Integration of Nanofiltration Hollow Fiber Membranes with Coagulation-Flocculation to Treat Colored Wastewater from a Dyestuff Manufacturer: A Pilot-Scale Study

A positively charged nanofiltration (NF) hollow fiber membrane with an antifouling feature has been fabricated and scaled up to pilot scale to treat colored wastewater from a dyestuff manufacturer with the aid of the coagulation-flocculation (CF) process. An effective CF formulation, i.e., iron chloride/anionic polyacrylamide (IC/APAM) = 800/100 ppm, has been identified to treat the NF concentrate stream. The challenges of membrane fouling and processing concentrate streams can be effectively managed by the integrated NF CF process. The NF process is able to achieve 82% and 67% removal of color and chemical oxygen demand (COD) from the colored wastewater, respectively; while the CF process can remove 91% of color and 81% of COD from the NF concentrate stream. NF and CF were found to complement each other. The NF process alone always generates a concentrate stream, but it can effectively reduce the wastewater volume. The CF processes are particularly favorable for treating small volume concentrate streams. These advantages make the NF CF process propitious for users located in land- or space-limited places and countries.