Disadvantages of advection sand sedimentation tank?

(1) The water plant is established in BOT mode, the water plant staffing is small, 4 people per shift production staff, manual sand removal is relatively labor intensive. (2) water treatment plant for urban sewage and part of the industrial wastewater, the design of water intake quality COD = 450mg / l, BOD5 = 200mg / l, SS = 200mg / l, but the actual operation process, due to the proportion of industrial wastewater in the water accounted for a higher proportion, and most of the industrial wastewater is not up to standards or untreated, resulting in the coming of the water concentration of SS and COD The concentration of SS and COD in the incoming water is much higher than the design value, which causes a large amount of sedimentary organic pollutants to be discharged into the sand storage tank with the sand particles when the sand is discharged, thus increasing the emissions. (3) Regular manual sand cleaning, the organic matter in the sand storage pool is very easy to decay, resulting in a relatively harsh environment, especially in the hot summer, the smell is even worse, manual sand cleaning need to wear protective tools; winter temperatures are low, the discharged mud and water mixture is easy to freeze, and it is extremely inconvenient to remove. Comprehensive the above problems, artificial sand cleaning labor intensity, poor working environment, from the perspective of long-term operation and improve the working environment of the water plant workers, decided to carry out technological transformation of the desanding system, to be transformed into a mechanical desanding as the main, artificial desanding as a complementary way.