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Wastewater renovation and reuse
361
RECYCLING OF MUNICIPAL WASTEWATER Wastewater Renovation and Reuse. Frank M. D'Itri (Editor). Volume 3, Pollution Engineering and Technology Series. Marcel Dekker, Basel, Switzerland, 705 pp., SwFr. 130.00, ISBN 0-8247-6505-2. An International Conference on the Renovation and Reuse of Wastewater Through Aquatic and Terrestrial Systems was convened in Bellagio, Italy during 16--21 July 1975. The conference was sponsored by the Institute of Water Research of Michigan State University and the Rockefeller Foundation. Scientists from nine countries -- Denmark, The Netherlands, Israel, the United Kingdom, Hungary, Canada, West Germany, Mexico, and the United States -- presented t w e n t y papers on a broad range of topics concerned with recycling of municipal wastewater. The conference proceedings are recorded in this book. The central theme of the conference was evaluating the biologically based approach to the reclamation and reuse of wastewater from large population centers. Since wastewater contains both water and nutrients, it may be considered as a renewable resource which can be recycled through growing plants. In chapters 1, 2, 3, 6 and 7 of the conference proceedings, soil--plant recycling systems which are irrigated with treated as well as untreated municipal wastewater are described. These terrestrial systems are generally land extensive and provide improvement of water quality with relatively low requirements for technology and operating costs. Trees and agricultural crops may be selected which yield economically useful products. Savings in costs o f fertilization and irrigation are presented as major benefits for the terrestrial recycling systems. The sale of forest and agricultural products helps to offset maintenance and operating expenses. In arid regions long-term irrigation of soil--plant systems with wastewater may result in an undesirable accumulation of salts in the soil. Thus the total quantity of water from rainfall and wastewater must exceed evapotranspiration in order to avoid salinization of the soil profile. A thorough presentation of nitrification and denitrification in soils irrigated with wastewater is given in Chapter 10. I n t e r m i t t e n t application of wastewater to terrestrial systems is presented as superior to continuous application due to cyclic nitrification of NH4-N to NO3-N during aerobic periods and removal of NO3-N by denitrification during anaerobic periods. Municipal wastewaters are usually composed of both domestic and industrial wastes which contain a wide range of undesirable human pathogens and toxic chemicals. Chapters 11 and 12 provide an excellent overview of public health implications of wastewater reuse. Untreated domestic sewage is a potential source of a wide variety of enteric pathogens for such diseases as cholera, typhoid, amoebic dysentery, infectious hepatitis, and schistosomiasis. Chlorination of domestic water inactivates pathogenic bacteria but not pathogenic enteric viruses. Viruses can be inactivated by more advanced wastewater treatment processes such as the use o f ozone, but the treatment is rather costly. Viruses pose a particular problem in waste-
362
water recycling in soil--plant systems. Very low levels of enteroviruses, such as those related to infectious hepatitis, in water may present a potential health hazard. The fate of viruses in wastewater-irrigated softs is discussed in chapters 13 and 14. Although softs generally are effective filters for bacteria, experimental results seem to indicate that viruses may be subject to some movement with water through sandy soils. The length of time that a virus can survive in the soil is not generally known, but evidence indicates that viruses can survive in sandy softs in Florida for at least 28 days. Apparently improvements are greatly needed in quantitative techniques used in the detection of viruses in water. The presence o f organic biocides such as pesticides and toxic heavy metals such as mercury, lead, and cadmium in municipal wastewater poses special problems for terrestrial recycling systems. Chapters 8 and 9 deal with this topic. Many of these chemicals are carcinogenic and may contaminate soft, water and food products as a result of wastewater-irrigation of terrestrial systems. Land disposal of untreated sewage may remove 80--85% of the nitrogen, 96% of the phosphorus, and as much as 100% of the heavy metals in softs which contain large quantities of clay minerals, organic matter, or hydroxides of Fe and A1. Heavy metals have been observed to accumulate in the t o p 3 0 - 4 0 cm of sandy softs in The Netherlands. Although sorption of heavy metals by soil constituents appears to be largely irreversible, longterm accumulation of these chemicals may pose potential problems of soil pollution and sterilization. Hydroponic and aquaculture recycling systems for the reclamation of municipal wastewater are discussed in chapters 4, 5, 15, 16 and 17. Pilot plants have been established to use marine aquaculture techniques for the removal of nutrients from water through algae--shellfish--invertebrates--lobs t e r - f l o u n d e r food chains. Cultivation of vegetable crops using freshwater hydroponic techniques has also been established to remove nutrients from wastewater. Secondary treated wastewater was used in both of these projects. Fish grown in wastewater-fed aquaculture systems are presented as a potential source of protein for human consumption. A perspective on research needs in wastewater recycling is given in Chapter 18. A major research need is for detailed consideration to effects of heavy metals, biocides, and pathogens in biologically based wastewater recycling. Public attitudes toward recycling o f municipal wastewater are presented in Chapter 19. This b o o k is a valuable compilation of recent attempts to use terrestrial and aquaculture methods to recycle wastewater. The diversity of topics presented in the b o o k should appeal to readers from a wide range of backgrounds. Scientists with broad forestry and agricultural specialities should find this b o o k a particularly useful source o f information. Hydrologists, civil engineers, and soil physicists, however, may be disappointed since the b o o k lacks a systematic presentation of water and solute transport in wastewaterirrigated soils. A systematic discussion of water and solute uptake by plant
363
roots is also missing and may limit the usefulness of the book to agronomists, horticulturists and botanists. ROBERT S. MANSELL (Gainsville, Fla, U.S.A.)
