Zhejiang Huaqingyuan Biotechnology Co., Ltd.

March 2016

Operation and maintenance of rural domestic sewage treatment terminal

Status analysis and improvement suggestions

I. Overview

Rural domestic sewage is one of the main causes of regional water pollution in my country, and it is also one of the restrictive factors in the construction of a new socialist countryside in my country. In recent years, due to the regional concentration of rural dwellings and the popularization of water and toilet improvements, the discharge or direct discharge of rural domestic sewage after pretreatment in septic tanks has become the main reason for the deterioration of the rural water environment.

The rural population is relatively small compared to towns and towns, and more dispersed, far away from the sewage pipe network, so the investment cost of centralized management is relatively high. Generally, natural villages are used to collect domestic sewage by district and build treatment terminals for centralized treatment and discharge into natural water bodies. Depending on the number of village households collected, the treatment scale of the domestic sewage treatment terminal is generally 5-100m3/d.

In general, my country's rural domestic sewage has the characteristics of being scattered and difficult to collect, small in scale, many discharge points, and the rural economic foundation is relatively weak, lack of professional management personnel, and large differences in climate and regional characteristics between North and South.

The Fourth Plenary Session of the Thirteenth Zhejiang Provincial Party Committee proposed that the breakthroughs in sewage treatment, flood prevention, drainage of waterlogging, water supply, and water conservation (ie "five water governance") should be used to force transformation and upgrading. Therefore, in order to actively promote the "five water co-governance", do a good job in the construction and operation and maintenance of rural domestic sewage treatment terminals, which is of great significance to the construction of new rural areas, alleviating water shortages, improving the ecological environment of villages and towns, and improving the quality of life of farmers.

2. Current status of domestic sewage treatment in rural areas

In recent years, our province has built a considerable number of rural domestic sewage treatment terminals in various rural areas, forming a batch of mature domestic sewage treatment processes, which can be divided into biological treatment processes and ecological treatment processes according to process types. The main types of treatment processes include biological filter, contact oxidation, MBR (membrane biological treatment) method, integrated A/O or A2/O membrane method, etc. Eco-type treatment processes mainly include soil infiltration, artificial wetlands, etc. The currently widely used treatment method is the integrated A/O or A2/O membrane method + constructed wetland bio-ecological combined treatment process. Because the main equipment is a glass fiber reinforced plastic tank buried in the ground, it is also called underground micro-power Integrated treatment equipment + artificial wetland treatment process.

However, due to the lack of long-term effective management of the domestic sewage treatment terminals that have been built, a considerable number of treatment terminals are operating abnormally and the quality of the treated effluent is unstable, which obviously cannot play its due role.

3. Problems in the operation and maintenance of rural domestic sewage treatment terminals

Taking the widely used underground micro-power integrated processing equipment + artificial wetland processing terminal as an example, the following problems mainly exist in the operation process:

1. Weak impact resistance

Due to the uneven drainage of domestic sewage, there are great changes in different time periods. For example, there is less water during the day and night, and the 4 to 5 hours drainage in the evening accounts for more than 70% of the total daily drainage, and when there are large-scale banquets in the village, Both the concentration and discharge of domestic sewage will increase significantly. Therefore, the uneven discharge of domestic sewage will have a greater impact on the treatment terminal.

The micro-power integrated treatment equipment generally uses activated sludge attached to natural microorganisms. Since these natural microorganisms have not been screened, their activity is lower than that of specially screened special microorganisms. When the concentration and discharge of domestic sewage are too large, due to Failed to be effectively treated, so the quality of the effluent water deteriorates, and the excessively fast water flow will also cause microorganisms to fall off the biofilm and lose with the sewage, thereby reducing the treatment efficiency of the treatment terminal biochemical system.

