Wastewater Engineering Lecturer:
Tower 1/ Aras
Ext. Sludge Treatment DA/RH
Screening Bar Screen - Manual - Mechanical Fine Screen - Rotary screen
Thickening Gravity Thickening Flotation Thickening - Dissolved air - Disperse air - Vacuum - Biological Centrifugal Thickening - Nozzle-disk - Solid bowl - Basket Moving Belt System
Stabilisation Anaerobic Digestion - Standard rate - High rate - Two-stage Aerobic Digestion Lime Stabilisation
Dewatering Drying Beds Lagooning Filter Press Belt Press Centrifuge
DISPLACEMENT PUMPS usually used to transfer sludge from one location to another. Sludge has higher solids content compared to sewage suitable to use this type of pump.
ďƒ DISSOLVED AIR FLOTATION (DAF) is allowed for STP<1000PE. DAF
is a unit operation used to separate solid or liquid particles from a liquid phase. Separation is brought about by introducing fine gas (usually air) bubbles into the liquid phase. The bubbles attach to the particulate matter, and the buoyant force of the combined particle and as bubbles is great enough to cause the particle to rise to the surface. Particles that have a higher density than the liquid can thus be made to rise. The rising of particles with lower density than the liquid can also be facilitated. In wastewater treatment, floatation is used principally to remove suspended matter and to concentrate biosolids. The principal advantages of flotation over sedimentation are that very small or light particles that settle slowly can be removed more completely and in a shorter time. Once the particles have been floated to the surface, they can be collected by skimming operation.
THICKENINGis one of the most common methods used and is accomplished in a tank similar in design to a conventional sedimentation tank. Normally, a circular tank is used, and dilute sludge is fed to a centre feed well. The feed sludge is allowed to settle and compact and the thickened sludge is withdrawn from the conical tank bottom. Conventional sludge collecting mechanisms with deep trusses or vertical pickets stir the sludge gently, thereby opening up channels for water to escape and promoting densification. The supernatant flow that results is drawn off and returned to either the primary settling tank, the influent of the treatment plant, or a return ďƒ Flow treatment process. The thickened sludge is pump to the digesters or dewatering equipment as required : thus, storage space must be provided for the sludge.
THICKENING – carried out using mechanised equipment. Examples include Rotary Drum Thickener, Belt Thickener, Centrifuge
ANAEROBIC and AEROBIC DIGESTORS – Aerobic digestion is similar to activated
sludge systems. When activated sludge is mixed with primary sludge there will be both direct oxidation of the organic matter in the primary sludge & endogenous oxidation of the cell tissue. Anaerobic digestion process requires no oxygen supply and it produces methane. It consists of two main steps: the complex organics are first broken down to simpler compounds (eg fatty acids), and then further broken down to methane and carbon dioxide. Digested solids concentration is 4-6%.
Sludge Dewatering Trenching
Sludge Lagoon( Trenching site at Assam Kumbang, Taiping
Trenching site at Pengkalan Hulu, Perak
Trenching site at Labis, Segamat
Sludge Treatment / Dewatering Centralised Sludge Treatment Facility
Mechanised Centrifuge Decanter
Sludge Disposal Sludge Disposal Landfills
Sludge Reuse Agriculture Reforestation Landscaping Compost Co-composting Oil extraction Power generation Bricks, tiles, slab Considerations on Sludge Disposal / Reuse Land availability Legislative Crop/Tree selection Sludge quality Water contamination Odour