2nd International Conference on Recycling and Reuse, İstanbul, Turkey, 4 June - 06 July 2014, pp.243
Multiport diffusers including marine outfalls are widely used for domestic wastewater discharge into marine environment with a suitable dilution. Lifespan of these systems can be various in a 30-100 years range. Flow rate of a marine outfall at the end of the lifespan is one of very important factor to determine the size and dilution level of the whole system. During its operational process, the flow rate of an outfall will gradually increase because of increasing population. However, the system should be designed considering the maximum flow capacity. As a consequence, starting first operational days, a marine outfall will have lesser flow rate than its design capacity. This partially wastewater filled diffuser condition could be dangerous for the system about dilution rate decrease or clogging because of lowered internal velocity in the diffuser and/or low amount of wastewater jet initial velocity passing thorough port. Sea water intrusion could be also possible with a reverse flow into the diffuser pipe. In order to protect the system, “duckbill” elastomer check valves could be used to maintain both one-way flow from a port and increase the jet velocity reducing open port area. This apparatus could also be mounted to the port after the construction and during operational period of an outfall. However, internal hydraulics and initial dilution performance will possibly be changed about this constructive difference.
In this study, originally designed with open port including multiport diffuser using marine outfalls were investigated about before and after duckbill check valve mounted conditions. A series of marine outfalls were hydraulically designed then their initial dilution values were calculated from Fan and Brooks line source conditions. 150 mm diameter size was selected for circular and sharp edged diffuser ports. Then 150mm sized duckbill valve mounted conditions were investigated about internal diffuser hydraulics and its initial dilution effects on environmental performance.