Schmutzdecke - A filtration layer of slow sand filter

Slow sand filtration has been an effective means of treating water for the control of microbiological contaminants. Schmutzdecke is the layer of the microbial community that is responsible for treating the water through the sand bed. As water passes through this biological layer, foreign particles are trapped and essentially eaten by bacteria forms on this layer. Development of Schmutzdecke layer depends on available microbes in raw water, food supply, oxygen supply, residence time, and wetting of sand bed. Generally, 13 types of bacterial community are found in the Schmutzdecke layer, in which Pseudomonas stutzeri bacteria are dominant.