THE CHEMICAL WORLD THIS WEEK

terms of economics, is probably the most significant development in water pollution control in this century." J. Goffe Benson, president of Carbide's Linde division which developed the process, says it opens an enormous market for oxygen makers. "We be­lieve that by the 1980's waste treat­ment facilities will become one of the nation's largest oxygen consumers, probably surpassing that now used by the steel industry, which is a little more than 12 million tons annually." The process has also been called "a startling money saver," and a "signif­icant breakthrough."

Linde's Dr. John R. McWhirter, who invented the system, says "there is little doubt that this process will be that primarily used over the next 5 to 10 years for secondary treatment plants throughout the world."

It won't take long to tell if Car­bide's claims are hyperbole or solid fact. The process has been demon­strated successfully for a year at Ba-tavia, N.Y. The city of Cincinnati will pilot plant the UNOX process and compare it with the performance of a conventional air treatment plant. The city will then decide which type plant to build.

Many communities in the U.S. have no sewage treatment facilities today. Under the President's recent proposal to Congress, about 4000 secondary waste treatment plants in the U.S. would be constructed in the next eight years. Carbide estimates capital re­quirements for new and expanded waste treatment facilities for the next 10 to 15 years at $20 to $60 billion.

Mr. Wilson says that a waste treat­ment plant that previously would have cost $50 million can be built for about $35 million and operated at a savings of approximately $1 million a year. Capital savings vary with different size units and depend on whether an

Carbide's Wilson

Lavish with superlatives

old plant is being converted or a new one is being built. The company gives a range of 3 1 % to more than 50% for potential capital savings with annual operating savings of 40 to 50% over conventional plants.

In the Linde system, the aeration tank is subdivided by baffles to create a multistage system. Waste water, sludge, and oxygen travel concurrently through the aerator. The pressure in the gas enclosures is held slightly above atmospheric.

Heart of the Linde system is a sparger which mixes oxygen with waste water and recycled sludge. Dr. McWhirter says that the oxygen is piped through hollow agitator shafts in its multistage system and is dis­persed into the mixed liquor through a unique rotating sparger device.

Carbide says the UNOX process produces a significantly better effluent quality with respect to biological and chemical oxygen demand and sus­pended solids. The Linde division of­

fers the process for sale on a turn-key basis as an overall part of a treatment plant. A paidup license fee is in­cluded as part of the overall system's capital cost. The firm will sell the oxygenation system with a perform­ance guarantee. Oxygen would be supplied from an on-site plant or through sale of an oxygen plant.

SWEETENERS:

Saccharin Suspect The pellet implantation technique that produced bladder tumors with cyclamate has now pointed the finger of suspicion at saccharin as well. Bladder cancer occurred in 47% of the mice in a group of 66 in which Dr. George T. Bryan, University of Wis­consin medical school, had surgically implanted cholesterol pellets contain­ing saccharin. Cancer also was found in 52% of another group of 64. Pel­lets of pure cholesterol implanted in other mice as controls also produced bladder cancer, but at lower rates: 13% of a group of 63 and 12% of a group of 43.

A report on the saccharin test re­sults was sent by Dr. Bryan last No­vember to Food and Drug Administra­tion and Science magazine. Science may publish the report soon, but word of the results appeared in The Washington Post last week.

FDA is sending Dr. Bryan's report to the National Academy of Sciences-National Research Council's Food Protection Committee for a review of saccharin safety that will include all earlier studies as well. FDA expects to receive a report from the commit­tee in a few months.

FDA sources indicate that there is little likelihood that the Delaney clause will be invoked to ban saccha­rin based on the present evidence. FDA and National Cancer Institute (NCI) officials have agreed that the pellet implantation technique isn't suitable for indicating hazards from a compound when eaten. A mixture of sodium cyclamate and sodium sac­charin was fed to rats in the tests that led to the ban on cyclamates last Oc­tober.

Relevant evidence can come from animal feeding tests, but two such studies are only now getting under way and probably won't produce re­sults before the end of 1971. Dr. John Weisburger and Dr. Elizabeth Weisburger at NCI began late in 1969 to feed saccharin as 1 and 5% of the diet of female and male mice and rats. The Weisburgers are trying to con­firm the results of tests in 1951 that used the same feeding levels and found no indication of cancer. FDA is just beginning its own studies.

Carbide waste treatment plant at Batavia, N.Y.

Merely replacing air with oxygen

MARCH 23, 1970 C&EN 17