Water reuse: an unfinished agenda The summary comments at the E P A Symposium on Protocol Deuelopment: Criteria and Standards f o r Potable Reuse and Feasible Alternatiues, Warrenton, Va., July 29-31, I980 C. C. Johnson, Jr. C. C. Johnson Associates Silver Spring, Md. 2091 0
This particular symposium was one that the Drinking Water Council has long hoped would occur. Briefly, let us look at the purpose for the symposium so that we get things in the proper perspective. The purpose of this symposium was not to develop specific criteria and standards, but to provide guidance with respect to approaches, problems, solutions, and needed research for establishing a pathway to protocol development and potable reuse criteria and standards for consideration of nonpotable options. The two basic charges were to recommend: basic principles that can be used in the decision-making process specific experiments which can be constructed, with their interpretations, that will help answer the questions that remain. This symposium brought together scientists and engineers involved in the six technical disciplines of water reuse-toxicology, engineering, chemistry, groundwater, microbiology, and nonpotable options. Representatives from each discipline presented an issue statement at the beginning of the conference. These statements were then discussed and rewritten in the workshop sessions. Chairmen of the workshops included I. H. Suffet of Drexel University (chemistry), Russell Culp of Clean Water Consultants (engineering), Paul Roberts of Stanford University (groundwater recharge), Richard Englebrecht of the 1304
Environmental Science & Technology
University of St. Louis (microbiology), Robert Neal of Vanderbilt University (toxicology), and Jerry Gilbert of Brown & Caldwell Engineers (nonpotable options). Final positions and recommendations from each of the disciplines were presented on the last day.
What are the issues? Lloyd Fowler of the Santa Clara Water Valley District said that there are two basic issues involved. First, potable reuse should be the result of a need: either potable water is in short supply or there is a reason to extend good-quality water for other purposes. Second, whatever potable reuse considerations are given, the quality is important and public health must be protected. H e believes that the existing water supply standards are adequate, but that direct reuse poses additional questions. Dan Okun of the University of North Carolina sounded a note of caution and said that we need to review the sanitary survey so that we know what is happening to the source and why. W e should save the highest, cleanest sources for the highest priority of use, drinking water. H e reminded us that 95% of the public water systems serve less than 10 000 population units. H e said that the Drinking Water Act does not address the quality of the source but this should be considered under congressional mandate. H e also said that preventive health benefitsthe benefits of acting before a catastrophe arises-should be paramount in our thinking. Ken Miller of CH2M/Hill had a slightly different focus. H e said that the time for developing criteria for standards of potable reuse is now, but
that reuse should occur only after all other options have been exhausted. However, the ideal of using an uncontaminated source for potable water should not deter us from pursuing reuse technology. H e also was concerned about process reliability and the flexibility in the selection of the treatment processes. Finally, he said that standards for health must relate to economics, process technology, public acceptance, health effects, and most of all, the real world. Dr. F. J. J. Brinkman of the World Health Organization related some of the experiences they had with the many plants set up for nonpotable reuse in Europe and also some set up for limited direct reuse. One popular mode that they have become familiar with and have exhibited some interest in is river bank infiltration. H e also noted that they have working parameters for reuse that are similar to those in California for standards for infiltration and injection of reuse water into the groundwater source. Duane Baumann of Southern Illinois University brought a perspective on public acceptance. H e reported on an attitude survey that noted that social acceptance of potable reuse was not an obstacle, given an educated public. H e said the major obstacle probably is in the minds of the public health officials and engineers. Robert Madancy of the Department of Interior O W R T (Office of Water Research & Technology), the spokesman for the nonpotable and other alternatives sector, raised the $64 000 questions, ones that most people try to stay away from: What is potable reuse? What is direct reuse? What is indirect reuse? Take the stretch of the Ohio River between
0013-936X/80/0914-1304$01.00/0 @ 1980 American Chemical Society
Pittsburgh and Cincinnati, he said. Is Cincinnati’s water direct or indirect if upstream discharges are 2000 ft away, 200 ft away, or 2 ft away? You need to think about that. H e also pointed out that figures show that potable reuse is only, or probably less than, 1% of all the reuse projections to the year 2000. But he did recognize that public health is the most significant aspect associated with potable reuse. The formal charges for the workshop deliberations were essentially: Consider the source. Consider water quality. Consider treatment. Consider monitoring needs. My summary from hereon will address comments on these four elements as well as other matters that evolved from my observations of the workshops, the deliberations, the review of the issue papers, the summary statements, and the recommendations. I did sit in, albeit a short time, on each workshop, which meant that I got a disconnected view in terms of the discussions that were carried on. Thus, the observations that I bring now are somewhat permeated with my own philosophy.
