The hospital sewage treatment equipment has replaced septic tanks with very low removal rates, and the treated effluent cannot meet the national comprehensive discharge standards. Field applications have shown that hospital sewage treatment equipment is a highly effective and easy to manage domestic sewage treatment device. The removal of organic pollutants and ammonia nitrogen by hospital sewage treatment equipment mainly relies on the AO biological treatment process in the equipment.
Select the process based on the size, nature, and discharge direction of the hospital's wastewater treatment. According to hospital classification, it is divided into infectious disease hospitals and comprehensive hospitals. The discharge direction of hospital sewage after treatment is divided into two categories: discharging into natural water bodies and discharging into urban sewage treatment plants through municipal sewers.
The process used for hospital sewage treatment must ensure that the treated effluent meets the standard. The three main processes used are: primary treatment to enhance treatment effectiveness, secondary treatment, and simple biochemical treatment.
The principle of process selection is:
1. Infectious disease hospitals must adopt secondary treatment and carry out pre disinfection treatment.
2. Hospitals at or above the county level that discharge treated effluent into natural water bodies must adopt secondary treatment.
3. Comprehensive hospitals that discharge treated effluent into urban sewers (downstream with secondary sewage treatment plants) recommend using secondary treatment, and for those using primary treatment processes, the treatment effect must be strengthened.
4. For small comprehensive hospitals in economically underdeveloped areas, simple biochemical treatment can be used as a transitional measure when conditions are not available, and then gradually achieve secondary treatment or primary treatment with enhanced treatment effects. （2） Taking into account the above principles, the application of different treatment processes is compared in the hospital sewage treatment process designed in this scheme. With the continuous development of sewage treatment technology, the commonly used processes developed in recent years at home and abroad include:
1. The primary treatment process that enhances the treatment effect should be strengthened for comprehensive hospitals where the treated effluent ultimately enters the secondary treatment urban sewage treatment plant. This will increase the removal rate of SS and reduce the amount of disinfectant used. There are two ways to enhance the effectiveness of primary treatment: modifying the existing primary treatment process to improve removal efficiency and adopting primary strengthening treatment technology.
(1) The process flow for sewage treatment in general hospitals (without infectious disease wards) can adopt the process of "pretreatment → first level enhanced treatment → disinfection". By using coagulation precipitation (filtration) to remove particles carrying viruses and bacteria, the disinfection effect is improved and the amount of disinfectant used is reduced, thereby avoiding the adverse effects of excessive disinfectant use on the environment.