Underground Sewage Treatment Equipment

1. Features of HJ Equipment

u Can be buried underground

u No sludge production

u No impact on the surroundings

u Fully automatic control, no need for personnel management

u Easy operation and convenient maintenance

u Advanced process with excellent results

u Long service life

2. Several Usage Methods of HJ Equipment

u The equipment is generally installed underground, with the upper part usable as green space, parking lots, roads, etc.

u The equipment can also be semi-buried, with the burial depth determined according to your needs.

u The equipment can also be placed above ground outdoors.

u If the equipment is used in cold regions, the inspection hole can be raised to bury the equipment below the frost line.

u The equipment does not need to be arranged in a standard layout and can be placed as needed.

3. Material Description of HJ Equipment

u All-stainless steel structure

u A₃ steel plate structure

u Fiberglass reinforced plastic (FRP) structure

u Two external shapes: modular and cylindrical

4. Process Description of HJ Equipment

The HJ equipment is designed primarily for treating domestic sewage and similar industrial organic wastewater. Its main approach is the use of the well-established biochemical treatment technology—contact oxidation method. Water quality design parameters are calculated based on general domestic water quality standards, with an average influent BOD₅ of 200 mg/L and effluent BOD₅ of 20 mg/L. It consists of six parts: (1) Anaerobic tank, (2) Multi-stage contact oxidation tank, (3) Secondary sedimentation tank, (4) Disinfection tank and disinfection device, (5) Sludge tank, (6) Blower room and blower. Each part is described as follows:

(1) Anaerobic Tank

The regulating tank wastewater is pumped to the anaerobic tank for anaerobic treatment. The tank is equipped with special fillers, and the oxygen content is controlled below 0.5 mg/L. The wastewater stays in the anaerobic tank for about 2.5 hours.

(2) Multi-stage Contact Oxidation Tank: The effluent from the anaerobic tank flows by gravity to the contact tank for biochemical treatment. The contact tank is divided into three stages, with a total retention time of 5-6 hours. For enhanced equipment, the contact oxidation time can exceed 8 hours. The filler is a novel elastic filler, easy to form a biofilm and not prone to clogging. The specific surface area of the filler is 160 m²/m³, and the air-to-water ratio in the contact tank is about 12-15:1. (Note: The HJ-0.5 m³/h contact tank has two stages.)

(3) Secondary Sedimentation Tank: The wastewater after biochemical treatment flows by gravity to the secondary sedimentation tank, with an upward flow rate of 0.1-0.15 mm/s. Sludge is lifted to the sludge tank by air.

(4) Disinfection Tank and Disinfection Device: The disinfection tank follows the standard "TJ14-74" with a 30-minute retention time. For hospital wastewater, the retention time can be increased to 1-1.5 hours.

Disinfection is achieved by contact dissolution of solid chlorine tablets. The disinfection device can adjust the dosing amount according to the effluent flow rate, ensuring more dosing for more flow and less dosing for less flow. Other disinfection devices can be configured as needed. (Note: For industrial wastewater, the disinfection tank and device may be omitted.)

(5) Sludge Tank: All sludge from the primary and secondary sedimentation tanks is lifted by air to the sludge tank of the HJ equipment for aerobic digestion. The supernatant from the sludge tank is returned to the contact oxidation tank for further treatment. After digestion, very little residual sludge remains, typically requiring cleaning every 1-2 years. Cleaning can be done by a vacuum truck inserting into the sludge tank through the inspection hole for suction and transport.

(6) Blower Room and Blower: The blower room is constructed separately with color steel plates, featuring double-layer sound insulation at the inlet, with silencers and blower filters to ensure no noise during operation. Two Roots blowers are used, capable of automatic alternating operation, with a single blower's service life exceeding 30,000 hours.

5. Equipment Technical Parameters

Equipment Technical Parameters Table

Note: 1. When the influent BOD₅ ≤ 200 mg/L, the effluent BOD₅ ≤ 20 mg/L.

2. The company reserves the right to modify technical parameters without prior notice to users.

HJ Treatment Capacity and Influent/Effluent BOD Relationship Table

6. Structure and Construction of HJ Equipment

Since the HJ equipment is buried underground, maintenance and upkeep are relatively difficult. Therefore, the design considers its maintenance-free nature. The entire equipment has a reasonable and reliable structure, and even if some faults occur, they can be accessed through various inspection holes. All facilities of the HJ equipment are set in several tanks, which can be made of full stainless steel plates. The tanks are connected with stainless steel pipes, ensuring a service life of over 30 years.

If users have budget constraints, they can purchase tanks made of Q235A steel plates with a thickness of 8 mm. The tanks are connected with seamless steel pipes. Both the inside and outside of the equipment are coated with epoxy coal tar or FRP anti-corrosion coatings recommended by the Ministry of Chemical Industry. Generally, the equipment is coated with 6 layers: 2 primer coats and 4 top coats. The anti-corrosion life can generally exceed 10 years.

The entire HJ equipment is designed for maintenance and upkeep over 10 years.

7. HJ Equipment Matching Pumps

The pumps matched with HJ equipment are used to lift wastewater from the regulating tank to the HJ equipment. The pumps are anti-clogging tearing-type submersible sewage pumps.

