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Waste Water Treatment Presentation
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Wastewater TreatmentBataan 2020, Inc.March 9, 2013
What is wastewater treatmentUsually refer to sewage treatment or industrial wastewater treatmentprocess of removing contaminants from wastewater
GoalsTo produce waste stream (effluent)To produce solid waste (sludge)To discharge or reuse them back into the environment
Where does wastewater come from?Residences (kitchen, bathroom)Commercial institutionIndustrial institution (usually require specialized treatment process)
How can it be treated?Collected and transported via a network of pipes and pump stations to a municipal/industrial wastewater treatment plant
3 stages of water treatmentPrimarysolids are separated Secondarydissolved biological matter is converted into a solid mass by using water-borne bacteriaTertiarybiological solids are neutralized then disposedtreated water may be disinfected chemically or physically
Types of treatmentMechanical treatmentInfluentRemoval of large objects Removal of sand and grit Primary Sedimentation Biological treatmentTrickling bed filterActivated sludgeChemical treatmentDisinfection
Preliminary treatmentRemove large objectsEx: sticks, rags, toilet paper, tamponsRaked screenClog equipment in sewage treatment plant
Treatment stages - Primary treatmenttypical materials that are removed during primary treatment includefats, oils, and greases (aka FOG)sand, gravels and rocks (aka grit)larger settleable solids including human waste, and floating materials
Methods used in primary treatmentSand catcherRemove sand and gritControl wastewater velocitySand grit and stone settleKeep suspended organic matter in waterDamage equipments in the remaining treatment stageLandfill
Primary Sedimentation TankRemove grease, oilFecal solid settle, floating material rise to the surfaceProduce a homologous liquid for later biological treatmentFecal sludge are pumped to sludge treatment plant
Treatment stages - Secondary treatmentDegrade biological content (dissolved organic matter) of the sewageEx: human waste, food waste, soaps, detergentAdded bacteria and protozoa into sewage3 different approachesFixed film systemSuspended film systemLagoon system
Three approachesFixed Film Systemsgrow microorganisms on substrates such as rocks, sand or plastic wastewater is spread over the substrateEx: Trickling filters, rotating biological contactors
Trickling filters bedSpread wastewater over microorganismmade of coke (carbonised coal), limestone chips or specially fabricated plastic mediaOptimize their thickness by insect or worm grazing
Suspended Film Systemsstir and suspend microorganisms in wastewater settled out as a sludge pumped back into the incoming wastewater Ex: Activated sludge, extended aeration
Activated sludgemixed community of microorganismsBoth aerobic and anaerobic bacteria may existBiological floc is formed
5 physical components of activated sludge processaeration tank oxygen is introduced into the system
aeration source ensure that adequate oxygen is fed into the tank provided pure oxygen or compressed air
secondary clarifiers activated-sludge solids separate from the surrounding wastewater
Activated sludge outflow linePump activated sludge back to the aeration tank Effluent outflow linedischarged effluent into bay or tertiary treatment plant
Lagoon Systemshold the waste-water for several months natural degradation of sewage Usually reeds are preferred
Treatment stages Tertiary treatmentremove disease-causing organisms from wastewater 3 different disinfection processChlorinationUV light radiationOzonation
Chlorination Most commonAdvantages: low cost & effectiveDisadvantages: chlorine residue could be harmful to environment
UV light radiationDamage the genetic structure of bacteria, viruses and other pathogens.Advantages: no chemicals are usedwater taste more naturalDisadvantages: high maintenance of the UV-lamp
OzonationOxidized most pathogenic microorganismsAdvantages: safer than chlorination fewer disinfection by-productDisadvantage: high cost
What can effluent use for?discharged into a stream, river, bay, lagoon or wetland used for the irrigation of a golf course, green way or parkIf its sufficiently clean, it can be used for groundwater recharge
Advanced TreatmentNitrogen removalAmmonia (NH3) nitrite (NO2-) nitrate (NO3-)Phosphorous removalPrecipitation with iron or aluminums saltLead to eutrophicationMay cause algae bloom
Sludge treatmentPrimary sludge usually have strong odorsSecondary sludge have high concentration of microorganismGoals of treatments are:Reduce odorsRemove water reduce volumeDecompose organic matter
Untreated sludge are about 97 percent water Settling can reduce about 92 to 96 percent of water dried sludge is called a sludge cake
3 different sludge treatmentsAerobic digestionAnaerobic digestioncomposting
Aerobic digestionBacterial processNeed oxygenConsume organic matterConvert into carbon dioxide (CO2)
Anaerobic digestionBacterial processDo not require oxygenConsume organic matterProduce biogas, which can be used in generators for electricity
Composting aerobic processrequires the correct mix of carbon, nitrogen, oxygen and water with sludgeGenerate large amount of heat
Sludge disposalSuperheat sludge and convert into small granules that are rich in nitrogenSell it to local farmer as fertilizerSpread sludge cake on the fieldSave landfill space
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