as per communication with worker and tech maker regarding selenoid v/v oil water separator inspect to Hai Bao 2,He didtn change the selenoid v/v。because date time have 2 time overflow from vent if i make standby the OWS,and have full my sludge tank the fresh water。on the way to sila port we try operate STP-sewage treatment plan as per Require ADNOC to use On 4 NM。the main black pipe going to STP and to O/B we closed,we have start STP to auto is running but have bubble(vent motor)at bowl toilet。if we open v/v main grey pipe to STP the bubble gone。 - is that have to open both them the pipe black and grey to STP? - why just black pipe we open bubble coming to bowl toilet ?