Why is so much sewage sludge generated?
The most common treatment method of sewage water is known as the activated sludge treatment process, which was first developed in the UK over 100 years ago. In this process, microbes are added to treat the sludge by consuming organic sludge material (excreta). Until recently, this method was considered the best practice because of its easy execution; treated water is aerated into a tank where microbes eat the organic material. However, recent arguments against the method have pointed out its weak points.
For this method to treat a large volume of sewage water, a large amount of microbes is required, which means that a large volume of air also needs to be generated to support the large microbial colonies. Consequently, a great amount of electric power is required to run the air blower. Also, microbes have a high generation cycle rate, which produces a high volume of excess sludge from the additional byproduct of dead microbial content. With increased environmental awareness among societies, these problem points have become global issues. Although we call it “sewage sludge”, a large portion actually consists of dead microbial matter.