Sludge treatment and disposal
- 2. Sludge - organic matter which settles down in primary and secondary sedimentation tanks. Decomposition of organic matter - foul gas, pollution, health hazards.
- 3. Domestic sewage Industrial sewage Water treatment plants
- 5. PHYSICAL includes moisture, density, color, texture, fluidity and plasticity etc. CHEMICAL includes organic matter, volatile solids, Nitrogen, phosphate, fats etc.
- 6. Main objectives Digestion of organic matter by Common methods. Destruction of pathogenic organisms. Safe and aesthetically acceptable disposal of sludge. By product of methane is used as fuel & and helps in controlling temperature and also generates power.
- 7. • 1. 2. 3. 4. Thickening or concentration Reduction of moisture content of raw sludge. Helps in reducing capacity of digestion tank and provides control of digestion condition. It can produce sludge of less than 10% solid content. Units of thickening are gravity thickener, floatation thickener, elutriation thickener.
- 8. • 1. 2. 3. 4. 5. Digestion or Stabilization Results in reduction of organic content. Improved drain ability. Greatly reduces odor of the pollutant matter Overall reduction in the volume of the sludge finally to be deposed. Units of digestion are– anaerobic & aerobic
- 9. • • Anaerobic digestion— converts sludge into liquid & gases and also reduces odor, volume, putrescence & produces gases. Bacteria like saprophytic organisms are present that react on complex organic matter and decomposed.
- 10. Temperature of anaerobic digestion Mesophilic digestion Thermophilic digestion
- 11. Dewatering produces sludge of greater than 10% solid content and is used after digestion process. sludge drying beds. Centrifugation mechanical methods by vacuum filtration.
- 13. Drying beds are generally used for dewatering of well digested sludges. Attempts to air dry raw sludge usually result in odor problems. Sludge drying beds consist of perforated or open joint drainage pipe laid within a gravel base.
- 14. Partial disposal Incineration—sludge burnt in incinerator. Ultimate disposal disposal by crops land disposal by oceans
- 15. MISCONCEPTIONS unimportant additional operation, increase in total cost of waste water treatment. IMPORTANCE represents SS and BOD loads, impact of biological processes, stabilized sludge considers hygienic and aesthetic requirements, aerobic digestion contains lower BOD value than anaerobic digestion.
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Editor's Notes
- saprophytic organism - an organism that feeds on dead organic matter especially a fungus or bacterium