The questions I listed perhaps 20 or 25 questions that I wanted this kind of symposium to answer. I’ll share with you only eight, because I think they are the most significant. Is it possible to establish criteria and standards for potable reuse which will protect the public health? Drinking water standards are to be applied to source waters from a protected source. What does this mean to a consideration of potable reuse? Will the public knowingly accept direct reuse? Does the available scientific and technical data allow the establishment and implementation of acceptable water quality standards? What is the most likely or prevalent nature of water reuse and what is its significance or impact on public water supplies? Does our knowledge of hydrogeology, soil characteristics, and the interaction of wastewater products allow us to predict the fate of contaminants following groundwater recharge? With respect to water quality and the absence of certainty, what risk to the public health are we willing to take? What are the gaps in our knowledge that can be and should be filled by research when we consider the subject of potable water reuse?
The first thing I noted in most of the workshops was a common concern about the definitions we use for potable reuse and nonpotable reuse. The definitions should skirt the buzz words and recognize the reality. For example, new terms crept into the terminology of several discussants and reporters. Robert Neal talked about planned and unplanned reuse; another report talked about controlled and uncontrolled reuse. I suggest that the definition of potable reuse is planned and unplanned, controlled and uncontrolled use of wastewater for domestic purposes. Nonpotable reuse is characterized as wastewater used for agricultural, industrial, and other purposes.
Some examples Planned and controlled reuse are in existence in Israel, South Africa, the Netherlands, Germany, and so forth.
Every community water treatment plant that exists below the discharge of a wastewater treatment plant is in the mode of unplanned reuse.
But we don’t have to go overseas to get examples. W e have our own experiences in California, Long Island, and other places in terms of groundwater recharge. In terms of a raw water supply source, work is being done in Virginia. Within the terms of a developed protocol and with approval of the EPA and the state of Virginia, the Upper Occoquan Sewage Authority was allowed to develop an A W T plant that discharges its effluent into the water reservoir from which Fairfax County takes its raw water supply and produces drinking water. This is a good example of a direct reuse situation. They did it on the basis of the best knowledge they had, the best technology they could devise, and the best reliability they could design. It’s working and it’s the kind of demonstration from which wisdom is taken. We’ll know later on whether or not it was a good or bad experience.
Unplanned reuse Every community water treatment plant that exists below the discharge of a wastewater treatment plant is in the
mode of unplanned reuse. The only difference is the distance that separates one pipe from the other. Dallas, for example, has to contend with discharge from Denton. Ken Miller told me the community of Thornton, Colo., which is right below Denver, is taking the direct discharge from the Denver wastewater treatment plant. Long Island water is an example of planned reuse. There are other areas of the country where wastewater effluents are purposely discharged above aquifers so that wastewaters percolate into the groundwater table and eventually may be reused. Other situations are planned solely for discharge to the ground in a relatively safe manner, for example, in Muskegon, Mich. Direct reuse was planned in Chanute, Kan., in the 1950s because there was a need for water due to drought. The point I a m trying to make is that direct, indirect, and potable reuse are realities. There is nothing new about them, except maybe our concern. That is why I think this was such a valuable conference. We are now beginning to come to terms with polluted water sources and how they affect our daily need to produce an acceptable water supply. Once the workshops adjusted to dealing with source waters from polluted sources, regardless of the unquantifiable measure of direct or indirect reuse, they were free to address the problems associated with producing or maintaining potable water that is protective of the public’s health. Practically all the groups believed that their deliberations are applicable to all polluted waters, regardless of source. That is an important conclusion to draw from this kind of workshop. It is commonly recognized that the waste characteristics and the degree of pollution involved in potable water reuse influence the microbiological, chemical, and toxicological aspects of potable water quality in new and different ways when compared with the past practices associated with water treatment and quality assurance. There was general agreement in the approaches recommended for dealing with these aspects. Practically all of the groups were of the opinion that a single set of water quality standards should apply at the tap, regardless of the source of the raw water to be treated for drinking. Almost all groups agreed that additional information is needed for raw water coming from highly polluted sources in order to treat it properly. With the exception of one work group, all recognized deficiencies in Volume 14, Number 11, November 1980
1305
