J. Q. Citizen: "Did you notice our new regional sewage plant down by the river? We're real proud: It's state-of-the-art and meets all governmental discharge standards." Tax Collector: "That's great, because you won't mind paying $1,200 or so per year for this service for the next 20 years."
J. Q. Citizen: "Wait a minute. We can't afford that!"
In the past, when federal and state governments paid for wastewater treatment, user fees amounted to several hundred dollars per year per residence served. Today, with great reductions in federal and state aid, it is not unusual for municipalities to have user fees for new sewage facilities exceeding $1,000 per year. Unfortunately, many municipal facilities are at capacity or overburdened and must be replaced.
In comparison to many countries, the United States is in an enviable position in that most of its sewage is treated before being discharged into surface waters or groundwater. Three-quarters of U.S. sewage production is collected and treated, and most of the remainder is treated in on-site septic tanks and disposed of in underground leach fields. Unfortunately, both methods of treatment produce significant quantities of residue that cannot be released into the water supply. Furthermore, dissolved nutrients pass through most conventional treatment facilities and are discharged into receiving waters along with treated sewage.
Improvements in sewage-treatment facilities in the United States over the last 20-25 years have benefited many receiving waters, and studies report that fish and other species are returning to once-polluted waterways. Nonetheless, there is increasing evidence that yesterday's acceptable standard for sewage effluents is unacceptable. Increasing levels of treatment are being demanded by regulatory agencies and the public.
In a study conducted at Cornell University, the author and a team of researchers have developed a highly efficient new wastewater-treatment system. It converts wastes such as domestic sewage into clean water, containing minimal nutrients and bacteria, and clean, renewable energy, yet generates no sludge.
The state of the art
Most communities are required to treat to "secondary standards," which require removal of more than 85 percent of the gross pollutants. However, these standards cover only suspended and biodegradable matter, disregarding other pollutants, such as toxic heavy metals, toxic organics, and the dissolved plant nutrients nitrogen and phosphorus. In some locations, dictated by local conditions, further, or "tertiary," treatment may be required.
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