Effective removal of nitrogen and phosphorus from a black-odorous water by novel oxygen-loaded adsorbents

Black-odorous water, caused by hypoxia and overloading of nitrogen and phosphorus, is ubiquitous in global urban rivers. In this study, we developed oxygen-loaded adsorbents by loading oxygen into activated carbon, Attapulgite, Phoslock, and Muscovite via vacuum-pressure swing method, and investigated their aeration and removal efficiency of phosphate, ammonia nitrogen, and total nitrogen in black-odorous water. Results showed that the addition of oxygen-loaded coal-based columnar activated carbon (OCC) or oxygen-loaded Muscovite (OM) alone could increase the dissolved oxygen (DO) concentration at the sediment-water interface to more than 6 mg center dot L-1 on the first day, and OCC could maintain the high level of oxidation-reduction potential (ORP) (up to + 327 mV) for 15 days. Most oxygen-loaded adsorbents remarkably reduced phosphate in water, essentially from 0.27 mg center dot L-1 to < 0.05 mg center dot L-1. Additionally, ammonia nitrogen and total nitrogen were reduced by more than 50 % by adding materials after oxygen loading treatment. The 16 s RNA results showed that Dechloromonas was dominant in abundance, and the reduction of nitrogen was mainly affected by microbial activity. Our results provided a series of oxygen-loaded adsorbent materials with potential engineering applications for rapid treatment of urban black-odorous water.

Automated summary

Black-odorous water is a common problem in urban rivers worldwide. This study developed oxygen-loaded adsorbents and investigated their ability to aerate and remove various pollutants in black-odorous water. The results showed that these materials effectively increased dissolved oxygen concentration, reduced phosphate, ammonia nitrogen, and total nitrogen levels, and were influenced by microbial activity. The findings provide potential engineering applications for rapid treatment of urban black-odorous water.