In the core process of sewage treatment and water purification, the inclined plate sedimentation tank is extremely critical. It faces many difficulties when it is in operation, which affects its own efficiency and overall water quality treatment.
1. Key elements of sedimentation. The middle part of the inclined plate and inclined tube is laminar flow. Although the inlet and outlet are disturbed by the inlet and outlet water, the overall water flow is stable and conducive to sedimentation. Because the sedimentation distance and time are short, sufficient flocculation before entering the water is essential. The upward flow is suitable for high turbidity water because of the small interference of muddy water density flow; the downward flow is suitable for low turbidity water.
2. The turbidity problem of the effluent. There are three reasons: First, the water distribution is uneven. The imbalance of water distribution at the inlet will cause turbulence or too fast flow rate, causing the settled sludge to float again; second, the "short flow" phenomenon, which destroys the stability of the flocs and causes them to break; third, the opening range of the flower wall is small, and the through-hole flow rate is higher than that of the horizontal flow sedimentation tank, causing the alum flowers to break up again and flush out the dead mud, resulting in increased turbidity of the effluent.
The solution is as follows: First, optimize the inclined plate structure. The inclined plate is 60° to the horizontal plane and fins are added to reduce the Reynolds number, strengthen the viscosity, shorten the particle settling path, and make high-density particles easier to settle. Secondly, accurately distribute water, use perforated flower wall to distribute water, and control the flow rate at the starting end of the water distribution area to 0.010-0.018m/s. Finally, add a rectifier section and a diversion wall, add a horizontal flow rectifier section in front of the pool (accounting for 1/3 of the total length), reduce the horizontal flow rate and rectify, and add a diversion wall to the horizontal section and the inclined pipe section to increase the rising flow rate of the inclined pipe, enhance the sedimentation efficiency and impact resistance.
3. Mud bucket and mud discharge problems. Mechanical mud discharge is prone to produce dead corners for scraping mud at the edge and end of the sedimentation tank, causing mud accumulation. If the mud discharge pipe design is unreasonable, it will also affect the smooth mud discharge.
The solution includes pool type modification and mud discharge optimization. The pool type is modified to reduce dead corners for scraping mud, and a large mud bucket is used for gravity mud discharge, which has small local water flow disturbance, is not easy to be blocked, and has a large mud sliding angle, which can completely slide mud. If a mud scraper is used for mud discharge, the number of mud drainage ditches at the bottom of the pool is increased to improve the mud discharge effect, ensure the stable operation of the inclined plate sedimentation tank, and improve the overall level of sewage treatment and water purification.
