AN INTEGRATED NANOFILTRATION + EVAPORATION SOLUTION FOR HIGH STRENGTH RUBBER WASTEWATER TREATMENT, WATER REUSE AND ZERO LIQUID DISCHARGE

摘要

Treatment of wastewater from the demoulding process in rubber part manufacturing,where polymeric demoulding agents are used, has been a challenge to the industry due toits high strength (COD＞10,000 mg/L) and low biodegradability of the main organiccontent in the wastewater. Currently, a thermal process, typically boilers followed byevaporators, is commonly employed to treat the wastewater at rubber factories. Besidesfrequent boiler maintenance due to severe fouling caused by the wastewater, high energycosts are nearly prohibitive. At Cikautxo, a rubber part manufacturer located in theBasque Country in Spain, the energy bill is currently approximately €4.2/m~3 treatedwastewater.PROMETHEUS is a research project funded by the European Commission under the 7thFramework Programme with an aim to develop an integrated solution for treatment ofrubber wastewater. Following an initial bench-scale membrane screening a pilot studywas carried out at Cikautxo in the first half of 2012 to test the proposed solution.Nanofiltration with a NF270 membrane was tested and reject water from NF270 wascollected and then fed to a full size compression-driven evaporator for further volumereduction.Without any pre-treatment, the nanofiltration process was able to be maintained at apermeate flux of 11 liter/m~2/h for over 30 hours in-between flux recovery cleanings. Ahigher treating capacity for the evaporator was observed for treating the NF reject incomparison with the boiler blowdown, due to lower salt concentrations in the NF reject.The NF+evaporator solution can reduce the energy costs by 55% (down to €1.9/m~3treated wastewater).