YIELD FROM WATER
Water Production Functions for Irrigated Agriculture. R.W. Hexem and E.O. Heady. Iowa State University Press, Ames, Iowa, 1978, xvi + 215 pp., 149 tables in microfiche, ISBN 0-8138-1785-4, US$ 8.95. The book is an extended report from research about yield response to water. The irrigation experiments described were conducted in Colorado, Texas, Kansas, Arizona and California for corn, cotton, wheat and sugar beets over the years 1968--1971 inclusive. Evaluated production functions represent a mathematical formulation expressing the relationships between growth factors and yield. Concepts of production functions are i n t e ~ a t e d into a decision-making framework, for profit maximisation when two inputs (water and nitrogen) are used to produce a single o u t p u t (yield). The work of Hexem and Heady is an excellent introduction to recent economic analysis of irrigated agriculture. Several variations of independent variables are used in analysis, but most important are water and nitrogen. Yield (Y) is expressed in pounds per acre, water (W) represents acre-inches of water applied after planting plus total rainfall exceeding 0.25 inch at any occurrence during the growing season plus either water applied during a preplant irrigation or an estimate of available soil moisture at planting (and sometimes minus available soil moisture at harvest), fertilizer (N) denotes pounds of nitrogen applied per acre plus estimates of preplant soil nitrogen available for plant growth. A selected number of water-related production function studies are reviewed, for Y = f(W,N), where f is an unspecific function form. Relationship f should be known a priori and selection of an algebraic form directly imposes restraints on the nature of response allowed in the function. The authors evaluate the applicability, appropriateness and flexibility of alternative p r o d u c tion functions, but all models are primarily used to predict a final yield rather than to explain a growth or a development. Polynomials or exponential functions are considered in detail. As an example quadratic, square root and three-halves polynomials were routinely 'fitted' to the experimental data and in selected instances three-parameter Mitscherlich and five-parameter Mitscherlich--Baule exponential models were also fitted to the data. Parameters were estimated by linear or nonlinear regres-
RECYCLING OF MUNICIPAL WASTEWATER Wastewater Renovation and Reuse. Frank M. D'Itri (Editor). Volume 3, Pollution Engineering and Technology Series. Marcel Dekker, Basel, Switzerland, 705 pp., SwFr. 130.00, ISBN 0-8247-6505-2. An International Conference on the Renovation and Reuse of Wastewater Through Aquatic and Terrestrial Systems was convened in Bellagio, Italy during 16--21 July 1975. The conference was sponsored by the Institute of Water Research of Michigan State University and the Rockefeller Foundation. Scientists from nine countries -- Denmark, The Netherlands, Israel, the United Kingdom, Hungary, Canada, West Germany, Mexico, and the United States -- presented t w e n t y papers on a broad range of topics concerned with recycling of municipal wastewater. The conference proceedings are recorded in this book. The central theme of the conference was evaluating the biologically based approach to the reclamation and reuse of wastewater from large population centers. Since wastewater contains both water and nutrients, it may be considered as a renewable resource which can be recycled through growing plants. In chapters 1, 2, 3, 6 and 7 of the conference proceedings, soil--plant recycling systems which are irrigated with treated as well as untreated municipal wastewater are described. These terrestrial systems are generally land extensive and provide improvement of water quality with relatively low requirements for technology and operating costs. Trees and agricultural crops may be selected which yield economically useful products. Savings in costs o f fertilization and irrigation are presented as major benefits for the terrestrial recycling systems. The sale of forest and agricultural products helps to offset maintenance and operating expenses. In arid regions long-term irrigation of soil--plant systems with wastewater may result in an undesirable accumulation of salts in the soil. Thus the total quantity of water from rainfall and wastewater must exceed evapotranspiration in order to avoid salinization of the soil profile. A thorough presentation of nitrification and denitrification in soils irrigated with wastewater is given in Chapter 10. I n t e r m i t t e n t application of wastewater to terrestrial systems is presented as superior to continuous application due to cyclic nitrification of NH4-N to NO3-N during aerobic periods and removal of NO3-N by denitrification during anaerobic periods. Municipal wastewaters are usually composed of both domestic and industrial wastes which contain a wide range of undesirable human pathogens and toxic chemicals. Chapters 11 and 12 provide an excellent overview of public health implications of wastewater reuse. Untreated domestic sewage is a potential source of a wide variety of enteric pathogens for such diseases as cholera, typhoid, amoebic dysentery, infectious hepatitis, and schistosomiasis. Chlorination of domestic water inactivates pathogenic bacteria but not pathogenic enteric viruses. Viruses can be inactivated by more advanced wastewater treatment processes such as the use o f ozone, but the treatment is rather costly. Viruses pose a particular problem in waste-
362
