1. Course TEN-702 Industrial waste management unit-2 Lecture -10

2. Pretreatment – Grit Removal Grit is typically removed during pre- treatment at larger plants –Grit can cause premature wear of equipment –Becomes cleaning issue if not removed Aerated grit tanks and vortex systems are common grit removal processes Grit removal systems typically employ a classifier/washer

3. Pretreatment – Grit Removal Vortex grit unit Unit rotates to suspend light organics Heavy, dense grit settles to bottom

4. Pretreatment – Grit Removal Grit removal requires “hardened” pump Classifier and washer Washed material into dumpster

5. Pretreatment – Grit Removal Aerated grit tank Diffused air suspends light weight organics Heavy, dense grit settles to bottom of tank Submersible pump in tank

6. Pretreatment – Grit Removal Aerated grit tank also has classifier and washer Note that washed grit is deposited to screw conveyor

7. Pretreatment - Equalization Some sanitary collection systems have high levels of infiltration and inflow (I/I) that result in excessive peak flows –I/I is storm water and ground water that enters sanitary system –Present in all systems, but can be excessive Removing I/I is difficult, and best solution may be to build Equalization tank

8. Pretreatment - Equalization Influent EQ Basin

9. Pretreatment – Odor Control Raw wastewater is often odorous, usually due to the lack of dissolved oxygen Covered channels and tanks often control odor sufficiently Pretreatment Buildings are ventilated and can be source of odor. Odor control equipment is used to limit odors from the Pretreatment Building, and from tanks

10. Pretreatment – Odor Control Activated carbon systems are common Biofilters can be used Chemical addition sometimes used reduce odor potential from downstream additions

11. Pretreatment – Odor Control Activated carbon odor control equipment Odorous compounds adsorb to the activated carbon

12. Pretreatment – Chem. Addition Chemical addition for pH control Nutrient addition for industrial wastewaters

13. Assignment-3 Why is equilization necessary in a wastewater treatment plant.? With appropriate diagrams describe the difference between on-line and off-line equilization.

14. Equilization Tank QUQU QSQS Equilization Tank QUQU QSQS On line/off line equalization Variable flow, QU is influent to the equalization tank.? However, a steady flow QS is effluent from this tank.? When QU>QS, excess wastewater is stored in the tank.? When QU<QS, the deficit is made up from the wastewater stored in the tank. When Q U > Q S, the difference, i.e., Q U -Q S is stored in the equalization tank.? When Q U < Q S, the difference, i.e., Q S -Q U is supplied from the equalization tank. On-Line Equalization: Off-line Equalization

15. thanks! In next lecture we will primary clarifier in detail