**2.1 Classes of industrial wastes**

Industries generate various kinds of waste depending on their manufacturing processes and the finished product being produced, which are classified according *Perspective Chapter: Industrial Waste Landfills DOI: http://dx.doi.org/10.5772/intechopen.108787*


**Table 1.**

*Type of industrial waste according to industry sector [7].*

to their state/nature, degradation potential and toxicology, and hydrocarbon content [8]. Generally speaking, industrial waste can be classified as biodegradable and nonbiodegradable wastes. The different classes and more specifically, types of industrial wastes generated during any manufacturing process are described in the following section.

#### *2.1.1 Biodegradable and nonbiodegradable industrial wastes*

Industries generate wastes that may or may not be decomposed by microorganisms (such as bacteria, fungi, algae, protozoa) when deposited in landfills.

#### *2.1.1.1 Biodegradable industrial wastes*

Biodegradable industrial wastes are produced from industrial processes, which generate decomposable material in which decomposition is caused by microbial activities and the material is then converted to gas and water. These kinds of industrial wastes are similar to municipal wastes and are usually generated by food processing and agro-allied industries, slaughterhouses and dairy industries, etc. [8]. These wastes are nonhazardous, do not require special kind of treatment, and are mostly solid. They include such wastes as animal bones, fur, wheat, animal skin, leather, wool, discarded fruits, and so on [8].

#### *2.1.1.2 Nonbiodegradable industrial wastes*

These are industrial wastes that cannot be decomposed into gases and water. They are generated by industries such as fertilizer, chemical and petroleum, drugs and

pharmaceutical, mechanical, dye industries, nuclear power plants, polymer processing, construction, foundry, metal, and steel plants [8]. Examples of this waste are polyethylene terephthalate (PET) plastics, fly ash, synthetic fibers, glass, gypsum, and radioactive wastes [8]. Most landfills consist of nonbiodegradable industrial waste due to their nondecomposing nature [8]. Other types of industrial wastes can further be divided into the following types based on their nature.

### **2.2 Types of industrial wastes based on their nature**

#### *2.2.1 Industrial solid waste*

Industrial solid waste (**Figure 2**) is produced by specific manufacturing processes and can either be biodegradable or be nonbiodegradable but mostly, it is neither municipal nor hazardous wastes [8]. It encompasses a wide range of materials of varying environmental toxicity [8]. Typically, this range of waste materials would include paper, packaging materials, waste from food processing and agrochemical, oils, solvents, resins, paints and sludges, glass, ceramics, stones, metals, plastics, rubber, leather, wood, cloth, straw, abrasives, etc. [8]. Generally, according to Ref. [5] there are about 43 different industrial solid waste material ranges that can be categorized into 5 groups, which include the following:


The major generators of industrial solid wastes are the thermal power plants producing coal ash, integrated iron and steel mills producing blast furnace slag and steel melting slag, nonferrous industries like aluminum, zinc, and copper producing red mud and tailings, sugar industries generating press mud, pulp, and paper industries producing lime and fertilizer and allied industries producing gypsum, and food and pharmaceutical industries producing solid food and biomedical wastes, respectively [9]. It is important to note that there is a distinction between solid and liquid industrial wastes because they are handled very differently and are generated on largely different scales [9].
