Indeed, according to the World Health Organisation, water pollution has been defined by the addition of any alien material from either natural or other sources into a water body, thereby changing the natural qualities of water and making it unusable for its intended purpose which could be domestic use, recreational use, etc. Therefore, since only < 1% of the world’s fresh water is accessible for direct human use, when this freshwater becomes polluted, measures must be put in place to cleanse the water from the majority of its impurities. Thus, one method that is commonly used to remove effluents from waterways are sewage treatment plants which are known as centralized systems simply because it is usually located in the central area of a main town or city (Globalchange 2006) A sewage treatment plant may be defined by an industrial structure that treats water that has been used for domestic and other purposes and then discarded. Furthermore, sewage contains a wide variety of contaminants, both chemical and biological and, if not treated, poses a threat to health; hence the industrial structure removes up to 90% of the biological and chemical waste products from the water thus …show more content…
With regard to the advantages, sewage treatment plants can treat a large amount of sewage quickly and also the industrial structure uses a relatively small area. However, its disadvantages are; the industrial structure is expensive to build and maintain as there are high capital and operating costs, and sewage effluent may still contain large numbers of pathogens when it leaves the treatment plant. Furthermore, treatment plants produce waste in the form of sludge and if not properly disposed of, can pollute the surrounding environment leading to fish kills among other aquatic mishaps as is the case in Trinidad and Tobago (Sewerage and sewage treatment