environmental action foundarion solid waste project Sewage Sludge Back To Th6 Land? Bloomington, Indiana, 1976. When farmer Ron Nehrig discover- ed the sewage sludge he'd used as a soil conditioner was heavily contaminated with cancer-causing PCBs, he became concerned about his family's health. Upon his insistence city officials tested the milk from a family cow that had grazed on the sludge-treated pasture. They found the milk fat contained twice the amount of PCBs allowed by the Federal government. Farmer Nehrig's pliaht is part of a sludge crisis that threatens to engulf many communities, bringing with it a possible environ- msntal nightmare. As municipal wastewater treatment plants spuw out over 25 billion gallons of sludge daily, cities are hard pressed to find disposal methods that are both economically acceptable and environmentally sound. Ironically, the onslaught of sludge is a direct result of the battle against water pollution: the cleaner we get our waters, the more .sludge we produce. The disposal dilemma is becoming in- creasingly acute as communities upgrade their sewage treatment processes (as required by the 1972 Federal Water Pollution Con- trol Act). The Environmental Protection Agency (EPA) esti- mates that by 1985 we -yill have to contend with at least twice as much sludge as we face today. Every time anyone flushes the toilet, does their laundry, or uses the garbage disposal they create sludge. Largely due to the contribution of local industries that use the public sewage system, municipal sludge often contains detectable amounts of heavy metals and toxic chemicals that may endanger human health and pollute the environment. Currently about 15 percent of the nation's sludge is dumped into the ocean, 35 percent is burned (incinerated), 25 percent is buried (landfilled), and 25 percent is spread on the land as a soil conditioner (landspread). However, this pattern is rapidly changing as the result of environmental legislation and the rising costs of' traditional disposal methods. Because of mounting evidence of serious damage to the marine ecosystem,' EPA has ruled that all ocean dumping of sludge must cease by 1981. Simultaneously, incineration is being priced out of range for most communities; only the largest cities can pay for expensive fuel and adequate air pollution control equipment. With more and more sludge and fewer places to put it, cities are looking to the land as the answer to their sludge disposal woes. Because urban landfill space is rapidly disappearing, com- munities are trying to keep as much out of the landfill as possible. This means that wherever it.is practical, cities are likely to find landspreading the most attractive disposal alternative. At first glance, landspreading urban sludge appears to be the ideal solution to a compiicated problem: an otherwise wasted resource, loaded with soil-enriching organics, can be used to build the soil and close the ecological circle. This sounds like the perfect environmental answer, and both city officials and much of the environmental community tout it as such. But there's a catch. If sludge contaminants have caused enough concern to ban sludge from the ocean, there is good reason to fear the same contaminants will wreak havoc on the land, particularly if they enter the food chain. Scientists, environmentalists, and offices within EPA sharply disagree as to just how much of a hazard is posed by applying sludge to farm land. These experts heatedly debate what levels of heavy metals, toxic chemicals, and pathogens (disease-causing organisms) are "safe;" some believe that even sludges low in heavy metals are dangerous on food chain crops, while others claim that vegetables can be safely grown on highly contaminated sludges. The unfortunate result of this numbers squabble is that the public may be misled about the seriousness of the problem. Close examination of the evidence indicates that there is cause for grave concern. He Leavy metals, including cadmium, chromium, lead, mercury, nickel, and zinc, can accumulate in food chain plants and animals in sufficient concentrations to endanger human health. The U.S. Food and Druq Administration (FDA) has singled out 21; ------- cadmium as the greatest threat to human health through the food supply. Cadmium is a persistent, pervasive metal that has entered our environment primarily as a result of the mining and refining of zinc ores. It is mainly used by the electroplating industry, the pigments and compounds industries, and the metallurgy industry, and it ends up in products ranging from motor oil to television tubes. Even present levels of cadmium in our air, drinking water, cigarette tobacco and food cause some scientists concern. Cad- mium is a cumulative poison that is retained mostly in the liver and kidneys. In high concentrations it is known to cause acute kidney disease, and it has been linked with cancer in tin smelter workers; in much lower concentrations it has been associated with hypertension and heart disease. Scientists worry most about the lower exposure chronic diseases, for we already absorb more cadmium than prescribed by international standards. Both the Food and Agricultural Organization and the WHAT IS IN SLUDGE? Sludge, a watery substance typically composed of 90 to 95 percent water and 5 to 10 percent solids, is the end product of the wastewater cleanup process. When sewage from homes and industries enters a wastewater treatment plant it undergoes primary treatment to strain out large solids and grit. In 70 percent of our communities it then undergoes further processing — secondary treatment — which removes up to 90 percent of the organic material present in the effluent. If there is no other processing, raw sludge results; it is very smelly in this form, and contains large numbers'of disease-causing organisms (pathogens). In most cases, the sludge is further treated and is con- verted into a less toxic, less chemically active form. This pro- cess, known as stabilization, eliminates most of the odor and pathogen problems. The basic ways of stabilizing sludge are digestion, composting, and chemical treatment; digestion is most common. • Digestion is a biological process in which micro- organisms interact with the sludge either in the presence of air (aerobically) or