In Boston, an urgent need for new sewage treatment facilities may quadruple water rates in the next decade. This scenario is repeated in cities nationwide as aging facilities crumble under increased loads and a sewage mix vastly more toxic now than it once was. A radical, cost-effective solution may be at hand, however. For two years now, Bert V. Elkins has been running the San Diego Region Water Reclamation's experimental Santee facility. In that time he has seen enough to know that the United States -- indeed the whole world -- no longer needs to fear its accumulating sewage waste.
Because of a radically new technology known as Coordinate Chemical Bonding Adsorbtion (CCBA), he claims that sewage waste can easily and inexpensively be turned into two very saleable products: clean water and a lightweight aggregate for concrete blocks and other masonry products, including roofing tiles.
Results at Santee have proved so encouraging that funding for a full-sized plant in San Diego has passed the US House of Representatives and is awaiting Senate approval.
So confident is Mr. Elkins -- along with Dr. George C. Harrison, the 3M (Minnesota Mining & Manufacturing) Company scientist who developed the process -- that he recently imported raw sewage from neighboring Mexico. Tanker loads of the stuff were trucked across the border from neighboring Tijuana every day for about six weeks to prove the system could handle some of the most contaminated sewage on the continent (Mexico has no sewage restrictions), and make it not only harmless but useful as well.
Buoyed by the Tijuana success, the Santee Wastewater Reclamation Facility recently began adding heavy metal sludges (cadmium, cobalt, nickel, chromium, lead, etc.) from industry to the local sewage it has been processing for the past two years. Results have been equally successful, they say. Only mercury, polyvinyl alcohol, and certain radioactive gases cannot be processed.
Of particular significance is the fact that a CCBA (pronounced ``see'-bah'') operation can do all this at far less cost than a conventional sewage treatment plant, which produces a waste byproduct that must either be incinerated (with a consequent threat to air quality) or buried, at a time when appropriate landfill sites are fast running out. In other words, the new technology is able to totally remove a contaminating waste from the environment, its developers claim, something never previously accomplished in sewage treatment.
Dr. Harrison of Roseville, Minn., is a coordinate bonding expert, which means simply that he specializes in getting one material to bind, bond, otherwise combine with another, often very different, material. He found he could readily get sewage contaminants to combine and separate from the water -- but that still left a solid sludge to be disposed of. That problem was solved when he introduced clay into the mix. By binding the waste with the clay, he created a material that could be baked into a harmless form that is useful in construction.
The Santee pilot plant has been working so successfully that Dr. Harrison and the project's many backers hope the rest of the nation will quickly take note. They reason that if the highly contaminated Tijuana waste or local sewage with a heavy injection of industrial sludges can be effectively treated, then no waste elsewhere will present problems. They envision a much cleaner environment for perhaps a quarter of the cost of conventional treatment.
It all sounds too good to be true, which is one reason Dr. Harrison believes so many cities and towns shut the door in his face before he found the San Diego Region Water Reclamation Agency.
The system works this way: clay, along with coagulating chemicals (polyacrylic acid and alum), is added to the sewage. This causes the solids, including the heavy metal toxins and any pesticides, to cling to the clay and form a heavy flock which settles as a thick sludge. The clean water, proven to be acceptable for swimming and irrigation with minimal further treatment, is then decanted off.
The remaining solids are then extruded into spaghetti-like strands which are cut into tiny pieces. When fired at 2,000 degrees F., the organic materials (including pesticides) within the clay particles burn off. The additional energy provided by the burning wastes causes the clay pieces to puff up into lightweight pellets. At the same time, the heavy metals are converted into harmless silicates bonded permanently in the ceramics. Metals in this form are so tightly held that where they occur in nature no process devised by man can extract them economically. Dr. Harrison makes this point to indicate how non-threatening they are to the environment.
Extrapolations from the Santee project suggest that a full-sized CCBA treatment plant would take up much less land, and building costs would be from 15 to 35 percent of a conventional sewage plant of equal capacity. Labor costs would be similarly reduced. The energy costs involved in producing the ceramic aggregate and its subsequent handling costs could be recovered by the sale of the end product.
San Diego engineers are ready to build a full-sized sewage treatment plant capable of recovering 3 million gallons of water a day and producing some 15 tons of construction material. Construction of the new facility will begin as soon as the funding receives Senate approval.