks of the river, the serious warning zone is covering 26.80% of the total area for groundwater, and the groundwater is distressed with a risk of moderate pollution. While the tremendous warning area for groundwater pollution is distributed in over 70.13% of the total area, thus, putting in a state of high-risk pollution. The warning degree of groundwater pollution in typical water source areas was identified, and the possible alarming warning instance can be forecast. Based on the warning degree, the governance protection area and key protection area were divided. The corresponding prevention and control measures were put forward after formulating the prevention and control plan of groundwater pollution based on this kind of study.

Synergistic Tandem Solar Electricity-Water Generators

Summary Energy and clean water are two intertwined fundamental elements for human civilization and sustainable development. Here, we devise a monolithic tandem solar electricity-water generator that synergistically produces electricity and clean water by utilizing the full spectrum of solar irradiance. The tandem generator has two components: a top infrared-transparent photovoltaic device using above-band-gap photons, and a bottom solar water purifier using the below-band-gap photons. More strikingly, a well-designed water-proof thermal interconnecting layer (WTIL) makes these two components work synergistically: the bottom purifier serves as an evaporative cooler of the top solar cell to increase its efficiency, whereas the thermalization energy of the top cell is reutilized by the bottom purifier for producing more clean water. We experimentally demonstrate that a prototype hybrid tandem solar device with WTIL can generate electricity with a power output of 204 W m−2 and purify water at a rate of 0.80 kg m−2 h−1 under 1-sun illumination.

Overview of surface water hazards in China coalmines

Abstract Among all recorded water disasters in China coalmines, 10% can be attributed to surface water, making it one of the top water hazards. Based on the analysis of cases of surface water hazards in China coalmines, this article determined surface water sources and inrush conduits as the major factors that have caused water inrush disasters in mines, and classified surface water hazards in China coalmines into 15 types according to those major factors and gave definitions of each type of surface water hazard. Then, it is proposed that there are different types of surface water hazards in different coal-bearing regions by analyzing the relationship to terrain features, climatic impact and mining conditions. Finally, we discuss how typical water sources and inrush conduits work together in hazard formation, in addition to the characteristics and corresponding preventative technologies. The propositions can be of reference for exchanges with other mining countries and regions on surface water hazard treatment.

Inorganic fouling mitigation by salinity cycling in batch reverse osmosis

Enhanced fouling resistance has been observed in recent variants of reverse osmosis (RO) desalination which use time-varying batch or semi-batch processes, such as closed-circuit RO (CCRO) and pulse flow RO (PFRO). However, the mechanisms of batch processes' fouling resistance are not well-understood, and models have not been developed for prediction of their fouling performance. Here, a framework for predicting reverse osmosis fouling is developed by comparing the fluid residence time in batch and continuous (conventional) reverse osmosis systems to the nucleation induction times for crystallization of sparingly soluble salts. This study considers the inorganic foulants calcium sulfate (gypsum), calcium carbonate (calcite), and silica, and the work predicts maximum recovery ratios for the treatment of typical water sources using batch reverse osmosis (BRO) and continuous reverse osmosis. The prediction method is validated through comparisons to the measured time delay for CaSO4 membrane scaling in a bench-scale, recirculating reverse osmosis unit. The maximum recovery ratio for each salt solution (CaCO3, CaSO4) is individually predicted as a function of inlet salinity, as shown in contour plots. Next, the maximum recovery ratios of batch and conventional RO are compared across several water sources, including seawater, brackish groundwater, and RO brine. Batch RO's shorter residence times, associated with cycling from low to high salinity during each batch, enable significantly higher recovery ratios and higher salinity than in continuous RO for all cases examined. Finally, representative brackish RO brine samples were analyzed to determine the maximum possible recovery with batch RO. Overall, the induction time modeling methodology provided here can be used to allow batch RO to operate at high salinity and high recovery, while controlling scaling. The results show that, in addition to its known energy efficiency improvement, batch RO has superior inorganic fouling resistance relative to conventional RO.