2. Microbial aging and death

As the treatment time goes by, there are more and more aging and dead microorganisms in the treatment terminal biochemical system. These aging and dead microorganisms cause the proliferation of filamentous bacteria, the sludge structure is loose, the volume increases, the settling performance is poor, and it floats on the water surface. , Flowing out with water, that is, the phenomenon of sludge expansion. Sludge expansion not only affects the quality of the effluent, but also makes the efficiency of the treatment system worse, or even collapse.

In order to prevent sludge expansion and ensure system treatment efficiency, the general solution is to regularly remove this part of the aging and dead sludge from the biochemical system (that is, the remaining sludge) and add new activated sludge. However, most processing terminals cannot be effectively maintained due to lack of management, so processing efficiency is getting worse and worse.

3. Lack of maintenance of constructed wetlands

Constructed wetland is a treatment process in which sewage is purified through the filtration and adsorption of wetland filter materials, the absorption of wetland plant roots, and the decomposition of aerobic and anaerobic microbial flora. Its main function is to reduce the turbidity of domestic sewage by filtering and adsorbing filter media, and for plants to absorb nitrogen and phosphorus nutrients in domestic sewage. However, since wilted plants are not replaced regularly (usually once every 3 months), and the filter material is not cleaned and replaced, as time goes by, the plants continue to wither, the absorption capacity becomes weaker, and the filter material gradually becomes clogged. The filtration and adsorption effect is getting worse and worse.

4. The equipment lacks maintenance and overhaul

Due to lack of management, the equipment (such as fans, pumps, etc.) of the domestic sewage treatment terminal is not regularly maintained as required, which is likely to cause malfunctions and damage. When the equipment is damaged, there is no dedicated person to repair it. Therefore, the domestic sewage treatment terminal often works well when it is first built. However, after a period of time, due to equipment failure or damage and no timely maintenance, the terminal operates abnormally and the effluent quality deteriorates.

4. Suggestions for improvement of operation and maintenance of rural domestic sewage treatment terminal

The operation and maintenance of the domestic sewage treatment terminal is a long-term and responsible work that requires continuous investment in manpower and material resources. In order to ensure the normal operation of the terminal and treat the effluent to meet the discharge standards, in view of the problems existing in the current terminal operation and maintenance process, the following improvement suggestions are proposed:

1. Do a good job in training and management of operation and maintenance personnel, and clarify the responsibilities of operation and maintenance personnel

The operation and maintenance personnel are the main persons responsible for ensuring the normal operation of the domestic sewage treatment terminal. Therefore, the operation and maintenance company should provide necessary operation and maintenance training for the operation and maintenance personnel, so that the operation and maintenance personnel are familiar with the maintenance and management objects (including equipment, processes, etc.), Familiar with maintenance methods and maintenance technical indicators, skilled in operation, and designate fixed operation and maintenance personnel for each domestic sewage treatment terminal, fully responsible for the daily operation and maintenance of the terminal, and conduct necessary assessments for operation and maintenance personnel. Only by establishing a stable and complete operation and maintenance team, can the terminal operation and maintenance work be done well.

Although all domestic sewage treatment terminals are operated under automatic control, abnormalities will inevitably occur. Therefore, as an operation and maintenance personnel, their main responsibilities are as follows:

(1) Carry out daily inspection and maintenance of the rural domestic sewage treatment terminal in accordance with the operating procedures, and make a good operation and maintenance record. Deal with abnormal situations in time;

(2) Observe the operation of each part of the terminal, sample the raw water of the adjustment pool and the water output from the sampling well, and understand the water inflow and outflow in time.

(3) Collect the biochemical system mixture for microscopic inspection to check the status of microorganisms and activated sludge. When it is found that the microorganisms are greatly reduced and the activated sludge becomes worse, the microorganisms should be added in time;

(4) Carry out daily maintenance of electromechanical equipment to ensure the normal operation of electromechanical equipment and reduce damage;

(5) When it is found that the rural domestic sewage treatment facilities are damaged, repair them in time. If the facility management personnel cannot repair, they should report to the owner and the operation and maintenance unit in a timely manner and provide repair opinions;

(6) Major accidents need to be analyzed in time and handled properly, and the accidents and handling conditions should be reported to the owners and operation and maintenance units in a timely manner.

