WaterSubject

The transport of adsorptive solutes in soils and aquifers plays an important role in a variety of fields, including leaching of agrochemicals from soil surface to groundwater, uptake of soil nutrients by plant roots and remediation of contaminated soils and aquifers; and how to model it has been an interest over the past few decades. Traditional mathematical models treat movement and adsorptive reaction of solute as two separated processes, with the transport parameters associated with the movement determined from displacement experiment and ... Read More

Distributed parameter models are used to simulate groundwater flow, but the reliability of results is strongly dependent on whether the model parameters are properly identified. However, the real geological structure of an aquifer is generally very complex and mostly unknown. More data are required for identifying a more complex parameter structure, and there is always the problem of over-parameterization. Additionally, the inverse problem of parameter structure identification is highly non-linear and non-convex; hence, gradient-based algorithms often get trapped in local optima. On ... Read More

The typical conventional water treatment train in Korea is composed of coagulation, sedimentation, sand filtration, and disinfection. Most of the water treatment plants (WTPs) (i.e., 97%) in Korea take their raw water from surface water, and turbidity of raw water can be increased up to 1000 NTU during the rainy season (June-August), but turbidity of tap water is less than 0.2 NTU in most Korean cities. Turbidity of surface water can be removed up to 99% in most developed countries' WTPs, but ... Read More

In United States, chlorine dioxide (ClO2) was first used as a disinfectant to control taste and odor problems in the 1940s. However, because of high chemical cost and failure and inefficiency of the generation equipment, ClO2 has not become a widely used primary disinfectant in drinking water treatment facilities during the 1960s and 1970s. Due to the concerns about disinfection byproducts resulting from the use of chlorine in drinking water treatment, ClO2 is increasingly being considered as an alternative disinfectant for drinking ... Read More

Organic pollutants are often present in drinking water, groundwater, and domestic and industrial wastewaters. A water treatment based on the chemical oxidation of organic compounds by advanced oxidation processes (AOPs) that is useful for purifying drinking water, groundwater and for cleaning industrial wastewater has been reported recently. Several of these studies have focused on using these systems as a pre-treatment for biological systems when the dissolved organic matter is toxic, inhibitory or recalcitrant to microorganisms. The degradation and mineralization of organic pollutants ... Read More

A number of chemicals exist in the environment that affect the endocrine system and produce an adverse effect on aquatic life, animals, and potentially humans. There is increasing evidence that these compounds can alter endocrine functions and may disrupt growth, development, and reproduction by interfering with the production of the endocrine system. Accordingly, because of the role of estrogenic chemicals, often referred to as environmental estrogens, in contributing to the development of hormone-dependent cancers, disorders of the reproductive tract, and other effects, ... Read More

Transport problems involving sequentially decaying contaminants are frequently analyzed by groundwater hydrologists to assess water quality issues associated with environmental and health hazards. Examples of sequentially decaying contaminants include radioactive waste materials, chlorinated solvents, and nitrogenous species. Several types of models, using both analytical and numerical procedures, have been formulated for solving these sequentially coupled reactive transport problems and . Although numerical models are capable of solving complex and heterogeneous problems, their performance often needs to be tested against experimental datasets or ... Read More

The hydraulic control of contaminated groundwater is commonly achieved through the use of pumping wells. When long-term hydraulic containment is required, the cost of treating the water pumped from the aquifer can become prohibitive. An open, vertical barrier wall may be used in conjunction with extraction wells to provide hydraulic containment at significantly lower pumping rates than can be achieved using wells alone. The cost of constructing the barrier wall may be justified by the cost savings associated with the decreased pumping ... Read More