Plate Settler Research Articles

Introduction of plate settler for combined sewer overflow treatment

Osaka City is first in Japan to employ plate settler by means of coping with CSO. Construction of the settler at Ebie Sewage Treatment Plant was commenced in 1991, and will be completed in a few years. Prior to the construction was conducted an experiment of settling treatment using sloping-plate with an existing pre-aeration tank. The detention time in the experiment device was about 10 minutes to attain an average removal rate of 70% for influent SS. This report describes the experiment of the settling treatment using sloping-plates, and outlines the design of plate settler that are currently under construction.

Studies of sedimentation in settlers with packing

This paper deals with packed-type (multicurrent) settlers, which — compared to conventional ones — display a number of advantages. Two experimental stands, viz. with tubular elements and plate packing, have been constructed. Eight kinds of suspensions were tested. The results of investigations of tubular and plate settlers constituted a basis for the determination of sedimentation effectiveness being a function of dimensionless groups. Moreover, the experimental results have served to verify models and calculational methods, quoted in the literature.

Introduction of plate settler for combined sewer overflow treatment

Osaka City is first in Japan to employ plate settler by means of coping with CSO. Construction of the settler at Ebie Sewage Treatment Plant was commenced in 1991, and will be completed in a few years. Prior to the construction was conducted an experiment of settling treatment using sloping-plate with an existing preaeration tank. The detention time in the experiment device was about 10 minutes to attain an average removal rate of 70% for influent SS.This report describes the experiment of the settling treatment using sloping-plates, and outlines the design of plate settler that are currently under construction.

Continuous gravity separation of concentrated bidisperse suspensions in an inclined plate settler

An experimental study for the continuous separation of concentrated bidisperse suspensions in an inclined plate settler has been conducted. The bidisperse suspension examined consisted of light polystyrene and heavy polyvinyl chloride beads in a salt solution. The effects of the feed total solids concentration, feed flow rate, angle of inclination and split ratio (defined as the ratio of either the underflow or the overflow to the feed flow rate) on the performance of the settler were examined. For a feed having high total solids volume fraction lateral non-homogeneities in the form of instabilities (fingers) were observed in the settler. The recovery of the heavy particles in the underflow stream significantly increased as the concentration of the light particles in the feed was increased. However, this had an adverse effect on the recovery of the light particles in the overflow stream at low feed flow rate and an angle of inclination of 30°. The enhancement in the recovery of the particles due to the presence of local instabilities for the vertical settler was much greater than that at an angle of inclination of 30°. A previous model due to Masliyah et al. was found to predict the experimental measurements for the dilute bidisperse suspensions. For high feed total solids volume fractions where strong instabilities were present, the model was used to assess the improvement in the settler performance as a result of these instabilities.

Application of Pipe Flocculator and Cross-Flow Tilted Plate Settler for Effective Separation of Precipitate from Electroplating Wastewater

During a research program, the flocculation and settling of suspended solids in electroplating wastewater were tested. The experimental unit comprised a pipe flocculator and a cross-flow tilted plate settler. The experiment showed high efficiency of the system at short flocculation and settling times: τf = 50 s and τc = 11 min., respectively.

Gravity separation of concentrated bidisperse suspensions in inclined plate settlers

Sedimentation rates of concentrated bidisperse suspensions containing light and heavy particles in inclined channels have been measured for two different fluid-particle systems. The first system consists of spherical polystyrene and polymethyl methacrylate beads in a salt solution and the second consists of spherical polystyrene and glass beads in a sucrose solution. Settling experiments have been conducted in two different rectangular channels of 4 × 6 cm and 3 × 8 cm cross sections. The angle of inclination was varied from 0° to 30° from the vertical. The initial concentration of the light and heavy particles in the suspension was varied from 8 to 20 vol%. The influence of the Boycott effect, due to inclination, and the fingering phenomena, due to lateral segregation, on the separation of the light and heavy particle species within the bidisperse zone was evaluated. The separation rate was found to be significantly influenced by the angle of inclination and the total initial concentration of the suspension. The Boycott effect due to the increasing angle of inclination compliments the separation due to the fingering phenomena up to a certain angle. This limiting angle, beyond which the performance degrades, is found to be a function of total solids concentration.

A new package treatment unit

A no-recycle biological system is proposed as a package treatment unit. The system consists of an aerated packed column and an inclined plate settler combined through a sludge collection chamber. Experimental evaluation of the performance of the unit was carried out using synthetic and domestic wastewaters. Satisfactory levels of organic and suspended matter removals were achieved within the range of input variables studied. Functional relationships that would serve as a basis for the design of the proposed system are presented.

Sedimentation tank design for rural communities in the hilly regions of Nepal

Mathillo Semrang in rural Nepal relies on stream sources to provide drinking water. Erosion and deforestation of local terrain produces turbid water that requires treatment before distribution. The round gravity sedimentation technology currently employed is large in footprint and cannot handle large increases in influent flow rate and silt concentrations resulting from extreme weather events. In partnership with Nepal Water for Health (NEWAH) and Engineers Without Borders Australia (EWB), this project aimed to design a highly simplified, small footprint inclined plate settler (IPS) to treat influent flow-rates ranging from 0.25 to 4 L/s. A 76 % decrease in footprint was achieved by the IPS design for source flow-rates up to 4 L/s. Laboratory analysis revealed that a large inlet area along with a highly sloped floor is essential to the design which may prove problematic in the reduction of footprint in the design. Further research is needed to confirm this finding along with further collaboration with rural Nepalese communities and NEWAH.