. Removal of nitrate by an algal system. Water; Nitrates; Water; Algae. FIGURE 9 - EFFECT OF TUBE ANGLE ON SETTLING PATH OF SUSPENDED PARTICLE "The path traced by a particle settling in a tube is the resultant of two vectors: V, the ve- locity of flow through the tube, and vs, the settling velocity of the particle. It can be seen in Figure 9 that if the settling surfaces are inclined upward in the direction of flow, the settling path of the particle is altered be- cause the component of the settling velocity which is parallel to the tube wall, Vgw, is opposite in direction to the ve- loci
. Removal of nitrate by an algal system. Water; Nitrates; Water; Algae. FIGURE 9 - EFFECT OF TUBE ANGLE ON SETTLING PATH OF SUSPENDED PARTICLE "The path traced by a particle settling in a tube is the resultant of two vectors: V, the ve- locity of flow through the tube, and vs, the settling velocity of the particle. It can be seen in Figure 9 that if the settling surfaces are inclined upward in the direction of flow, the settling path of the particle is altered be- cause the component of the settling velocity which is parallel to the tube wall, Vgw, is opposite in direction to the ve- locity vector V. If V Is greater than Vg, the required length of the settling surface decreases as the angle Increases from zero up to about 25 to 30 deg. (at V » Vs) and then Increases, approaching infinity as the angle of inclination is Increased to 90 deg. For V< Vg the tray length continues to decrease with increasing angle," Use of the tubes also reduces turbulence and short- circuiting, thus promoting laminar flow of the water. With periodic flow reversal, or drainage, the inclination of the tubes facilitates removal of the algal floe. The coagulation- sedimentation step was designed to remove most of the sus- pended solldsj however, a mixed-media filter provided a final polishing of the effluent. After passing the filter, most of the clarified water went to discharge with only a small portion being stored In the backwash tank for back- washing the filter. The settled algal suspension from this unit normally was discharged into a holding sump to provide material for study of dewatering equipment. The Water Boy was used only to remove algae from growth pond water, that is, the concentration step. Controllable variables Included hydraulic detention time, type and amount of flocculate, and frequency of sludge re- moval. The unit, as tested at the lAWTC, required manual operation of the filter backwash and sludge removal cycles, Upflow Clarifier. In the upflow clarlf
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Keywords: ., bookcentury1900, booksubje, booksubjectalgae, booksubjectnitrates
