1. There are many by-products and complex water quality components.

2. The content of pollutants in wastewater is high, such as ammonia nitrogen, high salt, etc.

3. There are many toxic and harmful substances, especially those that pose a significant threat to microorganisms. For example, antibiotics, broad-spectrum antibiotics, are designed to kill various bacteria and microorganisms. Wastewater contains these substances, and entering the water will inevitably disrupt the ecological balance of microorganisms. Don't think about using microorganisms to degrade it.

4. Many products are difficult to degrade. From the current situation, the cost of sewage treatment is still relatively high. There is still a vast space for the research and development of new technologies for wastewater treatment in the future, which is worth exploring continuously.