There can be a number of classifications of industrial waste, based on their phase (solid, liquid or gas), toxicity (toxic or non-toxic), biodegradability (biodegradable or non-biodegradable), etc. Mostly we use the first two classifications. Solid wastes are a threat to our land, air and water sources, for example, fly ash generated from coal-based thermal power plants. Liquid wastes are typically disposed off on land or in surface water bodies, causing pollution to these natural resources. Dumping of industrial waste into surface waters (or ground water) is very common exercise. An example is Woburn, Massachusetts, where trichloroethylene (TCE) contaminated the ground water. Gaseous pollutants, such as NOx or SOx (among others) pollute our atmosphere. Toxicity of an industrial pollutant is also a matter of concern. Release of harmful chemicals such as chlorinated solvents (TCE, VC, etc.) or radioactive waste (spent uranium from nuclear reactors) or medical waste, can be a big threat to our health.
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