Cov txheej txheem tseem ceeb uas Polyaluminium Chloride (PAC) ua hauv coagulation yog them nyiaj nruab nrab. Txawm hais tias lub tswv yim ncaj nraim, nws feem ntau to taub yuam kev hauv kev xyaum, ua rau kev siv tshuaj tsis raug uas txo cov kev kho mob thiab nce nqi ua haujlwm.
Kab lus no muab cov lus piav qhia txog PAC tus nqi nruab nrab ntawm cov txheej txheem, suav nrog nws cov hauv paus ntsiab lus, qhov zoo ntawm lwm cov txheej txheem, thiab cuam tshuam rau kev siv tshuaj thiab sib xyaw cov tswv yim.
Vim li cas Particles tseem raug ncua: Lub luag haujlwm ntawm Surface Charge
Feem ntau cov khoom raug tshem tawm hauv dej-xws li av nplaum, silica, organic colloids, thiab cov kab mob - nqa cov nqi tsis zoo. Cov nqi no tshwm sim los ntawm anion adsorption, ionization ntawm cov pab pawg ua haujlwm saum npoo av, lossis cov kab laum tsis zoo hauv cov zaub mov.
Txhua qhov yog ib puag ncig los ntawm cov hluav taws xob ob txheej uas ib nrab tiv thaiv cov nqi tsis zoo. Txawm li cas los xij, thaum cov khoom sib ze, electrostatic repulsion tiv thaiv kev sib sau. Qhov no repulsion yog xam los ntawm zeta muaj peev xwm, feem ntau ntawm -20 mV thiab -40 mV nyob rau hauv tej yam ntuj tso turbid dej. Coagulation yuav tsum kov yeej no stability.
Yuav Ua Li Cas PAC Tau Txais Tus Nqi Neutralization
PAC yog ua ntej-polymerized aluminium coagulant nrog cov qauv dav dav [Al₂(OH)nCl₆₋ₙ]ₘ. Thaum yaj, nws tso tawm ntau yam ntawm cov khoom muaj txiaj ntsig zoo aluminium:
Monomeric: Al³⁺, Al(OH)²⁺, Al(OH)₂⁺
Polymeric: Al₂(OH)₂⁴⁺, Al₃(OH)₄⁵⁺
Polymers loj: Al₁₃O₄(OH)₂₄⁷⁺ (Al₁₃ polycation)
Cov cationic hom no sai sai adsorb mus rau qhov tsis zoo nqi particle nto, neutralizing tus nqi thiab txo cov zeta muaj peev xwm los ntawm -20 mus rau -40 mV mus rau zero. Nyob rau lub sijhawm no, electrostatic repulsion ploj zuj zus, cov khoom sib tsoo thiab ua raws, tsim cov flocs uas nyob.
Vim li cas PAC thiaj li muaj txiaj ntsig ntau dua li Alum
Tsis zoo li alum (aluminium sulfate), uas tso tawm Al³⁺ uas yuav tsum tau hydrolyze nyob rau hauv situ- txheej txheem rhiab rau pH thiab kub-PAC twb muaj ua ntej- tsim hom active (tshwj xeeb tshaj yog Al₁₃ polycations). Yog li ntawd, PAC muab:
Cov tshuaj tiv thaiv sai dua thaum noj
Kev ua tau zoo ntawm qhov kub thiab txias
Tsawg npaum li cas yuav tsum tau ua kom sib npaug
Cov txiaj ntsig zoo dua pH (5.0–9.0 vs. 6.5–7.5 rau alum)
Rau kev sib piv kev ua tau zoo:PAC vs. alum-Cov coagulant twg zoo dua?