(7) Responsible for the security of terminal facilities to prevent the facilities from being destroyed or stolen;

(8) Responsible for environmental sanitation and greening maintenance management around sewage treatment facilities. Clean the grille, sweep opening, inspection well, water collection well, etc. to avoid clogging the tube well.

 General operation and maintenance personnel should perform inspections on the domestic sewage treatment terminal at least once a week. Terminals connected to the remote control system should observe the operation of the terminal equipment every day. When an abnormal phenomenon is found, it should be dealt with on the spot in time, and the normal operation of the terminal should be restored as soon as possible. If it cannot be repaired immediately, the water intake should be stopped to prevent the water quality from exceeding the standard and possible greater damage.

2. Replenish microbial strains and activated sludge in time according to the status of the biochemical system

The core of the anaerobic and aerobic biochemical system is the microorganisms attached to the activated sludge, and the microorganisms and activated sludge are lost with the water after multiple impacts of the water flow. At the same time, as time goes by, some microorganisms age and die. In order to ensure the treatment efficiency of the biochemical system, the activated sludge in the biochemical system should be inspected regularly. If it is found that the number of microorganisms has been greatly reduced, the properties and activities have become poor, and the amount of activated sludge is too small, the biochemical system should be supplemented with microbial strains and activated sludge in time.

Due to the poor ability of natural microbes to resist impact load, it is recommended to supplement specially screened high-efficiency microbial strains, which have high-efficiency degradation of organic matter and reduce effluent CODCr. At the same time, they have high-efficiency ammonia nitrogen removal ability that natural microorganisms do not have. It can reduce CODCr while reducing CODCr. Ammonia nitrogen in domestic sewage.

The aging and death of microorganisms can easily cause sludge expansion, and appropriate amount of sludge reducing bacteria can be added according to the actual situation. Sludge reducing bacteria is a specially screened strain that specifically decomposes aging and dead microorganisms. It can break the cell membranes of aging and dead microorganisms, and use their cell fluid as food for other microorganisms. Through its action, it can eliminate aging and dead microorganisms. The sludge prevents the accumulation and expansion of the sludge, which greatly reduces the amount of surplus sludge, so that the surplus sludge can not be discharged for a long time, which greatly reduces the labor and cost of cleaning the surplus sludge.

3. Do a good job in the maintenance of constructed wetlands

Regularly check the growth of plants, and carry out pest control; timely replanting, pruning and cutting leaves, removing weeds, debris, garbage, etc., to keep the plants in good condition; timely removing wilted plants and replanting new plants (generally 3 Month/time) to prevent the return of organic matter and nitrogen and phosphorus to ensure the absorption capacity of plants.

Regularly check whether the filter system is blocked. If the filter material is blocked, measures should be taken to clean and repair it in time to ensure unblocked water flow.

4. Equipment maintenance and repair

The regular maintenance of the equipment should be carried out in strict accordance with the operating instructions of the equipment to ensure the normal operation of the equipment and prolong the service life of the equipment.

During each inspection, the operating conditions of the equipment should be inspected. If the equipment fails, the power supply of the equipment should be cut off immediately, and the maintenance should be carried out or the mechanics should be notified to carry out the maintenance or replacement.

Regularly check whether the switches and parts of the electric control system are normal, and whether the cables are in good condition. If any problems are found, the power supply should be cut off and repaired.

Equipment maintenance and repairs should be recorded in time for future reference.

