METHANE-DEPENDENT DENITRIFICATION APPLICATION FOR UREA AND AMMONIUM CONTAMINATED WASTEWATER TREATMENT

Tóm tắt

This study was conducted with synthetic wastewater from urea and ammonia (representing nitrogen fertilizer production wastewater) and additional carbon source of methane (CH4). Methane and air were supplied to microbial liquid phase using a bubble air stone aerator located at the bottom of a bioreactor with methane gas flowrate ranges from 1 to 2 L/h, air flowrate ranges from 3 to 6 L/h. There were three steps in the experiment with the first step served as acclimation period. Removal efficiency in the second step and the third step with total nitrogen concentration range from 100 to 300 mg/L and from 300 to 600 mg/L are 98.11 ± 0.5% and 81.58 ± 1.17%, respectively. The mixed liquor suspended solids (MLSS) at the end of step III increased by 4000 mg/L in compared with initial microorganism density. The optimal C/N ratio of the study was 6.63 at the methane gas and air flowrate of 2 L/h and 6 L/h, respectively. Denitrification rate reached its highest number of 11.4 mgN/L.h while total nitrogen (TN) was supplied at 600 mgN/L. Thereby, aerobic methane oxidation coupled to denitrification, AMO-D technology, is capable of treating wastewater containing high TN concentration (up to 600 mg/L) but poor in organic matter with methane as the additional source of carbon; and microorganisms could grow well in the condition where oxygen and methane were simultaneously supplied for methane oxidation and nitrogen removal.

Keywords: Organic carbon source, methane denitrification, urea, ammonia