Wastewater treatment plants include an inlet pump room and a sludge pump station. The water pumps in these areas are quite large, and a lifting device is needed to lift them for maintenance purposes.

Therefore, when designing the lifting device, it is important to consider the convenience of lifting, transporting, and maintaining the water pumps. Therefore, the following points should be noted during the design process.

First, determine a reasonable lifting height. This is because shorter steel wire ropes will directly affect the installation of the water pump.

Second, determine a reasonable installation height for the crane. Sufficient space must be reserved during installation. If the space is limited and the water pump is large, lifting will be inconvenient.

Third, use an electric single-beam overhead crane, This facilitates the lifting of the water pump. When the water pump needs repair, it can be lifted to the pump room platform. When the water pump needs to be returned to the factory, it can be directly lifted out of the pump room.

In areas with high groundwater levels, when the structure is emptied, it will be affected by buoyancy, which will have an adverse effect on the structure. To avoid this adverse effect, anti-buoyancy well design is generally adopted in wastewater treatment plants. However, in practical applications, due to the complexity of the operation, only professional technicians can operate it, which will increase the cost.

On the other hand, anti-buoyancy well design is prone to collapse, which will render the anti-buoyancy effect ineffective. To solve this problem and ensure the reliability of the anti-buoyancy design, The self-weight anti-buoyancy, weight anti-buoyancy, and anchor rod methods can be selected according to the specific situation of the wastewater treatment plant, to improve the effectiveness of the anti-buoyancy well design and ensure its normal operation.

Many wastewater treatment plants have sludge accumulation in the tanks, especially at the bends of the bioreactors, anaerobic tanks, and anoxic tanks, where sludge accumulation is more serious.

The accumulation of large amounts of sludge will directly affect the efficiency of wastewater treatment and cause serious consequences for the wastewater treatment plant. Therefore, this problem must be given sufficient attention.

The main reason for sludge accumulation in the tank is that the setting of the mixer is not scientific and reasonable, resulting in incomplete mixing of the sludge in the tank, which leads to sludge accumulation. When setting the mixer, many factors will affect it, such as the tank type, tank depth, and water quality of the structure, which will increase the difficulty of mixer setting and selection.

In order to completely mix the sludge in the tank, during the design process, the tank type of the structure should be fully optimized, and the anaerobic tank and anoxic tank should be set in a circulating flow form. A partition wall should be set between the two tanks, so that the mixer can achieve the circulation of wastewater, and there will be no dead corners during mixing, which will prevent sludge accumulation.

For rectangular structures, it is best to use high-speed small impellers for mixing, which can prevent sludge accumulation.

In addition, in addition to the setting of the mixer affecting the mixing effect, the selection of the mixer model will also directly affect the effect of wastewater treatment. Therefore, special attention should be paid to the selection of the mixer model. At present, general wastewater treatment plants use 2W/m3~8W/m3 mixers, but due to its large variation range, some problems will still occur during actual selection.

However, many mixer manufacturers will help wastewater treatment plants choose suitable mixer models because they have professional hydraulic calculation model software that can scientifically calculate the required model, quantity, and layout of the mixer for the wastewater treatment plant.

Therefore, wastewater treatment plants should fully consider the manufacturer's suggestions when selecting mixers and choose reasonable mixers.

For bioreactors, when selecting mixers, not only the above reasons should be considered, but also phenomena such as insufficient inflow or insufficient inflow pollutants should be considered to avoid sludge accumulation in the tank due to insufficient stirring capacity in the tank.

Most structures in wastewater treatment plants are water-containing structures. When they are inspected and maintained, the water in the tank must be drained. Therefore, when designing a wastewater treatment plant, the design of drain pipes and sumps must also be considered.

For some large wastewater treatment plants, there are mainly two methods.

The first method is to pass the drain pipe through the tank wall from below and lead it from the bottom of the tank to the outside. For this method, a corresponding sump is needed. However, since this method requires a very deep pipe burial depth, this will affect the overall burial depth of the wastewater pipes in the plant area. In addition, the protection of the drain pipe must be ensured to prevent leakage.

Another method is to pass the drain pipe out of the tank from the bottom. However, in order to prevent the waterproof casing from being cut off, we need to set the drain pipe above the armpit, which increases the distance between the drain pipe and the tank wall, so that the water in the tank cannot be completely drained. In this case, a corresponding sump needs to be set nearby to ensure that all the wastewater in the tank is drained. However, this method requires adding a water pump at the bottom of the tank, which increases power consumption and costs.

For some small wastewater treatment plants, the above two methods can also be used for air defense, but the actual situation of the wastewater treatment plant should also be considered to ensure connection with surrounding wastewater pipes.

For plant areas where the burial depth of the structure and the burial depth of the plant's wastewater pipes do not correspond, a sump can be set inside the structure to ensure that the wastewater in the tank can be discharged into the nearby wastewater pipe.

On the other hand, the relationship between the diameter of the drain pipe and the diameter of the plant's wastewater pipe should also be considered during the design process.

In previous designs, the two pipe diameters were usually kept the same. However, in actual operation, it was found that the flow rate of wastewater in the drain pipe was faster, while the flow rate in the plant's wastewater pipe was slower. If the diameters are the same, wastewater will emerge from the ground.

To avoid this phenomenon, during the design phase, ensure that the diameter of the vent pipe is slightly smaller than that of the plant's sewage pipe, thus ensuring the normal flow of sewage.

For wastewater treatment plants, electricity costs are the highest. To effectively reduce costs, we need to first reduce equipment power consumption. To achieve energy saving, wastewater treatment plants currently usually adopt measures to install variable frequency devices on major power-consuming equipment. Through variable frequency devices, the voltage and frequency of equipment such as blowers and lift pumps can be changed, so that the speed of the pump or blower can be controlled according to the flow rate, thereby reducing energy consumption.

However, in actual designs, wastewater treatment plants usually use ordinary blowers, which are designed with constant frequency and constant pressure and cannot adapt to the added variable frequency devices. The combination of the two devices may reduce operating efficiency, increase operating temperature, and reduce the blower's lifespan, resulting in more serious losses. This issue requires more comprehensive consideration during the design phase to reduce the cost of wastewater treatment plants.

The design of a wastewater treatment plant is a complex issue involving multiple professional technical problems, including architecture, equipment, and automated control. Only through scientific and reasonable design of each part can the normal operation of the wastewater treatment plant be ensured, costs effectively reduced, and maximum wastewater treatment efficiency achieved.