Green Education

  Conventional Activated sludge process ·          Conventional biological treatment of wastewater under aerobic conditions includes activated sludge process (ASP) and Trickling Filter. The ASP was developed in England in 1914. The activated sludge process consists of an aeration tank, where organic matter is stabilized by the action of bacteria under aeration and a secondary sedimentation tank (SST), where the biological cell mass is separated from the effluent of aeration tank and the settle sludge is recycled partly to the aeration tank and remaining is wasted (Figure 19.1). Recycling is necessary for activated sludge process. ·          The aeration conditions are achieved by the use of diffused or mechanical   aeration.   Loading Rate: The organic matter loading rate applied to the reactor is quantified as kg of BOD applied per unit volume of the reactor per day, called as vol...

  Concept of sedimentation What Is Sedimentation? Sedimentation is the process of separating small particles and sediments in water. This process happens naturally when water is still because gravity will pull the heavier sediments down to form a sludge layer. However, this action can be artificially stimulated in the  water treatment process . This mechanical assistance is called thickening. Why Is Sedimentation Used?   The sedimentation process is used to reduce particle concentration in the water. The advantage of sedimentation is that it minimizes the need for coagulation and flocculation. Typically, chemicals are needed for coagulation and flocculation, but improved sedimentation controls the need for additional chemicals. Additionally, sedimentation can be used after coagulation to increase the effectiveness of ongoing filtration in the process.   Types of Sedimentation process   Sedimentation is also called  clarification . Sedimen...