Waste water treatment

waste water

Any water that has been adversely affected in quality by an anthropogenic influence.

Comprises liquid waste discharged by:-

Domestic residencesCommercial properties or IndustryAgricultureMunicipal waste

Origin Human waste also known as black water Cesspit leakage Septic tank discharge Sewage treatment plant discharge Washing water also known as Grey water Groundwater infiltrated into sewage Seawater ingress (high volumes of salt and microbes) Direct ingress of river water (high volumes of micro-biota) Direct ingress of manmade liquids (illegal disposal of pesticides) Highway drainage Storm drains industrial site drainage (silt, sand, alkali, oil, chemical residues)

Major Contaminations in Wastewater

• Major contaminants in wastewater. Adapted from Metcalf and Eddy (1991).

Treatment of waste water

ContaminationBOD/COD/DO (8mg/L)Pollutants/ToxicantsTemperatureTurbiditypH

Primary Treatment

• Physical process

Secondary Treatment

• Biological process (Microbiological)

Tertiary Treatment (Advanced)

• Chemical process

Levels of waste water treatment

Primary Treatment Removal of solid waste (sludge) Includes:-Screening : Coarse solid which may clog the

mechanical equipments and pipes.Comminution: Grinding of coarse solids into

smaller and more uniform particles.Flotation: Separation of suspended and floatable

solids particles by air bubbles. Grit removal: Sand , ash, egg shell etc, of less

diameter than 0.2 mm. - inorganic – cannot be broken down by biological treatment process.

Secondary Treatment • Biological treatment process• Dissolved and non settling organic solids from the

primary efflient are removed.• Microbes plays an important role• Process envolved:-• Aerobic • Anareobic• Faacultative • Stablizattion of organic matter :• Respiration • Synthesis

Aerobic Biological treatment systems

HIGH RATE PROCESSES:• Activated Sludge process• Oxidation Pond• Trickling Filter• Biofilter• Rotating biological Contactor LOW RATE PROCESSES:• Facultative Stabilization pond• Aerated lagoons

Activated Sludge Process• Oxidizing carbonaceous matter: biological matter.• Oxidizing nitrogenous matter :

mainly ammonium and nitrogen in biological materials.

• Removing phosphate.• Driving off entrained gases carbondioxide,ammonia

nitrogen, etc.• Generating a bacterial floc that is easy to settle.• Generating a liquor that is low in dissolved or

suspended material.

Oxidation pond

Tertiary treatment

• If disinfection is placticed ,it is always final process, also called as “effluent Polishing”.

Filtration:• Activated carbon removes residual toxins.Logooning:• Settlement of further biological improvement in

man made ponds or lagoons• Highly aerobic and colonization by native

macrophytes.

References• A General Model for the Activated Sludge Process Dold, PL | Ekama, GA | Marais,

GR progress in Water Technology Vol 12, No 6 p Tor 47-77, 1980. 11 Fig, 2 Tab, 24 Ref. 

• Microbiological Basis of Phosphate Removal in the Activated Sludge Process for the Treatment of Wastewater G. W. FUHS AND MIN CHEN

• Influence of bacterial extracellular polymers on the membrane separation activatedsludgeprocessH. Nagaoka*, S. Ueda*, A. Miya*** Department of Civil Engineering, Musashi Institute of Technology, Tamazutsumi 1-28-1, Setagaya-ku, Tokyo 158, Japan** Biotechnology Department, Ebara Research Co. Ltd, Honfujisawa 4-2-1, Fujisawa-shi, Kanagawa-ken 251, Japan

• Biological treatment of wastewaters from a dye manufacturing company using a tricklingfilterM. Kornaros, , G. Lyberatos,Department of Chemical Engineering, University of Patras, 1 Karatheodori St., 26500 Patras, Greece

• Microbiology of foaming in activated sludge plantsJ. A. Soddell, R.J. Seviour,Article first published online: 11 MAR 2008 ;DOI: 10.1111/j.1365-2672.1990.tb01506.x

• Water Researcll Vol. 9, pp. 365 to 388. Pergamon Press 1975. Printed in Great Britain. FILAMENTOUS ORGANISMS OBSERVED IN ACTIVATED SLUDGE D. H. EIKELBOOM TNO Research Institute for Environmental Hygiene, P.O. Box 214, Delft, The Netherlands*