Which of the following methods is NOT used to reduce hazardous waste?

Direct disposal in landfills is not considered an effective method to reduce hazardous waste. Instead, it simply relocates the waste to a specific site without treating or reducing its harmful properties. This method poses significant risks to groundwater and soil contamination, as hazardous substances can leach from landfills over time, creating environmental hazards.

In contrast, bioremediation involves using microorganisms to break down or neutralize hazardous substances, effectively reducing the toxicity of the waste. Controlled incineration involves burning hazardous waste at high temperatures to destroy harmful compounds and convert waste into less hazardous materials, thus minimizing the volume and toxicity of the waste generated. Deep well injection is a method where hazardous waste is injected into deep underground wells, where it is isolated from the environment, although it must be done carefully to prevent contamination of groundwater.

The approach of direct disposal in landfills lacks the treatment and hazard reduction inherent in the other methods, making it less acceptable within practices aimed at minimizing hazardous waste risks.