Water and Wastewater TreatmentDISPOSAL TECHNOLOGYSCT 3043
Introduction• Wastewater– Any water that has been adversely affected in quality byanthropogenic influence.– Have variety of potential contaminants• Waste Treatment– Waste treatment is to restore organic matter and energyfrom waste streams– E.g. : composting and incineration.• Wastewater Treatment– The objective of wastewater treatment is depending onwhere the wastewater is to be sent after treatment.
Wastewater Treatment Methods• The waste treatment method can be classified intothree (3) main categories which is physical, chemicaland biological treatment method.• Physical Treatment Method (Gravity, electricalattraction, van der Walls or physical barrier) Screening Sedimentation Flotation Filtration
Wastewater Treatment Methods Chemical treatment method› Rely on chemical reactions. Chemical characteristics of thepollutants and chemical characteristics of the products.› Precipitation› Wet Oxidation› Ion Exchange› Chemisorption
Wastewater Treatment Methods• Biological treatment method– Use living organisms either to consume and break downinto a non-hazardous form.• Aerobic degradation• Anaerobic degradation• Microorganisms
Preliminary Treatment• Uses screens to remove the larger solid inorganicmaterial such as paper and plastic.• Followed by the removal of particles such as grit andsiltThe objective of preliminary treatment is theremoval of coarse solids and other large materialsoften found in raw wastewater.The purpose of screening also to protectdownstream mechanical plant from damage
Secondary TreatmentBiological process which breaks down dissolved and suspendedorganic solids by using naturally occurring micro-organisms. It iscalled the activated sludge process.Secondary treatment technologies include the basic activatedsludge process Activated Sludge Trickling Filters Rotating Biological Contactors
Tertiary Treatment• Use disinfection for tertiary treatment to reducepathogens, which are micro-organisms which canpose a risk to human health. – ChlorineEffluent storage• Although not considered a step in the treatmentprocess, a storage facility is, in most cases, a criticallink between the wastewater treatment plant andthe irrigation system.
Use of treated wastewatero Reuse of treated wastewater for irrigationo Soil injection and land spreadingo Animal feedo Recycling of bio-solids and sludge
Advantage of wastewatertreatment• To reduce the demand for fresh water drinkingsources• Reduce the amount of wastewater dischargedwithout treatment.• The preparation of the waste water rich in nutrientscan increase agricultural production in areas that lackwater resources.• It indirectly could also reduce the pollution of riversand groundwater flow.
Disadvantage of wastewatertreatment• If the process is carried out on a large scale, theresults of water and wastewater utilities may fall.• For some countries the seasonal, re-use of wastewater may also be used only in certain seasons.• The production of gases such as sulfuric acidproduced during the treatment process that can leadto chronic health problems.• Application of untreated waste water properly asirrigation water or injected water flow can causegroundwater contamination.
Summary• By now, you should be able to understand theconcept of water and wastewater treatmentReferencesNESC. 2005. Wastewater Reuse Conserves Water and Protect Waterways. USA:National Environmental Services Centre.EPA,1995. Waste Water Treatment Manuals Preliminary Treatment. Ireland.Environmental Protection AgencyDAF. August 2004. Eco-efficiency for Australian dairy processors. Australia: DairyAustralia.