Removal of Organic Matter from Water by Chemical Preoxidation Coupled with Biogenic Manganese Oxidation

Abstract

In the process of drinking water treatment, potassium permanganate and iron-manganese oxides are typical pre-oxidation methods that can not only effectively remove organic matters in drinking water, but also reduce the production of disinfection by-products (DBPs). However these two pre-oxidation methods will produce Mn2+ that is genotoxic. In order to solve this problem, a concept was proposed to connect biogenic-manganese oxidation technology after chemical oxidation. The manganese-oxidizing microbe may convert Mn2+ into the bio-manganese oxide, which can further remove the pollutants by its strong oxidative and adsorption capacity to improve water purification. In the simulated contaminated water composed of natural organic tyrosine (Tyr) and synthetic organic 2-Hydroxy-4-Methoxybenzophenone-5-Sulfonic Acid (BP-4), we verified the proposed the concept. Pre-oxidation by potassium permanganate or iron-manganese oxides efficiently removed Tyr, but had negligible effect on BP-4. During this, Mn2+ was generated. In the subsequent biological system, the manganese-oxidizing bacteria Pseudomonas sp. QJX-1 could utilize the Tyr for growth and oxidize Mn2+ to Mn4+ oxide. The generated manganese oxides could then effectively remove BP-4. In comparison, the moderate potassium permanganate preoxidation coupled with bio-manganese oxidation had a desirable treatment effect, with 100%, 50%, and 98.9% removals for Tyr, BP-4, and Mn2+, respectively. Importantly, the study provides a new method for drinking water treatment.