Testing of various membranes for removal of chemical oxygen demand in real fresh human urine using a cross-flow filtration system

ABSTRACT Urine is primarily composed of water (about 95%), with urea (around 2%), creatinine (approximately 0.1%), uric acid (about 0.03%), and various ions. Although human urine constitutes 1% of the volume of domestic wastewater, it contains significant amounts of chemical oxygen demand (COD) (∼10%). This study focused on the elimination of COD in urine using a cross-flow filtration system and testing the effectiveness of various membranes (microfiltration (MCE01), ultrafiltration (UP005 and UP010), and nanofiltration (NP010 and NF270)). The steady-state flux of the NF270 membrane increased from 10.8 to 23.9 L/m2/h as the pressure increased from 10 to 25 bar. A significant COD removal efficiency was obtained for the NF270 membrane at an operating pressure of 25 bar. COD concentration decreased from 7,392 to 1,270 mg/L with 82.8% rejection. In contrast, none of the membranes performed well in terms of urea removal efficiency. According to the findings, urea concentration decreased from 6,712 to 6,043 mg/L with 9.9% rejection. Moreover, ion contents (calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), ammonium (NH4+), phosphate (PO43−), sulfate (SO42−), and chloride (Cl−)) of the membrane permeates were also measured.