The secondary reverse osmosis equipment includes a two-stage RO device, a cleaning system, and an intermediate water tank.
RO reverse osmosis mainly removes dissolved salts, organics, silica colloids, macromolecular substances and particulates that have not been removed by pretreatment. The two-stage RO process can effectively remove ions in the water, and at the same time make the effluent meet the water inlet requirements of the subsequent EDI device process.
The reverse osmosis system consists of a 5μ filter, two high-pressure pumps and pressure vessels, and a reverse osmosis membrane. The first-stage reverse osmosis device RO is arranged in 2: 1, and 6 8-inch membranes are arranged in series. The water output is m3 / h, and the recovery rate is 75%. 8-inch membranes are arranged in series, the water output is m3 / h, and the recovery rate is 85%. The first stage of the membrane element is the low-pressure composite membrane CPA3 from Hydenen, and the second stage is the ultra-low-pressure composite membrane ESPA2 of Heidenen. (Select ESPA3 film)
In order to ensure the stable operation of the RO device, a UV sterilizer and a scale inhibitor dosing system are set before the RO. One UV sterilizer with a processing capacity of 17.6m3 / h, the main function is to kill bacteria in the water and prevent the RO membrane from being blocked. The ultraviolet lamp has an emission wavelength of 254 nm, an intensity of 30,000 μWs / cm2, and a sterilization rate of 99%.
In order to prevent scaling on the concentrated water side of the RO device, a scale inhibitor must be added to the incoming water. The scale inhibitor is FLOCON260, and the designed dosage is 2.4 mg / L. Or use PTP0100 scale inhibitor, the designed dosage is 1 mg / L.
In order to remove CO2 in the water, NaOH was added between the two ROs to adjust the pH of the effluent water of the first RO to 7.83, and the designed dosage of NaOH was 4.5 mg / L.
The RO cleaning system is a skid-mounted device that includes a cleaning tank, a 5 μm filter, and a cleaning pump. The RO system can be cleaned when scaling or fouling occurs in the RO system, and EDI can also be cleaned.
The function of the intermediate water tank is to store RO produced water and adjust the water volume, so that the system operation can be flexibly adjusted.
The conductivity of the water produced by the two-stage RO system is <10 μs / cm, the SiO2 content is <500 μg / L, and the TOC is <50 μg / L.