A case study on the wastewater treatment of a textile factory. Demonstration of the effectiveness of the UF + RO system for the recovery of process waters.
A textile factory was keen to improve the quality of the wastewater discharge from one of its factories. In order to recover the wastewater a UF + RO system was required. The treatment process combined a number of different steps to remove lint, chemicals, dye and large suspended solids before the wastewater was fed into the UF + RO system.
Textile wastewater coming from the factory first passes through a mesh filter to remove its lint.The water is then directed into a lavatory tank for gas washing, lowering its pH to 6-7. A heat exchanger cools the water to 35°C and transfers the heat to other process streams. The water is then sent to a homogenization tank for 2-hours of mixing, and during this phase heavy solids settle to the bottom of the tank and are pumped to sludge beds.
Remaining solids in the water are removed by electro-coagulation/flocculation, and a sedimentation tank allows sufficient time for the solids to settle.
Water passes through a 50 micron filter before entering Kristal® UF system, where turbidity is reduced by >95%. The UF permeate then enters a two-pass RO system, and the final product water is taken to the factory process tank for reuse.
A total of 30 Kristal® modules are installed, producing close to 2000
of UF permeate water to be fed into the RO system. The modules are arranged into three trains, having 10 modules each. Operating at about 93% recovery rate, Kristal® enables the treatment plant to recover a total of 1700 of RO product water, a high 85% overall recovery.
The remaining water enters an ozone contact tank for oxidation to remove 30% of its colour.
With the combined UF + RO wastewater plant, the Colombian textile company is not only able to reclaim 85% of its wastewater to be reused as process water, thus significantly cutting down its water consumption, it also greatly contributes to reducing wastewater discharge. This helps the factory to save water and energy costs, as well as wastewater discharge fees imposed by the government.
The UF pretreatment prior to RO keeps the lifespan of the RO membranes to a maximum, while at the same time improving the flux and providing a high UF recovery rate of about 93%.
The UF + RO plant has not only ensured a continuous supply of water to the textile factory, it also provides process water that is of consistently good quality.
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