A novel approach to an advanced tertiary wastewater treatment: Combination of a membrane bioreactor and an oyster-zeolite column

A combination of a microfiltration-membrane bioreactor (MBR) and oyster-zeolite (OZ) packed-bed adsorption column was studied for the first time to evaluate the advanced tertiary treatment of nitrogen and phosphorous. The membrane module was submerged in the bioreactor and aeration was operated intermittently for an optimal wastewater treatment performance. Artificial wastewater with CODcr of 220 mg/L, total nitrogen (T-N) of 45 mg/L, and total phosphorous (T-P) of 6 mg/L was used in submerged MBR with MLSS of 4,000–5,000 mg/L. The experiments were performed during a 100-day period with periodic membrane washing. The results showed that CODcr could be effectively removed in the MBR alone with over 96% removal efficiency. However, T-N and T-P removal efficiency was slightly lower than expected with only the MBR. The permeate from MBR was then passed through the OZ column for tertiary nutrient removal. The final effluent analysis confirmed that nutrients can be additionally removed resulting in over 90% and 53% removal efficiencies for T-N and T-P, respectively. The results of this study suggest that the waste oyster shell can be effectively reclaimed as an adsorbent in advanced tertiary wastewater treatment processes in combination with a MBR.