Them Neutralization vs. Sweep Flocculation
| Yam | Charge Neutralization | Sweep Flocculation |
|---|---|---|
| PAC koob tshuaj | qis | Siab dua |
| Mechanism | Tus nqi txo | Lub cev nkag mus rau hauv Al (OH) ₃ flocs |
| Siv tau particle loj | >0.1 µm | Txhua qhov ntau thiab tsawg |
| rhiab heev rau overdose | High (them nqi rov qab) | qis |
| Cov yam ntxwv ntawm Floc | Loj, compact | Loj, loj |
| Teeb meem ceev | Ceev ceev | Nruab nrab |
| Zoo tshaj plaws rau | High turbidity dej | Tsawg turbidity los yog ultrafine hais |
Hauv kev xyaum, ob qho tib si mechanisms tshwm sim ib txhij. Kev pom zoo PAC ntau npaum li cas, txiav txim siab los ntawm kev sim lub thawv, ua tiav qhov zoo tshaj plaws ntawm ob qho tib si.
Yuav Ua Li Cas Thaum PAC Overdosed
Charge neutralization yog koob tshuaj -sensitive. Ntawm qhov zoo tshaj plaws noj, particle nqi yog neutralized. Txawm li cas los xij, thaum PAC overdosed:
Particle nto ua saturated nrog txhuas hom
Tus nqi saum npoo av thim rov qab los ntawm qhov tsis zoo mus rau qhov zoo
Positively charged particles repel ib leeg
Turbidity nce es tsis txhob txo
Qhov tshwm sim no, hu ua restabilization, yog ib qho ua rau muaj kev ua haujlwm tsis zoo ntawm coagulation. Nws qhia txog qhov tseem ceeb ntawm kev xeem lub thawv los txiav txim siab npaum li cas - teb nkhaus.
Cov kev cuam tshuam rau PAC Dosing
Kev sib xyaw nrawm yog qhov tseem ceeb: Charge neutralization tshwm sim hauv milliseconds. Lub flash mixing cheeb tsam yuav tsum muaj G-tus nqi ntawm 200–400 s⁻¹ rau 30–60 vib nas this kom ntseeg tau tias muaj kev sib cais.
pH cuam tshuam rau aluminium speciation: Ntawm pH 6-8, hom polymeric loj thiab Al₁₃ polycations dominate, zoo tagnrho rau kev them nqi nruab nrab. Hauv qab pH 6, Al³⁺ dominates; saum toj no pH 9, tsis zoo them Al(OH)₄⁻ cov ntaub ntawv, txo coagulation efficiency.
Zeta muaj peev xwm qhia kev noj tshuaj: Lub hom phiaj zeta muaj peev xwm tom qab PAC koob tshuaj yog 0 txog -5 mV. Qhov txiaj ntsig zoo qhia tias muaj ntau dhau; cov nqi qis dua -10 mV qhia tias underdose.
Cov lus nug nquag
Q: Dab tsi yog qhov zoo tshaj plaws zeta muaj peev xwm tom qab PAC noj?
A: 0-5 mV. Cov txiaj ntsig zoo qhia txog kev kho kom rov zoo; qis dua -10 mV qhia tias noj tsis txaus.
Q: Puas yog tus nqi neutralization ua haujlwm sib npaug ntawm txhua hom particle?
A: Tsis yog. Clays teb tau kwv yees, thaum cov organic colloids thiab cov khoom siv roj ntsha tuaj yeem xav tau ntau dua.
Q: Puas tuaj yeem siv lub ntsuas hluav taws xob tam sim no rau kev tswj tsis siv neeg PAC?
A: Yog. Lub streaming tam sim no ntes (SCD) ntsuas cov nqi hluav taws xob hluav taws xob thiab tuaj yeem siv PAC dosing kom tswj tau qhov zoo tshaj qhov tsis zoo.
Xaus
Charge neutralization yog lub hauv paus txheej txheem los ntawm PAC destabilizes colloidal hais kom zoo turbidity thiab TSS tshem tawm. Nkag siab txog cov txheej txheem no- nws ua haujlwm li cas, nws txawv li cas ntawm cheb flocculation, thiab qhov tshwm sim ntawm overdosing - yog qhov tseem ceeb rau kev ua tiav kev kho mob zoo ib yam. PAC's pre-polymerized qauv ua rau nws yog ib qho zoo tshaj plaws inorganic coagulants rau nqi neutralization thoob plaws ntau yam dej chemistry. Optimizing nws daim ntawv thov pib nrog kev nkag siab txog chemistry qab nws.