Read water toxicity in minutesinstead of days! Microtox’“ acute water toxicity analyzer enables you t o perform bioassays quickly, accurately and economically. Test results correlate with other bioassay techniques that require doys t o perform. Beckman’s rapid test uses a specialized strain of luminescent bacteria as the bioassay organism, which can be handled as simply as a chemical reagent. All you need to do is prepare the dilutions o f the test sample. Test measurements a r e repeatable and reproducible, since standardization is m o r e easily accomplished with bacteria t h a n with higher organisms, such as fish. Beckman’s Microtox analyzer provides acute water toxicity measurement of a wide variety of toxicants, including phenolics, pesticides, heavy metals, aromatic and halogenated hydrocarbons, and complex effluents. For m o r e information on t h e Microtox toxicity analyzer, write: Beckman Instruments, Inc., 2500 H a r b o r Boulevard, Fullerton, California 92634
6ECKMAN CIRCLE 25 ON READER SERVICE CARD
1306
Environmental Science & Technology
the state of the art. These deficiencies were not considered insurmountable; they can be remedied by additional and specified research. I am somewhat discouraged, however, by the timetable associated with some problems that were cited. The engineering group was of the opinion that technology does not appear to be a limiting factor in the implementation of potable reuse. Perhaps the most difficult and as yet unanswered question is associated with health effects that may be attributed to treated water. The toxicologists suggested that new parameters are needed to deal with organics in drinking water. These parameters might take the form of biological end points. They also believe, along with the chemists, that animal studies can be designed to enable a measure of predictability and that establishment of standards can guide the design and operation of water treatment plants. Notice I have been using the term “water treatment plant.” One term that seems to create a problem is the use of “water reclamation plant.” I am not quite sure where that fits into the picture when we think of all the water plants for planned or unplanned potable reuse that are not water reclamation plants. Microbiologists agree that potable reuse raises new questions with respect to the presence, generation, elimination, and reduction of pathogens and toxins during treatment of highly polluted water. This may require new indicator organisms and different disinfectants than those that have been used and relied upon for the past 100 years. Even so, the answers can probably be supplied by appropriate research. Serious questions exist in my mind about the ability to predict the transport and transformation of metals, organics, and biologicals i n groundwater. Under these circumstances, either the doctrine of no significant deterioration or the concept of dedicated use should be applied to groundwater recharge or reuse of potable water for nonpotable purposes. The nonpotable reuse group believed that the problems of potable reuse are monumental, that the volume of water involved is inconsequential, and that the ultimate acceptance of direct potable reuse is improbable. They believed that emphasis should be placed on the more readily achievable solutions of problems associated with nonpotable reuse. I believe that any concept of controlled and uncontrolled, planned and unplanned reuse of wastewater should
be a local option, probably decided on the basis of need, while maintaining protection of public health as a top priority. It must be emphasized that few nonpotable uses exist that do not impact upon the quality of water supplies that now or may in the future be required for potable uses. Whether or not the public will accept potable reuse is probably an academic question. The fact is that they have in the past, they are now, and they probably will in the future. The public should be confident that our treatment processes are indeed producing the best water possible, and are in consonance with our scientifically established standards to protect the public health.
Where are we? The practice of potable reuse has been with us for a long time. W e need only to improve the product to keep pace with our knowledge and concern for health effects. It affects every community water supply that currently extracts water from an industrial or vulnerable stream or grossly contaminated aquifer. We can’t close down these water treatment processes while we obtain answers to the scientific and technical gaps that exist. W e must get on with the business at hand, of producing the best water we can from the sources we must use, in the presence of the best available knowledge, as inadequate as that may be. If our concern for water reuse is genuine, then it is strongly recommended that the deliberations, considerations, and recommendations of this symposium be related as applicable to all aspects of potable water supply production. Recognition of this concern should be incorporated into every EPA program that impacts upon the quality of raw water supply sources and the development and revision of national drinking water standards.
C . C. Johnson, Jr., is chairman of the National Drinking Water Council, established by the Safe Drinking Water Act of 1974 to procide advice to the EPA administrators. He heads an environmental engineering consultingfirm, C. C. Johnson Associates, in Silver Spring, Md. He is a retired assistant surgeon general of the U S . Public Health Seruice.
