Practical Wastewater Treatment

David L. Russell

• Editore: Wiley
• Anno: 2019
• ISBN:
  9781119527121
• Edizione: 2
• Argomento: Tecnología e ingeniería
• Categoria: Gestión medioambiental

The updated and expanded guide for handling industrial wastes and designing a wastewater treatment plant

The revised and updated second edition of Practical Wastewater Treatment provides a hands-on guide to industrial wastewater treatment theory, practices, and issues. It offers information for the effective design of water and wastewater treatment facilities and contains material on how to handle the wide-variety of industrial wastes. The book is based on a course developed and taught by the author for the American Institute of Chemical Engineers.

The author reviews the most current industrial practices and goals, describes how the water industry works, and covers the most important aspects of the industry. In addition, the book explores a wide-range of approaches for managing industrial wastes such as oil, blood, protein and more. A comprehensive resource, the text covers such basic issues as water pollution, wastewater treatment techniques, sampling and measurement, and explores the key topic of biological modeling for designing wastewater treatment plants. This important book:

• Offers an updated and expanded text for dealing with real-world wastewater problems
• Contains new chapters on: Reverse Osmosis and desalination; Skin and Membrane Filtration; and Cooling tower water treatment
• Presents a guide filled with helpful examples and diagrams that is ideal for both professionals and students
• Includes information for handling industrial wastes and designing water and wastewater treatment plants

Written for civil or chemical engineers and students, Practical Wastewater Treatment offers the information and techniques needed to solve problems of wastewater treatment.

1
Composition, Chemistry, and Regulatory Framework

Much water goeth by the mill

That the miller knoweth not of.

John Heywood (1497–1580)

1.1 Water Composition

Water is composed of two parts hydrogen and one part oxygen. It is not the materials of the water but the contaminants in it that make it important. If we look at a chemical reaction, we would be extremely satisfied with a reaction yield of 99% purity, as many reactions are in the 70–90% range. However, for water, even a 1% level of impurity is unacceptable. The levels of contaminants that we often consider insignificant in many products and foods can prevent us from using water. Impurities in water at the 1% level are equivalent to 10 000 ppm or mg l⁻¹. At that level, even things like sodium chloride, table salt, in the water will render it undrinkable or harmful if consumed. In other instances, even a few milligrams of the right compound can render the water unpalatable or unusable for many aquatic purposes.

From another standpoint, the challenges that are presented to a wastewater treatment plant can be formidable. From a process standpoint, the reaction yields we look for produce a treated effluent with contamination levels of less than 10 mg l⁻¹, and in a number of instances under 2 mg l⁻¹ of particular contaminants. That is pretty good for a waste stream which may start out at 500 mg l⁻¹ or more – it represents a 99.6% removal efficiency.

The usability of the water depends upon the compounds either dissolved in it or suspended in it. Contaminants can be organic or inorganic, solids or liquids. The usability of the water also depends upon the purpose of the use. For example, water used for cooling does not necessarily need to be of the same quality (purity) as that used for drinking or food preparation. Fecal and bacterial contamination of cooling water is often unavoidable in cooling towers, and tower water is treated with chemicals to reduce corrosion and inhibit excessive bacterial growth. In all cases, this water quality is not suitable for food preparation, nor for drinking. The sterility, turbidity, and dissolved constituents in the water are important quality control issues, but not all three are necessary for a specific use.

Water can also be too pure for a specific use. As an example, there are a number of locations worldwide that have their drinking water from thermal desalination sources. At one specific facility in the Middle East, the water is slightly above 43 °C, which is a bit uncomfortable for drinking, but because it is from a thermal desalination plant, it is distilled. Hence the water is aggressive because it is so low in carbonates and minerals that it has the effect of leaching the calcium from the asbestos‐cement piping, thus weakening it. Similarly, distilled water will corrode iron and steel piping, and drinking distilled water can also cause health problems such as diuresis, and a change in the electrolyte concentration in the body¹ .

1.2 Water Characteristics and Physical Properties

Water (H₂O) is dense, weighing in at 999.972 kg m⁻³, boiling at 99.98 °C (212.96 °F), and melting at 0.0 °C. It is the standard for viscosity, at 1 centipoise (cp) at 20 °C, and has a vapor pressure which is temperature‐dependent, from 611 Pa (0.180 in. of Hg) at 0 °C to 101 901.3548 Pa at 100 °C. The formula for vapor pressure of water in that range is

where A = 8.07131, B = 1730.63, and C = 233.426 and the temperature T is in Celsius be...