water recycling in soil--plant systems. Very low levels of enteroviruses, such as those related to infectious hepatitis, in water may present a potential health hazard. The fate of viruses in wastewater-irrigated softs is discussed in chapters 13 and 14. Although softs generally are effective filters for bacteria, experimental results seem to indicate that viruses may be subject to some movement with water through sandy soils. The length of time that a virus can survive in the soil is not generally known, but evidence indicates that viruses can survive in sandy softs in Florida for at least 28 days. Apparently improvements are greatly needed in quantitative techniques used in the detection of viruses in water. The presence o f organic biocides such as pesticides and toxic heavy metals such as mercury, lead, and cadmium in municipal wastewater poses special problems for terrestrial recycling systems. Chapters 8 and 9 deal with this topic. Many of these chemicals are carcinogenic and may contaminate soft, water and food products as a result of wastewater-irrigation of terrestrial systems. Land disposal of untreated sewage may remove 80--85% of the nitrogen, 96% of the phosphorus, and as much as 100% of the heavy metals in softs which contain large quantities of clay minerals, organic matter, or hydroxides of Fe and A1. Heavy metals have been observed to accumulate in the t o p 3 0 - 4 0 cm of sandy softs in The Netherlands. Although sorption of heavy metals by soil constituents appears to be largely irreversible, longterm accumulation of these chemicals may pose potential problems of soil pollution and sterilization. Hydroponic and aquaculture recycling systems for the reclamation of municipal wastewater are discussed in chapters 4, 5, 15, 16 and 17. Pilot plants have been established to use marine aquaculture techniques for the removal of nutrients from water through algae--shellfish--invertebrates--lobs t e r - f l o u n d e r food chains. Cultivation of vegetable crops using freshwater hydroponic techniques has also been established to remove nutrients from wastewater. Secondary treated wastewater was used in both of these projects. Fish grown in wastewater-fed aquaculture systems are presented as a potential source of protein for human consumption. A perspective on research needs in wastewater recycling is given in Chapter 18. A major research need is for detailed consideration to effects of heavy metals, biocides, and pathogens in biologically based wastewater recycling. Public attitudes toward recycling o f municipal wastewater are presented in Chapter 19. This b o o k is a valuable compilation of recent attempts to use terrestrial and aquaculture methods to recycle wastewater. The diversity of topics presented in the b o o k should appeal to readers from a wide range of backgrounds. Scientists with broad forestry and agricultural specialities should find this b o o k a particularly useful source o f information. Hydrologists, civil engineers, and soil physicists, however, may be disappointed since the b o o k lacks a systematic presentation of water and solute transport in wastewaterirrigated soils. A systematic discussion of water and solute uptake by plant
363
roots is also missing and may limit the usefulness of the book to agronomists, horticulturists and botanists. ROBERT S. MANSELL (Gainsville, Fla, U.S.A.)
YIELD FROM WATER
Water Production Functions for Irrigated Agriculture. R.W. Hexem and E.O. Heady. Iowa State University Press, Ames, Iowa, 1978, xvi + 215 pp., 149 tables in microfiche, ISBN 0-8138-1785-4, US$ 8.95. The book is an extended report from research about yield response to water. The irrigation experiments described were conducted in Colorado, Texas, Kansas, Arizona and California for corn, cotton, wheat and sugar beets over the years 1968--1971 inclusive. Evaluated production functions represent a mathematical formulation expressing the relationships between growth factors and yield. Concepts of production functions are i n t e ~ a t e d into a decision-making framework, for profit maximisation when two inputs (water and nitrogen) are used to produce a single o u t p u t (yield). The work of Hexem and Heady is an excellent introduction to recent economic analysis of irrigated agriculture. Several variations of independent variables are used in analysis, but most important are water and nitrogen. Yield (Y) is expressed in pounds per acre, water (W) represents acre-inches of water applied after planting plus total rainfall exceeding 0.25 inch at any occurrence during the growing season plus either water applied during a preplant irrigation or an estimate of available soil moisture at planting (and sometimes minus available soil moisture at harvest), fertilizer (N) denotes pounds of nitrogen applied per acre plus estimates of preplant soil nitrogen available for plant growth. A selected number of water-related production function studies are reviewed, for Y = f(W,N), where f is an unspecific function form. Relationship f should be known a priori and selection of an algebraic form directly imposes restraints on the nature of response allowed in the function. The authors evaluate the applicability, appropriateness and flexibility of alternative p r o d u c tion functions, but all models are primarily used to predict a final yield rather than to explain a growth or a development. Polynomials or exponential functions are considered in detail. As an example quadratic, square root and three-halves polynomials were routinely 'fitted' to the experimental data and in selected instances three-parameter Mitscherlich and five-parameter Mitscherlich--Baule exponential models were also fitted to the data. Parameters were estimated by linear or nonlinear regres-