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■ What regulations exist for boiler wastewater? There are additional regulations regarding the water quality standards for boiler wastewater under the Sewerage Act, the Water Pollution Control Act, and municipal ordinances. The Sewerage Act and the Water Pollution Control Act stipulate that the pH must be discharged between 5.8 and 8.6. ■ Why is the standard set around neutral? It is generally said that strongly acidic or alkaline wastewater can corrode sewer pipes and weaken the activity of microorganisms that clean wastewater at treatment plants. By establishing standards close to neutral, it is believed that such impacts are prevented. ■ Why is neutralization necessary? As mentioned previously, it is desirable to maintain the pH of boiler water between 11.0 and 11.8 for corrosion prevention inside the boiler. Therefore, high pH blowdown water must be neutralized before discharge, as discharging it directly would exceed the standards. ■ How is neutralization done? Typically, the pH of alkaline wastewater is lowered by adding an acid to adjust it within the standard values. Please feel free to consult us for more information.

■What does wastewater treatment technology do? Wastewater treatment technology is a method that separates particles and dissolved substances (such as organic matter) detected as BOD and COD from water, or transforms them into harmless, stable substances (such as CO2) for removal. Treatment methods are divided into four categories: physical treatment, chemical treatment, physicochemical treatment, and biological treatment. ■What do BOD and COD represent? BOD (Biochemical Oxygen Demand) indicates the amount of oxygen consumed by microorganisms when decomposing organic matter, while COD (Chemical Oxygen Demand) indicates the amount of oxygen consumed by oxidizing agents when decomposing organic matter. Higher values mean a reduction in dissolved oxygen in the water, which can adversely affect aquatic organisms. Generally, rivers are regulated by BOD, while lakes and marine areas are regulated by COD. ■How do the four treatment methods differ? 1. Physical treatment: Separates contaminants through processes like sedimentation and filtration. 2. Chemical treatment: Neutralizes contaminants through processes like neutralization and redox reactions. 3. Physicochemical treatment: Combines processes like coagulation-sedimentation and activated carbon adsorption. 4. Biological treatment: Decomposes organic matter using the power of microorganisms. ■Which treatment method should be chosen? The appropriate treatment method or combination depends on the types and concentrations of substances contained in the wastewater. Please feel free to consult with us first.

■What is the difference between drainage and wastewater? "Drainage" refers to the act of discharging water outside or the water that has been discharged. On the other hand, "wastewater" specifically refers to the dirty water that has been used. The key distinction between these two terms is that wastewater is in a dirty state due to treatment, while drainage water is not necessarily dirty. ■How does wastewater treatment create "clean water"? In production sites, various types of wastewater, such as polishing wastewater and cutting fluid wastewater, are generated. Wastewater treatment involves separating these wastewaters into clean water and contaminants through processes like coagulation treatment. In coagulation treatment, a coagulant is added to the fine particles of contaminants to cause them to clump together into larger masses, which are then removed through sedimentation and filtration. The cleaned water from wastewater treatment may be reused in the production site, but since treated water contains some chemical components, careful consideration should be given to whether it can be reused. ■Why are wastewater treatment and discharge standards necessary? Wastewater treatment is the process of treating wastewater to discharge water outside the factory. The discharge standards vary depending on the components contained in the wastewater. These standards are established to protect public water bodies such as rivers and seas, as well as groundwater, from pollution and to preserve the living environment.

The unique smell of the wastewater treatment plant. Are you just brushing it off with "Well, it's that kind of place, so it can't be helped"? In fact, that smell is a sign that can be life-threatening for workers. ■ The source of the smell like rotten eggs A typical foul odor generated in wastewater treatment is hydrogen sulfide (H2S, which smells like rotten eggs). The troublesome part is that its specific gravity is about 1.2 times that of air. This means it is heavier than air and accumulates in "low places" such as pits and tanks. While the smell may be faint above, there is a risk of suddenly plunging your head into a high-concentration layer when you bend down. ■ Moreover, the danger of "getting used to it" Hydrogen sulfide has a strong odor at low concentrations, but at high concentrations, it can numb the sense of smell, making it undetectable. This does not mean "it smells less than before = it has become safe"; rather, it indicates that you may have entered a dangerous zone. The inability to use the presence or absence of smell as a safety gauge is the most frightening aspect of this substance. Other foul-smelling substances, such as methyl mercaptan (which smells like rotten onions) and ammonia, also exist, each with different properties. We have summarized methods to ensure safety in wastewater treatment plant inspections not relying on smell but on systems in this document.

We would like to introduce a case of updating the diffusers in the aeration tank at factories with wastewater treatment facilities, such as fiber, dyeing, and silk factories. The water quality in the wastewater treatment tank changed at a certain point. There were concerns that the strong odor indicated that biological treatment was not effective. First, we temporarily halted the aeration equipment on-site and conducted an investigation of the air piping. It was discovered that the diffusers (aeration devices) that should have been installed at the bottom of the aeration tank were missing. We immediately reinstalled and inspected the diffusers, confirming normal aeration and recovery of the dissolved oxygen (DO) levels. [On-site concerns] - The water that used to be gray has turned dark. - The DO (dissolved oxygen concentration) is not increasing at all. - There is a strong odor, and it seems that biological treatment is not effective. *For more details, please download the PDF or feel free to contact us.*

We often receive inquiries about 'deodorants not being effective at sewage treatment facilities.' Do you have similar concerns? 'Even though there are deodorants, it still smells.' 'What can I do to enhance the effectiveness of the deodorants?' 'Which deodorant is the most effective?' A 'site manager at a purification center's sewage treatment facility' had such worries. 'The smell is strong, and the effectiveness of the deodorants we've used so far is diminishing.' What exactly is an 'effective deodorant'? It is a 'deodorant that works effectively at that specific site.' To verify the effectiveness at each site, conducting on-site investigations is effective. *For more detailed information, you can view it through the related links. For more details, please download the PDF or feel free to contact us.

We would like to introduce a case of maintenance and cleaning/recalibration of the DO meter at the wastewater treatment facility of a fiber manufacturer and dyeing factory. One day, an anomaly occurred in the biological treatment tank that processes factory wastewater. Various responses were attempted on-site, such as increasing aeration and adding chemicals, but no decisive improvement was achieved, and the overall instability of the treatment tank continued. We suspected a decrease in DO (dissolved oxygen) concentration within the biological treatment tank. Although no significant abnormalities were observed in the DO meter's displayed values, upon performing maintenance and cleaning/recalibration of the sensor, it became clear that the actual dissolved oxygen concentration was significantly lower than the measured values displayed. Based on this cause, we reviewed the aeration conditions, resulting in a recovery of microbial activity, which ultimately led to improvements in sedimentation. [On-site Issues] - Sludge does not settle in the downstream sedimentation tank. - Treated water is cloudy. - It seems that microorganisms are not functioning properly. *For more details, please download the PDF or feel free to contact us.*