Although the pollution of pile driving mud is not as harmful as other industrial sludge, and the difficulty of sludge dehydration is not as high as that of domestic sludge, its large output and multiple sources also cause troubles to engineering construction. In the construction of building cast-in-place piles, there are mud wall bored cast-in-place piles, rotary bored cast-in-place piles, punched cast-in-place piles, long spiral bored cast-in-place piles, dry operation piles and pipe sinking cast-in-place piles.

Pile driving waste mud contains a large amount of clay, sand, gravel, weathered rock, minerals and rock debris, etc. It has a high viscosity and cannot be discharged directly, and it is difficult to settle naturally. The current treatment method is to use a tank truck to transport the on-site mud water to a suburban landfill and let it dry naturally. This treatment method is primitive and backward, and it has caused many problems. First, the cost is high and the efficiency is low. When the construction is tight, the day and night transportation of tank trucks cannot meet the construction progress requirements. Second, the construction site environment is bad, and the overflow of muddy water makes it difficult to intervene. The engineering team often suffers huge fines because of the muddy water leaking into the sewer, causing pipe blockage. In addition, tank trucks often pollute the city environment because of muddy water leaking on the main roads in the city during transportation. According to the opinion, if a construction company secretly discharges mud or takes mud on the road, the construction site will be forced to suspend work for two months for rectification; the construction company in the county will stop accepting business qualifications in the county for two years, and the construction company outside the county will be directly cleared; the company will make a commitment before resuming work and submit a civilized construction deposit of 1 million yuan. If a similar situation occurs again, a fine of 1 million yuan will be imposed; for construction sites suspected of illegal mud discharge causing pollution of surrounding rivers, all work will be suspended in many aspects and will be resumed after verification.

The use area of the construction site itself is limited. If it is not handled in time, it will not only affect the construction, but also cause environmental pollution or water pollution and other public hazards.

What should we do when we encounter the above problems? At present, the best way to solve this problem is to use physical pressing technology.

First, build a sedimentation tank at the construction site, discharge the sewage into the sedimentation tank, remove suspended matter and oil substances, and neutralize them. After testing to meet the discharge standards, discharge them into the river.

During the drilling and grouting process, a screen is used to separate small gravel, sand and other solid particles in the mud, and the mud is discharged to the first sedimentation tank, the second sedimentation tank, and the third sedimentation tank for full sedimentation. During the construction process, the first sedimentation tank, the second sedimentation tank, and the third sedimentation tank are cleaned in time by an excavator, and the cleaned sediment is transported to the evaporation tank, and after natural dehydration and solidification, it is transported to the storage yard or the waste slag yard.

For the discarded mud water, flocculants are added to the mud water. Because the mud water It is a suspended liquid containing a certain amount of fine mud particles in water. High molecular flocculant is a kind of water-soluble polymer. When it is mixed with mud water, due to the functions of bridging, netting, adsorption and electrical neutralization, the flocculant can destroy the stability of mud water, causing mud particles to quickly condense and settle from the water, thereby achieving the effect of mud-water separation.

After the mud-water separation, it is realized by physical pressing equipment (belt Filter Press). After that, the sludge moves with the filter belt. The flipped sludge enters the wedge-shaped pre-pressing and dehydrating area of the pressing part and is slowly clamped by the filter belt of the pressing part, forming a sandwich-type angle layer, which is sequentially and slowly pre-pressed and filtered to reduce the residual free water in the mud layer to the minimum. As the upper and lower filter belts move forward slowly, the distance between the two filter belts gradually decreases, and the mud layer in the middle gradually hardens. A large amount of free water is removed by the large and small filter rollers, so that the mud cake can smoothly enter the extrusion dehydration area and enter the "S" pressing section.

In the "S" type pressing section, the sludge is sandwiched between the upper and lower filter cloths, and is repeatedly squeezed by several pressing rollers. When the upper and lower filter belts pass through the wave path formed by the staggered rollers, the upper and lower filter belts alternate in the upper and lower positions, which generates shear force on the clamped mud cake, and most of the water remaining in the sludge is filtered out, prompting the mud cake to be dehydrated again. The dry mud cake is then scraped off the filter belt by a scraper and transported to the sludge storage by a Belt conveyor or a shaftless screw conveyor. The upper and lower filter belts are reused after being rinsed for the next cycle of concentrated filtration. After that, the sewage becomes clear water and can directly meet the discharge standards.