The pumps have strong sewage discharge capacity, are clog-free, and can effectively pass solid particles with diameters of φ30-φ80 mm. The tearing mechanism of the pump can tear long fibrous materials, eliminating the need for a filter screen on the pump. The pumps can operate safely for over 8,000 hours.

The pumps are equipped with electrical protection switches, float switches, and automatic coupling devices. The HJ equipment is matched with two pumps, one of which is standby. Specific parameters refer to "5. Technical Parameters Table".

8. Selection of HJ Equipment

Before selecting HJ equipment, it is essential to understand the nature of the wastewater, influent quality, flow rate, and the required discharge standards.

The regulating tank is provided or constructed by the user, usually as a concrete tank. The capacity of the regulating tank must be determined based on drainage cycles, production processes, and other factors, generally 6-10 times the treatment capacity.

In the design, the HJ equipment can be buried underground, placed above ground, or semi-buried. The pipelines between the equipment tanks are provided by our company. Before operation, only the pipelines of the tanks and the inlet/outlet pipes need to be connected, and the cables need to be connected for operation.

If the equipment is used in cold regions, the inspection hole can be raised to bury the equipment below the frost line, allowing normal operation. In southern regions, the equipment can also be placed on outdoor ground without the need for a building.

The equipment can be arranged in a standard layout. If there are special circumstances, the equipment tanks can be arranged according to the terrain.

9. HJ Equipment Fully Automatic Microcomputer Control Cabinet

9-1. Manual and inspection circuits;

9-2. Automatic control circuits;

9-3. Specific usage instructions are as follows:

a. Each equipment is configured with two pumps, two blowers, and 1-3 solenoid valves;

b. The pumps are one standby and one in use, operating alternately; they start automatically at the working liquid level, lock at low liquid level, and both start simultaneously at the alarm water level; the two pumps can operate in联动 or separately;

c. The blowers are one standby and one in use, operating alternately; the two blowers can operate in联动 or separately;

d. If the equipment is停运 for a long time, exceeding 10 hours, to ensure the normal growth of the biofilm, the blower is periodically started intermittently to prevent the biofilm from dying and falling off;

e. The blowers and pumps are equipped with automatic detection声光 alarm systems and have overcurrent, overvoltage, and phase loss protection circuits;

f. Sludge discharge from the sedimentation tank is时序 controlled.

h. Two drainage pumps can be set after the equipment effluent as required by the user.

10. Installation, Use, and Maintenance of HJ Equipment

10-1. Installation: This equipment can be installed in two ways:一是 installed above ground,二是 installed below ground. According to the installation drawing and foundation drawing, the concrete base规格 is the same as the平面 installation drawing (foundation). The foundation must bear an average pressure of 5 t/m² or more and must be level. If the equipment is installed below ground, the relative elevation of the foundation should be the same as the equipment height. The excavation width around must be at least 500 mm from the foundation edge to facilitate pipeline installation.

According to the installation drawing, position the equipment, use a crane to lift the equipment into place, ensure the position and direction of the tanks are correct, the distances between them are accurate, and connect the equipment pipelines.

After installation, the equipment must be filled with water, and all pipeline ports must be tested for leaks. Adjust the two secondary sedimentation tank submerged weirs to the same level. After further confirmation that everything is proper, backfill the soil around the equipment and gaps, and level the ground. Connect the control lines from the electrical control cabinet to the equipment, and connect the electrical control cabinet to the power supply. When wiring, pay attention to the rotation direction of the blowers and motors, which must be the same as the direction indicated by the blowers.

Precautions: After installation, ensure that the equipment does not accumulate water during rain; the discharge pipeline of the equipment must be below -0.6 m relative to the ground; no heavy objects should be placed on the equipment, and no large vehicles should pass over it; generally, the internal wastewater should not be emptied to prevent the equipment from floating due to groundwater.

10-2.调试: Use the sewage pump to pump wastewater into the equipment at the rated flow rate, start the blower for aeration, and observe the condition of the filler in the contact tank daily. If an orange-yellow or orange-black film grows on the filler, the biofilm is cultivated. This process generally takes 7-15 days. For industrial organic wastewater, it is best to first cultivate the biofilm with domestic sewage and then gradually introduce industrial wastewater for biofilm acclimation.

10-3. Equipment Maintenance: HJ equipment must have a regular maintenance system. The main vulnerable parts are the blowers and pumps. The blower rotation direction must not be reversed. If sewage enters, it must be cleaned, and the oil must be replaced before use. Before starting the blower, ensure the air damper is open. The blower must be maintained every 10,000 hours of operation, and the pump must be maintained every 5,000-8,000 hours of operation.

11. Equipment Layout Drawing

Equipment Dimensions Table          (Unit: mm)

12. Blower Room

The blower room is made of color steel plates with internal sound absorption measures. The blower room houses two blowers and the electrical control cabinet. Both sides of the blower room have air inlets or louvers. The equipment foundation can be a general concrete platform. At the four corners of the blower room,预埋 four 250×250×12 steel plates for固定 welding of the blower room.