in the absence of air (anaerobically). Digested sludge may be left in liquid form or may be dewatered. • Composting is familiar to many. In this process wood chips, bark, organic refuse or some other bulking agent is a.ded to dewatered sludge. Over time the sludge decom- poses, producing temperatures as high as 140° F. The end product is an earthy, humus-like product that is almost odorless and pathogen-free. • Chemical treatment involves adding large amounts of lime. About three-quarters of sludge soiids are bio-degradable, organic materials that give sludge its soil-enriching reputa- tion. The remaining portion is composed largely of silica (sand), potassium, iron, and can contain trace amounts of heavy metals such as cadmium, lead, and mercury, and per- sistent toxic chemicals such DDT, aldrin, dieldrin, and poly- chlorinated biphenyls '(PCBs). It is this small portion of sewage sludge that is cause for serious concern. World Health Organization of the United Nations recommend a maximum cadmium intake of 57 to 71 micrograms per day from all sources; a recent FDA study concludes that the average American consumes 72 micrograms of cadmium daily from food and drink alone. Landspreading sludge on food crops causes such concern because sludges consistently have cadmium concentrations high above the average soil level of .15 parts per million (ppm); the sludge in over half of our communities has more than 16 ppm cadmium, and urban sludges have been found with more than 3600 ppm cadmium. Since food is our major source of cadmium intake, the large scale application of urban sludges to cadmium- absorbing leafy green vegetables and grains could significantly increase our intake. Salad lovers and cereal eaters beware! Dr. Charles Jelineck, FDA's Deputy Associate Director for Technology, warns that "new developments should not be established on a large scale that could cause a significant and possibly irreversible increase of cadmium in the food supply. The uncontrolled, widespread application of sewage sludge on land should be considered in this category." ' loxic organic compounds in sludge may also threaten human health and the environment. These very persistent chemicals include pesticides such as DDT, aldrin, dieldrin, and chlordane, as well as the polychlorinated biphenyls (PCBs) that ended up in farmer Nehrig's milk. What little we know about the fate of these substances in the ecosystem and tolerance levels in hu- mans is not reassuring. Toxic chemicals are potent, cancer-causing agents that already have embedded themselves in food chain plants and animals; any increased exposure should be avoided. Numerous pathogens, .or disease-causing organisms, are always present in municipal sludge. These include bacteria and viruses, such as salmonella and tuberculosis, and parasites. According to FDA's Dr. Jelineck, the main concern is that grazing animals or people may come into contact with these infectious agents. UNDER CONTROL? There are ways to minimize sludge's adverse impacts through careful site management and crop selection. Perhaps the most important of these measures is to maintain the soil in a neutral or slightly alkaline state (pH 6.5 or above) by applying lime. "Maintaining soil pH at 6.5 or above minimizes the migration of heavy metals," according to U.S. Department of Agriculture (USDA) heavy metal specialist Rufus Chaney. "The manage- ------- ment of a sludge disposal site is crucial in determining how much of a hazard the sludge will be. Even a good sludge can cause heavy metals problems if there isn't proper pH management." Unfortunately, little control currently exists over either sludge quality or its management. Despite enthusiasts' claims, there is no guarantee that safe sludge will be put on the land, or that there will be proper site management. This creates an opportunity for a wealth of abuses both on farms and home gardens. EPA case studies confirm that actual application practices seldom follow recommended controls. One survey found that only 5 out of 15 communities met USDA interim land- spreading criteria; 4 of the violators grossly exceeded the recommended cadmium limits. Another study of 25 sludge spreading sites found that none of the farmers sampled the content of the sludge before putting it on crops, and only a handful monitored the soil pH. The story is even worse for home gardeners who unwittingly are spreading "natural" fertilizers loaded with heavy metals on their vegetable plots. Treated urban sludges such as Milwaukee's "Milorganite" and Chicago's "Nu-Earth," for example, contain inordinately high amounts of cadmium. Milorganite averages around 112 ppm cadmium, and yet it is widely sold for garden application. Ironically, home farmers who grow their own "organic" vegetables are likely to suffer the most. WHAT WE CAN DO ABOUT IT Why are heavy metals and toxic organics in sludge in the first place? One important reason is that industries often are big users of municipal wastewater treatment systems. On the average, they contribute about 40 percent of what flows into an urban sewage plant. Since industrial chemicals and metals are largely responsible for the major environmental complications caused by sludge, it makes sense to attack the problem head on — at the source. Such an approach is called pretreatment. Extracting contaminants before they mix with residential sewage should significantly purify many sludges, and conse- quently should decrease the environmental risks of all dis- posal methods. A vigorous pretreatment program, while not the complete answer, is the only way to make more sludges acceptable for land application. EPA currently is writing pretreatment stan- dards for seven types of industries that discharge toxins and heavy metals into the municipal sewage system. By 1981 such standards will cover 21 major types of industries and will affect over 50,000 companies. The first seven standards were to have been issued by the beginning of July, 1977, but are several months behind schedule. It also is imperative to develop ways to control sludge land- spreadifig to ensure sites are properly maintained and applica- tion rates are adequately limited. Such management controls can be achieved both by state and federal regulations. Long- awaited federal guidance is on