Reworld, formerly Covanta (legal name; Reworld Holding Corporation), is a private energy-from-waste and industrial waste management services company headquartered in Florham Park, New Jersey. Most of its revenue comes from operating incineration facilities that serve a secondary purpose as power plants that burn trash as fuel. Reworld charges a fee for waste disposal and sells the electricity and metal slag produced from waste incineration.

Reworld was founded in 1939 as the Ogden Corporation. After starting as a public utility holding company it became a diverse conglomerate which had holdings in manufacturing, horse and greyhound racing, real estate, food, maritime transportation, arena management, and entertainment until its 2001 restructuring into a strictly energy business.

In 1939, Ogden Corporation was founded as a successor to Utilities Power and Light, a Chicago-based utilities holding company that had been under a court-ordered trusteeship since 1937. Its subsidiaries included the Laclede Gas Company, Interstate Power Company, Missouri Natural Gas Company, Missouri Electric Power Company, Central State Utilities Corporation, and Central States Power and Light Corporation. The Atlas Corporation controlled the Ogden Corporation from its founding until it was sold to the Allen family in 1951. Benjamin G. Brewster, general auditor for the Atlas Corporation, served as Ogden's first president. He was succeeded by Maurice L. Sindeband.

As part of the reorganization of the Utilities Power and Light, Ogden was obligated to divest its utility interests so that it would comply with the Public Utility Holding Company Act of 1935. By 1948, Ogden's only remaining utility holding was the Interstate Power Company.

In 1953, Ogden entered the manufacturing field when it acquired W. A. Case & Son Manufacturing Company, a manufacturer and distributor of plumbing and heating supplies, from Allen & Company. That same year the company purchased Teleregister from Western Union. In 1955, Ogden purchased Commercial Filters Corporation, an electronics and plumbing firm, and Luria Brothers & Co., an iron and steel scrap business. In 1957 the company purchased the Eimco Corporation and the American Foundry & Machine Company of Salt Lake City. Eimco manufactured filtration equipment and American Foundry & Machine made iron and steel castings. In 1959, Ogden acquired Avondale Marine Ways Inc., a New Orleans shipbuilding company.

In 1962, former Luria Brothers president Ralph E. Ablon became president and chairman of Ogden.

In 1966, Ogden acquired Tillie Lewis Foods, a California-based fruit and vegetable canner. Tillie Lewis was appointed to Ogden's board of directors, becoming the company's first female director. The following year, Ogden entered the frozen food business when it purchased Prosser Packers of Prosser, Washington. That same year it purchased ABC Consolidated, a food and refreshment firm that owned cafeterias, restaurants, snack bars, and the Nedick's fast food chain. Ogden's food division became one of the three biggest arena concession vendors in the United States. In 1968, Ogden purchased Mack Brothers, a company that manufactured frozen meats for airlines. In 1979, Ogden bought Progresso for $35 million. In 1986 Ogden Foods was sold to Pet, Inc. for $320 million.

In 1968, Ogden formed the Ogden Development Corporation after it purchased Charles Luckman Associates, a real estate, engineering, and architectural firm. Luckman was named president of Ogden Development.