Abstract:
This thesis studied the treatment of wastewater froin a vegetable-oil mill by nanofiltration membrancs in comparison with the activated sludge process. Wastewater froin the manufacturing process was tested by 4 types of membranes, i.e, LFIO, ES20,NTR-729HF and TW30-1812-75, at 35 'C and at different applied pressures, depending upon the membrane characteristics. The experimental results showed that NTR-729HF gave highest flux and lowest rejections whilc LFlO gave lowest flux but highest rejections. All nanofiltration membranes exhibited better treatment efficiency than the activated sludge process and TW30-1812-75 membrane was most suitablc since it can be used at lower applied pressures and also gave the treated water of standard qualities for recycling. An economic analysis comparing nanofiltration with activated sludge for the product waterof 15 rn3/hr revealed that for nanofiltration the expenses for investment, operatioil and inaintcnance were higher than those of activated sludge. The expenses of nanofiltration can be reduced if one considers that nanofiltration can replace ion-exchange process for treatment of raw water and a smaller activated sludge process is required for treatment of nanofiltration retentate