'water pre-treatment system operable under re-circulation technique to reduce wastage of ultra filtered in a process of pre-treatment of clarified raw water'

摘要

The invention relates to an improved water pre-treatment system operable under recirculation technique to reduce wastage of ultra filtered water in a pretreatment process of clarified raw water, the system comprises an ultra filtration (UF) unit operably connected to a Reverse osmosis (RO) unit which interlia connected to a de-mineralization (DM) unit to implement a chemical process of ion exchange through de-mineralization resins, wherein the UF unit is enabled to reduce total suspended solids (TSS) and organics from the received clarified raw water duly disinfected, to pretreat the TSS reduced water through chemical dosing in a flocculation device, to chemically condition the filtered water via a cartridge filter device with inlet and outlet valves and to transfer the conditioned water after measuring and ensuring a desired slit density index (SDI) of the water to said RO - unit, wherein the RO-unit is configured to receive the conditional water via a RO feed pump having membranes from the UF - unit, pressurize in various stages the treated water to remove the TDS including the entrapped carbon dioxides in the water by means of a plurality number of high pressure pumps and degassers, and transfer the water to said DM unit. The improvement is characterized in that the system is provided with a recirculation pipeline (10) including a bypass valve (8) disposed in between the RO feed pump (5) and Cartridge filter (7), the system is enabled during each startup to the RO feed pump (5) to place the cartridge filter inlet valve (6) in closed position and the recirculation / bypass valve (10) kept in open condition to start the RO feed pump (5) and re-circulate a contaminated UF permeate water in an UF permeate tank (4) to the UF unit (3) as an UF feed Water (1), the UF unit (3) rejecting the organics and minimize the turbidity of UF permeate water (11), to store the treated water in the UF permeate tank (4) to measure once the required turbidity is achieved the SDI online at the outlet of the RO feed pump (5), to throttle the bypass valve (8) in the recirculation line (10) to obtain required back pressure for SDI measurement, and to reiterate the activities till a desired SDI before Cartridge filter (6) inlet is achieved.