Introduction to the application of reverse osmosis in groundwater treatment
groundwater treatment option for reverse osmosis treatment technology in the
as a kind of water source, groundwater has a very wide distribution in China, water is relatively easy. But as a result of groundwater water quality often influenced by external factors such as climate, volatile. On a rainy day, for example, groundwater suspended solids ( SS) Will be very high, if the water if into the reverse osmosis system, the system will happen in a short period of time in irreversible fouling, so on the choice of treatment process to pay special attention to, the pretreatment process of reverse osmosis, generally can choose corresponding mechanical filter, to effectively reduce the uncertainty in the groundwater with high suspended solids fouling of reverse osmosis unit; Such as karst topography, groundwater hardness will be very big, usually by adding the corresponding scale inhibitor to prevent fouling of the reverse osmosis system. For the processing of groundwater, after many years of experience, now has a few good reverse osmosis process.
1) Coagulation filtration
because the influence of external factors such as well water from rain, well water, often with a large number of sediment turbidity change is bigger, is easy to cause the reverse osmosis pretreatment system work is not stable, so to join in the pretreatment of coagulation filtration, colloid, suspended impurities in the removal of groundwater, reduce turbidity. In the reverse osmosis treatment showed pollution index ( SDI) Measured, the requirement into the reverse osmosis device of feed water of SDI < 4. Because groundwater suspended matter more, and with great influence factors such as rain, so the pretreatment system often choose polyaluminium chloride as a coagulant, alum flowers form quickly and reticulate structure, sedimentation velocity faster.
2) Disc filter
as well is affected by external factors such as climate is very big, conventional filters, such as sand filter, many media filters, such as the instantaneous impact resistance well water containing high suspended matter and sediment, the backwashing cycle and production of uncertainty are in urgent need of the contradiction of water, usually the effect not beautiful, will bring the subsequent process. And disc filter because of its unique fold type structure, make the system under the impact of the silt etc. With high suspended solids, performance is relatively stable many, effectively ensure the effluent suspended solids ( SS) Low levels, can for subsequent always provide high quality water ultrafiltration membrane system, is a very important pretreatment process of groundwater treatment.
3) Ultrafiltration membrane filtration unit
ultrafiltration membrane system is mainly to remove the suspended solids in the water, SS) To ensure the reverse osmosis water SDI < 4. Normally the ultrafiltration membrane water SDI is very small, at about 2. Because the disc filter before ultrafiltration membrane system, and so the ultrafiltration membrane system into the water will not the emergence of sediment and suspended matter too much, will not appear in the running process of broken wires, thus ensuring the reverse osmosis water requirement for SDI. Generally selected ultrafiltration membrane material of poly (vinylidene fluoride PVDF) , aperture at about 20 nm.
normally, after ultrafiltration membrane filtration unit will add a water tank, used to store the ultrafiltration membrane filtration water, in order to prevent water tank in microbial breeding, will add some fungicides for sterilization processing, commonly used bactericides for sodium hypochlorite ( NaClO) 。
5) High-pressure pump
high pressure pump is to provide energy for reverse osmosis unit of must equipment, high pressure pump models are usually based on reverse osmosis system design selection of the software flow and pressure, high pressure pump lift inflow salt content has a lot to do, and also affected by the factors such as water temperature.
6) Scale inhibitor and reductant
because of the groundwater hardness and alkalinity are very high, in order to make the reverse osmosis system can better operation, the system always run in the absence of scaling, need according to the concrete adding the corresponding water quality scale inhibitor; Also because of the reverse osmosis pretreatment cic added oxidant sterilization, in reverse osmosis water when adding the reducing agent is needed to restore, the reverse osmosis system of residual chlorine water less than 0. 1ppm( Or ORP< 200mV) To meet the reverse osmosis system of water oxidation substance content requirements.
7) Security filters
due to ro before to add some chemicals, to prevent the granular agent did not dissolve into the reverse osmosis system, but also to provide double insurance (for reverse osmosis water SDI Ultrafiltration system is one of the insurance) , so I add security filters. Often the security filter filter aperture is 5 microns, flow depends on the water flow.
8) Reverse osmosis components and devices
reverse osmosis membrane element is the core component of reverse osmosis system, to choose and corresponding groundwater treatment membrane element, depending on the system design, can choose VONTRON LP21 - for the company Or LP22-8040 8040 membrane element of brackish water, reverse osmosis systems recovery rate at about 75%, at the same time, the system of the desalination rate is very high, under 97%, so as to effectively guarantee the water quality of effluent.