Clarifiers

Clarifiers are settling tanks built with mechanical means for continuous removal of solids being deposited by sedimentation. A clarifier is generally used to remove solid particulates or suspended solids from liquid for clarification and (or) thickening. Concentrated impurities, discharged from the bottom of the tank are known as sludge, while the particles that float to the surface of the liquid are called scum.

Technology

Although sedimentation might occur in tanks of other shapes, removal of accumulated solids is easiest with conveyor belts in rectangular tanks or with scrapers rotating around the central axis of circular tanks. Mechanical solids removal devices move as slowly as practical to minimize resuspension of settled solids. Tanks are sized to give water an optimal residence time within the tank. Economy favors using small tanks; but if flow rate through the tank is too high, most particles will not have sufficient time to settle, and will be carried with the treated water. Considerable attention is focused on reducing water inlet and outlet velocities to minimize turbulence and promote effective settling throughout available tank volume. Baffles are used to prevent fluid velocities at the tank entrance from extending into the tank; and overflow weirs are used to uniformly distribute flow from liquid leaving the tank over a wide area of the surface to minimize resuspension of settling particles.

Incline Plate Clarifiers

Incline plate clarifiers can be used in a range of industries including mining and metal finishing, as well as used to treat groundwater, industrial process water and backwash from sand filters. Incline plate clarifiers are ideal for applications where the solids loading is variable and solids sizing is fine and are more common than conventional clarifiers at many industrial sites due to their smaller footprint. One specific application is as pre-treatment stage for effluent entering membrane filters. Incline plate clarifiers are considered to be one of the best options for pre-treatment ahead of membrane filters. Their all steel design means there is a low chance that part of the inclined plate will chip off and be carried over into membrane, especially when compared to tube settlers which are constructed of plastic. Further incline plate clarifiers are able to maintain the required water quality to the membrane without the use of chemicals. This is a huge cost saving measure both in purchasing chemicals and limiting damage to the membrane, as membranes do not work well with the large particles contained in flocculants and coagulants. Incline plate clarifiers are also used in the municipal wastewater treatment processes. The most common wastewater application for incline plate clarifiers is as part of the tertiary treatment stage. Incline plate clarifiers can be integrated into the treatment process or stand-alone units can be used to increase the flow through existing water treatment plants. One option for integrating incline plate clarifiers into existing plants is for conventional or sludge blanket clarifiers to be upgraded by attaching a bundle of inclined plates or tubes before the overflow in the so-called “clear water zone”. This can increase the settling area by two-fold resulting in a decrease in the solids loading in the overflow.

Applications

Potable water treatment

通过导电凝结和絮凝过程使细细悬浮的颗粒聚集在一起并形成较大而更致密的颗粒,在澄清器中沉乐动-app直播降过程之前更快且稳定地沉降,允许在澄清器中分离颗粒以更有效且容易地发生颗粒- 帮助保护能量。首先使用这些方法分离颗粒组分可以减少如过滤的下游水处理过程的体积。乐动-app直播饮用水处理中的沉降通常遵循化学凝血和絮凝的步骤,允许将颗粒分组成更大尺寸的絮凝物。这增加了悬浮固体的沉降速度,并允许沉降胶体。聚电解质和铁硫酸盐导致水中的精细和悬浮的颗粒聚集在一起。在进入澄清剂之前,可以用这些凝结剂化学品处理水。在凝固后,大型机械桨絮凝允许凝结以形成更容易沉降的更密集颗粒。然后将水送到澄清器,其中通过允许更重和更大的颗粒沉降到澄清器的底部,从絮凝凝血中分离澄清的水。然后,颗粒形成需要定期去除和处理的污泥层。 Clarified water may then be passed through granular filters to remove any residual particles remaining in the water. Filtered water then flows to a pumping station for storage and use.

Waste water treatment

Mining

Methods used to treat suspended solids in mining wastewater include sedimentation and floc blanket clarification and filtration. Sedimentation is used by Rio Tinto Minerals to refine raw ore into refined borates. After dissolving the ore, the saturated borate solution is pumped into a large settling tank. Borates float on top of the liquor while rock and clay settles to the bottom.