Catálogo de publicaciones - libros

Water aeration has been long used in water treatment for the removal of odor and taste-causing compounds, the oxidation of iron and manganese, as well as corrosion control and aesthetics. Since the mid-1970s, however, the process has been used to remove carcinogenic and hazardous chemicals from water. These chemicals include volatile organics such as trihalomethanes, radon, trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, chloroform, and toluene. As a result, water aeration may be the single most important water treatment process used in the 21st century.

Air stripping is a process by which a liquid, usually water or wastewater, is brought into intimate contact with a gas, usually air, so that some undesirable substances present in the liquid phase can be released and carried away by the gas.

Adsorptive bubble separation process is a very effective technology for solid-liquid separation that has been in use outside the environmental engineering field for more than 60 years. Originally applied in the field of mining engineering, the process now provides the means for separation and/or concentration of 95% of the world’s base metals and other mineral compounds(1,2). Recently,the adsorptive bubble separation process has become increasingly important in such diverse applications as (a)the separation of algae,seeds,or bacteria from biological reactors,(b)removal of ink from re-pulped.

Historically, the use of activated carbon has been limited to treatment applications for drinking water. In the past two decades, more attention has been given to the potential use of activated carbons for wastewater treatment. The interest in such a process has stemmed from the growing concern over the quality of rain water from which we get our potable water. Concern exists for the protection of both surface and groundwater supplies throughout the nation. In 1974, the United States Environmental Protection Agency (US EPA) identified a total of 154 organic compounds in drinking waters

Filtration is the process by which particles are separated from a fluid by passing the fluid by passing the fluid through a permeable material (). The filtrations discussed in this chapter concern the removal of suspended solids, including some semi-colloids, from liquids. Ideally the liquid goes through and solids remain, building a permeable cake on the screen. With large, incompressible particles, this ideal situation can be approached. In practice, however, finer solids often pass through with only larger solids remaining on the screen. If the latter are at all compressible, the liquid flow is reduced to an uneconomical level and the solids stick to the screen, making it very difficult to clean. These difficulties occur in almost all organic liquid and food product filtrations. Diatomaceous earth filter aids, properly used in a diatomaceous filtration system as outlined in this chapter, offer practical and economical solutions to these filtration operational difficulties.

Wastewater treatment systems can be classified, in addition to pretreatment, as preliminary, primary, secondary, and tertiary (advanced) treatments. Pretreatment of industrial wastewater is required to prevent adverse effects on the municipal wastewater treatment plants. Preliminary treatment is considered as any physical or chemical process that precedes primary treatment. The preliminary treatment processes may consist of influent screening and grit removal. Its function is mainly to protect subsequent treatment units and to minimize operational problems. Primary treatment is defined as the physical or chemical treatment for the removal of settleable and floatable materials. The screened, degritted raw wastewater from preliminary treatment flows to the primary clarification tanks, which are part of the primary treatment facilities. Secondary wastewater treatment is the process that uses biological and chemical treatment to accomplish substantial removal of dissolved organics and colloidal materials. The secondary treatment facilities may be comprised of biological reactor and secondary clarification basins. Tertiary (advanced) wastewater treatment is used to achieve pollutant reductions by methods other than those used in primary and secondary treatments. The objective of tertiary wastewater treatment is to improve the overall removal of suspended solids, organic matter, dissolved solids, toxic substances, and nutrients.

With the rapid increase of demand in industries and daily life, water has become an increasingly valuable but scarcer resource for human being. Take Singapore as an example. Almost half of its water supply is being imported from Malaysia. The daily water consumption has risen eight times while the population has only grown three times since 1950 (

Several processes can be used to attract soluble ions from the liquid phase to the solid phase and among these is ion exchange, which is arguably the most widely used in the water treatment industry for this purpose (1-4). Ion exchange (IX) provides a means for transferring one or more ionic species from one liquid phase to another via intermediate solid resins. To achieve this, a group of ion species (the target ions) present in a solution is exchanged with another group of ion species belonging to a solid phase (IX resin or IXR). The target ions, which may be toxic, precious, or contaminants affecting water purity, are therefore concentrated on the resin, while nontoxic, precious or contaminating ions are released from the resin to replace them in the solution. The use of a regenerant on the IXR could, subsequently, release the target ions into solution again (i.e., the regenerant) and allow recovery of the IXR’s exchange capacity so that it may be applied again on more of the original solution.

Fluorine is the 13th most abundant element, and it is naturally introduced into the environment in both water and air().As a result, fluorine is present in small yet varying amounts in almost all soils, water supplies, plants, and animals. It is a normal constituent of our diets. The highest concentration of fluorine is found in our bones and teeth. The process of increasing or adding the trace element fluorine into drinking water in its ionic form as fluoride for the prevention of dental caries (tooth decay)is known as water fluoridation,whereas water defluoridation is the lowering of the naturally occurring fluoride level in drinking water to prevent dental fluorosis or the browning (mottling) of teeth ().In 2001,US Surgeon General David Satcher stated: “Water fluoridation continues to be a highly cost-effective strategy,even in areas where the overall caries level has declined and the cost of implementing water fluoridation has increased” (). It has been reported that the cost of fluoridation of public water systems averages $0.54 per person annually ().In recent years,water consumption from bottle water has increased;some of the water used for bottling has a suboptimal level of fluoride. This consumption may reduce the effectiveness of a community fluoridation program.

Natural water, such as surface water and groundwater, exists as an open system. Natural and/or synthesized organic substances, oxygen, nutrients are thus able to enter various waters. Owing to the presence of these key elements, microbial growth eventually becomes possible. Different microorganisms can therefore exist and grow in the waters. Similarly, domestic and industrial wastewater and treated wastewater contain significantly high amounts of microorganisms.