WATER TREATMENT PROCESSES Effluent Primary treatment Secondary Treatment runoff Tertiary treatment
Water Treatment Processes PRIMARY TREATMENT to prepare the wastewater for biological treatment Purpose Remove large solids, grit Remove oils, grease And suspended solids Adjust the ph treatment screening Flotation, Sedimentation Coagulation filtration Neutralization
Water Treatment Processes For process wastewaters to remove toxic pollutants - Heavy metal removal, precipitation - oxidation / reduction for toxic organic pollutants removal - adsorption i.e. Activated carbon - stripping, ion exchange etc.
Water Treatment Processes SECONDARY TREATMENT - Biological degradation of organic compounds (aerobic / anaerobic) - Microorganisms and solids will be allowed to settle - Recycle of a fraction of sludge ** toxic residues have to be removed prior to biological treatment **
Water Treatment Processes TERTIARY TREATMENT to remove specific types of residuals - filtration : to remove suspended or colloidal solids - adsorption, chemical oxidation : remove organics - ozonation, chlorination : disinfection ** all these processes have their place in overall Wastewater treatment scheme **
Water Treatment Processes SELECTION OF A TREATMENT PROCESS Depends upon : 1. Characteristics of the wastewater - Form of pollutants suspension colloidal dissolved - Biodegradability - Toxicity of the components
Water Treatment Processes 2. The required effluent quality 3. The costs 4. The availibility of land
Preliminary analysis Water Treatment Processes Organic stream volatile Stream +heavy metals Toxic/ nonbiodegradable Mineral stream Toxic substance treatment biodegradable Equalization, neutralization Oil, grease, solids removal Biological treatment Final disposal
Technologies for toxic wastewaters treatment Ion exchange Reverse osmosis Discharge recycle, treatment filtration Granular carbon adsorption water Precipitation Oxidation/ reduction Heavy metals Anaerobic treatment Wet air oxidation Chemical oxidation Organics Air or Stream stripping Volatile Organics NH 3
Biological waste treatment Method mode of degree of land operation treatment requirement Lagoon - intermittent intermediate earth dug - continuous 10-60 days discharge retention - facultative - anaerobic Aerated complete mix high in summer earth basins Lagoon low in winter 8.55-17.1 m 2 /(m 3 /d)
Method mode of degree of land operation treatment requirement Activated complete mixed >90 % earth or concrete Sludge plug flow removal 0.56 2.62 sludge recycle of organics m 2 /(m 3 /d) Trickling continuous intermediate 5.52-34.4 Filter application or high m 2 /(1000m 3 /d) RBC multistage intermediate continuous or high Anaerobic complete mix intermediate
Physical and chemical waste treatment Method waste mode degree of treatment Ion plating continuous demineralized water Exchange nuclear filtration product recovery Reduction plating batch complete removal Precipitation heavy metal of Cr & heavy metals Coagulation paper board batch complete removal refinery of suspended rubber, paint and colloidal matters textile
Water Treatment Processes Method waste mode degree of treatment Adsorption toxic or column of complete removal organic activated of most organics refractory carbon Chemical toxic & batch or partial or Oxidation refractory continuous O 3 complete oxidation organics or catalyzed H 2 O 2
Ex. Municipal wastewater Water Treatment Processes Water screening Sedimentation tank disinfection clarifier Aeration tank Land uses Sludge thickening Anearobic digesters Belt presses
Water Treatment Processes Ex. Drinking water Raw water (source water) Coagulation/ flocculation sedimentation Disinfection filtration (Layer of charcoal, sand,gravel)
Pure water treatment Water Treatment Processes
Ex. Oil removal and separation Corrugated Plate Interceptors (CPI s) Efficient gravity separators Removal of gross solids and free oil >75% free oil removal Dissolved Air Flotation (DAF)
Ex. Wastewater from sulfite Pulp and paper Conventional treatment comprises 1. Preliminary treatment 2. Primary or physical treatment (sedimentation) 3. Secondary or biological treatment (activated sludge, aerated 1 lagoons or biofiltration) 4. Sludge treatments (sludge dewatering)