Organic Distribution Characteristics and Influence on Drinking Water Quality in the Typical Water Sources for Towns in the Southwest Hilly Area of China

This study analyzed the organic distribution characteristics of original and treated water and their impacts on drinking water quality using a conventional water treatment process in the typical water supply sources for towns in the southwest hilly area of China. The results showed that the water supply source in this area is micro-polluted water. Dissolved organics of low molecular weight accounted for the great majority of the organics, with the proportion ranging from 50% to 80%. There were 53 kinds and 14 classes of organics, including alkanes, esters, phenolic compounds, and benzenes, with the proportion from 80% to 90%. The amounts of organic acid, alkene, alcohols, and aldehyde were small, while the amounts of dichloromethane, phenol, and dibutyl-phthalate were relatively high. Herbicides, food additives, and antibiotics were detected, such as terbuthylazine, 2,6-di-tert-butyl-p-cresol, and nalidixic acid. The conventional water treatment process could efficiently remove the compounds with molecular weights higher than 10×103 and organic acid; however, it was limited greatly in its removal of alkanes, esters, phenolic compounds, and benzenes.

Profiles and risk assessment of phthalate acid esters (PAEs) in drinking water sources and treatment plants, East China.

This study is the first report describing the occurrence of 15 phthalate acid esters (PAEs) in the three typical water sources of YiXing City, Taihu Upper-River Basin, East China. The fate of target PAEs in the Jiubin drinking water treatment plant (JTP) was also analyzed. The amounts of Σ15PAE in the Hengshan (HS), Youche (YC), and Xijiu (XJ) water sources were relatively moderate, with mean values of 360, 357, and 697ngL-1, respectively. Bis(2-ethylhexyl) phthalate (DEHP) dominated the PAE concentration, making up 80% of the 15 total PAEs. The highest levels of Σ15PAE were found in HS, YC, and XJ in March 2015, January 2015, and July 2014, respectively. The occurrence and concentrations of these compounds were spatially dependent, and the mean concentrations of Σ15PAE in HS, YC, and XJ samples increased from the surface layer to the bottom layer with varied percentage increases. The removal efficiency of the PAEs in the finished water varied markedly, and the removal of PAEs by the JTP ranged from 12.8 to 64.5%. The potential ecosystem risk assessment indicated that the risk of PAEs was relatively low in these three water sources. However, risks posed by PAEs due to drinking water still exist; therefore, special attention should be paid to source control in the JTP, and advanced treatment processes for drinking water supplies should be implemented.

Purification effect of two typical water source vegetation buffer zones on land-sourced pollutants

Two vegetation buffer zones (tree-shrub-grass pattern and tree-grass pattern) were selected as test objects around Siming reservoir in Yuyao City of China. The effect of the storm runoff intensity (low and high intensity) and the buffer zone width (1 m, 3 m, 5 m, 7 m, 9 m, 12 m, 16 m) on pollutants (suspended solids, ammonium nitrogen and total phosphorus) was studied by the artificial simulation runoff. The results showed that with the increase of the width of buffer zone, the pollutant concentration was decreased. The purification effect of the two buffer zones on suspended solids and total phosphorus was basically stable at 52-55% and 34-37%, respectively. But the purification effect on ammonium nitrogen was the tree-shrub-grass pattern (69.7%) significantly better than that of tree-grass pattern (52.1%). The purification rate at the low runoff intensity was 1.8-2.0 times that at the high runoff intensity. The relationship between the purification rate and buffer zone width can be expressed by the natural logarithm equation, and the model adjustment coefficient was greater than 0.92.

Occurrence of organochlorine pesticides from typical water sources in YiXing City, Taihu Upper-River Basin, East China

This is the first report on the occurrence of 18 organochlorine pesticides (OCPs) in YiXing, Taihu Upper-River Basin, East China.

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in Northeast China

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impacts on public health. This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoir—the new and important water source of Harbin city in Northeast China. As drinking water is a major source for human exposure to PAEs, the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed. The results demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderate, ranging from 355.8 to 9226.5 ng/L, with the mean value of 2943.1 ng/L. DBP and DEHP dominated the PAE concentrations, which ranged from 52.5 to 4498.2 ng/L and 128.9 to 6570.9 ng/L, respectively. The occurrence and concentrations of these compounds were heavily spatially dependent. Meanwhile, the results on the waterworks samples suggested no significant differences in PAE levels with the input of the raw waters. Without effective and stable removal of PAEs after the conventional drinking water treatment in the waterworks (25.8% to 76.5%), the risks posed by PAEs through drinking water ingestion were still existing, which should be paid special attention to the source control in the Mopanshan Reservoir and some advanced treatment processes for drinking water supplies.