Reduction of Environmental Impact in Plants: Naoetsu Plant

The Naoetsu Plant has two power generators (in a cogeneration system using gas turbines), and it generates electricity and steam using natural gas as a fuel with low emissions of greenhouse and toxic gases. The steam is used for heating processes within the plant, as well as for generating electricity with steam turbines (in a combined system). We proactively promote initiatives for saving energy and reducing greenhouse gas emissions.

The plant uses large quantities of oxygen and nitrogen for chemical reaction processes and for ensuring safety in the facility. To this end, we use an air separator to isolate oxygen and nitrogen from the air to obtain these two gases at a stable level of quality. The exhaust gas from this process contains a high proportion of nitrogen, and we collect and reuse it to obtain more nitrogen gas while also saving energy.

The Naoetsu Plant has two large anaerobic wastewater treatment facilities. The methane (biogas) generated as a product of the wastewater purification process is effectively used as boiler fuel. In addition, we have deployed a carrier* that immobilizes fungi and bacteria in the existing aeration tank of our aerobic wastewater facilities, and have introduced technology that improves wastewater treatment capacity to produce treated water with a lower environmental impact.

We also have a sedimentation treatment facility that isolates the solids suspended in the water and purifies the water to be clean and clear.

The Naoetsu Plant promotes activities to reduce waste materials generated in manufacturing and processing. For example, we take the paper materials that would otherwise be discarded in the manufacturing process, and we effectively utilize them by making recycled paper. We are also proactively considering ways to recycle the solvents from chemical reaction processes or create formulations that allow them to be reused.

The plant’s wastewater treatment facilities separate and dehydrate the inorganic solids contained in the wastewater to make a solid sludge. This sludge is treated as industrial waste by an external contractor and is put to effective use as roadbed material and the like.

We replaced the dehydrator in the wastewater treatment facility with a new model with superior dehydration performance, which reduced the amount of water in the waste sludge, thereby reducing the weight of waste for disposal.

This has reduced the energy required to transport the waste to our external contractor. We are promoting activities that can contribute to reducing environmental impact by considering all processes up to the final treatment process.

Organic solvents used in chemical reaction processes are usually incinerated as industrial waste, but the Naoetsu Plant is working to reduce the amount of waste solvent that becomes industrial waste by refining and recycling solvents that have already been used. In FY2023, the plant achieved a reduction of 24 tons of waste solvents, thereby helping to conserve resources and reduce environmental impact.