News and Information

Return to list

Application of Ozone Technology in Wastewater Treatment Equipment Engineering

2021-03-30

Application of Ozone Technology in Wastewater Treatment Equipment Engineering

With the growing scarcity of natural water resources, the resource recovery of wastewater has increasingly attracted societal attention, and the reuse of treated wastewater has gradually become a stable source of reclaimed water. In recent years, there have been an increasing number of practical examples of wastewater reuse, including irrigation of green spaces and vegetation, water storage, municipal water supply, toilet flushing, industrial reuse, and replenishment of groundwater and reservoirs. Regardless of the specific application, disinfection remains an essential step in the wastewater reuse process.

Currently, liquid chlorine is the most commonly used disinfectant. The primary advantages of chlorine disinfection are its excellent disinfection efficacy and low cost. However, a significant drawback is that the disinfection process generates organochlorides. Adsorbable organic halides have now become a water quality control indicator applicable to all wastewater-discharging entities under the "Integrated Wastewater Discharge Standards" (GB 8978—1996). Moreover, chlorine disinfection increases the concentration of chloride ions in water; studies have shown that chloride ions are a major factor contributing to corrosion in water pipelines and plumbing fixtures. Ozone is a colorless gas with a slight odor. It is a powerful oxidizing agent with exceptional disinfection and sterilization capabilities, producing few disinfection byproducts and thus earning the nickname "green disinfectant."

Basic properties of ozone

① The oxidizing power of ozone

Ozone has a remarkably strong oxidizing ability—almost the strongest among all known oxidizing agents. This can be demonstrated by comparing their standard reduction potentials: in specific redox potentials, the standard potentials generated by oxygen, chlorine, chlorine dioxide, and manganese dioxide simply cannot match those of ozone. At the same time, ozone decomposes very rapidly in water; in aqueous solutions containing impurities, it quickly reverts back to oxygen, with a half-life of just 5.30 minutes. Its stability is further enhanced when the water temperature approaches 0°C. Studies have shown that the decomposition rate of ozone in water accelerates as both water temperature and pH increase. Due to its strong oxidizing properties, ozone reacts with virtually all metals except gold and platinum. It can oxidize numerous organic compounds and readily reacts with groups such as –SH, =S, –NH, =NH, –OH, and –CHO. It can also react with aromatic compounds, though at a slower rate. For aliphatic compounds, however, ozone exhibits almost no effect.

② The easy decomposability of ozone

Ozone not only possesses strong oxidizing properties but also exhibits relatively active chemical characteristics. At room temperature, it can decompose into oxygen, and during this decomposition...

releases 284 kJ/mol of heat during the process; expressed in chemical formula, this is:

2O3 ⇌ 3O2 (reversible)

The decomposition rate of ozone in the air is related to both temperature and the concentration of ozone itself. Studies have shown that the higher the temperature in the external environment, the faster ozone decomposes.

The higher the concentration, the faster its decomposition rate; and the rate at which ozone decomposes in water is influenced by both water temperature and pH. The higher the water temperature, the faster ozone decomposes, while the higher the pH—meaning the greater the alkalinity of the water—the faster ozone decomposes as well.

③ Corrosivity of ozone

Because ozone has high oxidizing power, it can oxidize nearly all metals in the air except platinum and gold. This also...

This demonstrates ozone’s corrosive nature. Moreover, ozone also has a strong corrosive effect on non-metallic materials. For this reason, in actual production...

A 25% chromium-iron alloy is commonly used to manufacture ozone-generating equipment. Moreover, in both the generating equipment and metering devices, ordinary rubber cannot be used as a sealing material; instead, corrosion-resistant silicone or acid-resistant rubber must be employed.

Previous:

How effective is the open-channel UV disinfection system in actually killing bacteria?

Next:

Advantages and Precautions for Medium-Pressure UV Disinfectors