Which method is known to allow for significant volume reduction of municipal solid wastes?

The method that allows for significant volume reduction of municipal solid wastes is both pyrolysis and high-temperature incineration.

Pyrolysis is a thermochemical process that involves the decomposition of organic material at elevated temperatures in the absence of oxygen. This process breaks down waste materials into smaller molecules, producing syngas, bio-oil, and char while significantly reducing the overall volume of the waste. The materials that are left after pyrolysis are considerably smaller than the original waste, making it an effective method for volume reduction.

High-temperature incineration, on the other hand, involves burning waste at very high temperatures, which not only converts materials into ash, gases, and heat but also significantly decreases the mass and volume of the original waste. During incineration, organic materials are consumed through combustion, effectively reducing the volume of the waste as it turns into gases and small quantities of ash.

Choosing both pyrolysis and high-temperature incineration acknowledges the effectiveness of these methods in reducing waste volumes considerably, therefore making this choice the most accurate.