(i) A substance that can change the physical and chemical constituents of air, water or soil, such that they adversely affect the well-being or survival of plants, animals, humans and the whole ecosystem, are called pollutants.
(ii) Waste is the discarded material from various sources or leftover material of various industrial processes.
(iii) Biomedical wastes are the wastes that are produced or generated by hospitals, clinics, nursing homes, labs, etc.
(iv) Biodegradable wastes are wastes that can be degraded by the action of microbes.
(v) Non-biodegradable wastes are wastes that cannot be degraded by the action of microbes.
(vi) Sewage is waste suspended in water which is composed of 70% organic and 30% inorganic waste.