Patent ID: 9028695
Filing Date: 2015-05-12
Classification: B01D,C02F

Abstract:
1. A process for producing reclaimed water, comprising the operations of: in a normal mode, putting ozone generated by an ozone generator into raw water to subject the raw water to ozone treatment; injecting a flocculant into the raw water after the ozone treatment; filtering the raw water by a separation membrane after the ozone treatment and the injection of the flocculant; measuring a transmembrane pressure, which is a pressure difference between an upstream side and a downstream side of the separation membrane, by measuring a gauge pressure and correcting the measured gauge pressure for at least one of a water temperature and an installed height difference of a pressure gauge, intermittently setting a cleaning mode to put a larger quantity of cleaning ozone than in the normal mode into the raw water so as to intermittently increase the concentration of a dissolved ozone, thereby cleaning the filtration membrane, determining a transmembrane rising speed by periodically measuring the transmembrane pressure immediately after backwashing the separation membrane and plotting the measured transmembrane pressure over time to determine when to inject the larger quantity of cleaning ozone in the cleaning mode, wherein when the transmembrane rising speed exceeds a first predetermined value, the ozone processor sets the cleaning mode to inject one of a first larger quantity of the ozone for a first predetermined time period and a second larger quantity of the ozone for a second predetermined time period, where the first larger quantity of the ozone is less than the second larger quantity of the ozone and the first predetermined time period is longer than the second predetermined time period.