The correct choice is (d) Noise
The best explanation: Noise is not a waste that is generated in the waste treatment processes as it is a sound which affects the environment but physically doesn’t. And it is not generated in waste treatment processes. Whereas, sludge, ash, organic solvents are generated during various processes like incineration, wet scrubbers, distillation etc. These are generated in waste treatment processes and can be a serious threat to the environment if not disposed of properly.