5. Improvement and perfection of the design and construction of rural domestic sewage treatment terminal

After years of development and improvement of rural domestic sewage treatment terminals, treatment processes and treatment facilities have gradually matured, and new technologies and new processes have continuously added to make them diversified. In view of the current problems in the construction of rural domestic sewage treatment terminal facilities, improvements and improvements should be made in the following aspects in the future:

1. The improvement of infrastructure facilities

At present, several common domestic sewage treatment terminals are basically buried. Underground burial has the advantages of saving ground occupation, greening, neat and beautiful appearance, and less water temperature loss in the pool, but it is very inconvenient for the maintenance of buried facilities. For this reason, when building a new terminal, electrical and mechanical equipment such as water pumps, fans, and electric control systems should be placed on the ground as much as possible for easy maintenance. An electrical control room can be built on the ground level to accommodate the mechanical and electrical equipment, and ventilation and heat dissipation should be provided. Necessary sound insulation and noise reduction.

For underground integrated treatment equipment, reasonable inspection ports should be set up to facilitate the cleaning and maintenance of the pool. All kinds of pipelines should be exposed to open channels and pipes, which is convenient for maintenance.

Part of the domestic sewage treatment terminal does not use the phosphorus removal process. When the total phosphorus concentration in the domestic sewage is high (because the phosphorus-containing washing powder is still widely used in my country, it is very common for farmers to wash the domestic sewage to cause high total phosphorus). Cause the total phosphorus in the effluent to exceed the standard. For such treatment terminals, special phosphorus removal devices should be added or constructed wetlands, aquatic plants, etc. should be used to remove phosphorus from domestic sewage to ensure that the treated effluent meets the discharge standards.

2. Replenish high-efficiency microbial agents as needed

Compared with high-efficiency microorganisms, the treatment efficiency of ordinary natural microorganisms is lower, and with the passage of time, the microorganisms continue to age and die, and some microorganisms are constantly lost due to hydraulic shocks, and the treatment effect is getting worse and worse.

To this end, it is necessary to supplement the microbial agents as needed according to the actual conditions of the biochemical system (such as regular microscopic examinations, if the number of microorganisms is found to be significantly reduced and the vitality is significantly reduced). Since the high-efficiency microorganisms that have been screened have a stronger ability to degrade pollutants than those in the natural world, supplementing high-efficiency microbial agents on demand can help improve the processing efficiency of the biochemical system, improve the ability to resist shock loads, and ensure the quality of the treated water Meet the emission requirements. In addition, adding sludge reducing bacteria can decompose aging and dead microorganisms, prevent sludge expansion, ensure the normal operation of the system, and ensure that the remaining sludge is not discharged for a long time.

When designing the rural domestic sewage treatment terminal, it is necessary to fully consider the addition of high-efficiency microbial inoculants. Generally, a dosing port is reserved at the entrance of the biochemical system to facilitate the addition of high-efficiency microbial inoculants.

3. Improve the remote control and monitoring system

Through the use of Internet (wireless or wired network) and Internet of Things technology, corresponding modules are added to the rural domestic sewage treatment terminal control system to send the operating status of the system in real time (the start and stop status of the equipment, the running time, as well as the drainage flow and statistics Etc.) and alarm data. These data can be seen anywhere through other PC or mobile phone clients to facilitate the monitoring of the system status, and timely discover and solve problems in the operation process. And can modify the state of the terminal's corresponding equipment through the remote software to achieve the purpose of remote control.

In the long run, in order to strengthen the supervision of rural domestic sewage treatment terminals, it is recommended to add video recording equipment to monitor the operation of the terminal in real time, and add online water quality analysis equipment, so that the environmental protection department can timely understand the drainage water quality and supervise the operation and maintenance. The unit does a good job of handling terminal operation and maintenance.

4. Adopt new processing technology and technology

With the continuous advancement of rural domestic sewage treatment technology, new treatment processes are still emerging in endlessly. The new treatment process often overcomes some of the shortcomings of the original process, reduces construction costs, saves floor space, and has a better treatment effect of effluent. It is more thoughtful in all aspects (developed by Zhejiang Huaqingyuan Biotechnology Co., Ltd.) The microbial treatment integrated machine technology has better solved the defects of the original treatment technology, and has been unanimously approved by the relevant departments). Therefore, promoting the development of new treatment processes will help to do a good job in the treatment of rural domestic sewage and improve the level of treatment technology.