In a urine cartridge or wastewater trap, equalized pressures and increased flow rate between its inlet and outlet compartments increases the life of the cartridge. The pressure equalizing is effected by placement of a separator between the two compartments to provide them with substantially equal volumes. The increased flow rate is created by a uniquely configured baffle positioned adjacent a pan at the bottom of the cartridge. The baffle configuration is shaped to provide a constriction that increases the flow velocity of the urine so that the fluid flow effects a channel along the bottom pan and through any solids deposited on the bottom pan. A diverter may be placed above the centrally located entry to the inlet compartment to create a circuitous path for preventing a disturbing impingement of the urine onto the sealant contained in the inlet compartment. To accommodate the centrally placed entry and its placement vis-a-vis the inlet compartment, the separator is bowed at its location adjacent the entry and towards the outlet compartment. To fit the configuration of the baffle, the separator is curved generally in a likewise manner.