Water Treatment Forms.


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Water Sources and Water Treatment. Drinking water ought to be basically free of malady bringing about organisms, yet regularly this is not the case.A expansive extent of the world\'s populace drinks microbially defiled water, particularly in creating countriesUsing the most ideal wellspring of water for consumable water supply and shielding it from microbial and synthetic pollution is the goalIn numerous
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Water Treatment Processes ENVR 890 Mark D. Sobsey Spring, 2007

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Water Sources and Water Treatment Drinking water ought to be basically free of sickness creating organisms, however regularly this is not the situation. An expansive extent of the total populace drinks microbially defiled water, particularly in creating nations Using the most ideal wellspring of water for consumable water supply and shielding it from microbial and substance tainting is the objective In numerous spots a sufficient supply of perfect water or water that can be shielded from sullying is not accessible The weight of giving microbially safe drinking water supplies from sullied characteristic waters rests upon water treatment forms The effectiveness of evacuation or inactivation of enteric organisms and other pathogenic microorganisms in particular water treatment forms has been resolved for a few microorganisms however not others. The capacity of water treatment procedures and frameworks to lessen waterborne malady has been resolved in epidemiological studies

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Summary of Mainline Water Treatment Processes Storage Disinfection Physical: UV radiation, heat, film channels Chemical: Chlorine, ozone, chlorine dioxide, iodine, other antimicrobial chemicals Filtration Rapid granular media Slow sand and other natural channels Membrane channels: miniaturized scale , ultra-, nano-and reverse osmosis Other physical-concoction expulsion forms Chemical coagulation, precipitation and complexation Adsorption: e.g., actuated carbon, bone scorch, and so forth, Ion trade: manufactured particle trade saps, zeolites, and so on .

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Water Treatment Processes: Storage Reservoirs, aquifers & different frameworks: store water shield it from sullying Factors affecting organism decreases (site-particular) confinement time temperature microbial action water quality: particulates, disintegrated solids, saltiness daylight sedimentation land use precipitation overflow or invasion

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Water Storage and Microbial Reductions Microbe levels diminished after some time by regular antimicrobial procedures and microbial demise/cease to exist Human enteric infections in surface water lessened 400-1,000-fold when put away 6‑7 months (The Netherlands) Indicator microscopic organisms diminishments were less broad, most likely because of recontamination by waterfowl. Protozoan sore diminishments (log 10 ) by capacity were 1.6 for Cryptosporidium and 1.9 for Giardia after around 5 months (The Netherlands; G.J Medema, Ph.D. diss.) Recent ICR information demonstrates lower protozoan levels in supply or lake sources than in waterway sources; proposes decreases in Giardia & Cryptosporidium by capacity

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Typical Surface Water Treatment Plant

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Chemical Coagulation-Flocculation Removes suspended particulate and colloidal substances from water, including microorganisms. Coagulation: colloidal destabilization Typically, include alum (aluminum sulfate) or ferric chloride or sulfate to the water with fast blending and controlled pH conditions Insoluble aluminum or ferric hydroxide and aluminum or iron hydroxo edifices frame These buildings ensnare and adsorb suspended particulate and colloidal material.

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Coagulation-Flocculation, Continued Flocculation: Slow blending (flocculation) that accommodates for a timeframe to advance the conglomeration and development of the insoluble particles (flocs). The particles impact, stick together abd become bigger The subsequent substantial floc particles are accordingly evacuated by gravity sedimentation (or direct filtration) Smaller floc particles are too little to settle and are expelled by filtration

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Microbe Reductions by Chemical Coagulation-Flocculation Considerable decreases of enteric microorganism fixations. Diminishments In lab and pilot scale field contemplates: >99 percent utilizing alum or ferric salts as coagulants Some studies report much lower expulsion efficiencies (<90%) Conflicting data might be identified with procedure control coagulant focus, pH and blending speed amid flocculation. Expected organism decreases bof 90-99%, if basic procedure variables are enough controlled No microorganism inactivation by alum or iron coagulation Infectious organisms stay in the synthetic floc The floc evacuated by settling and/or filtration must be appropriately figured out how to forestall pathogen introduction. Reusing back through the plant is undesirable Filter discharge must be sterilized/discarded appropriately.

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Cryptosporidium Removals by Coagulation (Jar Test Studies) Coagulant Dose (mg/L) Oocyst Removal, % (log 10 ) Alum 5 99.8 (2.7) 1 87 (0.9) 99.5 (2.3) 97 (1.5) Iron 6 5

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Granular Media Filtration Used to evacuate suspended particles (turbidity) incl. organisms. Generally, two sorts of granular media channels: Slow sand channels: uniform bed of sand; low stream rate <0.1 GPM/ft2 organic procedure: 1-2 cm "ooze" layer (schmutzdecke) Rapid sand channels: 1, 2 or 3 layers of sand/other media; >1 GPM/ft2 physical-synthetic procedure; profundity filtration Diatomaceous earth channels fossilized skeletons of diatoms (crystalline silicate); fine store; couple of 10s of micrometers; permeable

