Special Issue

New Development in Hydrosheric Environmental Protaction

Review

SIGNIFICANCE OF PHYSIOLOGICAL AND GENETIC DIVERSITIES OF AMMONIA OXIDIZERS FOR IMPROVING NITRIFICATION EFFICIENCY IN WASTEWATER TREATMENT PROCESSES

Yuichi Suwa (Ecological Chemistry and Microbiology Div., Hydrospheric Environmental Protection Dept., NIRE)
Kazuhiko Noto (Matsudo Research Laboratory, Hitachi Plant Construction and Engineering Co. Ltd)

Abstract
Ammonia oxidizers are almost solely responsible for oxidizing ammonia to nitrite in the global nitrogen cycle, which generally is a rate-limiting step in a nitrogen removal process of wastewater treatment system. Despite significance and importance of ammonia oxidizers in wastewater treatment engineering, biological data on these organisms has been rather poorly available because of difficulties in isolating and cultivating them. We have shown that the diversities in kinetic pattern as a function of substrate concentration, phylogeny based on 16S rDNA sequences, and functional gene sequences that are responsible for ammonia oxidation. These results raise a possibility of development of an advanced nitrogen removal engineering ; combination of organisms having different physiological features may result in better efficiency of ammonia oxidation. Performance of a bioreactor that was designed based on this concept was significantly improved. Genes cloned for examining their diversity can be used as molecular probes for precise and rapid analysis of ammonia oxidizers in wastewater treatment systems..

Key words : nitrification, ammonia-oxidizing bacteria, molecular ecology, bacterial diversity, waste water treatment

(Language:English)

Review

Biomethylation in the Natural Environment : A Review

Hiroaki TAO (Water Analysis Div., Hydrospheric Environmental ProtectionDept., NIRE)
O. S. Fatoki (Department of Chemistry, University of Fort Hare, South Africa)

Abstract
Some metals and metalloids are partially methylated by microorganisms in the nature. This phenomenon, called biomethylation, makes a big difference in the chemical and physical properties of the original elements, and changes their toxicity and their subsequent fate in the environment. To assess the impact of these elements on the environment, it is important to know the role and extent of biomethylation in the environment. This short review discusses the mechanism and role of biomethylation for environmentally important elements such as As, Hg, Sn, Pb, etc.

Key words : Biomethylation, Heavy metal, Metalloid

(Language:Japanese)

Original paper

Degradation of 2, 4-dinitrophenol (2, 4-DNP) by non-acclimated activated sludges augmented with 2, 4-DNP degraders.

Kotaro ENDOH (System safety Div., Safety Engineering Dept., NIRE)
Yasutoshi Matsui (Ecological Chemistry and Microbiology Div., Hydrospheric Environmental Protection Dept., NIRE)
Fumio Yamaguchi (Ecological Chemistry and Microbiology Div., Hydrospheric Environmental Protection Dept., NIRE)
Yoshitaka Yonezawa (NIRE,Chief Senior Researcher)
Yoshikuni Urushigawa (NIRE,Chief Senior Researcher)
Yuichi Suwa (Ecological Chemistry and Microbiology Div., Hydrospheric Environmental Protection Dept., NIRE)

Abstract
Two bacterial strains, D3213 and E22, which have constitutive and inducible degradability of 2, 4-dinitrophenol (2, 4-DNP) respectively were isolateds from activated sludge acclimated to 2, 4-DNP. To evaluate effects of those isolateds on 2, 4-DNP treatment in activated sludge, each strain was introduced into activated sludge taken from a municipal sewage plant. When each strain was inoculated at 0.3 or0.4% of total biomass, 2, 4-DNP was completely degraded in a day. Even when inoculum fraction was 0.03or 0.04%, 2, 4-DNP was degraded in 5 or 6 days irrespective of the strain, which had either constitutive or inducible degradability of 2, 4-DNP. No degradation was appeared in the activated sludge without inoculation of either strain up to 11 days. The results obtained suggest that the induction period of strain E22 was too short to be neglected in the 2, 4-DNP treatment and / or a lag period prior to the initiation of 2, 4-DNP degradation by strain D3213 may exist under the coexistence of more degradable substrate which repress the catabolism of 2, 4-DNP.

