There, a biological slime is produced containing micro- organisms that feed on the dissolved organic pollution as liquid trickles over a plastic grid structure down through the towers. Portions of the slime are constantly breaking away and are washed into secondary sedimentation tanks. This part of the system will be improved under the upgrading. Currently submerged pipes take the liquid to oxidation ponds. Clear liquid remains in the ponds for three weeks, mainly to kill bacteria by sunlight s ultra- violet disinfection.
Filter pumps in the engine room pump wastewater over the filters.