the horizon as a result of the Resource Conservation and Recovery Act of 1976. EPA's Office of Solid Waste currently is developing minimum criteria for the landspreading of sludge that will define acceptable practices. These criteria, due in by October, 1977, must be met by all state solid waste disposal programs. If a state refuses to comply with them, citizen suits can force it into action. CITIZENS AND SLUDGE We all have a large stake in sludge from start to finish: we create it and at the other end we pay for its disposal with our health, our tax dollars, and the integrity,of our environment. Given that many states and communities will be making impor- tant sludge decisions in the coming years, it is important for citizens to familiarize themselves with the problems and actively participate in the debate and its solutions. There are a number of things you can do: At home. Inform yourself about sludge and spread the word. For more information write to: Systems Management Division (AW-464), Office of Solid Waste, U.S.< Environmental Protec- tion Agency, Washington, D.C. 20460. j — If you use sludge fertilizer (other than your own home com- posted type) on your home vegetable' garden, make sure you know what's in it. It probably would ;be best not to grow any food in the sludge-treated garden, but at least stop growing the worst metal absorbers — leafy vegetables (i.e. spinach, lettuce, swiss chard), and root crops. Make certain your soil is above pH 6.5; lime it if necessary. In your community. Organize a group of concerned citizens and put sludge on the agenda at your next city council meeting. — Find out where your sewage sludjge goes, and which local in- dustries use the municipal wastewater treatment system. Common high polluters include the viscose rayon, vulcanized rubber, and paper industries (which discharge excess zinc) and the metal plating industry (which contributes copper, nickel, cadmium, and chromium). — If local produce is grown on sludge-fertilized soil, find out what is in the sludge and what, if any, management procedures are followed. If your city officials do not know the answers, prod them to find out. — If your community will be making sludge-related decisions. ------- ask hard questions about the safety of the proposed pro- gram. Try to make certain all of the risks and merits are taken into account. — Your community has the tools for making informed de- cisions; use them. EPA offers communities general assistance in assessing sludge disposal options, as well as guidance on proper sludge management and control. Have your city or county officials contact your regional EPA office for information. For specific advice, turn to USDA. For a nominal fee, USDA's Agri- cultural Extension Service often will analyze soil/sludge samples and give site-specific assistance to communities that landspread sludge. Your local government people should contact the county extension agent for assistance. * establishes adequate management controls if food-chain application is allowed. This includes setting specific low limits on how much heavy metals and nitrogen can be applied, pH control of 6.5 or above, and a conservative ceiling on the total amount of heavy metals that can accumulate in the soil. Provi- sions for adequate monitoring should be included. — Push for a strong pretreatment program both with state planners and your state officials. On the national scene. Write ^to your congressman and/or senator expressing your support of a vigorous pretreatment program, and ask them to inquire on your behalf what EPA is doing in this area. At the state level. Become actively involved in the sludge debate and voice your concerns to responsible state officials. States must develop a comprehensive sludge policy as part ot an overall solid waste management plan required under the Re- source Conservation and Recovery Act of 1976. You have a legal right to be part of that planning process, so take advantage of it. — Insist that state planners address the sludge issue thoroughly and responsibly. Tell them you want a policy that: • puts primary emphasis on applying sludge to devastated areas such as stripmines and gravel pits and provides that the land will not be used for food chain crops if large quantities of sludge are applied. • encourages the use of sludge on ornamental lands such as golf courses, rights of way, flower gardens and parks. Even here there should be limits on the amount of sludge applied so as to avoid water contamination. • encourages establishing "sludge farms" for careful dis- posal of the maximum amount of sludge the environment can safely tolerate. This land would have to be "dedicated," or legally restricted for sludge disposal, to ensure that food chain crops are not grown. • discourages landspreading sludge on food-chain crops, and forbids putting it on leafy green vegetables, tobacco, and root crops. It is time that government and citizens alike focus our atten- tion on this obscure — but important — issue and find better ways of dealing witn sludge berore it poisons us and our environment. Let's make certain we are making the best possible decisions about sludge, the much-ignored effluent of affluence. For further reading: "Municipal Sludge: What Shall We Do With It?" by the League of Women Voters (pub. no. 627, 50 cents). Contact LWV Education Fund, 1730 M Street, N.W., Washing- ton, D.C.20036. EAF has detailed fact sheets on specific sludge problems and promises. The Environmental Action Foundation is a non-profit, tax-exempt citizens' organization devoted to research and education on a variety of environmental issues. The Solid Waste Project is an information clearinghouse and citizens'.communication network. The Garbage Guide is produced by the project staff: Kay Pitcher. Elizabeth Tennant, and Merchant Wentworth. This project has been financed in part with federal funds from the Environmental Protection Agency under the grant number T90551- 01-0. The contents do not necessarily reflect the views and policies of the Environmental Protection Agency nor does mention of trade names or commercial products constitute endorsement or recommen- dation for use. Reprinted with permission of the Environmental Action Foundation. U.S. EPA, 1979. SW-805 environmental action foundation ------- |