Waste continued urban

Evidence of the need for continuous action can be found in the massive waste treatment plants in urban areas and septic systems in rural communities. In the developed world, the problem is under nominal control, and this allows us a complacency not evident in the rest of the world. In undeveloped countries, the return of water free of nutrients and bacteria to the enviromnent is a goal to be anticipated and a luxury few can afford. 

In addition to the fact that the nonpoint sources result from diffuse locations, point sources also tend to be transient in time, although not always. For example, agriculture, silviculture, and urban and suburban runoff tend to be transient, resulting from flows due to precipitation at various times of the year. Other inputs such as the atmospheric input and leaching of substances out of solid waste disposal sites are more or less continuous. 

The roots of environmental microbiology also lie in urban waste management and treatment. The field originally focused on monitoring the movement of pathogens and treating them within natural and urban environments to protect municipal water quality and public health. As the world became more urbanized in the late nineteenth century, the incidence of communicable diseases such as typhoid fever and cholera increased. To combat the spread of diseases, cities and communities began to treat water with various filtration and disinfectant methods. For the most part, such approaches to water treatment were instrumental in the elimination of waterborne bacterial diseases in developed countries, and disinfection processes continue to be widely used. 

According to Figure 7.4, the polyethylene (PE) polymer still remains the most commonly found in the urban environment. However, recent data collected in major Brazilian cities show that PET ranks second as municipal waste, with approximately 20% of its use, highlighting and enabling continuous production of new products from recycled polymer. 

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