Salida Sanitary District
6200 Pirrone Road
The Intermitent Cycle Extended Aeration System (ICEAS)

Untreated wastewater (influent) flows to the Intermitent Cycle Extended Aeration System (ICEAS). Each ICEAS tank holds approximately 500,000 gallons. The plant uses 3 tanks to handle the average daily flow of wastewater. Air compressors are used to keep each tank under aeration. The aeration mixes the new influent with bacteria and single cell organisms that have been growing in the ICEAS tanks. These organisms create a biomass that consume pollutants in the wastewater. In this picture the biomass and influent are under aeration.

After a two hour aeration cycle the air is turned off and the biomass mixture is allowed to settle. If the organisms in the biomass are healthy they have consumed the wastewater pollutants as food. As the biomass settles the clear water remains at the top of the tank.

After one hour of settling the clarified water will be skimmmed (decanted) from the surface. The large trough located at the opposite end of the tank is automatically lowered by the computer system.

The decant arm is slowly lowered skimming the treated water from the surface of the ICEAS tank. A boom in front of the trough keeps any floating material from being discharged. The water will drain to the effluent pumps where it's transferred to the rapid infiltration basins for disposal. The biomass in the ICEAS tank will be retained and reused to treat the incoming wastewater during the next cycle. Each treatment cycle(aeration, settling, and decant) takes 4 hours.

The ICEAS process requires a sophisticated aeration system to maintain a consistent source of oxygen to the biomass. An ICEAS tank has been drained for maintenance. Each tank has over 1000 fine bubble air diffusers that are visible at the bottom of the tank.

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