David W. Hendricks

Filtration as a Barrier to Passage of Cysts in Drinking Water

Numerous outbreaks of waterborne giardiasis have occurred in the United States since 1973. Generally, the causes have been inadequate disinfection or inadequate filtration (perhaps none), or sometimes both. Even though research on water filtration for Giardia cyst removal is expected to continue in the future, sufficient information on water filtration for cyst removal is available now to provide some guidance for engineers who design filtration plants and for operators who run them.

Operational efficiency of a pilot plant for wastewater reuse

Reuse of wastewaters for non-potable uses needs a higher than normal reliability in treatment plant operation and management, in order to ensure higher safety margins for public health and environmental protection. After a two-years research project on a pilot plant designed for agricoltural reuse, all control parameters used for the plant operation have been examined, in order to obtain useful observations on efficiency of each of the treatment units, for best overall performance. It was concluded that this type of package plant was able to produce a high quality effluent under various conditions, providing a good confidence on the reliability of the system.

Hans Albert Einstein – his life as a pioneering engineer

In 1991, Elizabeth Roboz Einstein (1904–1995) asked Professor John Kennedy (1933–1991), then Director of the Iowa Institute of Hydraulic Research (now named IIHR-Hydroscience & Engineering) at the University of Iowa, to consider writing a biography of her late husband, Hans Albert Einstein (1904– 1973). She was Hans Albert’s second wife (m. 1959), and an accomplished biochemist. For reference, his first wife was Frieda Knecht (1895–1958, m. 1927), who looked after their home and family as her main interest. To aid in this task and to document details. Elizabeth Einstein provided a trove of archived material dating from Hans Albert’s early childhood. In addition, there were former students, colleagues, friends, and children who were still around and available to be interviewed. The resulting biography of Hans Albert by Robert Ettema and Connie Mutel has a lot of intertwined stories and was developed over some 20 years while the authors fitted in other responsibilities. The genesis of the book and its writing is one story. It so happened that after the visit of Elizabeth Einstein in 1991, Professor Kennedy succumbed to a cancer and, at his request, Professor Ettema filled in as acting director of IIHR. Soon after, he started, with Connie Mutel, the biography of Hans Albert. Only a few in engineering could follow the unfolding of original knowledge generated by Hans Albert (about sediment transport), much less describe the mechanisms, but this was done by Professor Ettema with lucid clarity. Because of his knowledge and experience in the field, the career of Professor Ettema was a unique fit to co-author the Hans Albert biography. As a professional writer at IIHR, Connie Mutel ferreted out the stories of family and personal relationships of Hans Albert, and how his career evolved, and was also at IIHR at the same time – in 1991. Both “tracks”, the Hans Albert life-story and the technical unfolding of his developing knowledge, required much work (this can be appreciated when reading the book) and a subsequent seamless weaving of both tracks into an absorbing single story. The outcome is not only a technical review of Hans Albert’s work, but it is also a social history of the seven decades of his life. Seen from this larger perspective, the book describes (one view of) the idea of engineering research: the quest to understand a complex problem, its social context, and how these relate to practice. The book could be a text for a liberal arts freshman course as well as a key reference for graduate students and engineers in practice. The book has an immense amount of fodder for discussion and reflection, and gives an

Water Quality Modeling

The water use locus of a river basin is its stream system. Streams are sources of water supply and, at the same time, they function as sinks for used water. Two categories of used water of interest are: (1) point source discharges of treated waste water, i.e., from municipalities and industries, and (2) non-point source flows, i.e., from irrigated agriculture, urban storm water runoff, etc.

Fecal coliform densities in a Western watershed

This paper describes the areal distribution of fecal coliform densities within the stream system of the South Platte River basin in Colorado. Low densities, e.g., 0 to 99 fecal coliforms per 100 ml, were found in mountain streams, while higher densities, e.g., 10000 to 100000 and above were found in plains streams. About 49 % of the plains stations and 3 % of the mountain stations were not in compliance with the Colorado secondary contact recreation standard of 2000 fecal coliforms per 100 ml. The higher fecal coliform densities were associated with discharges from wastewater treatment plants. This is significant from a public health standpoint since the tainted waters are spread throughout the South Platte basin to irrigated lands via streams, canals, and reservoirs. Because of current federal and state policy encouraging land treatment and reuse, such practice should be reviewed with respect to compliance with proposed fecal coliform standards, and whether such standards should be adopted.

Water reuse planning by means of an input-output table

Ofrece una tabla de ingreso y salida adaptada al reuso de agua y proporciona un sistema de recursos de agua desarrollado para comprender y comparar nuevas aplicaciones del reuso de agua

A Usable Input-Output Flow Chart of a Municipal Water System (PDF)

A municipal water system is made up of a set of interacting components. Typical factors affecting system operation include sources of supply, water treatment plants, transmission pipelines, treated water storage, pipe grids, users, sewerage, and wastewater treatment plants. These factors are subject to incessant year-by-year change as populations increase, as new regulations are imposed, and as system components are modified or replaced. Planning for the nature and extent of these changes requires analyzing the interactions among components. For example, water treatment plant expansion must be understood from the standpoint of adequacy of sources of supply, magnitude of user demands, need for additional treated water storage, capacity of transmission pipelines, water losses during use, and so forth. To answer such questions, a technically oriented systems analysis is needed, the results of which must be communicable to those