Pre treatment: the "immune barrier" of sewage treatment system

In modern sewage treatment plants, the pretreatment unit is like the first line of defense of the human immune system, silently undertaking the most basic but crucial protective mission. This physical treatment system, consisting of grilles, sedimentation tanks, regulating tanks, and other structures, establishes a solid safety barrier for subsequent core processes such as biological treatment and deep treatment through precise material separation and water quality regulation. The precision of the pretreatment process directly determines the operational efficiency and economic benefits of the entire sewage treatment system.

1、 The core value system of pre-processing

The preprocessing system constructs a complete protection network through a three-level defense mechanism. The coarse grid intercepts large floating objects such as plastic bags and tree branches with a gap of 20-50mm, the middle grid reduces the gap to 5-10mm to capture small and medium-sized suspended objects, and the fine grid filters fine impurities such as hair and fibers with a precision mesh of 1-5mm. This progressive filtration system can remove over 98% of physical impurities in wastewater, effectively avoiding subsequent pipeline blockages and pump body wear.

In the sedimentation tank, precise separation of sand particles is achieved by controlling a flow rate of 0.3m/s. The cyclone sand remover utilizes a centrifugal force field to achieve a removal rate of 95% for sand particles with a diameter greater than 0.2mm. This precise sand control not only protects mechanical equipment, but also increases the organic matter content of sludge by more than 15%, significantly improving sludge dewatering performance.

The water quality balance function of the regulating tank reduces the fluctuation range of influent COD from ± 40% to ± 15%, and the hydraulic retention time design controls the pH fluctuation within 0.5 units. This stabilization treatment increases the processing efficiency of subsequent bioreactors by 20% and reduces the dosage of reagents by 30%, demonstrating significant economic benefits.

2、 Preprocessing innovation in technological iteration

The intelligent preprocessing system integrates machine vision and automatic control technology, and the AI sorting robotic arm can recognize and capture special pollutants in real time, achieving a processing efficiency five times that of manual operation. The practice of a 100000 ton sewage treatment plant shows that the intelligent sorting system reduces the cost of grid garbage treatment by 42% and the equipment failure rate by 68%.

The upgraded version of cyclone sand removal technology has increased the separation efficiency to 98% and reduced energy consumption by 35% compared to traditional sedimentation tanks. The nano bubble oil removal device generates 50nm level microbubbles, breaking through the 95% oil removal rate and reducing the amount of chemical demulsifier by 80%. The application of high-frequency microfiltration technology controls the SS of the pretreated effluent below 20mg/L, creating ideal conditions for membrane treatment processes.

The energy conversion innovation of the preprocessing unit is remarkable. The organic waste intercepted by the grid can be anaerobically digested to produce 0.5m ³/kgVS biogas, and the sand particles in the sedimentation tank can be recycled as building materials with a utilization rate of 90% after cleaning. A certain ecological sewage treatment plant can generate an additional income of 1.2 million yuan annually through pre-treatment and resource utilization.

3、 Warning of the cost of missing preprocessing

A sewage treatment plant in North China once experienced extensive blockage of MBR membrane modules due to a malfunction of the fine grid, resulting in direct economic losses exceeding 3 million yuan. The concentration of grease in the influent water of the sewage treatment station in the Pearl River Delta Industrial Park was out of control, resulting in the overflow of foam in the biological pool and the paralysis of the treatment system for 72 hours. These cases highlight the chain reaction caused by the failure of preprocessing.

Untreated sewage can increase the blockage rate of aerators by 5 times, accelerate the wear rate of water pump impellers by 3 times, and directly increase equipment maintenance costs. The biological treatment unit is affected by the impact load, resulting in a 40% decrease in nitrifying bacteria activity, a 35% decrease in denitrification efficiency, and a sudden drop in effluent compliance rate to below 60%.

From the perspective of full lifecycle cost analysis, for every 1 yuan invested in pre-treatment costs, 3 yuan of main process maintenance costs can be saved and 5 yuan of environmental risk costs can be reduced. The optimization of the pretreatment system can reduce the overall operating cost of sewage treatment plants by 18-25% and shorten the investment return cycle by 2-3 years.

The continuous evolution of pretreatment technology is reshaping the value chain of wastewater treatment. From a simple protective process to a resource recycling hub, from passive defense to active regulation, modern pretreatment systems have evolved into the "smart center" of sewage treatment plants. In the future, with the deep integration of materials science, the Internet of Things, artificial intelligence and other technologies, pre-processing units will unleash greater potential and provide a stronger foundation for water environment governance. In this era of ecological civilization, doing a good job in sewage treatment pretreatment is the first lifeline to safeguard the water resource cycle.