Catalytic oxidation of high-concentration ammonia in groundwater by a naturally formed co-oxide filter film

Abstract

A B S T R A C TOperation of a sand filter system in treating groundwater produces a high concentration of ammonia (2-2.8 mg L À1 ), iron (0.9-2 mg L À1 ) and manganese (1.2-1.7 mg L À1 ), and on the surfaces of quartz sands, a co-oxide filter film is formed. The removal of ammonia in the filter before and after the treatment of film-coated sands at high temperature and pressure and the transformation of nitrogen in filter bed were studied. The morphology and chemical composition of film-coated sands were studied by SEM and EDS, respectively, and the structure of the film material was characterized by XRD. The specific area and pore properties of quartz sands before and after the formation of the filter film were studied by the BET method. The X-ray photoelectron spectroscopy characterization was introduced to identify the chemsorb sites of dissolved oxygen and ammonia on the film surface. The results show that the film material consisting of iron and manganese oxides was amorphous; both specific area and pore volume of the sands got increased as the film was formed. Removal of ammonia in the filter was a catalytic oxidation process, and 90% of capacity of ammonia treatment was recovered in the 116 h operation after the film-coated sands got treated at high temperature and pressure, which was due to the restoration of the surface structure of the film. The dissolved oxygen was most possibly adsorbed on Mn atoms occurring as Mn 2 O 3 and MnO 2 , and the Fe atoms occurring as FeO while on the membrane surface, the Mn atoms in states of Mn 2 O 3 and MnO, and the Fe atoms in states of Fe 2 O 3 and FeO may be the chemsorb sites of ammonia.

Study on the Factors Affecting the Start-Up of Iron-Manganese Co-Oxide Filters for Ammonium and Manganese Removal from Groundwater

“…The results showed that the specific surface area increased from 0.106 m 2 /g (virgin sand) to 3.920 m 2 /g (filter media collected on 12th day). Cao et al reported that the increased specific surface area provided more active sites for NH 4 + -N catalytic oxidation, which played a decisive role in the catalytic oxidation process of NH 4 + -N [ 25 ].…”

Using Iron-Manganese Co-Oxide Filter Film to Remove Ammonium from Surface Water

“…The chemical catalytic oxidation of ammonium by MeO x has been proven in groundwater [ 11 , 29 ]. The study of Guo et al indicated that microorganisms may play a negligible role in the process of ammonium removal by MeO x in groundwater [ 11 ].…”

Ammonium removal by alkaline‐activated coconut coir from synthetic and ground waters

“…10 High ammonium concentrations in groundwater are difficult to handle because of limitation of inadequate dissolve oxygen (DO). 11 Some ammonium treatment methods have been developed such as steam stripping in packed columns to volatilize free ammonia, 12 using catalytic oxidation, 13,14 aeration combined with a chemical catalytic oxidation filter, 11 biological aerated filter, 15 and ion exchange onto clinoptilolite. 16 Although these methods have their own advantages and disadvantages, they are not easy to apply for ammonium removal from groundwater for suburban and rural communities in Viet Nam, where are lack of centralized supply water treatment plants.…”