The EnviroCAAT CI/ID batch reactor process is a modified sequencing batch reactor (SBR) that operates in a single vessel with continuous inflow and intermittent discharge, rather than the fill and draw process of a conventional SBR. The unit can provide, in sequence, both anaerobic and aerobic treatment, thus the capability to reduce total nitrogen and phosphorous, as well as handle high strength organic loading. 

Properly sized, the EnviroCAAT eliminates the need for septic tanks to accomplish primary treatment of the raw wastewater, thus reducing the tank volume required for an effective system, and the resultant capital costs. 

Used alone, it can often meet permit levels for subsurface disposal systems without additional treatment.  Used in conjunction with the high effluent quality of the EnviroFilter, the combined system can meet the most stringent permit levels for surface water disposal, including levels for total nitrogen and phosphorous, at surprisingly affordable capital cost levels with modest operation & maintenance costs.


The first chamber of the two-chamber EnviroCAAT tank is the primary settling chamber, separated from the anaerobic/aerobic (AA) chamber by a full baffle wall with a narrow horizontal opening about mid-height.  It will act as an equalization basin since the level will vary as water is stored and removed from the tank.  Here, there is settling of the solids and separation of the FOG, with BOD reductions ofabout 55% and TSS reduction of about 70%.

The water level in the tank is maintained above the level of the horizontal opening to prevent FOG migration through the wall and into the next basin. 

The sludge level in this basin is also maintained so that it stays below the horizontal opening to prevent migration into the next basin.

In the second (AA) chamber are submersible aerators capable of being maintained from the surface. They can also be used as anaerobic mixers when nutrient removal is needed by turning off the air supply. 

Each treatment sequence is controlled by programmable timers. If nutrient removal is not required, the first phase is aerobic mixing using the submersible aerators. The next phase is settling and occurs after the aerators are turned off. After adequate settling time, submersible discharge pumps suspended in the clear zone of the basin remove the treated effluent during the decant phase.

During the decant phase, waste sludge can also be removed and pumped back to the primary treatment chamber. If nutrient removal is desired, the first phase is anaerobic mixing with the air supply to the submersible aerators turned off. This allows denitrification to occur utilizing organic influent from the primary settling chamber as a food source. After the denitrification period, the air supply is turned on and the aerobic mixing phase begins followed by the settling and decant phases.

During the entire process, influent flow to the primary settling chamber is not interrupted and influent through the baffle wall to the AA chamber is similarly continuous.  The process is controlled on a time basis, not a flow basis, for consistent loading.


The primary settling tank uses gravity and flotation to remove gross solids and FOG from the influent wastewater. In the AA chamber, suspended growth activated sludge along with nutrient removal processes are utilized for treatment.


Used as a standalone treatment system for subsurface disposal, the EnviroCAAT can deliver effluent BOD levels below 30 mg/L with TSS in the 30 mg/l range.

Used in conjunction with an EnviroFilter, the combination system can deliver BOD/TSS/Ammonia levels below 5/5/0.5 mg/L.  When nutrient removal is required, the system can reduce total nitrogen levels to less than 5 mg/L, and phosphorous to less than 1 mg/L.