A federal trial on charges surrounding an alleged $1.3 million in bribes paid to win contracts to haul Chicago's sewage ended today with the convictions of a prominent Southern businessman and four other persons.

The Southerner is Frederic B. (Fritz) Ingram, 43, the handsome and socially correct chairman of Ingram Corp. of New Orleans, one of the largest family-held enterprises in the United States. He admitted on the witness stand that he had authorized $730,000 in payoffs in the early 1970s to win contracts from Chicago's Metropolitan Sanitary District to transport treated sewage by barge and pipeline to a landfill 160 miles south of the city.

Ingram contended that he was a victim of extortion by sanitary district officials and "members of the Daley machine" - the late Mayor Richard J. Daley's Democratic organization - but the jury didn't buy it. He was found guilty of conspiracy, 15 counts of interstate travel in furtherance of racketeering and 13 counts of wire fraud (interstate use of a telephone to commit a crime).

His brother, E. Bronson Ingram, 47, who brought golfer Arnold Palmer to the stand as a character witness, was acquitted of similar charges, although he admitted that he arranged a $100,000 loan to meet one alleged payoff demand from Chicago officials for a 1972 contract.

Former Ingram Corp. senior vice president William Joseph Benton, 55, testifying under a grant of immunity, was the government's star witness during the eight-week trial before U.S. District Court Judge John F. Grady, Benton told an almost incredible story of international financial maneuvers and surreptitious meetings in hotels to deliver payoffs for $43 million worth of contracts.

Defense lawyers contended that Benton fabricated much of the bribery story to escape prosecution and cover up his own illegal activities.

James Neal, a former Watergate prosecutor who defended Bronson Ingram, declared that Benson "would rather climb trees and tell lies than stay on the ground and tell the truth." Other defense lawyers called Benton a "master thief," "cheat," "Machiavelli," "artful dodger," "conniver," and "con man."

Prosecutors admitted that Benton "was no angel," but emphasized that a variety of documents introduced in the trial backed up his version of the bribe scheme.

The testimony indicated that in 1970, when the sanitary district decided to begin transporting the sludge to Fulton County instead of burning it, Edwin T. Bull, a Joliet, Ill., barge operator, introduced Benton to Franklin H. Weber, who prosecutors identified as the principal conduit for the bribes.

The jury found Bull, 62, guilty of conspiracy, 15 counts of interstate travel fraud and one count of wire fraud.

Weber, who was paid $50,000 salary by Ingram Corp. over 30 months, portrayed himself on the stand as an honest, hard-working engineer who got involved in the case because he is a life-long environmentalist with a special interest in the sanitary district's waste-disposal problems. On Benton's orders, Weber testified, he went to Italy and Switzerland four times to cash letters of credit totaling $280,000, which he said was intended as bribes for foreign officials in an attempt to win a $2.5 billion Iraqi-Turkish pipeline contract. He said the bribery attempt was unsuccessful.

Prosecutors contended the $280,000 was actually used for bribes in Chicago. In all, they said, Weber "laundered" $706,633 in payoffs, $155,000 of which was passed to Robert McPartlin, a "collector" for the Daley organization.

Weber and McPartlin, 51, who served in the Illinois legislature for 16 years before his political career fell victim to the scandal, each were found guilty of conspiracy, 15 travel fraud counts and 13 wire fraud counts.

The jury found Valentine Janicki, 56, guilty of conspiracy, 15 racketeering counts, 13 wire fraud counts and two income tax evasion counts. He was accused of accepting $150,000 of the Ingram cash.

Janicki, a former sanitary district commissioner, had testified that he took no money and worked diligently toward his "dream" of improving the environment. "Yes, he had a dream," Assistant U.S. Attorney Steven P. Handler responded to the jury, "a dream he was not going to leave the sanitary district a poor man."