The secondary treatment system consists of a two stage biological system. The first stage is the Captor Pad process followed by a conventional activated sludge process. The Captor process uses 1" x 1" x 1/2" sponge pads which support the process microbiology. Primary effluent flow is split and enters two aerated Captor tanks which contain approximately ten million pads each. At average daily flow conditions, the Captor process provides 1 hour hydraulic detention time. the average pad solids concentration since startup is 114 mg/pad and the average M.L.S.S. concentration including pad solids is 6,270 mg/l. The aeration in each Captor tank provides a rolling action from the effluent end toward the influent end and maintains a D.O. of between 2-3 mg/l. A pad cleaning system, including a pump and mechanical squeezer, provides a means of stripping excess solids from the pads.
The performance of the Captor system is noted in the table below.
|
Parameter |
Inf. Avg. mg/l |
Range mg/l |
Eff. Avg mg/l | Range mg/l | Rem. % | Range % |
|
CBOD (soluble) |
92 | 43-155 | 8.5 | 4-17 | 91 | 81-96 |
|
Ammonia |
17 | 6-23 | 5.3 | 1.3-10 | 69 | 45-93 |