Key words : 2, 4-dinitrophenol, activated sludge, degrmadation

(Language:English)

Original paper

Behaviour of Mo, Sb, and Ni in Leaching from Polluted Soil

Mamoru Tominaga (Water Analysis Div., Hydrospheric Environmental Protection Dept., NIRE)
Shigeru Terashima (GeologicalSurvey of Japan)
Kenji Bansho (Ebara Engineering Service Co.)
Kazuya Kawamata (The Municipal Office of Hitachinaka)

Abstract
The new 25 Items Requiring Surveillance in Environmental Quality Standards for Water are not enacted in Environmental Quality Standards for Soil, but will be presently in future because significant impact on human health and living environment and ecosystems by soil pollution. Thus, it is essential to have advanced techniques for analysis of these Items Requiring Surveillance in polluted soil. The purpose of this research is to present novel techniques in analytical method and leaching method of Mo, Sb, and Ni in Items Requiring Surveillance for polluted soils. To clarify the characteristics of leaching behaviour from polluted soil, leaching tests for 24 hours were investigated for Mo, Sb and Ni in artificial polluted soils, each of which were a mixture of urban soil and oxide, sulfide and water-soluble compound. Mo and Sb in these polluted soil leached at 70-90% after 6 hours. Leaching amount of Mo, Sb and Ni was interfered by matrix substances in soil and leaching ratio to total amount of these elements was very low. Especially, leaching of Mo and Sb depended on pH value in leaching solvent and organic substances in these polluted soils. Repeated tests resulted in similar significant amount of leachate. These results differ from those of heavy metals which were found from variable leaching test. It is important to select extraction condition and leaching test corresponding to the purpose of test.

Key words : Molybdenum, Antimony, Nickel, soil, leaching

(Language:Japanese)

Review

Enzymatic Removal of Hazardous Chemicals from Wastewater

Kenji TATSUMI, Hiroyasu ICHIKAWA and Shinji WADA
(Advanced Water Treatment Div., Hydrospheric Environmental Protection Dept., NIRE)

Abstract
An enzymatic approach for the removal of toxic chemicals from industrial wastewater has attracted much interest recently. The principle of these enzymatic treatments is that carcinogenic chemicals such as phenols and aromatic amines are polymerized to form less water-soluble substances, and then the precipitate is separated from water by filtration. However, there has been almost no discussion about the contamination due to the remaining soluble enzyme and non-precipitated products in the aquatic solution after enzymatic treatment.

In this paper, we show our recent investigations : a combination treatment of an enzyme and a coagulant, and treatment by immobilized enzyme, and review the present status and future prospect of enzymatic wastewater treatment.

Key words : Enzyme, Chlorophenol, Coagulant, Immobilization, Immobilized enzyme, Chitosan

(Language:Japanese)

Review

Enzymatic Incorporation of Hazardous Chemicals into Humic Substances

Kenji TATSUMI(Advanced Water Treatment Div., Hydrospheric Environmental Protection Dept., NIRE)
Kengo MORIMOTO (Inter-Spheric Environment Div., Environmental Assessment Dept., NIRE)

Abstract
During the humification process, various organic chemicals are incorporated in soil and sediment humus. This constitutes one of the major reactions by which these chemicals are transformed in nature. It is very difficult, however, to characterize the linkage between humic substances and other chemicals, because humic substances are complex and heterogeneous. In this paper, our model experiments using a simple humus constituent to provide information concerning the mechanism and binding sites are shown.

Key words : Enzyme, Bioremediation, Humic substances, Dioxin, Pentachlorophenol

(Language:Japanese)

Review

Creation of pleasant water environment byozone usage in sewage and industrial wastewater

Nobuyuki TAKAHASHI (Advanced Water Treatment Div., Hydrospheric Environmental Protection Dept., NIRE)
Sueo NAGASAWA (Planning and Research Div., Water Re-use promotion Center)

Abstract
This paper summarizes the present state and prospect of ozone usage in sewage and industrial wastewater for the creation of a pleasant water environment.

The development of some technologies is needed to advance ozone usage in sewage and industrial wastewater : an effective usage of biological treatability induced by ozonation, an advanced degradation of organic compounds by combined use of ozone and other physico-chemical treatment methods, and the establishment of an optimum ozone generation and utilization system. At present, ozone usage in sewage and industrial wastewater remains mostly in the laboratories or pilot-scale examinations. However, the solution of the above three technical items will result in the advance in re-usage of treated water, the newly development of water source in urban areas and applications to environmental furification technologies as well as further usage in sewage and industrial wastewater. Ozone usage in these fields is expected to bring about a big demand of 0.14~0.15 million tons per year in the future. The research and development in both effective generation and long-term preservation technologies as well as widespread usage will lead to the creation of a pleasant water environment.

Key words : Ozone usage, Sewage, Industrial wastewater, Pleasant water environment

(Language:Japanese)