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Slow Sand Filters Less broadly utilized for substantial US civil water supplies Effective; broadly utilized as a part of Europe; little water supplies; creating nations Filter through a 3‑ to 5‑foot profound bed of unstratified sand stream rate ~0.05 gallons every moment per square foot. Natural development creates in the upper surface of the sand is basically in charge of molecule and organism evacuation. Powerful without pretreatment of the water by coagulation‑flocculation Periodically clean by evacuating, cleaning and supplanting the upper few inches of organically dynamic sand

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Microbial Reductions by Slow Sand Filtration Effective in expelling enteric microorganisms from water. Infection evacuations >99% in lab models of moderate sand channels. Up to 4 log 10 ; no irresistible infections recouped from channel effluents Field concentrates: actually happening enteric infections expulsions 97 to >99.8 percent; normal 98% generally; Comparable evacuations of E. coli microbes. Infection removals=99‑99.9%; high microscopic organisms evacuations (UK study) Parasite expulsions: Giardia lamblia blisters adequately expelled Expected expulsions  99%

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Roughing Filter Used in creating nations economical low upkeep nearby materials Remove substantial solids Remove microorganisms 1-2 log 10 bacterial diminishment 90% turbidity decrease

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Microbe Reductions by Rapid Granular Media Filters Ineffective to expel enteric organisms unless went before by concoction coagulation‑flocculation. Gone before substance coagulation‑flocculation & sedimentation Enteric organism evacuations of 90->99 % accomplished. Field (pilot) ponders: fast sand filtration went before by iron coagulation‑flocculation: infection evacuation <50% (poor control?). Giardia lamblia : expulsions not generally high; identified with turbidity evacuation; >99% expulsions reported when streamlined. Expulsion not high unless turbidity is lessened to  0.2 NTU. Least expulsions soon after channel discharging Microbes fundamentally expelled in channel by captured floc particles. By and large, can accomplish  90% microbial expulsions from water when gone before by substance coagulation‑flocculation.

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Microbe Reductions by Chemical Coagulation-Flocculation and Filtration of River Water by Three Rx Plants in The Netherlands Plant 1 utilized two phases of iron coagulation‑flocculation‑sedimentation. Plant 2 utilized iron coagulation‑flocculation‑sedimentation and quick filtration Plant 3 utilized iron coagulation‑flotation‑rapid filtration.

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Cryptosporidium Removals by Sand Filtration Reduction Type Rate (M/hr) Coagulation % (log 10 ) Rapid, shallow 5 No 65 (0.5) Rapid, shallow 5 Yes 90 (1.0) Rapid, profound 6 Yes 99.999 (5.0) Slow 0.2 No 99.8 (2.7)

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Cryptosporidium Removal by Coagulation and Direct Filtration Log 10 Reduction of Run No. Cryptosporidium Turbidity 1 3.1 1.3 2 2.8 1.2 3 2.7 0.7 4 1.5 0.2* Mean 2.5 0.85 Raw water turbidity = 0.0 - 5.0 NTU Alum coagulation-flocculation; Anthracite-sand-sand filtration; 5 GPM/ft 2 *Suboptimum alum dosage Ongerth & Pecoraro. JAWWA, Dec., 1995

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Reported Removals of Cryptosporidium Oocysts by Physical-Chemical Water Treatment Processes (Bench, Pilot and Field Studies) Process Log 10 Reduction Clarification by: Coagulation flocculation-sedimentation <1 - 2.6 or Flotation Rapid Filtration (pre-coagulated) 1.5 - >4.0 Both Processes <2.5 - >6.6 Slow Sand Filtration >3.7 Diatomaceous Earth Filtration >4.0 Coagulation + Microfiltration >6.0 Ultrafiltration >6.0

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Cryptosporidium Reductions by Coagulation and Filtration Laboratory contemplates on oocyst evacuation: - Jar test coagulation with 1 hr. setting = 2.0 - 2.7 log 10 - Sand filtration, no coagulant, 10 cm bed profundity = 0.45 log 10 - Sand filtration, in addition to coagulation, 10 cm bed profundity = 1.0 log 10 Gregory et al., 1991. Last Report. Dept. of the Environ., UK

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Membrane Filters More late improvement and use in drinking water Microfilters: a few tenths of M to M measurement pore size nano-& ultra-channels: maintenance by atomic weight cutoff Typically 1,000-100,000 MWCO Reverse osmosis channels: pore estimate sufficiently little to evacuate broke up salts; used to desalinate (desalt) water and in addition molecule expulsion High >99.99% evacuation of cell organisms Virus expulsions high >9.99% in ultra-, nano-and RO channels Virus evacuations lower (  99%) by microfilters Membrane and film seal uprightness basic to successful execution

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Cryptosporidium Reductions by Membrane Filtration Log 10 Cryptosporidium Reduction Membrane, Type Pore Size A, MF 0.2 µm >4.4 B, MF 0.2 µm >4.4 C, MF 0.1 µm 4.2->4.8 D, UF 500 KD >4.8 E, UF 300 KD >4.8 F, UF 100 KD

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