We conducted wastewater treatment tests using columns on artificial soil aggregates, formed by blending diverse materials with soil. After the test, we assessed phosphate adsorption capacity, microbial community biomass carbon content, and carbon source utilization functions in the materials. During the treatment process, the phosphate adsorption capacities decreased due to phosphate adsorption except for artificial soil aggregate mixed with iron powder. The capacities of those mixed with iron powder increased. Higher biomass carbon content was found in the upper part of the columns and in materials with more organic matter. Microorganisms played a role in wastewater treatment; however, excessive biofilm growth might have hindered the efficiency. Carbon source utilization functions in the upper parts of the columns were similar; however, the differences became larger from the middle parts to the lower parts, likely due to variations in microbial habitat and wastewater treatment processes.

Copper-cadmium reduced naphthylethylenediamine absorption spectrophotometry is one of the methods for analyzing nitrogen components in water, but it uses cadmium, a toxic substance, as a reducing agent. In this study, we developed a method to measure nitrogen components including nitrate nitrogen by reducing nitric acid and nitrite to ammonia using the copper-zinc reduction method with zinc instead of the copper-cadmium reduction method using continuous flow analysis（CFA）. Since the reagents used in the copper-zinc reduction inhibit the coloration of indophenol blue method, ammonia was separated from the inhibitors by an ammonia gas permeation method using a PTFE membrane filter to reduce the effect on the coloration. Comparison of the developed method with the conventional method showed that the lower detection limit of the instrument and the lower quantification limit of the developed method were equivalent to those of the conventional method. In addition, a good correlation was obtained by comparing the measurement results of actual samples such as seawater, environmental water, river water, and wastewater.