Treatment of Urea Waste Water over Coconut Shell Activated Carbon Tethered Urease

Urease was successfully tethered onto coconut shell activated carbon (AC) granules. Degradation of urea was carried out in packed bed over the tethered urease. For 75% of retained activity, the tethered urease shows a broader temperature range of 42~80°C, compared to 45~75°C for the free enzyme. Similarly, the tethered urease has an increased resistance against the changes of pH. For a relative activity of 80%, the free urease had a pH range of 6.2-7.4, while it was 6.5–8.0 for the tethered urease. The Km values of the free and tethered ureases were 22.60 mg/mL and 7.43 mg/mL, respectively. And the Vm values were actually very close (~23.5 mg/min ) for both the tethered and free ureases. The catalytic performance of the tethered urease was tested in a packed bed reactor. The relative activity was maintained over 80% after 50 h of running in degradation of urea.