vol.61-2 (2023/7/31)

Overview and trends of the Offensive Odor Control Law

During the high-growth period, factory production increased, and houses were built nearby. Offensive odor pollution has become a problem throughout Japan. The Offensive Odor Control Law was enacted in 1972. The Offensive Odor Control Law is aimed at preserving the living environment of the residents. Factories that were emitting odors were regulated by law. There are two types of evaluation methods for odors. The first is regulation of the concentration of specific malodorous substances. The second is the odor index using the human olfactory. In the future, it is important to expand the areas regulated by the odor index, which can be consistent with the damage caused to residents.

Overview and trends of Volatile Organic Compounds emission regulations under the Air Pollution Control Law

Volatile Organic Compounds (VOCs) are one of the precursors of Suspended Particulate Matter (SPM) and photochemical oxidants. Japan has been working on reducing VOCs emissions from fixed sources through an appropriate combination of regulatory control under the Air Pollution Control Law and voluntary corporate effort by business operators. As a result, the target of reducing VOCs by about 30% compared to FY2000 by FY2010 was achieved. SPM has also achieved 100% of environmental standards, however the environmental standard achievement rate for photochemical oxidants remains still extremely low. For this reason, we decided to continue the VOCs emission control system and continue to follow up on the VOCs emission status. In addition, based on the “Photochemical Oxidant Countermeasures Working Plan” announced in 2022, we are verifying our efforts so far and studying more effective countermeasures.

Introduction of various deodor methods applied for air pollution control and evaluation of their performance

As one of the environmental problems surrounding us, there is an offensive odor problem including exhaust gas odor from factories, hospitals, as well as kitchen exhaust odor from restaurants and food shops. As countermeasures, the following deodorization technologies have already been established: scrubbing method, adsorption method, combustion method, ozone deodorization method, plasma deodorization method, photocatalyst deodorization method, biological deodorization method, deodorant method, and dilution / dispersion method. However, without the prudent selection of equipment after sufficient understanding of its principles and features, expected effects can hardly be obtained. This paper discusses the principles and features of deodorization technologies required for planning deodorizing equipment.

Efforts to be carbon-neutral of combustion-type exhaust gas treatment equipment

Combustion-type exhaust gas treatment equipment are currently widely used in high-concentration exhaust gas treatment. However, it is necessary to reduce more energy consumption to cope with carbon neutrality. To that end, we should consider measures to further increase the thermal efficiency of the deodorizer and use an auxiliary heat recovery system to reduce fuel consumption throughout the factory. The article explains how to maintain original performance from aging deterioration of equipment. It also explains fuel saving examples by reviewing current combustion-type exhaust gas treatment equipment due to changes in exhaust gas conditions from the factory.

Effective use of Regenerative Thermal Oxidizer

Here we introduce three examples of our energy-saving technologies for exhaust treatment using RTO (regenerative thermal oxidizer). The first is to improve agitation of process gas by installing aperture plates in the combustion chamber, the second is to lower the temperature of VOC oxidation and decomposition by using a heat-resistant catalyst, and the third is to integrate the air conditioning system of a drying facility with the exhaust gas treatment system.

Types of VOC concentrators and applications

Volatile Organic Compounds (VOCs) are causative substances of odors, photochemical smog, fine particulate matter (PM_2.5) and must be detoxified before being discharged from factory/facilities. The facilities, such as combustion and recovery equipment, for detoxifying large exhaust gas which contains low concentration VOC become huge, and require much operation cost. On the other hand, if the VOC concentrator is applied as pre-stage equipment of detoxification treatment equipment, it can concentrate the low concentration and large air volume VOC exhaust gas to high concentration and small air volume. It greatly helps to reduce the cost and CO₂ emission.

Kinds and characteristic of cleanroom equipment

Air cleaner for business use is used now in wide field such as electronics industry, food industry, pharmaceutical industry and biological safety field, etc. Air cleaner is improved by specified demands of each field. Representative air cleaner that are biological safety cabinet, clean bench, clean booth, clean unit, air shower, pass box, infection control equipment, is described for characteristic and usage precautions.