What are the main characteristics of rural domestic sewage? What are the difficulties in sewage treatment?

The main feature of rural domestic sewage is that most of the rural population is not densely distributed, so the concentration of rural sewage is low. As long as it changes, it is the change of day and night water volume, that is, the disconnection of sewage discharge. Usually, garbage disposal has three peak periods: morning, middle and evening. About 40% of garbage disposal is in the morning, and the sewage discharge at night is little or even zero. When rural areas are used as tourist attractions and farmhouses, not only the diurnal variation coefficient is large, but also the seasonal variation coefficient is large.

Most of rural sewage comes from kitchen water, washing water and flushing water, and their characteristics are not much different. In addition to rich nitrogen and phosphorus organic matter, it also contains pathogenic bacteria and their organisms, including fungi and Escherichia coli. Compared with nitrogen and phosphorus, carbon monoxide content is insufficient; Compared with pollutants such as Escherichia coli, the turbidity is also slightly higher; BOD and COD are usually 0.4-0.6, and the ratio of carbon to nitrogen is usually less than 5, which affects the removal rate of total nitrogen in sewage treatment.

In addition, the quality of rural sewage is slightly different at different times of a natural day. For example, when cooking during the day, the concentrations of animal and vegetable fat and SS are higher, and the concentrations of nitrogen, phosphorus and detergent are also higher. In addition, rural domestic sewage basically does not contain heavy metals and other substances.

Most rural areas do not have a good drainage system. Except for some villages and pilot villages with better economic conditions, the combined system is still adopted in most areas. Due to the limitation of operation and maintenance funds, the village Committee is responsible for the operation and management of some sewage treatment facilities rather than professional and technical personnel, which leads to inaction when the equipment fails. Moreover, the villagers do not pay enough attention to the treatment of rural domestic sewage, so they can't check and maintain it regularly, which also leads to hidden dangers in the use of sewage treatment equipment.